userdiff style: declare patterns with consistent style
[git] / remote.c
1 #include "cache.h"
2 #include "config.h"
3 #include "remote.h"
4 #include "refs.h"
5 #include "refspec.h"
6 #include "object-store.h"
7 #include "commit.h"
8 #include "diff.h"
9 #include "revision.h"
10 #include "dir.h"
11 #include "tag.h"
12 #include "string-list.h"
13 #include "mergesort.h"
14 #include "strvec.h"
15 #include "commit-reach.h"
16 #include "advice.h"
17
18 enum map_direction { FROM_SRC, FROM_DST };
19
20 struct counted_string {
21         size_t len;
22         const char *s;
23 };
24 struct rewrite {
25         const char *base;
26         size_t baselen;
27         struct counted_string *instead_of;
28         int instead_of_nr;
29         int instead_of_alloc;
30 };
31 struct rewrites {
32         struct rewrite **rewrite;
33         int rewrite_alloc;
34         int rewrite_nr;
35 };
36
37 static struct remote **remotes;
38 static int remotes_alloc;
39 static int remotes_nr;
40 static struct hashmap remotes_hash;
41
42 static struct branch **branches;
43 static int branches_alloc;
44 static int branches_nr;
45
46 static struct branch *current_branch;
47 static const char *pushremote_name;
48
49 static struct rewrites rewrites;
50 static struct rewrites rewrites_push;
51
52 static int valid_remote(const struct remote *remote)
53 {
54         return (!!remote->url) || (!!remote->foreign_vcs);
55 }
56
57 static const char *alias_url(const char *url, struct rewrites *r)
58 {
59         int i, j;
60         struct counted_string *longest;
61         int longest_i;
62
63         longest = NULL;
64         longest_i = -1;
65         for (i = 0; i < r->rewrite_nr; i++) {
66                 if (!r->rewrite[i])
67                         continue;
68                 for (j = 0; j < r->rewrite[i]->instead_of_nr; j++) {
69                         if (starts_with(url, r->rewrite[i]->instead_of[j].s) &&
70                             (!longest ||
71                              longest->len < r->rewrite[i]->instead_of[j].len)) {
72                                 longest = &(r->rewrite[i]->instead_of[j]);
73                                 longest_i = i;
74                         }
75                 }
76         }
77         if (!longest)
78                 return url;
79
80         return xstrfmt("%s%s", r->rewrite[longest_i]->base, url + longest->len);
81 }
82
83 static void add_url(struct remote *remote, const char *url)
84 {
85         ALLOC_GROW(remote->url, remote->url_nr + 1, remote->url_alloc);
86         remote->url[remote->url_nr++] = url;
87 }
88
89 static void add_pushurl(struct remote *remote, const char *pushurl)
90 {
91         ALLOC_GROW(remote->pushurl, remote->pushurl_nr + 1, remote->pushurl_alloc);
92         remote->pushurl[remote->pushurl_nr++] = pushurl;
93 }
94
95 static void add_pushurl_alias(struct remote *remote, const char *url)
96 {
97         const char *pushurl = alias_url(url, &rewrites_push);
98         if (pushurl != url)
99                 add_pushurl(remote, pushurl);
100 }
101
102 static void add_url_alias(struct remote *remote, const char *url)
103 {
104         add_url(remote, alias_url(url, &rewrites));
105         add_pushurl_alias(remote, url);
106 }
107
108 struct remotes_hash_key {
109         const char *str;
110         int len;
111 };
112
113 static int remotes_hash_cmp(const void *unused_cmp_data,
114                             const struct hashmap_entry *eptr,
115                             const struct hashmap_entry *entry_or_key,
116                             const void *keydata)
117 {
118         const struct remote *a, *b;
119         const struct remotes_hash_key *key = keydata;
120
121         a = container_of(eptr, const struct remote, ent);
122         b = container_of(entry_or_key, const struct remote, ent);
123
124         if (key)
125                 return strncmp(a->name, key->str, key->len) || a->name[key->len];
126         else
127                 return strcmp(a->name, b->name);
128 }
129
130 static inline void init_remotes_hash(void)
131 {
132         if (!remotes_hash.cmpfn)
133                 hashmap_init(&remotes_hash, remotes_hash_cmp, NULL, 0);
134 }
135
136 static struct remote *make_remote(const char *name, int len)
137 {
138         struct remote *ret, *replaced;
139         struct remotes_hash_key lookup;
140         struct hashmap_entry lookup_entry, *e;
141
142         if (!len)
143                 len = strlen(name);
144
145         init_remotes_hash();
146         lookup.str = name;
147         lookup.len = len;
148         hashmap_entry_init(&lookup_entry, memhash(name, len));
149
150         e = hashmap_get(&remotes_hash, &lookup_entry, &lookup);
151         if (e)
152                 return container_of(e, struct remote, ent);
153
154         CALLOC_ARRAY(ret, 1);
155         ret->prune = -1;  /* unspecified */
156         ret->prune_tags = -1;  /* unspecified */
157         ret->name = xstrndup(name, len);
158         refspec_init(&ret->push, REFSPEC_PUSH);
159         refspec_init(&ret->fetch, REFSPEC_FETCH);
160
161         ALLOC_GROW(remotes, remotes_nr + 1, remotes_alloc);
162         remotes[remotes_nr++] = ret;
163
164         hashmap_entry_init(&ret->ent, lookup_entry.hash);
165         replaced = hashmap_put_entry(&remotes_hash, ret, ent);
166         assert(replaced == NULL);  /* no previous entry overwritten */
167         return ret;
168 }
169
170 static void add_merge(struct branch *branch, const char *name)
171 {
172         ALLOC_GROW(branch->merge_name, branch->merge_nr + 1,
173                    branch->merge_alloc);
174         branch->merge_name[branch->merge_nr++] = name;
175 }
176
177 static struct branch *make_branch(const char *name, size_t len)
178 {
179         struct branch *ret;
180         int i;
181
182         for (i = 0; i < branches_nr; i++) {
183                 if (!strncmp(name, branches[i]->name, len) &&
184                     !branches[i]->name[len])
185                         return branches[i];
186         }
187
188         ALLOC_GROW(branches, branches_nr + 1, branches_alloc);
189         CALLOC_ARRAY(ret, 1);
190         branches[branches_nr++] = ret;
191         ret->name = xstrndup(name, len);
192         ret->refname = xstrfmt("refs/heads/%s", ret->name);
193
194         return ret;
195 }
196
197 static struct rewrite *make_rewrite(struct rewrites *r,
198                                     const char *base, size_t len)
199 {
200         struct rewrite *ret;
201         int i;
202
203         for (i = 0; i < r->rewrite_nr; i++) {
204                 if (len == r->rewrite[i]->baselen &&
205                     !strncmp(base, r->rewrite[i]->base, len))
206                         return r->rewrite[i];
207         }
208
209         ALLOC_GROW(r->rewrite, r->rewrite_nr + 1, r->rewrite_alloc);
210         CALLOC_ARRAY(ret, 1);
211         r->rewrite[r->rewrite_nr++] = ret;
212         ret->base = xstrndup(base, len);
213         ret->baselen = len;
214         return ret;
215 }
216
217 static void add_instead_of(struct rewrite *rewrite, const char *instead_of)
218 {
219         ALLOC_GROW(rewrite->instead_of, rewrite->instead_of_nr + 1, rewrite->instead_of_alloc);
220         rewrite->instead_of[rewrite->instead_of_nr].s = instead_of;
221         rewrite->instead_of[rewrite->instead_of_nr].len = strlen(instead_of);
222         rewrite->instead_of_nr++;
223 }
224
225 static const char *skip_spaces(const char *s)
226 {
227         while (isspace(*s))
228                 s++;
229         return s;
230 }
231
232 static void read_remotes_file(struct remote *remote)
233 {
234         struct strbuf buf = STRBUF_INIT;
235         FILE *f = fopen_or_warn(git_path("remotes/%s", remote->name), "r");
236
237         if (!f)
238                 return;
239         remote->configured_in_repo = 1;
240         remote->origin = REMOTE_REMOTES;
241         while (strbuf_getline(&buf, f) != EOF) {
242                 const char *v;
243
244                 strbuf_rtrim(&buf);
245
246                 if (skip_prefix(buf.buf, "URL:", &v))
247                         add_url_alias(remote, xstrdup(skip_spaces(v)));
248                 else if (skip_prefix(buf.buf, "Push:", &v))
249                         refspec_append(&remote->push, skip_spaces(v));
250                 else if (skip_prefix(buf.buf, "Pull:", &v))
251                         refspec_append(&remote->fetch, skip_spaces(v));
252         }
253         strbuf_release(&buf);
254         fclose(f);
255 }
256
257 static void read_branches_file(struct remote *remote)
258 {
259         char *frag;
260         struct strbuf buf = STRBUF_INIT;
261         FILE *f = fopen_or_warn(git_path("branches/%s", remote->name), "r");
262
263         if (!f)
264                 return;
265
266         strbuf_getline_lf(&buf, f);
267         fclose(f);
268         strbuf_trim(&buf);
269         if (!buf.len) {
270                 strbuf_release(&buf);
271                 return;
272         }
273
274         remote->configured_in_repo = 1;
275         remote->origin = REMOTE_BRANCHES;
276
277         /*
278          * The branches file would have URL and optionally
279          * #branch specified.  The default (or specified) branch is
280          * fetched and stored in the local branch matching the
281          * remote name.
282          */
283         frag = strchr(buf.buf, '#');
284         if (frag)
285                 *(frag++) = '\0';
286         else
287                 frag = (char *)git_default_branch_name(0);
288
289         add_url_alias(remote, strbuf_detach(&buf, NULL));
290         refspec_appendf(&remote->fetch, "refs/heads/%s:refs/heads/%s",
291                         frag, remote->name);
292
293         /*
294          * Cogito compatible push: push current HEAD to remote #branch
295          * (master if missing)
296          */
297         refspec_appendf(&remote->push, "HEAD:refs/heads/%s", frag);
298         remote->fetch_tags = 1; /* always auto-follow */
299 }
300
301 static int handle_config(const char *key, const char *value, void *cb)
302 {
303         const char *name;
304         size_t namelen;
305         const char *subkey;
306         struct remote *remote;
307         struct branch *branch;
308         if (parse_config_key(key, "branch", &name, &namelen, &subkey) >= 0) {
309                 if (!name)
310                         return 0;
311                 branch = make_branch(name, namelen);
312                 if (!strcmp(subkey, "remote")) {
313                         return git_config_string(&branch->remote_name, key, value);
314                 } else if (!strcmp(subkey, "pushremote")) {
315                         return git_config_string(&branch->pushremote_name, key, value);
316                 } else if (!strcmp(subkey, "merge")) {
317                         if (!value)
318                                 return config_error_nonbool(key);
319                         add_merge(branch, xstrdup(value));
320                 }
321                 return 0;
322         }
323         if (parse_config_key(key, "url", &name, &namelen, &subkey) >= 0) {
324                 struct rewrite *rewrite;
325                 if (!name)
326                         return 0;
327                 if (!strcmp(subkey, "insteadof")) {
328                         if (!value)
329                                 return config_error_nonbool(key);
330                         rewrite = make_rewrite(&rewrites, name, namelen);
331                         add_instead_of(rewrite, xstrdup(value));
332                 } else if (!strcmp(subkey, "pushinsteadof")) {
333                         if (!value)
334                                 return config_error_nonbool(key);
335                         rewrite = make_rewrite(&rewrites_push, name, namelen);
336                         add_instead_of(rewrite, xstrdup(value));
337                 }
338         }
339
340         if (parse_config_key(key, "remote", &name, &namelen, &subkey) < 0)
341                 return 0;
342
343         /* Handle remote.* variables */
344         if (!name && !strcmp(subkey, "pushdefault"))
345                 return git_config_string(&pushremote_name, key, value);
346
347         if (!name)
348                 return 0;
349         /* Handle remote.<name>.* variables */
350         if (*name == '/') {
351                 warning(_("config remote shorthand cannot begin with '/': %s"),
352                         name);
353                 return 0;
354         }
355         remote = make_remote(name, namelen);
356         remote->origin = REMOTE_CONFIG;
357         if (current_config_scope() == CONFIG_SCOPE_LOCAL ||
358             current_config_scope() == CONFIG_SCOPE_WORKTREE)
359                 remote->configured_in_repo = 1;
360         if (!strcmp(subkey, "mirror"))
361                 remote->mirror = git_config_bool(key, value);
362         else if (!strcmp(subkey, "skipdefaultupdate"))
363                 remote->skip_default_update = git_config_bool(key, value);
364         else if (!strcmp(subkey, "skipfetchall"))
365                 remote->skip_default_update = git_config_bool(key, value);
366         else if (!strcmp(subkey, "prune"))
367                 remote->prune = git_config_bool(key, value);
368         else if (!strcmp(subkey, "prunetags"))
369                 remote->prune_tags = git_config_bool(key, value);
370         else if (!strcmp(subkey, "url")) {
371                 const char *v;
372                 if (git_config_string(&v, key, value))
373                         return -1;
374                 add_url(remote, v);
375         } else if (!strcmp(subkey, "pushurl")) {
376                 const char *v;
377                 if (git_config_string(&v, key, value))
378                         return -1;
379                 add_pushurl(remote, v);
380         } else if (!strcmp(subkey, "push")) {
381                 const char *v;
382                 if (git_config_string(&v, key, value))
383                         return -1;
384                 refspec_append(&remote->push, v);
385                 free((char *)v);
386         } else if (!strcmp(subkey, "fetch")) {
387                 const char *v;
388                 if (git_config_string(&v, key, value))
389                         return -1;
390                 refspec_append(&remote->fetch, v);
391                 free((char *)v);
392         } else if (!strcmp(subkey, "receivepack")) {
393                 const char *v;
394                 if (git_config_string(&v, key, value))
395                         return -1;
396                 if (!remote->receivepack)
397                         remote->receivepack = v;
398                 else
399                         error(_("more than one receivepack given, using the first"));
400         } else if (!strcmp(subkey, "uploadpack")) {
401                 const char *v;
402                 if (git_config_string(&v, key, value))
403                         return -1;
404                 if (!remote->uploadpack)
405                         remote->uploadpack = v;
406                 else
407                         error(_("more than one uploadpack given, using the first"));
408         } else if (!strcmp(subkey, "tagopt")) {
409                 if (!strcmp(value, "--no-tags"))
410                         remote->fetch_tags = -1;
411                 else if (!strcmp(value, "--tags"))
412                         remote->fetch_tags = 2;
413         } else if (!strcmp(subkey, "proxy")) {
414                 return git_config_string((const char **)&remote->http_proxy,
415                                          key, value);
416         } else if (!strcmp(subkey, "proxyauthmethod")) {
417                 return git_config_string((const char **)&remote->http_proxy_authmethod,
418                                          key, value);
419         } else if (!strcmp(subkey, "vcs")) {
420                 return git_config_string(&remote->foreign_vcs, key, value);
421         }
422         return 0;
423 }
424
425 static void alias_all_urls(void)
426 {
427         int i, j;
428         for (i = 0; i < remotes_nr; i++) {
429                 int add_pushurl_aliases;
430                 if (!remotes[i])
431                         continue;
432                 for (j = 0; j < remotes[i]->pushurl_nr; j++) {
433                         remotes[i]->pushurl[j] = alias_url(remotes[i]->pushurl[j], &rewrites);
434                 }
435                 add_pushurl_aliases = remotes[i]->pushurl_nr == 0;
436                 for (j = 0; j < remotes[i]->url_nr; j++) {
437                         if (add_pushurl_aliases)
438                                 add_pushurl_alias(remotes[i], remotes[i]->url[j]);
439                         remotes[i]->url[j] = alias_url(remotes[i]->url[j], &rewrites);
440                 }
441         }
442 }
443
444 static void read_config(void)
445 {
446         static int loaded;
447         int flag;
448
449         if (loaded)
450                 return;
451         loaded = 1;
452
453         current_branch = NULL;
454         if (startup_info->have_repository) {
455                 const char *head_ref = resolve_ref_unsafe("HEAD", 0, NULL, &flag);
456                 if (head_ref && (flag & REF_ISSYMREF) &&
457                     skip_prefix(head_ref, "refs/heads/", &head_ref)) {
458                         current_branch = make_branch(head_ref, strlen(head_ref));
459                 }
460         }
461         git_config(handle_config, NULL);
462         alias_all_urls();
463 }
464
465 static int valid_remote_nick(const char *name)
466 {
467         if (!name[0] || is_dot_or_dotdot(name))
468                 return 0;
469
470         /* remote nicknames cannot contain slashes */
471         while (*name)
472                 if (is_dir_sep(*name++))
473                         return 0;
474         return 1;
475 }
476
477 const char *remote_for_branch(struct branch *branch, int *explicit)
478 {
479         if (branch && branch->remote_name) {
480                 if (explicit)
481                         *explicit = 1;
482                 return branch->remote_name;
483         }
484         if (explicit)
485                 *explicit = 0;
486         return "origin";
487 }
488
489 const char *pushremote_for_branch(struct branch *branch, int *explicit)
490 {
491         if (branch && branch->pushremote_name) {
492                 if (explicit)
493                         *explicit = 1;
494                 return branch->pushremote_name;
495         }
496         if (pushremote_name) {
497                 if (explicit)
498                         *explicit = 1;
499                 return pushremote_name;
500         }
501         return remote_for_branch(branch, explicit);
502 }
503
504 const char *remote_ref_for_branch(struct branch *branch, int for_push)
505 {
506         if (branch) {
507                 if (!for_push) {
508                         if (branch->merge_nr) {
509                                 return branch->merge_name[0];
510                         }
511                 } else {
512                         const char *dst, *remote_name =
513                                 pushremote_for_branch(branch, NULL);
514                         struct remote *remote = remote_get(remote_name);
515
516                         if (remote && remote->push.nr &&
517                             (dst = apply_refspecs(&remote->push,
518                                                   branch->refname))) {
519                                 return dst;
520                         }
521                 }
522         }
523         return NULL;
524 }
525
526 static struct remote *remote_get_1(const char *name,
527                                    const char *(*get_default)(struct branch *, int *))
528 {
529         struct remote *ret;
530         int name_given = 0;
531
532         read_config();
533
534         if (name)
535                 name_given = 1;
536         else
537                 name = get_default(current_branch, &name_given);
538
539         ret = make_remote(name, 0);
540         if (valid_remote_nick(name) && have_git_dir()) {
541                 if (!valid_remote(ret))
542                         read_remotes_file(ret);
543                 if (!valid_remote(ret))
544                         read_branches_file(ret);
545         }
546         if (name_given && !valid_remote(ret))
547                 add_url_alias(ret, name);
548         if (!valid_remote(ret))
549                 return NULL;
550         return ret;
551 }
552
553 struct remote *remote_get(const char *name)
554 {
555         return remote_get_1(name, remote_for_branch);
556 }
557
558 struct remote *pushremote_get(const char *name)
559 {
560         return remote_get_1(name, pushremote_for_branch);
561 }
562
563 int remote_is_configured(struct remote *remote, int in_repo)
564 {
565         if (!remote)
566                 return 0;
567         if (in_repo)
568                 return remote->configured_in_repo;
569         return !!remote->origin;
570 }
571
572 int for_each_remote(each_remote_fn fn, void *priv)
573 {
574         int i, result = 0;
575         read_config();
576         for (i = 0; i < remotes_nr && !result; i++) {
577                 struct remote *r = remotes[i];
578                 if (!r)
579                         continue;
580                 result = fn(r, priv);
581         }
582         return result;
583 }
584
585 static void handle_duplicate(struct ref *ref1, struct ref *ref2)
586 {
587         if (strcmp(ref1->name, ref2->name)) {
588                 if (ref1->fetch_head_status != FETCH_HEAD_IGNORE &&
589                     ref2->fetch_head_status != FETCH_HEAD_IGNORE) {
590                         die(_("Cannot fetch both %s and %s to %s"),
591                             ref1->name, ref2->name, ref2->peer_ref->name);
592                 } else if (ref1->fetch_head_status != FETCH_HEAD_IGNORE &&
593                            ref2->fetch_head_status == FETCH_HEAD_IGNORE) {
594                         warning(_("%s usually tracks %s, not %s"),
595                                 ref2->peer_ref->name, ref2->name, ref1->name);
596                 } else if (ref1->fetch_head_status == FETCH_HEAD_IGNORE &&
597                            ref2->fetch_head_status == FETCH_HEAD_IGNORE) {
598                         die(_("%s tracks both %s and %s"),
599                             ref2->peer_ref->name, ref1->name, ref2->name);
600                 } else {
601                         /*
602                          * This last possibility doesn't occur because
603                          * FETCH_HEAD_IGNORE entries always appear at
604                          * the end of the list.
605                          */
606                         BUG("Internal error");
607                 }
608         }
609         free(ref2->peer_ref);
610         free(ref2);
611 }
612
613 struct ref *ref_remove_duplicates(struct ref *ref_map)
614 {
615         struct string_list refs = STRING_LIST_INIT_NODUP;
616         struct ref *retval = NULL;
617         struct ref **p = &retval;
618
619         while (ref_map) {
620                 struct ref *ref = ref_map;
621
622                 ref_map = ref_map->next;
623                 ref->next = NULL;
624
625                 if (!ref->peer_ref) {
626                         *p = ref;
627                         p = &ref->next;
628                 } else {
629                         struct string_list_item *item =
630                                 string_list_insert(&refs, ref->peer_ref->name);
631
632                         if (item->util) {
633                                 /* Entry already existed */
634                                 handle_duplicate((struct ref *)item->util, ref);
635                         } else {
636                                 *p = ref;
637                                 p = &ref->next;
638                                 item->util = ref;
639                         }
640                 }
641         }
642
643         string_list_clear(&refs, 0);
644         return retval;
645 }
646
647 int remote_has_url(struct remote *remote, const char *url)
648 {
649         int i;
650         for (i = 0; i < remote->url_nr; i++) {
651                 if (!strcmp(remote->url[i], url))
652                         return 1;
653         }
654         return 0;
655 }
656
657 static int match_name_with_pattern(const char *key, const char *name,
658                                    const char *value, char **result)
659 {
660         const char *kstar = strchr(key, '*');
661         size_t klen;
662         size_t ksuffixlen;
663         size_t namelen;
664         int ret;
665         if (!kstar)
666                 die(_("key '%s' of pattern had no '*'"), key);
667         klen = kstar - key;
668         ksuffixlen = strlen(kstar + 1);
669         namelen = strlen(name);
670         ret = !strncmp(name, key, klen) && namelen >= klen + ksuffixlen &&
671                 !memcmp(name + namelen - ksuffixlen, kstar + 1, ksuffixlen);
672         if (ret && value) {
673                 struct strbuf sb = STRBUF_INIT;
674                 const char *vstar = strchr(value, '*');
675                 if (!vstar)
676                         die(_("value '%s' of pattern has no '*'"), value);
677                 strbuf_add(&sb, value, vstar - value);
678                 strbuf_add(&sb, name + klen, namelen - klen - ksuffixlen);
679                 strbuf_addstr(&sb, vstar + 1);
680                 *result = strbuf_detach(&sb, NULL);
681         }
682         return ret;
683 }
684
685 static int refspec_match(const struct refspec_item *refspec,
686                          const char *name)
687 {
688         if (refspec->pattern)
689                 return match_name_with_pattern(refspec->src, name, NULL, NULL);
690
691         return !strcmp(refspec->src, name);
692 }
693
694 static int omit_name_by_refspec(const char *name, struct refspec *rs)
695 {
696         int i;
697
698         for (i = 0; i < rs->nr; i++) {
699                 if (rs->items[i].negative && refspec_match(&rs->items[i], name))
700                         return 1;
701         }
702         return 0;
703 }
704
705 struct ref *apply_negative_refspecs(struct ref *ref_map, struct refspec *rs)
706 {
707         struct ref **tail;
708
709         for (tail = &ref_map; *tail; ) {
710                 struct ref *ref = *tail;
711
712                 if (omit_name_by_refspec(ref->name, rs)) {
713                         *tail = ref->next;
714                         free(ref->peer_ref);
715                         free(ref);
716                 } else
717                         tail = &ref->next;
718         }
719
720         return ref_map;
721 }
722
723 static int query_matches_negative_refspec(struct refspec *rs, struct refspec_item *query)
724 {
725         int i, matched_negative = 0;
726         int find_src = !query->src;
727         struct string_list reversed = STRING_LIST_INIT_NODUP;
728         const char *needle = find_src ? query->dst : query->src;
729
730         /*
731          * Check whether the queried ref matches any negative refpsec. If so,
732          * then we should ultimately treat this as not matching the query at
733          * all.
734          *
735          * Note that negative refspecs always match the source, but the query
736          * item uses the destination. To handle this, we apply pattern
737          * refspecs in reverse to figure out if the query source matches any
738          * of the negative refspecs.
739          *
740          * The first loop finds and expands all positive refspecs
741          * matched by the queried ref.
742          *
743          * The second loop checks if any of the results of the first loop
744          * match any negative refspec.
745          */
746         for (i = 0; i < rs->nr; i++) {
747                 struct refspec_item *refspec = &rs->items[i];
748                 char *expn_name;
749
750                 if (refspec->negative)
751                         continue;
752
753                 /* Note the reversal of src and dst */
754                 if (refspec->pattern) {
755                         const char *key = refspec->dst ? refspec->dst : refspec->src;
756                         const char *value = refspec->src;
757
758                         if (match_name_with_pattern(key, needle, value, &expn_name))
759                                 string_list_append_nodup(&reversed, expn_name);
760                 } else if (refspec->matching) {
761                         /* For the special matching refspec, any query should match */
762                         string_list_append(&reversed, needle);
763                 } else if (!refspec->src) {
764                         BUG("refspec->src should not be null here");
765                 } else if (!strcmp(needle, refspec->src)) {
766                         string_list_append(&reversed, refspec->src);
767                 }
768         }
769
770         for (i = 0; !matched_negative && i < reversed.nr; i++) {
771                 if (omit_name_by_refspec(reversed.items[i].string, rs))
772                         matched_negative = 1;
773         }
774
775         string_list_clear(&reversed, 0);
776
777         return matched_negative;
778 }
779
780 static void query_refspecs_multiple(struct refspec *rs,
781                                     struct refspec_item *query,
782                                     struct string_list *results)
783 {
784         int i;
785         int find_src = !query->src;
786
787         if (find_src && !query->dst)
788                 BUG("query_refspecs_multiple: need either src or dst");
789
790         if (query_matches_negative_refspec(rs, query))
791                 return;
792
793         for (i = 0; i < rs->nr; i++) {
794                 struct refspec_item *refspec = &rs->items[i];
795                 const char *key = find_src ? refspec->dst : refspec->src;
796                 const char *value = find_src ? refspec->src : refspec->dst;
797                 const char *needle = find_src ? query->dst : query->src;
798                 char **result = find_src ? &query->src : &query->dst;
799
800                 if (!refspec->dst || refspec->negative)
801                         continue;
802                 if (refspec->pattern) {
803                         if (match_name_with_pattern(key, needle, value, result))
804                                 string_list_append_nodup(results, *result);
805                 } else if (!strcmp(needle, key)) {
806                         string_list_append(results, value);
807                 }
808         }
809 }
810
811 int query_refspecs(struct refspec *rs, struct refspec_item *query)
812 {
813         int i;
814         int find_src = !query->src;
815         const char *needle = find_src ? query->dst : query->src;
816         char **result = find_src ? &query->src : &query->dst;
817
818         if (find_src && !query->dst)
819                 BUG("query_refspecs: need either src or dst");
820
821         if (query_matches_negative_refspec(rs, query))
822                 return -1;
823
824         for (i = 0; i < rs->nr; i++) {
825                 struct refspec_item *refspec = &rs->items[i];
826                 const char *key = find_src ? refspec->dst : refspec->src;
827                 const char *value = find_src ? refspec->src : refspec->dst;
828
829                 if (!refspec->dst || refspec->negative)
830                         continue;
831                 if (refspec->pattern) {
832                         if (match_name_with_pattern(key, needle, value, result)) {
833                                 query->force = refspec->force;
834                                 return 0;
835                         }
836                 } else if (!strcmp(needle, key)) {
837                         *result = xstrdup(value);
838                         query->force = refspec->force;
839                         return 0;
840                 }
841         }
842         return -1;
843 }
844
845 char *apply_refspecs(struct refspec *rs, const char *name)
846 {
847         struct refspec_item query;
848
849         memset(&query, 0, sizeof(struct refspec_item));
850         query.src = (char *)name;
851
852         if (query_refspecs(rs, &query))
853                 return NULL;
854
855         return query.dst;
856 }
857
858 int remote_find_tracking(struct remote *remote, struct refspec_item *refspec)
859 {
860         return query_refspecs(&remote->fetch, refspec);
861 }
862
863 static struct ref *alloc_ref_with_prefix(const char *prefix, size_t prefixlen,
864                 const char *name)
865 {
866         size_t len = strlen(name);
867         struct ref *ref = xcalloc(1, st_add4(sizeof(*ref), prefixlen, len, 1));
868         memcpy(ref->name, prefix, prefixlen);
869         memcpy(ref->name + prefixlen, name, len);
870         return ref;
871 }
872
873 struct ref *alloc_ref(const char *name)
874 {
875         return alloc_ref_with_prefix("", 0, name);
876 }
877
878 struct ref *copy_ref(const struct ref *ref)
879 {
880         struct ref *cpy;
881         size_t len;
882         if (!ref)
883                 return NULL;
884         len = st_add3(sizeof(struct ref), strlen(ref->name), 1);
885         cpy = xmalloc(len);
886         memcpy(cpy, ref, len);
887         cpy->next = NULL;
888         cpy->symref = xstrdup_or_null(ref->symref);
889         cpy->remote_status = xstrdup_or_null(ref->remote_status);
890         cpy->peer_ref = copy_ref(ref->peer_ref);
891         return cpy;
892 }
893
894 struct ref *copy_ref_list(const struct ref *ref)
895 {
896         struct ref *ret = NULL;
897         struct ref **tail = &ret;
898         while (ref) {
899                 *tail = copy_ref(ref);
900                 ref = ref->next;
901                 tail = &((*tail)->next);
902         }
903         return ret;
904 }
905
906 void free_one_ref(struct ref *ref)
907 {
908         if (!ref)
909                 return;
910         free_one_ref(ref->peer_ref);
911         free(ref->remote_status);
912         free(ref->symref);
913         free(ref);
914 }
915
916 void free_refs(struct ref *ref)
917 {
918         struct ref *next;
919         while (ref) {
920                 next = ref->next;
921                 free_one_ref(ref);
922                 ref = next;
923         }
924 }
925
926 int ref_compare_name(const void *va, const void *vb)
927 {
928         const struct ref *a = va, *b = vb;
929         return strcmp(a->name, b->name);
930 }
931
932 static void *ref_list_get_next(const void *a)
933 {
934         return ((const struct ref *)a)->next;
935 }
936
937 static void ref_list_set_next(void *a, void *next)
938 {
939         ((struct ref *)a)->next = next;
940 }
941
942 void sort_ref_list(struct ref **l, int (*cmp)(const void *, const void *))
943 {
944         *l = llist_mergesort(*l, ref_list_get_next, ref_list_set_next, cmp);
945 }
946
947 int count_refspec_match(const char *pattern,
948                         struct ref *refs,
949                         struct ref **matched_ref)
950 {
951         int patlen = strlen(pattern);
952         struct ref *matched_weak = NULL;
953         struct ref *matched = NULL;
954         int weak_match = 0;
955         int match = 0;
956
957         for (weak_match = match = 0; refs; refs = refs->next) {
958                 char *name = refs->name;
959                 int namelen = strlen(name);
960
961                 if (!refname_match(pattern, name))
962                         continue;
963
964                 /* A match is "weak" if it is with refs outside
965                  * heads or tags, and did not specify the pattern
966                  * in full (e.g. "refs/remotes/origin/master") or at
967                  * least from the toplevel (e.g. "remotes/origin/master");
968                  * otherwise "git push $URL master" would result in
969                  * ambiguity between remotes/origin/master and heads/master
970                  * at the remote site.
971                  */
972                 if (namelen != patlen &&
973                     patlen != namelen - 5 &&
974                     !starts_with(name, "refs/heads/") &&
975                     !starts_with(name, "refs/tags/")) {
976                         /* We want to catch the case where only weak
977                          * matches are found and there are multiple
978                          * matches, and where more than one strong
979                          * matches are found, as ambiguous.  One
980                          * strong match with zero or more weak matches
981                          * are acceptable as a unique match.
982                          */
983                         matched_weak = refs;
984                         weak_match++;
985                 }
986                 else {
987                         matched = refs;
988                         match++;
989                 }
990         }
991         if (!matched) {
992                 if (matched_ref)
993                         *matched_ref = matched_weak;
994                 return weak_match;
995         }
996         else {
997                 if (matched_ref)
998                         *matched_ref = matched;
999                 return match;
1000         }
1001 }
1002
1003 static void tail_link_ref(struct ref *ref, struct ref ***tail)
1004 {
1005         **tail = ref;
1006         while (ref->next)
1007                 ref = ref->next;
1008         *tail = &ref->next;
1009 }
1010
1011 static struct ref *alloc_delete_ref(void)
1012 {
1013         struct ref *ref = alloc_ref("(delete)");
1014         oidclr(&ref->new_oid);
1015         return ref;
1016 }
1017
1018 static int try_explicit_object_name(const char *name,
1019                                     struct ref **match)
1020 {
1021         struct object_id oid;
1022
1023         if (!*name) {
1024                 if (match)
1025                         *match = alloc_delete_ref();
1026                 return 0;
1027         }
1028
1029         if (get_oid(name, &oid))
1030                 return -1;
1031
1032         if (match) {
1033                 *match = alloc_ref(name);
1034                 oidcpy(&(*match)->new_oid, &oid);
1035         }
1036         return 0;
1037 }
1038
1039 static struct ref *make_linked_ref(const char *name, struct ref ***tail)
1040 {
1041         struct ref *ret = alloc_ref(name);
1042         tail_link_ref(ret, tail);
1043         return ret;
1044 }
1045
1046 static char *guess_ref(const char *name, struct ref *peer)
1047 {
1048         struct strbuf buf = STRBUF_INIT;
1049
1050         const char *r = resolve_ref_unsafe(peer->name, RESOLVE_REF_READING,
1051                                            NULL, NULL);
1052         if (!r)
1053                 return NULL;
1054
1055         if (starts_with(r, "refs/heads/")) {
1056                 strbuf_addstr(&buf, "refs/heads/");
1057         } else if (starts_with(r, "refs/tags/")) {
1058                 strbuf_addstr(&buf, "refs/tags/");
1059         } else {
1060                 return NULL;
1061         }
1062
1063         strbuf_addstr(&buf, name);
1064         return strbuf_detach(&buf, NULL);
1065 }
1066
1067 static int match_explicit_lhs(struct ref *src,
1068                               struct refspec_item *rs,
1069                               struct ref **match,
1070                               int *allocated_match)
1071 {
1072         switch (count_refspec_match(rs->src, src, match)) {
1073         case 1:
1074                 if (allocated_match)
1075                         *allocated_match = 0;
1076                 return 0;
1077         case 0:
1078                 /* The source could be in the get_sha1() format
1079                  * not a reference name.  :refs/other is a
1080                  * way to delete 'other' ref at the remote end.
1081                  */
1082                 if (try_explicit_object_name(rs->src, match) < 0)
1083                         return error(_("src refspec %s does not match any"), rs->src);
1084                 if (allocated_match)
1085                         *allocated_match = 1;
1086                 return 0;
1087         default:
1088                 return error(_("src refspec %s matches more than one"), rs->src);
1089         }
1090 }
1091
1092 static void show_push_unqualified_ref_name_error(const char *dst_value,
1093                                                  const char *matched_src_name)
1094 {
1095         struct object_id oid;
1096         enum object_type type;
1097
1098         /*
1099          * TRANSLATORS: "matches '%s'%" is the <dst> part of "git push
1100          * <remote> <src>:<dst>" push, and "being pushed ('%s')" is
1101          * the <src>.
1102          */
1103         error(_("The destination you provided is not a full refname (i.e.,\n"
1104                 "starting with \"refs/\"). We tried to guess what you meant by:\n"
1105                 "\n"
1106                 "- Looking for a ref that matches '%s' on the remote side.\n"
1107                 "- Checking if the <src> being pushed ('%s')\n"
1108                 "  is a ref in \"refs/{heads,tags}/\". If so we add a corresponding\n"
1109                 "  refs/{heads,tags}/ prefix on the remote side.\n"
1110                 "\n"
1111                 "Neither worked, so we gave up. You must fully qualify the ref."),
1112               dst_value, matched_src_name);
1113
1114         if (!advice_push_unqualified_ref_name)
1115                 return;
1116
1117         if (get_oid(matched_src_name, &oid))
1118                 BUG("'%s' is not a valid object, "
1119                     "match_explicit_lhs() should catch this!",
1120                     matched_src_name);
1121         type = oid_object_info(the_repository, &oid, NULL);
1122         if (type == OBJ_COMMIT) {
1123                 advise(_("The <src> part of the refspec is a commit object.\n"
1124                          "Did you mean to create a new branch by pushing to\n"
1125                          "'%s:refs/heads/%s'?"),
1126                        matched_src_name, dst_value);
1127         } else if (type == OBJ_TAG) {
1128                 advise(_("The <src> part of the refspec is a tag object.\n"
1129                          "Did you mean to create a new tag by pushing to\n"
1130                          "'%s:refs/tags/%s'?"),
1131                        matched_src_name, dst_value);
1132         } else if (type == OBJ_TREE) {
1133                 advise(_("The <src> part of the refspec is a tree object.\n"
1134                          "Did you mean to tag a new tree by pushing to\n"
1135                          "'%s:refs/tags/%s'?"),
1136                        matched_src_name, dst_value);
1137         } else if (type == OBJ_BLOB) {
1138                 advise(_("The <src> part of the refspec is a blob object.\n"
1139                          "Did you mean to tag a new blob by pushing to\n"
1140                          "'%s:refs/tags/%s'?"),
1141                        matched_src_name, dst_value);
1142         } else {
1143                 BUG("'%s' should be commit/tag/tree/blob, is '%d'",
1144                     matched_src_name, type);
1145         }
1146 }
1147
1148 static int match_explicit(struct ref *src, struct ref *dst,
1149                           struct ref ***dst_tail,
1150                           struct refspec_item *rs)
1151 {
1152         struct ref *matched_src, *matched_dst;
1153         int allocated_src;
1154
1155         const char *dst_value = rs->dst;
1156         char *dst_guess;
1157
1158         if (rs->pattern || rs->matching || rs->negative)
1159                 return 0;
1160
1161         matched_src = matched_dst = NULL;
1162         if (match_explicit_lhs(src, rs, &matched_src, &allocated_src) < 0)
1163                 return -1;
1164
1165         if (!dst_value) {
1166                 int flag;
1167
1168                 dst_value = resolve_ref_unsafe(matched_src->name,
1169                                                RESOLVE_REF_READING,
1170                                                NULL, &flag);
1171                 if (!dst_value ||
1172                     ((flag & REF_ISSYMREF) &&
1173                      !starts_with(dst_value, "refs/heads/")))
1174                         die(_("%s cannot be resolved to branch"),
1175                             matched_src->name);
1176         }
1177
1178         switch (count_refspec_match(dst_value, dst, &matched_dst)) {
1179         case 1:
1180                 break;
1181         case 0:
1182                 if (starts_with(dst_value, "refs/")) {
1183                         matched_dst = make_linked_ref(dst_value, dst_tail);
1184                 } else if (is_null_oid(&matched_src->new_oid)) {
1185                         error(_("unable to delete '%s': remote ref does not exist"),
1186                               dst_value);
1187                 } else if ((dst_guess = guess_ref(dst_value, matched_src))) {
1188                         matched_dst = make_linked_ref(dst_guess, dst_tail);
1189                         free(dst_guess);
1190                 } else {
1191                         show_push_unqualified_ref_name_error(dst_value,
1192                                                              matched_src->name);
1193                 }
1194                 break;
1195         default:
1196                 matched_dst = NULL;
1197                 error(_("dst refspec %s matches more than one"),
1198                       dst_value);
1199                 break;
1200         }
1201         if (!matched_dst)
1202                 return -1;
1203         if (matched_dst->peer_ref)
1204                 return error(_("dst ref %s receives from more than one src"),
1205                              matched_dst->name);
1206         else {
1207                 matched_dst->peer_ref = allocated_src ?
1208                                         matched_src :
1209                                         copy_ref(matched_src);
1210                 matched_dst->force = rs->force;
1211         }
1212         return 0;
1213 }
1214
1215 static int match_explicit_refs(struct ref *src, struct ref *dst,
1216                                struct ref ***dst_tail, struct refspec *rs)
1217 {
1218         int i, errs;
1219         for (i = errs = 0; i < rs->nr; i++)
1220                 errs += match_explicit(src, dst, dst_tail, &rs->items[i]);
1221         return errs;
1222 }
1223
1224 static char *get_ref_match(const struct refspec *rs, const struct ref *ref,
1225                            int send_mirror, int direction,
1226                            const struct refspec_item **ret_pat)
1227 {
1228         const struct refspec_item *pat;
1229         char *name;
1230         int i;
1231         int matching_refs = -1;
1232         for (i = 0; i < rs->nr; i++) {
1233                 const struct refspec_item *item = &rs->items[i];
1234
1235                 if (item->negative)
1236                         continue;
1237
1238                 if (item->matching &&
1239                     (matching_refs == -1 || item->force)) {
1240                         matching_refs = i;
1241                         continue;
1242                 }
1243
1244                 if (item->pattern) {
1245                         const char *dst_side = item->dst ? item->dst : item->src;
1246                         int match;
1247                         if (direction == FROM_SRC)
1248                                 match = match_name_with_pattern(item->src, ref->name, dst_side, &name);
1249                         else
1250                                 match = match_name_with_pattern(dst_side, ref->name, item->src, &name);
1251                         if (match) {
1252                                 matching_refs = i;
1253                                 break;
1254                         }
1255                 }
1256         }
1257         if (matching_refs == -1)
1258                 return NULL;
1259
1260         pat = &rs->items[matching_refs];
1261         if (pat->matching) {
1262                 /*
1263                  * "matching refs"; traditionally we pushed everything
1264                  * including refs outside refs/heads/ hierarchy, but
1265                  * that does not make much sense these days.
1266                  */
1267                 if (!send_mirror && !starts_with(ref->name, "refs/heads/"))
1268                         return NULL;
1269                 name = xstrdup(ref->name);
1270         }
1271         if (ret_pat)
1272                 *ret_pat = pat;
1273         return name;
1274 }
1275
1276 static struct ref **tail_ref(struct ref **head)
1277 {
1278         struct ref **tail = head;
1279         while (*tail)
1280                 tail = &((*tail)->next);
1281         return tail;
1282 }
1283
1284 struct tips {
1285         struct commit **tip;
1286         int nr, alloc;
1287 };
1288
1289 static void add_to_tips(struct tips *tips, const struct object_id *oid)
1290 {
1291         struct commit *commit;
1292
1293         if (is_null_oid(oid))
1294                 return;
1295         commit = lookup_commit_reference_gently(the_repository, oid, 1);
1296         if (!commit || (commit->object.flags & TMP_MARK))
1297                 return;
1298         commit->object.flags |= TMP_MARK;
1299         ALLOC_GROW(tips->tip, tips->nr + 1, tips->alloc);
1300         tips->tip[tips->nr++] = commit;
1301 }
1302
1303 static void add_missing_tags(struct ref *src, struct ref **dst, struct ref ***dst_tail)
1304 {
1305         struct string_list dst_tag = STRING_LIST_INIT_NODUP;
1306         struct string_list src_tag = STRING_LIST_INIT_NODUP;
1307         struct string_list_item *item;
1308         struct ref *ref;
1309         struct tips sent_tips;
1310
1311         /*
1312          * Collect everything we know they would have at the end of
1313          * this push, and collect all tags they have.
1314          */
1315         memset(&sent_tips, 0, sizeof(sent_tips));
1316         for (ref = *dst; ref; ref = ref->next) {
1317                 if (ref->peer_ref &&
1318                     !is_null_oid(&ref->peer_ref->new_oid))
1319                         add_to_tips(&sent_tips, &ref->peer_ref->new_oid);
1320                 else
1321                         add_to_tips(&sent_tips, &ref->old_oid);
1322                 if (starts_with(ref->name, "refs/tags/"))
1323                         string_list_append(&dst_tag, ref->name);
1324         }
1325         clear_commit_marks_many(sent_tips.nr, sent_tips.tip, TMP_MARK);
1326
1327         string_list_sort(&dst_tag);
1328
1329         /* Collect tags they do not have. */
1330         for (ref = src; ref; ref = ref->next) {
1331                 if (!starts_with(ref->name, "refs/tags/"))
1332                         continue; /* not a tag */
1333                 if (string_list_has_string(&dst_tag, ref->name))
1334                         continue; /* they already have it */
1335                 if (oid_object_info(the_repository, &ref->new_oid, NULL) != OBJ_TAG)
1336                         continue; /* be conservative */
1337                 item = string_list_append(&src_tag, ref->name);
1338                 item->util = ref;
1339         }
1340         string_list_clear(&dst_tag, 0);
1341
1342         /*
1343          * At this point, src_tag lists tags that are missing from
1344          * dst, and sent_tips lists the tips we are pushing or those
1345          * that we know they already have. An element in the src_tag
1346          * that is an ancestor of any of the sent_tips needs to be
1347          * sent to the other side.
1348          */
1349         if (sent_tips.nr) {
1350                 const int reachable_flag = 1;
1351                 struct commit_list *found_commits;
1352                 struct commit **src_commits;
1353                 int nr_src_commits = 0, alloc_src_commits = 16;
1354                 ALLOC_ARRAY(src_commits, alloc_src_commits);
1355
1356                 for_each_string_list_item(item, &src_tag) {
1357                         struct ref *ref = item->util;
1358                         struct commit *commit;
1359
1360                         if (is_null_oid(&ref->new_oid))
1361                                 continue;
1362                         commit = lookup_commit_reference_gently(the_repository,
1363                                                                 &ref->new_oid,
1364                                                                 1);
1365                         if (!commit)
1366                                 /* not pushing a commit, which is not an error */
1367                                 continue;
1368
1369                         ALLOC_GROW(src_commits, nr_src_commits + 1, alloc_src_commits);
1370                         src_commits[nr_src_commits++] = commit;
1371                 }
1372
1373                 found_commits = get_reachable_subset(sent_tips.tip, sent_tips.nr,
1374                                                      src_commits, nr_src_commits,
1375                                                      reachable_flag);
1376
1377                 for_each_string_list_item(item, &src_tag) {
1378                         struct ref *dst_ref;
1379                         struct ref *ref = item->util;
1380                         struct commit *commit;
1381
1382                         if (is_null_oid(&ref->new_oid))
1383                                 continue;
1384                         commit = lookup_commit_reference_gently(the_repository,
1385                                                                 &ref->new_oid,
1386                                                                 1);
1387                         if (!commit)
1388                                 /* not pushing a commit, which is not an error */
1389                                 continue;
1390
1391                         /*
1392                          * Is this tag, which they do not have, reachable from
1393                          * any of the commits we are sending?
1394                          */
1395                         if (!(commit->object.flags & reachable_flag))
1396                                 continue;
1397
1398                         /* Add it in */
1399                         dst_ref = make_linked_ref(ref->name, dst_tail);
1400                         oidcpy(&dst_ref->new_oid, &ref->new_oid);
1401                         dst_ref->peer_ref = copy_ref(ref);
1402                 }
1403
1404                 clear_commit_marks_many(nr_src_commits, src_commits, reachable_flag);
1405                 free(src_commits);
1406                 free_commit_list(found_commits);
1407         }
1408
1409         string_list_clear(&src_tag, 0);
1410         free(sent_tips.tip);
1411 }
1412
1413 struct ref *find_ref_by_name(const struct ref *list, const char *name)
1414 {
1415         for ( ; list; list = list->next)
1416                 if (!strcmp(list->name, name))
1417                         return (struct ref *)list;
1418         return NULL;
1419 }
1420
1421 static void prepare_ref_index(struct string_list *ref_index, struct ref *ref)
1422 {
1423         for ( ; ref; ref = ref->next)
1424                 string_list_append_nodup(ref_index, ref->name)->util = ref;
1425
1426         string_list_sort(ref_index);
1427 }
1428
1429 /*
1430  * Given only the set of local refs, sanity-check the set of push
1431  * refspecs. We can't catch all errors that match_push_refs would,
1432  * but we can catch some errors early before even talking to the
1433  * remote side.
1434  */
1435 int check_push_refs(struct ref *src, struct refspec *rs)
1436 {
1437         int ret = 0;
1438         int i;
1439
1440         for (i = 0; i < rs->nr; i++) {
1441                 struct refspec_item *item = &rs->items[i];
1442
1443                 if (item->pattern || item->matching || item->negative)
1444                         continue;
1445
1446                 ret |= match_explicit_lhs(src, item, NULL, NULL);
1447         }
1448
1449         return ret;
1450 }
1451
1452 /*
1453  * Given the set of refs the local repository has, the set of refs the
1454  * remote repository has, and the refspec used for push, determine
1455  * what remote refs we will update and with what value by setting
1456  * peer_ref (which object is being pushed) and force (if the push is
1457  * forced) in elements of "dst". The function may add new elements to
1458  * dst (e.g. pushing to a new branch, done in match_explicit_refs).
1459  */
1460 int match_push_refs(struct ref *src, struct ref **dst,
1461                     struct refspec *rs, int flags)
1462 {
1463         int send_all = flags & MATCH_REFS_ALL;
1464         int send_mirror = flags & MATCH_REFS_MIRROR;
1465         int send_prune = flags & MATCH_REFS_PRUNE;
1466         int errs;
1467         struct ref *ref, **dst_tail = tail_ref(dst);
1468         struct string_list dst_ref_index = STRING_LIST_INIT_NODUP;
1469
1470         /* If no refspec is provided, use the default ":" */
1471         if (!rs->nr)
1472                 refspec_append(rs, ":");
1473
1474         errs = match_explicit_refs(src, *dst, &dst_tail, rs);
1475
1476         /* pick the remainder */
1477         for (ref = src; ref; ref = ref->next) {
1478                 struct string_list_item *dst_item;
1479                 struct ref *dst_peer;
1480                 const struct refspec_item *pat = NULL;
1481                 char *dst_name;
1482
1483                 dst_name = get_ref_match(rs, ref, send_mirror, FROM_SRC, &pat);
1484                 if (!dst_name)
1485                         continue;
1486
1487                 if (!dst_ref_index.nr)
1488                         prepare_ref_index(&dst_ref_index, *dst);
1489
1490                 dst_item = string_list_lookup(&dst_ref_index, dst_name);
1491                 dst_peer = dst_item ? dst_item->util : NULL;
1492                 if (dst_peer) {
1493                         if (dst_peer->peer_ref)
1494                                 /* We're already sending something to this ref. */
1495                                 goto free_name;
1496                 } else {
1497                         if (pat->matching && !(send_all || send_mirror))
1498                                 /*
1499                                  * Remote doesn't have it, and we have no
1500                                  * explicit pattern, and we don't have
1501                                  * --all or --mirror.
1502                                  */
1503                                 goto free_name;
1504
1505                         /* Create a new one and link it */
1506                         dst_peer = make_linked_ref(dst_name, &dst_tail);
1507                         oidcpy(&dst_peer->new_oid, &ref->new_oid);
1508                         string_list_insert(&dst_ref_index,
1509                                 dst_peer->name)->util = dst_peer;
1510                 }
1511                 dst_peer->peer_ref = copy_ref(ref);
1512                 dst_peer->force = pat->force;
1513         free_name:
1514                 free(dst_name);
1515         }
1516
1517         string_list_clear(&dst_ref_index, 0);
1518
1519         if (flags & MATCH_REFS_FOLLOW_TAGS)
1520                 add_missing_tags(src, dst, &dst_tail);
1521
1522         if (send_prune) {
1523                 struct string_list src_ref_index = STRING_LIST_INIT_NODUP;
1524                 /* check for missing refs on the remote */
1525                 for (ref = *dst; ref; ref = ref->next) {
1526                         char *src_name;
1527
1528                         if (ref->peer_ref)
1529                                 /* We're already sending something to this ref. */
1530                                 continue;
1531
1532                         src_name = get_ref_match(rs, ref, send_mirror, FROM_DST, NULL);
1533                         if (src_name) {
1534                                 if (!src_ref_index.nr)
1535                                         prepare_ref_index(&src_ref_index, src);
1536                                 if (!string_list_has_string(&src_ref_index,
1537                                             src_name))
1538                                         ref->peer_ref = alloc_delete_ref();
1539                                 free(src_name);
1540                         }
1541                 }
1542                 string_list_clear(&src_ref_index, 0);
1543         }
1544
1545         *dst = apply_negative_refspecs(*dst, rs);
1546
1547         if (errs)
1548                 return -1;
1549         return 0;
1550 }
1551
1552 void set_ref_status_for_push(struct ref *remote_refs, int send_mirror,
1553                              int force_update)
1554 {
1555         struct ref *ref;
1556
1557         for (ref = remote_refs; ref; ref = ref->next) {
1558                 int force_ref_update = ref->force || force_update;
1559                 int reject_reason = 0;
1560
1561                 if (ref->peer_ref)
1562                         oidcpy(&ref->new_oid, &ref->peer_ref->new_oid);
1563                 else if (!send_mirror)
1564                         continue;
1565
1566                 ref->deletion = is_null_oid(&ref->new_oid);
1567                 if (!ref->deletion &&
1568                         oideq(&ref->old_oid, &ref->new_oid)) {
1569                         ref->status = REF_STATUS_UPTODATE;
1570                         continue;
1571                 }
1572
1573                 /*
1574                  * If the remote ref has moved and is now different
1575                  * from what we expect, reject any push.
1576                  *
1577                  * It also is an error if the user told us to check
1578                  * with the remote-tracking branch to find the value
1579                  * to expect, but we did not have such a tracking
1580                  * branch.
1581                  *
1582                  * If the tip of the remote-tracking ref is unreachable
1583                  * from any reflog entry of its local ref indicating a
1584                  * possible update since checkout; reject the push.
1585                  */
1586                 if (ref->expect_old_sha1) {
1587                         if (!oideq(&ref->old_oid, &ref->old_oid_expect))
1588                                 reject_reason = REF_STATUS_REJECT_STALE;
1589                         else if (ref->check_reachable && ref->unreachable)
1590                                 reject_reason =
1591                                         REF_STATUS_REJECT_REMOTE_UPDATED;
1592                         else
1593                                 /*
1594                                  * If the ref isn't stale, and is reachable
1595                                  * from from one of the reflog entries of
1596                                  * the local branch, force the update.
1597                                  */
1598                                 force_ref_update = 1;
1599                 }
1600
1601                 /*
1602                  * If the update isn't already rejected then check
1603                  * the usual "must fast-forward" rules.
1604                  *
1605                  * Decide whether an individual refspec A:B can be
1606                  * pushed.  The push will succeed if any of the
1607                  * following are true:
1608                  *
1609                  * (1) the remote reference B does not exist
1610                  *
1611                  * (2) the remote reference B is being removed (i.e.,
1612                  *     pushing :B where no source is specified)
1613                  *
1614                  * (3) the destination is not under refs/tags/, and
1615                  *     if the old and new value is a commit, the new
1616                  *     is a descendant of the old.
1617                  *
1618                  * (4) it is forced using the +A:B notation, or by
1619                  *     passing the --force argument
1620                  */
1621
1622                 if (!reject_reason && !ref->deletion && !is_null_oid(&ref->old_oid)) {
1623                         if (starts_with(ref->name, "refs/tags/"))
1624                                 reject_reason = REF_STATUS_REJECT_ALREADY_EXISTS;
1625                         else if (!has_object_file(&ref->old_oid))
1626                                 reject_reason = REF_STATUS_REJECT_FETCH_FIRST;
1627                         else if (!lookup_commit_reference_gently(the_repository, &ref->old_oid, 1) ||
1628                                  !lookup_commit_reference_gently(the_repository, &ref->new_oid, 1))
1629                                 reject_reason = REF_STATUS_REJECT_NEEDS_FORCE;
1630                         else if (!ref_newer(&ref->new_oid, &ref->old_oid))
1631                                 reject_reason = REF_STATUS_REJECT_NONFASTFORWARD;
1632                 }
1633
1634                 /*
1635                  * "--force" will defeat any rejection implemented
1636                  * by the rules above.
1637                  */
1638                 if (!force_ref_update)
1639                         ref->status = reject_reason;
1640                 else if (reject_reason)
1641                         ref->forced_update = 1;
1642         }
1643 }
1644
1645 static void set_merge(struct branch *ret)
1646 {
1647         struct remote *remote;
1648         char *ref;
1649         struct object_id oid;
1650         int i;
1651
1652         if (!ret)
1653                 return; /* no branch */
1654         if (ret->merge)
1655                 return; /* already run */
1656         if (!ret->remote_name || !ret->merge_nr) {
1657                 /*
1658                  * no merge config; let's make sure we don't confuse callers
1659                  * with a non-zero merge_nr but a NULL merge
1660                  */
1661                 ret->merge_nr = 0;
1662                 return;
1663         }
1664
1665         remote = remote_get(ret->remote_name);
1666
1667         CALLOC_ARRAY(ret->merge, ret->merge_nr);
1668         for (i = 0; i < ret->merge_nr; i++) {
1669                 ret->merge[i] = xcalloc(1, sizeof(**ret->merge));
1670                 ret->merge[i]->src = xstrdup(ret->merge_name[i]);
1671                 if (!remote_find_tracking(remote, ret->merge[i]) ||
1672                     strcmp(ret->remote_name, "."))
1673                         continue;
1674                 if (dwim_ref(ret->merge_name[i], strlen(ret->merge_name[i]),
1675                              &oid, &ref, 0) == 1)
1676                         ret->merge[i]->dst = ref;
1677                 else
1678                         ret->merge[i]->dst = xstrdup(ret->merge_name[i]);
1679         }
1680 }
1681
1682 struct branch *branch_get(const char *name)
1683 {
1684         struct branch *ret;
1685
1686         read_config();
1687         if (!name || !*name || !strcmp(name, "HEAD"))
1688                 ret = current_branch;
1689         else
1690                 ret = make_branch(name, strlen(name));
1691         set_merge(ret);
1692         return ret;
1693 }
1694
1695 int branch_has_merge_config(struct branch *branch)
1696 {
1697         return branch && !!branch->merge;
1698 }
1699
1700 int branch_merge_matches(struct branch *branch,
1701                                  int i,
1702                                  const char *refname)
1703 {
1704         if (!branch || i < 0 || i >= branch->merge_nr)
1705                 return 0;
1706         return refname_match(branch->merge[i]->src, refname);
1707 }
1708
1709 __attribute__((format (printf,2,3)))
1710 static const char *error_buf(struct strbuf *err, const char *fmt, ...)
1711 {
1712         if (err) {
1713                 va_list ap;
1714                 va_start(ap, fmt);
1715                 strbuf_vaddf(err, fmt, ap);
1716                 va_end(ap);
1717         }
1718         return NULL;
1719 }
1720
1721 const char *branch_get_upstream(struct branch *branch, struct strbuf *err)
1722 {
1723         if (!branch)
1724                 return error_buf(err, _("HEAD does not point to a branch"));
1725
1726         if (!branch->merge || !branch->merge[0]) {
1727                 /*
1728                  * no merge config; is it because the user didn't define any,
1729                  * or because it is not a real branch, and get_branch
1730                  * auto-vivified it?
1731                  */
1732                 if (!ref_exists(branch->refname))
1733                         return error_buf(err, _("no such branch: '%s'"),
1734                                          branch->name);
1735                 return error_buf(err,
1736                                  _("no upstream configured for branch '%s'"),
1737                                  branch->name);
1738         }
1739
1740         if (!branch->merge[0]->dst)
1741                 return error_buf(err,
1742                                  _("upstream branch '%s' not stored as a remote-tracking branch"),
1743                                  branch->merge[0]->src);
1744
1745         return branch->merge[0]->dst;
1746 }
1747
1748 static const char *tracking_for_push_dest(struct remote *remote,
1749                                           const char *refname,
1750                                           struct strbuf *err)
1751 {
1752         char *ret;
1753
1754         ret = apply_refspecs(&remote->fetch, refname);
1755         if (!ret)
1756                 return error_buf(err,
1757                                  _("push destination '%s' on remote '%s' has no local tracking branch"),
1758                                  refname, remote->name);
1759         return ret;
1760 }
1761
1762 static const char *branch_get_push_1(struct branch *branch, struct strbuf *err)
1763 {
1764         struct remote *remote;
1765
1766         remote = remote_get(pushremote_for_branch(branch, NULL));
1767         if (!remote)
1768                 return error_buf(err,
1769                                  _("branch '%s' has no remote for pushing"),
1770                                  branch->name);
1771
1772         if (remote->push.nr) {
1773                 char *dst;
1774                 const char *ret;
1775
1776                 dst = apply_refspecs(&remote->push, branch->refname);
1777                 if (!dst)
1778                         return error_buf(err,
1779                                          _("push refspecs for '%s' do not include '%s'"),
1780                                          remote->name, branch->name);
1781
1782                 ret = tracking_for_push_dest(remote, dst, err);
1783                 free(dst);
1784                 return ret;
1785         }
1786
1787         if (remote->mirror)
1788                 return tracking_for_push_dest(remote, branch->refname, err);
1789
1790         switch (push_default) {
1791         case PUSH_DEFAULT_NOTHING:
1792                 return error_buf(err, _("push has no destination (push.default is 'nothing')"));
1793
1794         case PUSH_DEFAULT_MATCHING:
1795         case PUSH_DEFAULT_CURRENT:
1796                 return tracking_for_push_dest(remote, branch->refname, err);
1797
1798         case PUSH_DEFAULT_UPSTREAM:
1799                 return branch_get_upstream(branch, err);
1800
1801         case PUSH_DEFAULT_UNSPECIFIED:
1802         case PUSH_DEFAULT_SIMPLE:
1803                 {
1804                         const char *up, *cur;
1805
1806                         up = branch_get_upstream(branch, err);
1807                         if (!up)
1808                                 return NULL;
1809                         cur = tracking_for_push_dest(remote, branch->refname, err);
1810                         if (!cur)
1811                                 return NULL;
1812                         if (strcmp(cur, up))
1813                                 return error_buf(err,
1814                                                  _("cannot resolve 'simple' push to a single destination"));
1815                         return cur;
1816                 }
1817         }
1818
1819         BUG("unhandled push situation");
1820 }
1821
1822 const char *branch_get_push(struct branch *branch, struct strbuf *err)
1823 {
1824         if (!branch)
1825                 return error_buf(err, _("HEAD does not point to a branch"));
1826
1827         if (!branch->push_tracking_ref)
1828                 branch->push_tracking_ref = branch_get_push_1(branch, err);
1829         return branch->push_tracking_ref;
1830 }
1831
1832 static int ignore_symref_update(const char *refname)
1833 {
1834         int flag;
1835
1836         if (!resolve_ref_unsafe(refname, 0, NULL, &flag))
1837                 return 0; /* non-existing refs are OK */
1838         return (flag & REF_ISSYMREF);
1839 }
1840
1841 /*
1842  * Create and return a list of (struct ref) consisting of copies of
1843  * each remote_ref that matches refspec.  refspec must be a pattern.
1844  * Fill in the copies' peer_ref to describe the local tracking refs to
1845  * which they map.  Omit any references that would map to an existing
1846  * local symbolic ref.
1847  */
1848 static struct ref *get_expanded_map(const struct ref *remote_refs,
1849                                     const struct refspec_item *refspec)
1850 {
1851         const struct ref *ref;
1852         struct ref *ret = NULL;
1853         struct ref **tail = &ret;
1854
1855         for (ref = remote_refs; ref; ref = ref->next) {
1856                 char *expn_name = NULL;
1857
1858                 if (strchr(ref->name, '^'))
1859                         continue; /* a dereference item */
1860                 if (match_name_with_pattern(refspec->src, ref->name,
1861                                             refspec->dst, &expn_name) &&
1862                     !ignore_symref_update(expn_name)) {
1863                         struct ref *cpy = copy_ref(ref);
1864
1865                         cpy->peer_ref = alloc_ref(expn_name);
1866                         if (refspec->force)
1867                                 cpy->peer_ref->force = 1;
1868                         *tail = cpy;
1869                         tail = &cpy->next;
1870                 }
1871                 free(expn_name);
1872         }
1873
1874         return ret;
1875 }
1876
1877 static const struct ref *find_ref_by_name_abbrev(const struct ref *refs, const char *name)
1878 {
1879         const struct ref *ref;
1880         const struct ref *best_match = NULL;
1881         int best_score = 0;
1882
1883         for (ref = refs; ref; ref = ref->next) {
1884                 int score = refname_match(name, ref->name);
1885
1886                 if (best_score < score) {
1887                         best_match = ref;
1888                         best_score = score;
1889                 }
1890         }
1891         return best_match;
1892 }
1893
1894 struct ref *get_remote_ref(const struct ref *remote_refs, const char *name)
1895 {
1896         const struct ref *ref = find_ref_by_name_abbrev(remote_refs, name);
1897
1898         if (!ref)
1899                 return NULL;
1900
1901         return copy_ref(ref);
1902 }
1903
1904 static struct ref *get_local_ref(const char *name)
1905 {
1906         if (!name || name[0] == '\0')
1907                 return NULL;
1908
1909         if (starts_with(name, "refs/"))
1910                 return alloc_ref(name);
1911
1912         if (starts_with(name, "heads/") ||
1913             starts_with(name, "tags/") ||
1914             starts_with(name, "remotes/"))
1915                 return alloc_ref_with_prefix("refs/", 5, name);
1916
1917         return alloc_ref_with_prefix("refs/heads/", 11, name);
1918 }
1919
1920 int get_fetch_map(const struct ref *remote_refs,
1921                   const struct refspec_item *refspec,
1922                   struct ref ***tail,
1923                   int missing_ok)
1924 {
1925         struct ref *ref_map, **rmp;
1926
1927         if (refspec->negative)
1928                 return 0;
1929
1930         if (refspec->pattern) {
1931                 ref_map = get_expanded_map(remote_refs, refspec);
1932         } else {
1933                 const char *name = refspec->src[0] ? refspec->src : "HEAD";
1934
1935                 if (refspec->exact_sha1) {
1936                         ref_map = alloc_ref(name);
1937                         get_oid_hex(name, &ref_map->old_oid);
1938                         ref_map->exact_oid = 1;
1939                 } else {
1940                         ref_map = get_remote_ref(remote_refs, name);
1941                 }
1942                 if (!missing_ok && !ref_map)
1943                         die(_("couldn't find remote ref %s"), name);
1944                 if (ref_map) {
1945                         ref_map->peer_ref = get_local_ref(refspec->dst);
1946                         if (ref_map->peer_ref && refspec->force)
1947                                 ref_map->peer_ref->force = 1;
1948                 }
1949         }
1950
1951         for (rmp = &ref_map; *rmp; ) {
1952                 if ((*rmp)->peer_ref) {
1953                         if (!starts_with((*rmp)->peer_ref->name, "refs/") ||
1954                             check_refname_format((*rmp)->peer_ref->name, 0)) {
1955                                 struct ref *ignore = *rmp;
1956                                 error(_("* Ignoring funny ref '%s' locally"),
1957                                       (*rmp)->peer_ref->name);
1958                                 *rmp = (*rmp)->next;
1959                                 free(ignore->peer_ref);
1960                                 free(ignore);
1961                                 continue;
1962                         }
1963                 }
1964                 rmp = &((*rmp)->next);
1965         }
1966
1967         if (ref_map)
1968                 tail_link_ref(ref_map, tail);
1969
1970         return 0;
1971 }
1972
1973 int resolve_remote_symref(struct ref *ref, struct ref *list)
1974 {
1975         if (!ref->symref)
1976                 return 0;
1977         for (; list; list = list->next)
1978                 if (!strcmp(ref->symref, list->name)) {
1979                         oidcpy(&ref->old_oid, &list->old_oid);
1980                         return 0;
1981                 }
1982         return 1;
1983 }
1984
1985 /*
1986  * Compute the commit ahead/behind values for the pair branch_name, base.
1987  *
1988  * If abf is AHEAD_BEHIND_FULL, compute the full ahead/behind and return the
1989  * counts in *num_ours and *num_theirs.  If abf is AHEAD_BEHIND_QUICK, skip
1990  * the (potentially expensive) a/b computation (*num_ours and *num_theirs are
1991  * set to zero).
1992  *
1993  * Returns -1 if num_ours and num_theirs could not be filled in (e.g., ref
1994  * does not exist).  Returns 0 if the commits are identical.  Returns 1 if
1995  * commits are different.
1996  */
1997
1998 static int stat_branch_pair(const char *branch_name, const char *base,
1999                              int *num_ours, int *num_theirs,
2000                              enum ahead_behind_flags abf)
2001 {
2002         struct object_id oid;
2003         struct commit *ours, *theirs;
2004         struct rev_info revs;
2005         struct strvec argv = STRVEC_INIT;
2006
2007         /* Cannot stat if what we used to build on no longer exists */
2008         if (read_ref(base, &oid))
2009                 return -1;
2010         theirs = lookup_commit_reference(the_repository, &oid);
2011         if (!theirs)
2012                 return -1;
2013
2014         if (read_ref(branch_name, &oid))
2015                 return -1;
2016         ours = lookup_commit_reference(the_repository, &oid);
2017         if (!ours)
2018                 return -1;
2019
2020         *num_theirs = *num_ours = 0;
2021
2022         /* are we the same? */
2023         if (theirs == ours)
2024                 return 0;
2025         if (abf == AHEAD_BEHIND_QUICK)
2026                 return 1;
2027         if (abf != AHEAD_BEHIND_FULL)
2028                 BUG("stat_branch_pair: invalid abf '%d'", abf);
2029
2030         /* Run "rev-list --left-right ours...theirs" internally... */
2031         strvec_push(&argv, ""); /* ignored */
2032         strvec_push(&argv, "--left-right");
2033         strvec_pushf(&argv, "%s...%s",
2034                      oid_to_hex(&ours->object.oid),
2035                      oid_to_hex(&theirs->object.oid));
2036         strvec_push(&argv, "--");
2037
2038         repo_init_revisions(the_repository, &revs, NULL);
2039         setup_revisions(argv.nr, argv.v, &revs, NULL);
2040         if (prepare_revision_walk(&revs))
2041                 die(_("revision walk setup failed"));
2042
2043         /* ... and count the commits on each side. */
2044         while (1) {
2045                 struct commit *c = get_revision(&revs);
2046                 if (!c)
2047                         break;
2048                 if (c->object.flags & SYMMETRIC_LEFT)
2049                         (*num_ours)++;
2050                 else
2051                         (*num_theirs)++;
2052         }
2053
2054         /* clear object flags smudged by the above traversal */
2055         clear_commit_marks(ours, ALL_REV_FLAGS);
2056         clear_commit_marks(theirs, ALL_REV_FLAGS);
2057
2058         strvec_clear(&argv);
2059         return 1;
2060 }
2061
2062 /*
2063  * Lookup the tracking branch for the given branch and if present, optionally
2064  * compute the commit ahead/behind values for the pair.
2065  *
2066  * If for_push is true, the tracking branch refers to the push branch,
2067  * otherwise it refers to the upstream branch.
2068  *
2069  * The name of the tracking branch (or NULL if it is not defined) is
2070  * returned via *tracking_name, if it is not itself NULL.
2071  *
2072  * If abf is AHEAD_BEHIND_FULL, compute the full ahead/behind and return the
2073  * counts in *num_ours and *num_theirs.  If abf is AHEAD_BEHIND_QUICK, skip
2074  * the (potentially expensive) a/b computation (*num_ours and *num_theirs are
2075  * set to zero).
2076  *
2077  * Returns -1 if num_ours and num_theirs could not be filled in (e.g., no
2078  * upstream defined, or ref does not exist).  Returns 0 if the commits are
2079  * identical.  Returns 1 if commits are different.
2080  */
2081 int stat_tracking_info(struct branch *branch, int *num_ours, int *num_theirs,
2082                        const char **tracking_name, int for_push,
2083                        enum ahead_behind_flags abf)
2084 {
2085         const char *base;
2086
2087         /* Cannot stat unless we are marked to build on top of somebody else. */
2088         base = for_push ? branch_get_push(branch, NULL) :
2089                 branch_get_upstream(branch, NULL);
2090         if (tracking_name)
2091                 *tracking_name = base;
2092         if (!base)
2093                 return -1;
2094
2095         return stat_branch_pair(branch->refname, base, num_ours, num_theirs, abf);
2096 }
2097
2098 /*
2099  * Return true when there is anything to report, otherwise false.
2100  */
2101 int format_tracking_info(struct branch *branch, struct strbuf *sb,
2102                          enum ahead_behind_flags abf)
2103 {
2104         int ours, theirs, sti;
2105         const char *full_base;
2106         char *base;
2107         int upstream_is_gone = 0;
2108
2109         sti = stat_tracking_info(branch, &ours, &theirs, &full_base, 0, abf);
2110         if (sti < 0) {
2111                 if (!full_base)
2112                         return 0;
2113                 upstream_is_gone = 1;
2114         }
2115
2116         base = shorten_unambiguous_ref(full_base, 0);
2117         if (upstream_is_gone) {
2118                 strbuf_addf(sb,
2119                         _("Your branch is based on '%s', but the upstream is gone.\n"),
2120                         base);
2121                 if (advice_status_hints)
2122                         strbuf_addstr(sb,
2123                                 _("  (use \"git branch --unset-upstream\" to fixup)\n"));
2124         } else if (!sti) {
2125                 strbuf_addf(sb,
2126                         _("Your branch is up to date with '%s'.\n"),
2127                         base);
2128         } else if (abf == AHEAD_BEHIND_QUICK) {
2129                 strbuf_addf(sb,
2130                             _("Your branch and '%s' refer to different commits.\n"),
2131                             base);
2132                 if (advice_status_hints)
2133                         strbuf_addf(sb, _("  (use \"%s\" for details)\n"),
2134                                     "git status --ahead-behind");
2135         } else if (!theirs) {
2136                 strbuf_addf(sb,
2137                         Q_("Your branch is ahead of '%s' by %d commit.\n",
2138                            "Your branch is ahead of '%s' by %d commits.\n",
2139                            ours),
2140                         base, ours);
2141                 if (advice_status_hints)
2142                         strbuf_addstr(sb,
2143                                 _("  (use \"git push\" to publish your local commits)\n"));
2144         } else if (!ours) {
2145                 strbuf_addf(sb,
2146                         Q_("Your branch is behind '%s' by %d commit, "
2147                                "and can be fast-forwarded.\n",
2148                            "Your branch is behind '%s' by %d commits, "
2149                                "and can be fast-forwarded.\n",
2150                            theirs),
2151                         base, theirs);
2152                 if (advice_status_hints)
2153                         strbuf_addstr(sb,
2154                                 _("  (use \"git pull\" to update your local branch)\n"));
2155         } else {
2156                 strbuf_addf(sb,
2157                         Q_("Your branch and '%s' have diverged,\n"
2158                                "and have %d and %d different commit each, "
2159                                "respectively.\n",
2160                            "Your branch and '%s' have diverged,\n"
2161                                "and have %d and %d different commits each, "
2162                                "respectively.\n",
2163                            ours + theirs),
2164                         base, ours, theirs);
2165                 if (advice_status_hints)
2166                         strbuf_addstr(sb,
2167                                 _("  (use \"git pull\" to merge the remote branch into yours)\n"));
2168         }
2169         free(base);
2170         return 1;
2171 }
2172
2173 static int one_local_ref(const char *refname, const struct object_id *oid,
2174                          int flag, void *cb_data)
2175 {
2176         struct ref ***local_tail = cb_data;
2177         struct ref *ref;
2178
2179         /* we already know it starts with refs/ to get here */
2180         if (check_refname_format(refname + 5, 0))
2181                 return 0;
2182
2183         ref = alloc_ref(refname);
2184         oidcpy(&ref->new_oid, oid);
2185         **local_tail = ref;
2186         *local_tail = &ref->next;
2187         return 0;
2188 }
2189
2190 struct ref *get_local_heads(void)
2191 {
2192         struct ref *local_refs = NULL, **local_tail = &local_refs;
2193
2194         for_each_ref(one_local_ref, &local_tail);
2195         return local_refs;
2196 }
2197
2198 struct ref *guess_remote_head(const struct ref *head,
2199                               const struct ref *refs,
2200                               int all)
2201 {
2202         const struct ref *r;
2203         struct ref *list = NULL;
2204         struct ref **tail = &list;
2205
2206         if (!head)
2207                 return NULL;
2208
2209         /*
2210          * Some transports support directly peeking at
2211          * where HEAD points; if that is the case, then
2212          * we don't have to guess.
2213          */
2214         if (head->symref)
2215                 return copy_ref(find_ref_by_name(refs, head->symref));
2216
2217         /* If a remote branch exists with the default branch name, let's use it. */
2218         if (!all) {
2219                 char *ref = xstrfmt("refs/heads/%s",
2220                                     git_default_branch_name(0));
2221
2222                 r = find_ref_by_name(refs, ref);
2223                 free(ref);
2224                 if (r && oideq(&r->old_oid, &head->old_oid))
2225                         return copy_ref(r);
2226
2227                 /* Fall back to the hard-coded historical default */
2228                 r = find_ref_by_name(refs, "refs/heads/master");
2229                 if (r && oideq(&r->old_oid, &head->old_oid))
2230                         return copy_ref(r);
2231         }
2232
2233         /* Look for another ref that points there */
2234         for (r = refs; r; r = r->next) {
2235                 if (r != head &&
2236                     starts_with(r->name, "refs/heads/") &&
2237                     oideq(&r->old_oid, &head->old_oid)) {
2238                         *tail = copy_ref(r);
2239                         tail = &((*tail)->next);
2240                         if (!all)
2241                                 break;
2242                 }
2243         }
2244
2245         return list;
2246 }
2247
2248 struct stale_heads_info {
2249         struct string_list *ref_names;
2250         struct ref **stale_refs_tail;
2251         struct refspec *rs;
2252 };
2253
2254 static int get_stale_heads_cb(const char *refname, const struct object_id *oid,
2255                               int flags, void *cb_data)
2256 {
2257         struct stale_heads_info *info = cb_data;
2258         struct string_list matches = STRING_LIST_INIT_DUP;
2259         struct refspec_item query;
2260         int i, stale = 1;
2261         memset(&query, 0, sizeof(struct refspec_item));
2262         query.dst = (char *)refname;
2263
2264         query_refspecs_multiple(info->rs, &query, &matches);
2265         if (matches.nr == 0)
2266                 goto clean_exit; /* No matches */
2267
2268         /*
2269          * If we did find a suitable refspec and it's not a symref and
2270          * it's not in the list of refs that currently exist in that
2271          * remote, we consider it to be stale. In order to deal with
2272          * overlapping refspecs, we need to go over all of the
2273          * matching refs.
2274          */
2275         if (flags & REF_ISSYMREF)
2276                 goto clean_exit;
2277
2278         for (i = 0; stale && i < matches.nr; i++)
2279                 if (string_list_has_string(info->ref_names, matches.items[i].string))
2280                         stale = 0;
2281
2282         if (stale) {
2283                 struct ref *ref = make_linked_ref(refname, &info->stale_refs_tail);
2284                 oidcpy(&ref->new_oid, oid);
2285         }
2286
2287 clean_exit:
2288         string_list_clear(&matches, 0);
2289         return 0;
2290 }
2291
2292 struct ref *get_stale_heads(struct refspec *rs, struct ref *fetch_map)
2293 {
2294         struct ref *ref, *stale_refs = NULL;
2295         struct string_list ref_names = STRING_LIST_INIT_NODUP;
2296         struct stale_heads_info info;
2297
2298         info.ref_names = &ref_names;
2299         info.stale_refs_tail = &stale_refs;
2300         info.rs = rs;
2301         for (ref = fetch_map; ref; ref = ref->next)
2302                 string_list_append(&ref_names, ref->name);
2303         string_list_sort(&ref_names);
2304         for_each_ref(get_stale_heads_cb, &info);
2305         string_list_clear(&ref_names, 0);
2306         return stale_refs;
2307 }
2308
2309 /*
2310  * Compare-and-swap
2311  */
2312 static void clear_cas_option(struct push_cas_option *cas)
2313 {
2314         int i;
2315
2316         for (i = 0; i < cas->nr; i++)
2317                 free(cas->entry[i].refname);
2318         free(cas->entry);
2319         memset(cas, 0, sizeof(*cas));
2320 }
2321
2322 static struct push_cas *add_cas_entry(struct push_cas_option *cas,
2323                                       const char *refname,
2324                                       size_t refnamelen)
2325 {
2326         struct push_cas *entry;
2327         ALLOC_GROW(cas->entry, cas->nr + 1, cas->alloc);
2328         entry = &cas->entry[cas->nr++];
2329         memset(entry, 0, sizeof(*entry));
2330         entry->refname = xmemdupz(refname, refnamelen);
2331         return entry;
2332 }
2333
2334 static int parse_push_cas_option(struct push_cas_option *cas, const char *arg, int unset)
2335 {
2336         const char *colon;
2337         struct push_cas *entry;
2338
2339         if (unset) {
2340                 /* "--no-<option>" */
2341                 clear_cas_option(cas);
2342                 return 0;
2343         }
2344
2345         if (!arg) {
2346                 /* just "--<option>" */
2347                 cas->use_tracking_for_rest = 1;
2348                 return 0;
2349         }
2350
2351         /* "--<option>=refname" or "--<option>=refname:value" */
2352         colon = strchrnul(arg, ':');
2353         entry = add_cas_entry(cas, arg, colon - arg);
2354         if (!*colon)
2355                 entry->use_tracking = 1;
2356         else if (!colon[1])
2357                 oidclr(&entry->expect);
2358         else if (get_oid(colon + 1, &entry->expect))
2359                 return error(_("cannot parse expected object name '%s'"),
2360                              colon + 1);
2361         return 0;
2362 }
2363
2364 int parseopt_push_cas_option(const struct option *opt, const char *arg, int unset)
2365 {
2366         return parse_push_cas_option(opt->value, arg, unset);
2367 }
2368
2369 int is_empty_cas(const struct push_cas_option *cas)
2370 {
2371         return !cas->use_tracking_for_rest && !cas->nr;
2372 }
2373
2374 /*
2375  * Look at remote.fetch refspec and see if we have a remote
2376  * tracking branch for the refname there. Fill the name of
2377  * the remote-tracking branch in *dst_refname, and the name
2378  * of the commit object at its tip in oid[].
2379  * If we cannot do so, return negative to signal an error.
2380  */
2381 static int remote_tracking(struct remote *remote, const char *refname,
2382                            struct object_id *oid, char **dst_refname)
2383 {
2384         char *dst;
2385
2386         dst = apply_refspecs(&remote->fetch, refname);
2387         if (!dst)
2388                 return -1; /* no tracking ref for refname at remote */
2389         if (read_ref(dst, oid))
2390                 return -1; /* we know what the tracking ref is but we cannot read it */
2391
2392         *dst_refname = dst;
2393         return 0;
2394 }
2395
2396 /*
2397  * The struct "reflog_commit_array" and related helper functions
2398  * are used for collecting commits into an array during reflog
2399  * traversals in "check_and_collect_until()".
2400  */
2401 struct reflog_commit_array {
2402         struct commit **item;
2403         size_t nr, alloc;
2404 };
2405
2406 #define REFLOG_COMMIT_ARRAY_INIT { NULL, 0, 0 }
2407
2408 /* Append a commit to the array. */
2409 static void append_commit(struct reflog_commit_array *arr,
2410                           struct commit *commit)
2411 {
2412         ALLOC_GROW(arr->item, arr->nr + 1, arr->alloc);
2413         arr->item[arr->nr++] = commit;
2414 }
2415
2416 /* Free and reset the array. */
2417 static void free_commit_array(struct reflog_commit_array *arr)
2418 {
2419         FREE_AND_NULL(arr->item);
2420         arr->nr = arr->alloc = 0;
2421 }
2422
2423 struct check_and_collect_until_cb_data {
2424         struct commit *remote_commit;
2425         struct reflog_commit_array *local_commits;
2426         timestamp_t remote_reflog_timestamp;
2427 };
2428
2429 /* Get the timestamp of the latest entry. */
2430 static int peek_reflog(struct object_id *o_oid, struct object_id *n_oid,
2431                        const char *ident, timestamp_t timestamp,
2432                        int tz, const char *message, void *cb_data)
2433 {
2434         timestamp_t *ts = cb_data;
2435         *ts = timestamp;
2436         return 1;
2437 }
2438
2439 static int check_and_collect_until(struct object_id *o_oid,
2440                                    struct object_id *n_oid,
2441                                    const char *ident, timestamp_t timestamp,
2442                                    int tz, const char *message, void *cb_data)
2443 {
2444         struct commit *commit;
2445         struct check_and_collect_until_cb_data *cb = cb_data;
2446
2447         /* An entry was found. */
2448         if (oideq(n_oid, &cb->remote_commit->object.oid))
2449                 return 1;
2450
2451         if ((commit = lookup_commit_reference(the_repository, n_oid)))
2452                 append_commit(cb->local_commits, commit);
2453
2454         /*
2455          * If the reflog entry timestamp is older than the remote ref's
2456          * latest reflog entry, there is no need to check or collect
2457          * entries older than this one.
2458          */
2459         if (timestamp < cb->remote_reflog_timestamp)
2460                 return -1;
2461
2462         return 0;
2463 }
2464
2465 #define MERGE_BASES_BATCH_SIZE 8
2466
2467 /*
2468  * Iterate through the reflog of the local ref to check if there is an entry
2469  * for the given remote-tracking ref; runs until the timestamp of an entry is
2470  * older than latest timestamp of remote-tracking ref's reflog. Any commits
2471  * are that seen along the way are collected into an array to check if the
2472  * remote-tracking ref is reachable from any of them.
2473  */
2474 static int is_reachable_in_reflog(const char *local, const struct ref *remote)
2475 {
2476         timestamp_t date;
2477         struct commit *commit;
2478         struct commit **chunk;
2479         struct check_and_collect_until_cb_data cb;
2480         struct reflog_commit_array arr = REFLOG_COMMIT_ARRAY_INIT;
2481         size_t size = 0;
2482         int ret = 0;
2483
2484         commit = lookup_commit_reference(the_repository, &remote->old_oid);
2485         if (!commit)
2486                 goto cleanup_return;
2487
2488         /*
2489          * Get the timestamp from the latest entry
2490          * of the remote-tracking ref's reflog.
2491          */
2492         for_each_reflog_ent_reverse(remote->tracking_ref, peek_reflog, &date);
2493
2494         cb.remote_commit = commit;
2495         cb.local_commits = &arr;
2496         cb.remote_reflog_timestamp = date;
2497         ret = for_each_reflog_ent_reverse(local, check_and_collect_until, &cb);
2498
2499         /* We found an entry in the reflog. */
2500         if (ret > 0)
2501                 goto cleanup_return;
2502
2503         /*
2504          * Check if the remote commit is reachable from any
2505          * of the commits in the collected array, in batches.
2506          */
2507         for (chunk = arr.item; chunk < arr.item + arr.nr; chunk += size) {
2508                 size = arr.item + arr.nr - chunk;
2509                 if (MERGE_BASES_BATCH_SIZE < size)
2510                         size = MERGE_BASES_BATCH_SIZE;
2511
2512                 if ((ret = in_merge_bases_many(commit, size, chunk)))
2513                         break;
2514         }
2515
2516 cleanup_return:
2517         free_commit_array(&arr);
2518         return ret;
2519 }
2520
2521 /*
2522  * Check for reachability of a remote-tracking
2523  * ref in the reflog entries of its local ref.
2524  */
2525 static void check_if_includes_upstream(struct ref *remote)
2526 {
2527         struct ref *local = get_local_ref(remote->name);
2528         if (!local)
2529                 return;
2530
2531         if (is_reachable_in_reflog(local->name, remote) <= 0)
2532                 remote->unreachable = 1;
2533 }
2534
2535 static void apply_cas(struct push_cas_option *cas,
2536                       struct remote *remote,
2537                       struct ref *ref)
2538 {
2539         int i;
2540
2541         /* Find an explicit --<option>=<name>[:<value>] entry */
2542         for (i = 0; i < cas->nr; i++) {
2543                 struct push_cas *entry = &cas->entry[i];
2544                 if (!refname_match(entry->refname, ref->name))
2545                         continue;
2546                 ref->expect_old_sha1 = 1;
2547                 if (!entry->use_tracking)
2548                         oidcpy(&ref->old_oid_expect, &entry->expect);
2549                 else if (remote_tracking(remote, ref->name,
2550                                          &ref->old_oid_expect,
2551                                          &ref->tracking_ref))
2552                         oidclr(&ref->old_oid_expect);
2553                 else
2554                         ref->check_reachable = cas->use_force_if_includes;
2555                 return;
2556         }
2557
2558         /* Are we using "--<option>" to cover all? */
2559         if (!cas->use_tracking_for_rest)
2560                 return;
2561
2562         ref->expect_old_sha1 = 1;
2563         if (remote_tracking(remote, ref->name,
2564                             &ref->old_oid_expect,
2565                             &ref->tracking_ref))
2566                 oidclr(&ref->old_oid_expect);
2567         else
2568                 ref->check_reachable = cas->use_force_if_includes;
2569 }
2570
2571 void apply_push_cas(struct push_cas_option *cas,
2572                     struct remote *remote,
2573                     struct ref *remote_refs)
2574 {
2575         struct ref *ref;
2576         for (ref = remote_refs; ref; ref = ref->next) {
2577                 apply_cas(cas, remote, ref);
2578
2579                 /*
2580                  * If "compare-and-swap" is in "use_tracking[_for_rest]"
2581                  * mode, and if "--force-if-includes" was specified, run
2582                  * the check.
2583                  */
2584                 if (ref->check_reachable)
2585                         check_if_includes_upstream(ref);
2586         }
2587 }