Merge branch 'tr/maint-1.6.0-send-email-irt' into maint
[git] / rerere.c
1 #include "cache.h"
2 #include "string-list.h"
3 #include "rerere.h"
4 #include "xdiff/xdiff.h"
5 #include "xdiff-interface.h"
6
7 /* if rerere_enabled == -1, fall back to detection of .git/rr-cache */
8 static int rerere_enabled = -1;
9
10 /* automatically update cleanly resolved paths to the index */
11 static int rerere_autoupdate;
12
13 static char *merge_rr_path;
14
15 static const char *rr_path(const char *name, const char *file)
16 {
17         return git_path("rr-cache/%s/%s", name, file);
18 }
19
20 static int has_resolution(const char *name)
21 {
22         struct stat st;
23         return !stat(rr_path(name, "postimage"), &st);
24 }
25
26 static void read_rr(struct string_list *rr)
27 {
28         unsigned char sha1[20];
29         char buf[PATH_MAX];
30         FILE *in = fopen(merge_rr_path, "r");
31         if (!in)
32                 return;
33         while (fread(buf, 40, 1, in) == 1) {
34                 int i;
35                 char *name;
36                 if (get_sha1_hex(buf, sha1))
37                         die("corrupt MERGE_RR");
38                 buf[40] = '\0';
39                 name = xstrdup(buf);
40                 if (fgetc(in) != '\t')
41                         die("corrupt MERGE_RR");
42                 for (i = 0; i < sizeof(buf) && (buf[i] = fgetc(in)); i++)
43                         ; /* do nothing */
44                 if (i == sizeof(buf))
45                         die("filename too long");
46                 string_list_insert(buf, rr)->util = name;
47         }
48         fclose(in);
49 }
50
51 static struct lock_file write_lock;
52
53 static int write_rr(struct string_list *rr, int out_fd)
54 {
55         int i;
56         for (i = 0; i < rr->nr; i++) {
57                 const char *path;
58                 int length;
59                 if (!rr->items[i].util)
60                         continue;
61                 path = rr->items[i].string;
62                 length = strlen(path) + 1;
63                 if (write_in_full(out_fd, rr->items[i].util, 40) != 40 ||
64                     write_in_full(out_fd, "\t", 1) != 1 ||
65                     write_in_full(out_fd, path, length) != length)
66                         die("unable to write rerere record");
67         }
68         if (commit_lock_file(&write_lock) != 0)
69                 die("unable to write rerere record");
70         return 0;
71 }
72
73 static void ferr_write(const void *p, size_t count, FILE *fp, int *err)
74 {
75         if (!count || *err)
76                 return;
77         if (fwrite(p, count, 1, fp) != 1)
78                 *err = errno;
79 }
80
81 static inline void ferr_puts(const char *s, FILE *fp, int *err)
82 {
83         ferr_write(s, strlen(s), fp, err);
84 }
85
86 static int handle_file(const char *path,
87          unsigned char *sha1, const char *output)
88 {
89         git_SHA_CTX ctx;
90         char buf[1024];
91         int hunk_no = 0;
92         enum {
93                 RR_CONTEXT = 0, RR_SIDE_1, RR_SIDE_2, RR_ORIGINAL,
94         } hunk = RR_CONTEXT;
95         struct strbuf one = STRBUF_INIT, two = STRBUF_INIT;
96         FILE *f = fopen(path, "r");
97         FILE *out = NULL;
98         int wrerror = 0;
99
100         if (!f)
101                 return error("Could not open %s", path);
102
103         if (output) {
104                 out = fopen(output, "w");
105                 if (!out) {
106                         fclose(f);
107                         return error("Could not write %s", output);
108                 }
109         }
110
111         if (sha1)
112                 git_SHA1_Init(&ctx);
113
114         while (fgets(buf, sizeof(buf), f)) {
115                 if (!prefixcmp(buf, "<<<<<<< ")) {
116                         if (hunk != RR_CONTEXT)
117                                 goto bad;
118                         hunk = RR_SIDE_1;
119                 } else if (!prefixcmp(buf, "|||||||") && isspace(buf[7])) {
120                         if (hunk != RR_SIDE_1)
121                                 goto bad;
122                         hunk = RR_ORIGINAL;
123                 } else if (!prefixcmp(buf, "=======") && isspace(buf[7])) {
124                         if (hunk != RR_SIDE_1 && hunk != RR_ORIGINAL)
125                                 goto bad;
126                         hunk = RR_SIDE_2;
127                 } else if (!prefixcmp(buf, ">>>>>>> ")) {
128                         if (hunk != RR_SIDE_2)
129                                 goto bad;
130                         if (strbuf_cmp(&one, &two) > 0)
131                                 strbuf_swap(&one, &two);
132                         hunk_no++;
133                         hunk = RR_CONTEXT;
134                         if (out) {
135                                 ferr_puts("<<<<<<<\n", out, &wrerror);
136                                 ferr_write(one.buf, one.len, out, &wrerror);
137                                 ferr_puts("=======\n", out, &wrerror);
138                                 ferr_write(two.buf, two.len, out, &wrerror);
139                                 ferr_puts(">>>>>>>\n", out, &wrerror);
140                         }
141                         if (sha1) {
142                                 git_SHA1_Update(&ctx, one.buf ? one.buf : "",
143                                             one.len + 1);
144                                 git_SHA1_Update(&ctx, two.buf ? two.buf : "",
145                                             two.len + 1);
146                         }
147                         strbuf_reset(&one);
148                         strbuf_reset(&two);
149                 } else if (hunk == RR_SIDE_1)
150                         strbuf_addstr(&one, buf);
151                 else if (hunk == RR_ORIGINAL)
152                         ; /* discard */
153                 else if (hunk == RR_SIDE_2)
154                         strbuf_addstr(&two, buf);
155                 else if (out)
156                         ferr_puts(buf, out, &wrerror);
157                 continue;
158         bad:
159                 hunk = 99; /* force error exit */
160                 break;
161         }
162         strbuf_release(&one);
163         strbuf_release(&two);
164
165         fclose(f);
166         if (wrerror)
167                 error("There were errors while writing %s (%s)",
168                       path, strerror(wrerror));
169         if (out && fclose(out))
170                 wrerror = error("Failed to flush %s: %s",
171                                 path, strerror(errno));
172         if (sha1)
173                 git_SHA1_Final(sha1, &ctx);
174         if (hunk != RR_CONTEXT) {
175                 if (output)
176                         unlink(output);
177                 return error("Could not parse conflict hunks in %s", path);
178         }
179         if (wrerror)
180                 return -1;
181         return hunk_no;
182 }
183
184 static int find_conflict(struct string_list *conflict)
185 {
186         int i;
187         if (read_cache() < 0)
188                 return error("Could not read index");
189         for (i = 0; i+1 < active_nr; i++) {
190                 struct cache_entry *e2 = active_cache[i];
191                 struct cache_entry *e3 = active_cache[i+1];
192                 if (ce_stage(e2) == 2 &&
193                     ce_stage(e3) == 3 &&
194                     ce_same_name(e2, e3) &&
195                     S_ISREG(e2->ce_mode) &&
196                     S_ISREG(e3->ce_mode)) {
197                         string_list_insert((const char *)e2->name, conflict);
198                         i++; /* skip over both #2 and #3 */
199                 }
200         }
201         return 0;
202 }
203
204 static int merge(const char *name, const char *path)
205 {
206         int ret;
207         mmfile_t cur, base, other;
208         mmbuffer_t result = {NULL, 0};
209         xpparam_t xpp = {XDF_NEED_MINIMAL};
210
211         if (handle_file(path, NULL, rr_path(name, "thisimage")) < 0)
212                 return 1;
213
214         if (read_mmfile(&cur, rr_path(name, "thisimage")) ||
215                         read_mmfile(&base, rr_path(name, "preimage")) ||
216                         read_mmfile(&other, rr_path(name, "postimage")))
217                 return 1;
218         ret = xdl_merge(&base, &cur, "", &other, "",
219                         &xpp, XDL_MERGE_ZEALOUS, &result);
220         if (!ret) {
221                 FILE *f = fopen(path, "w");
222                 if (!f)
223                         return error("Could not open %s: %s", path,
224                                      strerror(errno));
225                 if (fwrite(result.ptr, result.size, 1, f) != 1)
226                         error("Could not write %s: %s", path, strerror(errno));
227                 if (fclose(f))
228                         return error("Writing %s failed: %s", path,
229                                      strerror(errno));
230         }
231
232         free(cur.ptr);
233         free(base.ptr);
234         free(other.ptr);
235         free(result.ptr);
236
237         return ret;
238 }
239
240 static struct lock_file index_lock;
241
242 static int update_paths(struct string_list *update)
243 {
244         int i;
245         int fd = hold_locked_index(&index_lock, 0);
246         int status = 0;
247
248         if (fd < 0)
249                 return -1;
250
251         for (i = 0; i < update->nr; i++) {
252                 struct string_list_item *item = &update->items[i];
253                 if (add_file_to_cache(item->string, ADD_CACHE_IGNORE_ERRORS))
254                         status = -1;
255         }
256
257         if (!status && active_cache_changed) {
258                 if (write_cache(fd, active_cache, active_nr) ||
259                     commit_locked_index(&index_lock))
260                         die("Unable to write new index file");
261         } else if (fd >= 0)
262                 rollback_lock_file(&index_lock);
263         return status;
264 }
265
266 static int do_plain_rerere(struct string_list *rr, int fd)
267 {
268         struct string_list conflict = { NULL, 0, 0, 1 };
269         struct string_list update = { NULL, 0, 0, 1 };
270         int i;
271
272         find_conflict(&conflict);
273
274         /*
275          * MERGE_RR records paths with conflicts immediately after merge
276          * failed.  Some of the conflicted paths might have been hand resolved
277          * in the working tree since then, but the initial run would catch all
278          * and register their preimages.
279          */
280
281         for (i = 0; i < conflict.nr; i++) {
282                 const char *path = conflict.items[i].string;
283                 if (!string_list_has_string(rr, path)) {
284                         unsigned char sha1[20];
285                         char *hex;
286                         int ret;
287                         ret = handle_file(path, sha1, NULL);
288                         if (ret < 1)
289                                 continue;
290                         hex = xstrdup(sha1_to_hex(sha1));
291                         string_list_insert(path, rr)->util = hex;
292                         if (mkdir(git_path("rr-cache/%s", hex), 0755))
293                                 continue;
294                         handle_file(path, NULL, rr_path(hex, "preimage"));
295                         fprintf(stderr, "Recorded preimage for '%s'\n", path);
296                 }
297         }
298
299         /*
300          * Now some of the paths that had conflicts earlier might have been
301          * hand resolved.  Others may be similar to a conflict already that
302          * was resolved before.
303          */
304
305         for (i = 0; i < rr->nr; i++) {
306                 int ret;
307                 const char *path = rr->items[i].string;
308                 const char *name = (const char *)rr->items[i].util;
309
310                 if (has_resolution(name)) {
311                         if (!merge(name, path)) {
312                                 if (rerere_autoupdate)
313                                         string_list_insert(path, &update);
314                                 fprintf(stderr,
315                                         "%s '%s' using previous resolution.\n",
316                                         rerere_autoupdate
317                                         ? "Staged" : "Resolved",
318                                         path);
319                                 goto mark_resolved;
320                         }
321                 }
322
323                 /* Let's see if we have resolved it. */
324                 ret = handle_file(path, NULL, NULL);
325                 if (ret)
326                         continue;
327
328                 fprintf(stderr, "Recorded resolution for '%s'.\n", path);
329                 copy_file(rr_path(name, "postimage"), path, 0666);
330         mark_resolved:
331                 rr->items[i].util = NULL;
332         }
333
334         if (update.nr)
335                 update_paths(&update);
336
337         return write_rr(rr, fd);
338 }
339
340 static int git_rerere_config(const char *var, const char *value, void *cb)
341 {
342         if (!strcmp(var, "rerere.enabled"))
343                 rerere_enabled = git_config_bool(var, value);
344         else if (!strcmp(var, "rerere.autoupdate"))
345                 rerere_autoupdate = git_config_bool(var, value);
346         else
347                 return git_default_config(var, value, cb);
348         return 0;
349 }
350
351 static int is_rerere_enabled(void)
352 {
353         const char *rr_cache;
354         int rr_cache_exists;
355
356         if (!rerere_enabled)
357                 return 0;
358
359         rr_cache = git_path("rr-cache");
360         rr_cache_exists = is_directory(rr_cache);
361         if (rerere_enabled < 0)
362                 return rr_cache_exists;
363
364         if (!rr_cache_exists &&
365             (mkdir(rr_cache, 0777) || adjust_shared_perm(rr_cache)))
366                 die("Could not create directory %s", rr_cache);
367         return 1;
368 }
369
370 int setup_rerere(struct string_list *merge_rr)
371 {
372         int fd;
373
374         git_config(git_rerere_config, NULL);
375         if (!is_rerere_enabled())
376                 return -1;
377
378         merge_rr_path = git_pathdup("MERGE_RR");
379         fd = hold_lock_file_for_update(&write_lock, merge_rr_path,
380                                        LOCK_DIE_ON_ERROR);
381         read_rr(merge_rr);
382         return fd;
383 }
384
385 int rerere(void)
386 {
387         struct string_list merge_rr = { NULL, 0, 0, 1 };
388         int fd;
389
390         fd = setup_rerere(&merge_rr);
391         if (fd < 0)
392                 return 0;
393         return do_plain_rerere(&merge_rr, fd);
394 }