Merge branch 'ar/unlink-err'
[git] / http-walker.c
1 #include "cache.h"
2 #include "commit.h"
3 #include "pack.h"
4 #include "walker.h"
5 #include "http.h"
6
7 #define PREV_BUF_SIZE 4096
8 #define RANGE_HEADER_SIZE 30
9
10 struct alt_base
11 {
12         char *base;
13         int got_indices;
14         struct packed_git *packs;
15         struct alt_base *next;
16 };
17
18 enum object_request_state {
19         WAITING,
20         ABORTED,
21         ACTIVE,
22         COMPLETE,
23 };
24
25 struct object_request
26 {
27         struct walker *walker;
28         unsigned char sha1[20];
29         struct alt_base *repo;
30         char *url;
31         char filename[PATH_MAX];
32         char tmpfile[PATH_MAX];
33         int local;
34         enum object_request_state state;
35         CURLcode curl_result;
36         char errorstr[CURL_ERROR_SIZE];
37         long http_code;
38         unsigned char real_sha1[20];
39         git_SHA_CTX c;
40         z_stream stream;
41         int zret;
42         int rename;
43         struct active_request_slot *slot;
44         struct object_request *next;
45 };
46
47 struct alternates_request {
48         struct walker *walker;
49         const char *base;
50         char *url;
51         struct strbuf *buffer;
52         struct active_request_slot *slot;
53         int http_specific;
54 };
55
56 struct walker_data {
57         const char *url;
58         int got_alternates;
59         struct alt_base *alt;
60         struct curl_slist *no_pragma_header;
61 };
62
63 static struct object_request *object_queue_head;
64
65 static size_t fwrite_sha1_file(void *ptr, size_t eltsize, size_t nmemb,
66                                void *data)
67 {
68         unsigned char expn[4096];
69         size_t size = eltsize * nmemb;
70         int posn = 0;
71         struct object_request *obj_req = (struct object_request *)data;
72         do {
73                 ssize_t retval = xwrite(obj_req->local,
74                                        (char *) ptr + posn, size - posn);
75                 if (retval < 0)
76                         return posn;
77                 posn += retval;
78         } while (posn < size);
79
80         obj_req->stream.avail_in = size;
81         obj_req->stream.next_in = ptr;
82         do {
83                 obj_req->stream.next_out = expn;
84                 obj_req->stream.avail_out = sizeof(expn);
85                 obj_req->zret = git_inflate(&obj_req->stream, Z_SYNC_FLUSH);
86                 git_SHA1_Update(&obj_req->c, expn,
87                             sizeof(expn) - obj_req->stream.avail_out);
88         } while (obj_req->stream.avail_in && obj_req->zret == Z_OK);
89         data_received++;
90         return size;
91 }
92
93 static void fetch_alternates(struct walker *walker, const char *base);
94
95 static void process_object_response(void *callback_data);
96
97 static void start_object_request(struct walker *walker,
98                                  struct object_request *obj_req)
99 {
100         char *hex = sha1_to_hex(obj_req->sha1);
101         char prevfile[PATH_MAX];
102         char *url;
103         char *posn;
104         int prevlocal;
105         unsigned char prev_buf[PREV_BUF_SIZE];
106         ssize_t prev_read = 0;
107         long prev_posn = 0;
108         char range[RANGE_HEADER_SIZE];
109         struct curl_slist *range_header = NULL;
110         struct active_request_slot *slot;
111         struct walker_data *data = walker->data;
112
113         snprintf(prevfile, sizeof(prevfile), "%s.prev", obj_req->filename);
114         unlink_or_warn(prevfile);
115         rename(obj_req->tmpfile, prevfile);
116         unlink_or_warn(obj_req->tmpfile);
117
118         if (obj_req->local != -1)
119                 error("fd leakage in start: %d", obj_req->local);
120         obj_req->local = open(obj_req->tmpfile,
121                               O_WRONLY | O_CREAT | O_EXCL, 0666);
122         /* This could have failed due to the "lazy directory creation";
123          * try to mkdir the last path component.
124          */
125         if (obj_req->local < 0 && errno == ENOENT) {
126                 char *dir = strrchr(obj_req->tmpfile, '/');
127                 if (dir) {
128                         *dir = 0;
129                         mkdir(obj_req->tmpfile, 0777);
130                         *dir = '/';
131                 }
132                 obj_req->local = open(obj_req->tmpfile,
133                                       O_WRONLY | O_CREAT | O_EXCL, 0666);
134         }
135
136         if (obj_req->local < 0) {
137                 obj_req->state = ABORTED;
138                 error("Couldn't create temporary file %s for %s: %s",
139                       obj_req->tmpfile, obj_req->filename, strerror(errno));
140                 return;
141         }
142
143         memset(&obj_req->stream, 0, sizeof(obj_req->stream));
144
145         git_inflate_init(&obj_req->stream);
146
147         git_SHA1_Init(&obj_req->c);
148
149         url = xmalloc(strlen(obj_req->repo->base) + 51);
150         obj_req->url = xmalloc(strlen(obj_req->repo->base) + 51);
151         strcpy(url, obj_req->repo->base);
152         posn = url + strlen(obj_req->repo->base);
153         strcpy(posn, "/objects/");
154         posn += 9;
155         memcpy(posn, hex, 2);
156         posn += 2;
157         *(posn++) = '/';
158         strcpy(posn, hex + 2);
159         strcpy(obj_req->url, url);
160
161         /* If a previous temp file is present, process what was already
162            fetched. */
163         prevlocal = open(prevfile, O_RDONLY);
164         if (prevlocal != -1) {
165                 do {
166                         prev_read = xread(prevlocal, prev_buf, PREV_BUF_SIZE);
167                         if (prev_read>0) {
168                                 if (fwrite_sha1_file(prev_buf,
169                                                      1,
170                                                      prev_read,
171                                                      obj_req) == prev_read) {
172                                         prev_posn += prev_read;
173                                 } else {
174                                         prev_read = -1;
175                                 }
176                         }
177                 } while (prev_read > 0);
178                 close(prevlocal);
179         }
180         unlink_or_warn(prevfile);
181
182         /* Reset inflate/SHA1 if there was an error reading the previous temp
183            file; also rewind to the beginning of the local file. */
184         if (prev_read == -1) {
185                 memset(&obj_req->stream, 0, sizeof(obj_req->stream));
186                 git_inflate_init(&obj_req->stream);
187                 git_SHA1_Init(&obj_req->c);
188                 if (prev_posn>0) {
189                         prev_posn = 0;
190                         lseek(obj_req->local, 0, SEEK_SET);
191                         ftruncate(obj_req->local, 0);
192                 }
193         }
194
195         slot = get_active_slot();
196         slot->callback_func = process_object_response;
197         slot->callback_data = obj_req;
198         obj_req->slot = slot;
199
200         curl_easy_setopt(slot->curl, CURLOPT_FILE, obj_req);
201         curl_easy_setopt(slot->curl, CURLOPT_WRITEFUNCTION, fwrite_sha1_file);
202         curl_easy_setopt(slot->curl, CURLOPT_ERRORBUFFER, obj_req->errorstr);
203         curl_easy_setopt(slot->curl, CURLOPT_URL, url);
204         curl_easy_setopt(slot->curl, CURLOPT_HTTPHEADER, data->no_pragma_header);
205
206         /* If we have successfully processed data from a previous fetch
207            attempt, only fetch the data we don't already have. */
208         if (prev_posn>0) {
209                 if (walker->get_verbosely)
210                         fprintf(stderr,
211                                 "Resuming fetch of object %s at byte %ld\n",
212                                 hex, prev_posn);
213                 sprintf(range, "Range: bytes=%ld-", prev_posn);
214                 range_header = curl_slist_append(range_header, range);
215                 curl_easy_setopt(slot->curl,
216                                  CURLOPT_HTTPHEADER, range_header);
217         }
218
219         /* Try to get the request started, abort the request on error */
220         obj_req->state = ACTIVE;
221         if (!start_active_slot(slot)) {
222                 obj_req->state = ABORTED;
223                 obj_req->slot = NULL;
224                 close(obj_req->local); obj_req->local = -1;
225                 free(obj_req->url);
226                 return;
227         }
228 }
229
230 static void finish_object_request(struct object_request *obj_req)
231 {
232         struct stat st;
233
234         close(obj_req->local); obj_req->local = -1;
235
236         if (obj_req->http_code == 416) {
237                 fprintf(stderr, "Warning: requested range invalid; we may already have all the data.\n");
238         } else if (obj_req->curl_result != CURLE_OK) {
239                 if (stat(obj_req->tmpfile, &st) == 0)
240                         if (st.st_size == 0)
241                                 unlink_or_warn(obj_req->tmpfile);
242                 return;
243         }
244
245         git_inflate_end(&obj_req->stream);
246         git_SHA1_Final(obj_req->real_sha1, &obj_req->c);
247         if (obj_req->zret != Z_STREAM_END) {
248                 unlink_or_warn(obj_req->tmpfile);
249                 return;
250         }
251         if (hashcmp(obj_req->sha1, obj_req->real_sha1)) {
252                 unlink_or_warn(obj_req->tmpfile);
253                 return;
254         }
255         obj_req->rename =
256                 move_temp_to_file(obj_req->tmpfile, obj_req->filename);
257
258         if (obj_req->rename == 0)
259                 walker_say(obj_req->walker, "got %s\n", sha1_to_hex(obj_req->sha1));
260 }
261
262 static void process_object_response(void *callback_data)
263 {
264         struct object_request *obj_req =
265                 (struct object_request *)callback_data;
266         struct walker *walker = obj_req->walker;
267         struct walker_data *data = walker->data;
268         struct alt_base *alt = data->alt;
269
270         obj_req->curl_result = obj_req->slot->curl_result;
271         obj_req->http_code = obj_req->slot->http_code;
272         obj_req->slot = NULL;
273         obj_req->state = COMPLETE;
274
275         /* Use alternates if necessary */
276         if (missing_target(obj_req)) {
277                 fetch_alternates(walker, alt->base);
278                 if (obj_req->repo->next != NULL) {
279                         obj_req->repo =
280                                 obj_req->repo->next;
281                         close(obj_req->local);
282                         obj_req->local = -1;
283                         start_object_request(walker, obj_req);
284                         return;
285                 }
286         }
287
288         finish_object_request(obj_req);
289 }
290
291 static void release_object_request(struct object_request *obj_req)
292 {
293         struct object_request *entry = object_queue_head;
294
295         if (obj_req->local != -1)
296                 error("fd leakage in release: %d", obj_req->local);
297         if (obj_req == object_queue_head) {
298                 object_queue_head = obj_req->next;
299         } else {
300                 while (entry->next != NULL && entry->next != obj_req)
301                         entry = entry->next;
302                 if (entry->next == obj_req)
303                         entry->next = entry->next->next;
304         }
305
306         free(obj_req->url);
307         free(obj_req);
308 }
309
310 #ifdef USE_CURL_MULTI
311 static int fill_active_slot(struct walker *walker)
312 {
313         struct object_request *obj_req;
314
315         for (obj_req = object_queue_head; obj_req; obj_req = obj_req->next) {
316                 if (obj_req->state == WAITING) {
317                         if (has_sha1_file(obj_req->sha1))
318                                 obj_req->state = COMPLETE;
319                         else {
320                                 start_object_request(walker, obj_req);
321                                 return 1;
322                         }
323                 }
324         }
325         return 0;
326 }
327 #endif
328
329 static void prefetch(struct walker *walker, unsigned char *sha1)
330 {
331         struct object_request *newreq;
332         struct object_request *tail;
333         struct walker_data *data = walker->data;
334         char *filename = sha1_file_name(sha1);
335
336         newreq = xmalloc(sizeof(*newreq));
337         newreq->walker = walker;
338         hashcpy(newreq->sha1, sha1);
339         newreq->repo = data->alt;
340         newreq->url = NULL;
341         newreq->local = -1;
342         newreq->state = WAITING;
343         snprintf(newreq->filename, sizeof(newreq->filename), "%s", filename);
344         snprintf(newreq->tmpfile, sizeof(newreq->tmpfile),
345                  "%s.temp", filename);
346         newreq->slot = NULL;
347         newreq->next = NULL;
348
349         if (object_queue_head == NULL) {
350                 object_queue_head = newreq;
351         } else {
352                 tail = object_queue_head;
353                 while (tail->next != NULL) {
354                         tail = tail->next;
355                 }
356                 tail->next = newreq;
357         }
358
359 #ifdef USE_CURL_MULTI
360         fill_active_slots();
361         step_active_slots();
362 #endif
363 }
364
365 static int fetch_index(struct walker *walker, struct alt_base *repo, unsigned char *sha1)
366 {
367         char *hex = sha1_to_hex(sha1);
368         char *filename;
369         char *url;
370         char tmpfile[PATH_MAX];
371         long prev_posn = 0;
372         char range[RANGE_HEADER_SIZE];
373         struct curl_slist *range_header = NULL;
374         struct walker_data *data = walker->data;
375
376         FILE *indexfile;
377         struct active_request_slot *slot;
378         struct slot_results results;
379
380         if (has_pack_index(sha1))
381                 return 0;
382
383         if (walker->get_verbosely)
384                 fprintf(stderr, "Getting index for pack %s\n", hex);
385
386         url = xmalloc(strlen(repo->base) + 64);
387         sprintf(url, "%s/objects/pack/pack-%s.idx", repo->base, hex);
388
389         filename = sha1_pack_index_name(sha1);
390         snprintf(tmpfile, sizeof(tmpfile), "%s.temp", filename);
391         indexfile = fopen(tmpfile, "a");
392         if (!indexfile)
393                 return error("Unable to open local file %s for pack index",
394                              tmpfile);
395
396         slot = get_active_slot();
397         slot->results = &results;
398         curl_easy_setopt(slot->curl, CURLOPT_FILE, indexfile);
399         curl_easy_setopt(slot->curl, CURLOPT_WRITEFUNCTION, fwrite);
400         curl_easy_setopt(slot->curl, CURLOPT_URL, url);
401         curl_easy_setopt(slot->curl, CURLOPT_HTTPHEADER, data->no_pragma_header);
402         slot->local = indexfile;
403
404         /* If there is data present from a previous transfer attempt,
405            resume where it left off */
406         prev_posn = ftell(indexfile);
407         if (prev_posn>0) {
408                 if (walker->get_verbosely)
409                         fprintf(stderr,
410                                 "Resuming fetch of index for pack %s at byte %ld\n",
411                                 hex, prev_posn);
412                 sprintf(range, "Range: bytes=%ld-", prev_posn);
413                 range_header = curl_slist_append(range_header, range);
414                 curl_easy_setopt(slot->curl, CURLOPT_HTTPHEADER, range_header);
415         }
416
417         if (start_active_slot(slot)) {
418                 run_active_slot(slot);
419                 if (results.curl_result != CURLE_OK) {
420                         fclose(indexfile);
421                         return error("Unable to get pack index %s\n%s", url,
422                                      curl_errorstr);
423                 }
424         } else {
425                 fclose(indexfile);
426                 return error("Unable to start request");
427         }
428
429         fclose(indexfile);
430
431         return move_temp_to_file(tmpfile, filename);
432 }
433
434 static int setup_index(struct walker *walker, struct alt_base *repo, unsigned char *sha1)
435 {
436         struct packed_git *new_pack;
437         if (has_pack_file(sha1))
438                 return 0; /* don't list this as something we can get */
439
440         if (fetch_index(walker, repo, sha1))
441                 return -1;
442
443         new_pack = parse_pack_index(sha1);
444         if (!new_pack)
445                 return -1; /* parse_pack_index() already issued error message */
446         new_pack->next = repo->packs;
447         repo->packs = new_pack;
448         return 0;
449 }
450
451 static void process_alternates_response(void *callback_data)
452 {
453         struct alternates_request *alt_req =
454                 (struct alternates_request *)callback_data;
455         struct walker *walker = alt_req->walker;
456         struct walker_data *cdata = walker->data;
457         struct active_request_slot *slot = alt_req->slot;
458         struct alt_base *tail = cdata->alt;
459         const char *base = alt_req->base;
460         static const char null_byte = '\0';
461         char *data;
462         int i = 0;
463
464         if (alt_req->http_specific) {
465                 if (slot->curl_result != CURLE_OK ||
466                     !alt_req->buffer->len) {
467
468                         /* Try reusing the slot to get non-http alternates */
469                         alt_req->http_specific = 0;
470                         sprintf(alt_req->url, "%s/objects/info/alternates",
471                                 base);
472                         curl_easy_setopt(slot->curl, CURLOPT_URL,
473                                          alt_req->url);
474                         active_requests++;
475                         slot->in_use = 1;
476                         if (slot->finished != NULL)
477                                 (*slot->finished) = 0;
478                         if (!start_active_slot(slot)) {
479                                 cdata->got_alternates = -1;
480                                 slot->in_use = 0;
481                                 if (slot->finished != NULL)
482                                         (*slot->finished) = 1;
483                         }
484                         return;
485                 }
486         } else if (slot->curl_result != CURLE_OK) {
487                 if (!missing_target(slot)) {
488                         cdata->got_alternates = -1;
489                         return;
490                 }
491         }
492
493         fwrite_buffer(&null_byte, 1, 1, alt_req->buffer);
494         alt_req->buffer->len--;
495         data = alt_req->buffer->buf;
496
497         while (i < alt_req->buffer->len) {
498                 int posn = i;
499                 while (posn < alt_req->buffer->len && data[posn] != '\n')
500                         posn++;
501                 if (data[posn] == '\n') {
502                         int okay = 0;
503                         int serverlen = 0;
504                         struct alt_base *newalt;
505                         char *target = NULL;
506                         if (data[i] == '/') {
507                                 /* This counts
508                                  * http://git.host/pub/scm/linux.git/
509                                  * -----------here^
510                                  * so memcpy(dst, base, serverlen) will
511                                  * copy up to "...git.host".
512                                  */
513                                 const char *colon_ss = strstr(base,"://");
514                                 if (colon_ss) {
515                                         serverlen = (strchr(colon_ss + 3, '/')
516                                                      - base);
517                                         okay = 1;
518                                 }
519                         } else if (!memcmp(data + i, "../", 3)) {
520                                 /* Relative URL; chop the corresponding
521                                  * number of subpath from base (and ../
522                                  * from data), and concatenate the result.
523                                  *
524                                  * The code first drops ../ from data, and
525                                  * then drops one ../ from data and one path
526                                  * from base.  IOW, one extra ../ is dropped
527                                  * from data than path is dropped from base.
528                                  *
529                                  * This is not wrong.  The alternate in
530                                  *     http://git.host/pub/scm/linux.git/
531                                  * to borrow from
532                                  *     http://git.host/pub/scm/linus.git/
533                                  * is ../../linus.git/objects/.  You need
534                                  * two ../../ to borrow from your direct
535                                  * neighbour.
536                                  */
537                                 i += 3;
538                                 serverlen = strlen(base);
539                                 while (i + 2 < posn &&
540                                        !memcmp(data + i, "../", 3)) {
541                                         do {
542                                                 serverlen--;
543                                         } while (serverlen &&
544                                                  base[serverlen - 1] != '/');
545                                         i += 3;
546                                 }
547                                 /* If the server got removed, give up. */
548                                 okay = strchr(base, ':') - base + 3 <
549                                         serverlen;
550                         } else if (alt_req->http_specific) {
551                                 char *colon = strchr(data + i, ':');
552                                 char *slash = strchr(data + i, '/');
553                                 if (colon && slash && colon < data + posn &&
554                                     slash < data + posn && colon < slash) {
555                                         okay = 1;
556                                 }
557                         }
558                         /* skip "objects\n" at end */
559                         if (okay) {
560                                 target = xmalloc(serverlen + posn - i - 6);
561                                 memcpy(target, base, serverlen);
562                                 memcpy(target + serverlen, data + i,
563                                        posn - i - 7);
564                                 target[serverlen + posn - i - 7] = 0;
565                                 if (walker->get_verbosely)
566                                         fprintf(stderr,
567                                                 "Also look at %s\n", target);
568                                 newalt = xmalloc(sizeof(*newalt));
569                                 newalt->next = NULL;
570                                 newalt->base = target;
571                                 newalt->got_indices = 0;
572                                 newalt->packs = NULL;
573
574                                 while (tail->next != NULL)
575                                         tail = tail->next;
576                                 tail->next = newalt;
577                         }
578                 }
579                 i = posn + 1;
580         }
581
582         cdata->got_alternates = 1;
583 }
584
585 static void fetch_alternates(struct walker *walker, const char *base)
586 {
587         struct strbuf buffer = STRBUF_INIT;
588         char *url;
589         struct active_request_slot *slot;
590         struct alternates_request alt_req;
591         struct walker_data *cdata = walker->data;
592
593         /* If another request has already started fetching alternates,
594            wait for them to arrive and return to processing this request's
595            curl message */
596 #ifdef USE_CURL_MULTI
597         while (cdata->got_alternates == 0) {
598                 step_active_slots();
599         }
600 #endif
601
602         /* Nothing to do if they've already been fetched */
603         if (cdata->got_alternates == 1)
604                 return;
605
606         /* Start the fetch */
607         cdata->got_alternates = 0;
608
609         if (walker->get_verbosely)
610                 fprintf(stderr, "Getting alternates list for %s\n", base);
611
612         url = xmalloc(strlen(base) + 31);
613         sprintf(url, "%s/objects/info/http-alternates", base);
614
615         /* Use a callback to process the result, since another request
616            may fail and need to have alternates loaded before continuing */
617         slot = get_active_slot();
618         slot->callback_func = process_alternates_response;
619         alt_req.walker = walker;
620         slot->callback_data = &alt_req;
621
622         curl_easy_setopt(slot->curl, CURLOPT_FILE, &buffer);
623         curl_easy_setopt(slot->curl, CURLOPT_WRITEFUNCTION, fwrite_buffer);
624         curl_easy_setopt(slot->curl, CURLOPT_URL, url);
625
626         alt_req.base = base;
627         alt_req.url = url;
628         alt_req.buffer = &buffer;
629         alt_req.http_specific = 1;
630         alt_req.slot = slot;
631
632         if (start_active_slot(slot))
633                 run_active_slot(slot);
634         else
635                 cdata->got_alternates = -1;
636
637         strbuf_release(&buffer);
638         free(url);
639 }
640
641 static int fetch_indices(struct walker *walker, struct alt_base *repo)
642 {
643         unsigned char sha1[20];
644         char *url;
645         struct strbuf buffer = STRBUF_INIT;
646         char *data;
647         int i = 0;
648         int ret = 0;
649
650         struct active_request_slot *slot;
651         struct slot_results results;
652
653         if (repo->got_indices)
654                 return 0;
655
656         if (walker->get_verbosely)
657                 fprintf(stderr, "Getting pack list for %s\n", repo->base);
658
659         url = xmalloc(strlen(repo->base) + 21);
660         sprintf(url, "%s/objects/info/packs", repo->base);
661
662         slot = get_active_slot();
663         slot->results = &results;
664         curl_easy_setopt(slot->curl, CURLOPT_FILE, &buffer);
665         curl_easy_setopt(slot->curl, CURLOPT_WRITEFUNCTION, fwrite_buffer);
666         curl_easy_setopt(slot->curl, CURLOPT_URL, url);
667         curl_easy_setopt(slot->curl, CURLOPT_HTTPHEADER, NULL);
668         if (start_active_slot(slot)) {
669                 run_active_slot(slot);
670                 if (results.curl_result != CURLE_OK) {
671                         if (missing_target(&results)) {
672                                 repo->got_indices = 1;
673                                 goto cleanup;
674                         } else {
675                                 repo->got_indices = 0;
676                                 ret = error("%s", curl_errorstr);
677                                 goto cleanup;
678                         }
679                 }
680         } else {
681                 repo->got_indices = 0;
682                 ret = error("Unable to start request");
683                 goto cleanup;
684         }
685
686         data = buffer.buf;
687         while (i < buffer.len) {
688                 switch (data[i]) {
689                 case 'P':
690                         i++;
691                         if (i + 52 <= buffer.len &&
692                             !prefixcmp(data + i, " pack-") &&
693                             !prefixcmp(data + i + 46, ".pack\n")) {
694                                 get_sha1_hex(data + i + 6, sha1);
695                                 setup_index(walker, repo, sha1);
696                                 i += 51;
697                                 break;
698                         }
699                 default:
700                         while (i < buffer.len && data[i] != '\n')
701                                 i++;
702                 }
703                 i++;
704         }
705
706         repo->got_indices = 1;
707 cleanup:
708         strbuf_release(&buffer);
709         free(url);
710         return ret;
711 }
712
713 static int fetch_pack(struct walker *walker, struct alt_base *repo, unsigned char *sha1)
714 {
715         char *url;
716         struct packed_git *target;
717         struct packed_git **lst;
718         FILE *packfile;
719         char *filename;
720         char tmpfile[PATH_MAX];
721         int ret;
722         long prev_posn = 0;
723         char range[RANGE_HEADER_SIZE];
724         struct curl_slist *range_header = NULL;
725         struct walker_data *data = walker->data;
726
727         struct active_request_slot *slot;
728         struct slot_results results;
729
730         if (fetch_indices(walker, repo))
731                 return -1;
732         target = find_sha1_pack(sha1, repo->packs);
733         if (!target)
734                 return -1;
735
736         if (walker->get_verbosely) {
737                 fprintf(stderr, "Getting pack %s\n",
738                         sha1_to_hex(target->sha1));
739                 fprintf(stderr, " which contains %s\n",
740                         sha1_to_hex(sha1));
741         }
742
743         url = xmalloc(strlen(repo->base) + 65);
744         sprintf(url, "%s/objects/pack/pack-%s.pack",
745                 repo->base, sha1_to_hex(target->sha1));
746
747         filename = sha1_pack_name(target->sha1);
748         snprintf(tmpfile, sizeof(tmpfile), "%s.temp", filename);
749         packfile = fopen(tmpfile, "a");
750         if (!packfile)
751                 return error("Unable to open local file %s for pack",
752                              tmpfile);
753
754         slot = get_active_slot();
755         slot->results = &results;
756         curl_easy_setopt(slot->curl, CURLOPT_FILE, packfile);
757         curl_easy_setopt(slot->curl, CURLOPT_WRITEFUNCTION, fwrite);
758         curl_easy_setopt(slot->curl, CURLOPT_URL, url);
759         curl_easy_setopt(slot->curl, CURLOPT_HTTPHEADER, data->no_pragma_header);
760         slot->local = packfile;
761
762         /* If there is data present from a previous transfer attempt,
763            resume where it left off */
764         prev_posn = ftell(packfile);
765         if (prev_posn>0) {
766                 if (walker->get_verbosely)
767                         fprintf(stderr,
768                                 "Resuming fetch of pack %s at byte %ld\n",
769                                 sha1_to_hex(target->sha1), prev_posn);
770                 sprintf(range, "Range: bytes=%ld-", prev_posn);
771                 range_header = curl_slist_append(range_header, range);
772                 curl_easy_setopt(slot->curl, CURLOPT_HTTPHEADER, range_header);
773         }
774
775         if (start_active_slot(slot)) {
776                 run_active_slot(slot);
777                 if (results.curl_result != CURLE_OK) {
778                         fclose(packfile);
779                         return error("Unable to get pack file %s\n%s", url,
780                                      curl_errorstr);
781                 }
782         } else {
783                 fclose(packfile);
784                 return error("Unable to start request");
785         }
786
787         target->pack_size = ftell(packfile);
788         fclose(packfile);
789
790         ret = move_temp_to_file(tmpfile, filename);
791         if (ret)
792                 return ret;
793
794         lst = &repo->packs;
795         while (*lst != target)
796                 lst = &((*lst)->next);
797         *lst = (*lst)->next;
798
799         if (verify_pack(target))
800                 return -1;
801         install_packed_git(target);
802
803         return 0;
804 }
805
806 static void abort_object_request(struct object_request *obj_req)
807 {
808         if (obj_req->local >= 0) {
809                 close(obj_req->local);
810                 obj_req->local = -1;
811         }
812         unlink_or_warn(obj_req->tmpfile);
813         if (obj_req->slot) {
814                 release_active_slot(obj_req->slot);
815                 obj_req->slot = NULL;
816         }
817         release_object_request(obj_req);
818 }
819
820 static int fetch_object(struct walker *walker, struct alt_base *repo, unsigned char *sha1)
821 {
822         char *hex = sha1_to_hex(sha1);
823         int ret = 0;
824         struct object_request *obj_req = object_queue_head;
825
826         while (obj_req != NULL && hashcmp(obj_req->sha1, sha1))
827                 obj_req = obj_req->next;
828         if (obj_req == NULL)
829                 return error("Couldn't find request for %s in the queue", hex);
830
831         if (has_sha1_file(obj_req->sha1)) {
832                 abort_object_request(obj_req);
833                 return 0;
834         }
835
836 #ifdef USE_CURL_MULTI
837         while (obj_req->state == WAITING) {
838                 step_active_slots();
839         }
840 #else
841         start_object_request(walker, obj_req);
842 #endif
843
844         while (obj_req->state == ACTIVE) {
845                 run_active_slot(obj_req->slot);
846         }
847         if (obj_req->local != -1) {
848                 close(obj_req->local); obj_req->local = -1;
849         }
850
851         if (obj_req->state == ABORTED) {
852                 ret = error("Request for %s aborted", hex);
853         } else if (obj_req->curl_result != CURLE_OK &&
854                    obj_req->http_code != 416) {
855                 if (missing_target(obj_req))
856                         ret = -1; /* Be silent, it is probably in a pack. */
857                 else
858                         ret = error("%s (curl_result = %d, http_code = %ld, sha1 = %s)",
859                                     obj_req->errorstr, obj_req->curl_result,
860                                     obj_req->http_code, hex);
861         } else if (obj_req->zret != Z_STREAM_END) {
862                 walker->corrupt_object_found++;
863                 ret = error("File %s (%s) corrupt", hex, obj_req->url);
864         } else if (hashcmp(obj_req->sha1, obj_req->real_sha1)) {
865                 ret = error("File %s has bad hash", hex);
866         } else if (obj_req->rename < 0) {
867                 ret = error("unable to write sha1 filename %s",
868                             obj_req->filename);
869         }
870
871         release_object_request(obj_req);
872         return ret;
873 }
874
875 static int fetch(struct walker *walker, unsigned char *sha1)
876 {
877         struct walker_data *data = walker->data;
878         struct alt_base *altbase = data->alt;
879
880         if (!fetch_object(walker, altbase, sha1))
881                 return 0;
882         while (altbase) {
883                 if (!fetch_pack(walker, altbase, sha1))
884                         return 0;
885                 fetch_alternates(walker, data->alt->base);
886                 altbase = altbase->next;
887         }
888         return error("Unable to find %s under %s", sha1_to_hex(sha1),
889                      data->alt->base);
890 }
891
892 static int fetch_ref(struct walker *walker, struct ref *ref)
893 {
894         struct walker_data *data = walker->data;
895         return http_fetch_ref(data->alt->base, ref);
896 }
897
898 static void cleanup(struct walker *walker)
899 {
900         struct walker_data *data = walker->data;
901         http_cleanup();
902
903         curl_slist_free_all(data->no_pragma_header);
904 }
905
906 struct walker *get_http_walker(const char *url, struct remote *remote)
907 {
908         char *s;
909         struct walker_data *data = xmalloc(sizeof(struct walker_data));
910         struct walker *walker = xmalloc(sizeof(struct walker));
911
912         http_init(remote);
913
914         data->no_pragma_header = curl_slist_append(NULL, "Pragma:");
915
916         data->alt = xmalloc(sizeof(*data->alt));
917         data->alt->base = xmalloc(strlen(url) + 1);
918         strcpy(data->alt->base, url);
919         for (s = data->alt->base + strlen(data->alt->base) - 1; *s == '/'; --s)
920                 *s = 0;
921
922         data->alt->got_indices = 0;
923         data->alt->packs = NULL;
924         data->alt->next = NULL;
925         data->got_alternates = -1;
926
927         walker->corrupt_object_found = 0;
928         walker->fetch = fetch;
929         walker->fetch_ref = fetch_ref;
930         walker->prefetch = prefetch;
931         walker->cleanup = cleanup;
932         walker->data = data;
933
934 #ifdef USE_CURL_MULTI
935         add_fill_function(walker, (int (*)(void *)) fill_active_slot);
936 #endif
937
938         return walker;
939 }