Merge branch 'lt/maint-wrap-zlib' into maint
[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(prevfile);
115         rename(obj_req->tmpfile, prevfile);
116         unlink(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(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         fchmod(obj_req->local, 0444);
235         close(obj_req->local); obj_req->local = -1;
236
237         if (obj_req->http_code == 416) {
238                 fprintf(stderr, "Warning: requested range invalid; we may already have all the data.\n");
239         } else if (obj_req->curl_result != CURLE_OK) {
240                 if (stat(obj_req->tmpfile, &st) == 0)
241                         if (st.st_size == 0)
242                                 unlink(obj_req->tmpfile);
243                 return;
244         }
245
246         git_inflate_end(&obj_req->stream);
247         git_SHA1_Final(obj_req->real_sha1, &obj_req->c);
248         if (obj_req->zret != Z_STREAM_END) {
249                 unlink(obj_req->tmpfile);
250                 return;
251         }
252         if (hashcmp(obj_req->sha1, obj_req->real_sha1)) {
253                 unlink(obj_req->tmpfile);
254                 return;
255         }
256         obj_req->rename =
257                 move_temp_to_file(obj_req->tmpfile, obj_req->filename);
258
259         if (obj_req->rename == 0)
260                 walker_say(obj_req->walker, "got %s\n", sha1_to_hex(obj_req->sha1));
261 }
262
263 static void process_object_response(void *callback_data)
264 {
265         struct object_request *obj_req =
266                 (struct object_request *)callback_data;
267         struct walker *walker = obj_req->walker;
268         struct walker_data *data = walker->data;
269         struct alt_base *alt = data->alt;
270
271         obj_req->curl_result = obj_req->slot->curl_result;
272         obj_req->http_code = obj_req->slot->http_code;
273         obj_req->slot = NULL;
274         obj_req->state = COMPLETE;
275
276         /* Use alternates if necessary */
277         if (missing_target(obj_req)) {
278                 fetch_alternates(walker, alt->base);
279                 if (obj_req->repo->next != NULL) {
280                         obj_req->repo =
281                                 obj_req->repo->next;
282                         close(obj_req->local);
283                         obj_req->local = -1;
284                         start_object_request(walker, obj_req);
285                         return;
286                 }
287         }
288
289         finish_object_request(obj_req);
290 }
291
292 static void release_object_request(struct object_request *obj_req)
293 {
294         struct object_request *entry = object_queue_head;
295
296         if (obj_req->local != -1)
297                 error("fd leakage in release: %d", obj_req->local);
298         if (obj_req == object_queue_head) {
299                 object_queue_head = obj_req->next;
300         } else {
301                 while (entry->next != NULL && entry->next != obj_req)
302                         entry = entry->next;
303                 if (entry->next == obj_req)
304                         entry->next = entry->next->next;
305         }
306
307         free(obj_req->url);
308         free(obj_req);
309 }
310
311 #ifdef USE_CURL_MULTI
312 static int fill_active_slot(struct walker *walker)
313 {
314         struct object_request *obj_req;
315
316         for (obj_req = object_queue_head; obj_req; obj_req = obj_req->next) {
317                 if (obj_req->state == WAITING) {
318                         if (has_sha1_file(obj_req->sha1))
319                                 obj_req->state = COMPLETE;
320                         else {
321                                 start_object_request(walker, obj_req);
322                                 return 1;
323                         }
324                 }
325         }
326         return 0;
327 }
328 #endif
329
330 static void prefetch(struct walker *walker, unsigned char *sha1)
331 {
332         struct object_request *newreq;
333         struct object_request *tail;
334         struct walker_data *data = walker->data;
335         char *filename = sha1_file_name(sha1);
336
337         newreq = xmalloc(sizeof(*newreq));
338         newreq->walker = walker;
339         hashcpy(newreq->sha1, sha1);
340         newreq->repo = data->alt;
341         newreq->url = NULL;
342         newreq->local = -1;
343         newreq->state = WAITING;
344         snprintf(newreq->filename, sizeof(newreq->filename), "%s", filename);
345         snprintf(newreq->tmpfile, sizeof(newreq->tmpfile),
346                  "%s.temp", filename);
347         newreq->slot = NULL;
348         newreq->next = NULL;
349
350         if (object_queue_head == NULL) {
351                 object_queue_head = newreq;
352         } else {
353                 tail = object_queue_head;
354                 while (tail->next != NULL) {
355                         tail = tail->next;
356                 }
357                 tail->next = newreq;
358         }
359
360 #ifdef USE_CURL_MULTI
361         fill_active_slots();
362         step_active_slots();
363 #endif
364 }
365
366 static int fetch_index(struct walker *walker, struct alt_base *repo, unsigned char *sha1)
367 {
368         char *hex = sha1_to_hex(sha1);
369         char *filename;
370         char *url;
371         char tmpfile[PATH_MAX];
372         long prev_posn = 0;
373         char range[RANGE_HEADER_SIZE];
374         struct curl_slist *range_header = NULL;
375         struct walker_data *data = walker->data;
376
377         FILE *indexfile;
378         struct active_request_slot *slot;
379         struct slot_results results;
380
381         if (has_pack_index(sha1))
382                 return 0;
383
384         if (walker->get_verbosely)
385                 fprintf(stderr, "Getting index for pack %s\n", hex);
386
387         url = xmalloc(strlen(repo->base) + 64);
388         sprintf(url, "%s/objects/pack/pack-%s.idx", repo->base, hex);
389
390         filename = sha1_pack_index_name(sha1);
391         snprintf(tmpfile, sizeof(tmpfile), "%s.temp", filename);
392         indexfile = fopen(tmpfile, "a");
393         if (!indexfile)
394                 return error("Unable to open local file %s for pack index",
395                              tmpfile);
396
397         slot = get_active_slot();
398         slot->results = &results;
399         curl_easy_setopt(slot->curl, CURLOPT_FILE, indexfile);
400         curl_easy_setopt(slot->curl, CURLOPT_WRITEFUNCTION, fwrite);
401         curl_easy_setopt(slot->curl, CURLOPT_URL, url);
402         curl_easy_setopt(slot->curl, CURLOPT_HTTPHEADER, data->no_pragma_header);
403         slot->local = indexfile;
404
405         /* If there is data present from a previous transfer attempt,
406            resume where it left off */
407         prev_posn = ftell(indexfile);
408         if (prev_posn>0) {
409                 if (walker->get_verbosely)
410                         fprintf(stderr,
411                                 "Resuming fetch of index for pack %s at byte %ld\n",
412                                 hex, prev_posn);
413                 sprintf(range, "Range: bytes=%ld-", prev_posn);
414                 range_header = curl_slist_append(range_header, range);
415                 curl_easy_setopt(slot->curl, CURLOPT_HTTPHEADER, range_header);
416         }
417
418         if (start_active_slot(slot)) {
419                 run_active_slot(slot);
420                 if (results.curl_result != CURLE_OK) {
421                         fclose(indexfile);
422                         return error("Unable to get pack index %s\n%s", url,
423                                      curl_errorstr);
424                 }
425         } else {
426                 fclose(indexfile);
427                 return error("Unable to start request");
428         }
429
430         fclose(indexfile);
431
432         return move_temp_to_file(tmpfile, filename);
433 }
434
435 static int setup_index(struct walker *walker, struct alt_base *repo, unsigned char *sha1)
436 {
437         struct packed_git *new_pack;
438         if (has_pack_file(sha1))
439                 return 0; /* don't list this as something we can get */
440
441         if (fetch_index(walker, repo, sha1))
442                 return -1;
443
444         new_pack = parse_pack_index(sha1);
445         if (!new_pack)
446                 return -1; /* parse_pack_index() already issued error message */
447         new_pack->next = repo->packs;
448         repo->packs = new_pack;
449         return 0;
450 }
451
452 static void process_alternates_response(void *callback_data)
453 {
454         struct alternates_request *alt_req =
455                 (struct alternates_request *)callback_data;
456         struct walker *walker = alt_req->walker;
457         struct walker_data *cdata = walker->data;
458         struct active_request_slot *slot = alt_req->slot;
459         struct alt_base *tail = cdata->alt;
460         const char *base = alt_req->base;
461         static const char null_byte = '\0';
462         char *data;
463         int i = 0;
464
465         if (alt_req->http_specific) {
466                 if (slot->curl_result != CURLE_OK ||
467                     !alt_req->buffer->len) {
468
469                         /* Try reusing the slot to get non-http alternates */
470                         alt_req->http_specific = 0;
471                         sprintf(alt_req->url, "%s/objects/info/alternates",
472                                 base);
473                         curl_easy_setopt(slot->curl, CURLOPT_URL,
474                                          alt_req->url);
475                         active_requests++;
476                         slot->in_use = 1;
477                         if (slot->finished != NULL)
478                                 (*slot->finished) = 0;
479                         if (!start_active_slot(slot)) {
480                                 cdata->got_alternates = -1;
481                                 slot->in_use = 0;
482                                 if (slot->finished != NULL)
483                                         (*slot->finished) = 1;
484                         }
485                         return;
486                 }
487         } else if (slot->curl_result != CURLE_OK) {
488                 if (!missing_target(slot)) {
489                         cdata->got_alternates = -1;
490                         return;
491                 }
492         }
493
494         fwrite_buffer(&null_byte, 1, 1, alt_req->buffer);
495         alt_req->buffer->len--;
496         data = alt_req->buffer->buf;
497
498         while (i < alt_req->buffer->len) {
499                 int posn = i;
500                 while (posn < alt_req->buffer->len && data[posn] != '\n')
501                         posn++;
502                 if (data[posn] == '\n') {
503                         int okay = 0;
504                         int serverlen = 0;
505                         struct alt_base *newalt;
506                         char *target = NULL;
507                         if (data[i] == '/') {
508                                 /* This counts
509                                  * http://git.host/pub/scm/linux.git/
510                                  * -----------here^
511                                  * so memcpy(dst, base, serverlen) will
512                                  * copy up to "...git.host".
513                                  */
514                                 const char *colon_ss = strstr(base,"://");
515                                 if (colon_ss) {
516                                         serverlen = (strchr(colon_ss + 3, '/')
517                                                      - base);
518                                         okay = 1;
519                                 }
520                         } else if (!memcmp(data + i, "../", 3)) {
521                                 /* Relative URL; chop the corresponding
522                                  * number of subpath from base (and ../
523                                  * from data), and concatenate the result.
524                                  *
525                                  * The code first drops ../ from data, and
526                                  * then drops one ../ from data and one path
527                                  * from base.  IOW, one extra ../ is dropped
528                                  * from data than path is dropped from base.
529                                  *
530                                  * This is not wrong.  The alternate in
531                                  *     http://git.host/pub/scm/linux.git/
532                                  * to borrow from
533                                  *     http://git.host/pub/scm/linus.git/
534                                  * is ../../linus.git/objects/.  You need
535                                  * two ../../ to borrow from your direct
536                                  * neighbour.
537                                  */
538                                 i += 3;
539                                 serverlen = strlen(base);
540                                 while (i + 2 < posn &&
541                                        !memcmp(data + i, "../", 3)) {
542                                         do {
543                                                 serverlen--;
544                                         } while (serverlen &&
545                                                  base[serverlen - 1] != '/');
546                                         i += 3;
547                                 }
548                                 /* If the server got removed, give up. */
549                                 okay = strchr(base, ':') - base + 3 <
550                                         serverlen;
551                         } else if (alt_req->http_specific) {
552                                 char *colon = strchr(data + i, ':');
553                                 char *slash = strchr(data + i, '/');
554                                 if (colon && slash && colon < data + posn &&
555                                     slash < data + posn && colon < slash) {
556                                         okay = 1;
557                                 }
558                         }
559                         /* skip "objects\n" at end */
560                         if (okay) {
561                                 target = xmalloc(serverlen + posn - i - 6);
562                                 memcpy(target, base, serverlen);
563                                 memcpy(target + serverlen, data + i,
564                                        posn - i - 7);
565                                 target[serverlen + posn - i - 7] = 0;
566                                 if (walker->get_verbosely)
567                                         fprintf(stderr,
568                                                 "Also look at %s\n", target);
569                                 newalt = xmalloc(sizeof(*newalt));
570                                 newalt->next = NULL;
571                                 newalt->base = target;
572                                 newalt->got_indices = 0;
573                                 newalt->packs = NULL;
574
575                                 while (tail->next != NULL)
576                                         tail = tail->next;
577                                 tail->next = newalt;
578                         }
579                 }
580                 i = posn + 1;
581         }
582
583         cdata->got_alternates = 1;
584 }
585
586 static void fetch_alternates(struct walker *walker, const char *base)
587 {
588         struct strbuf buffer = STRBUF_INIT;
589         char *url;
590         struct active_request_slot *slot;
591         struct alternates_request alt_req;
592         struct walker_data *cdata = walker->data;
593
594         /* If another request has already started fetching alternates,
595            wait for them to arrive and return to processing this request's
596            curl message */
597 #ifdef USE_CURL_MULTI
598         while (cdata->got_alternates == 0) {
599                 step_active_slots();
600         }
601 #endif
602
603         /* Nothing to do if they've already been fetched */
604         if (cdata->got_alternates == 1)
605                 return;
606
607         /* Start the fetch */
608         cdata->got_alternates = 0;
609
610         if (walker->get_verbosely)
611                 fprintf(stderr, "Getting alternates list for %s\n", base);
612
613         url = xmalloc(strlen(base) + 31);
614         sprintf(url, "%s/objects/info/http-alternates", base);
615
616         /* Use a callback to process the result, since another request
617            may fail and need to have alternates loaded before continuing */
618         slot = get_active_slot();
619         slot->callback_func = process_alternates_response;
620         alt_req.walker = walker;
621         slot->callback_data = &alt_req;
622
623         curl_easy_setopt(slot->curl, CURLOPT_FILE, &buffer);
624         curl_easy_setopt(slot->curl, CURLOPT_WRITEFUNCTION, fwrite_buffer);
625         curl_easy_setopt(slot->curl, CURLOPT_URL, url);
626
627         alt_req.base = base;
628         alt_req.url = url;
629         alt_req.buffer = &buffer;
630         alt_req.http_specific = 1;
631         alt_req.slot = slot;
632
633         if (start_active_slot(slot))
634                 run_active_slot(slot);
635         else
636                 cdata->got_alternates = -1;
637
638         strbuf_release(&buffer);
639         free(url);
640 }
641
642 static int fetch_indices(struct walker *walker, struct alt_base *repo)
643 {
644         unsigned char sha1[20];
645         char *url;
646         struct strbuf buffer = STRBUF_INIT;
647         char *data;
648         int i = 0;
649         int ret = 0;
650
651         struct active_request_slot *slot;
652         struct slot_results results;
653
654         if (repo->got_indices)
655                 return 0;
656
657         if (walker->get_verbosely)
658                 fprintf(stderr, "Getting pack list for %s\n", repo->base);
659
660         url = xmalloc(strlen(repo->base) + 21);
661         sprintf(url, "%s/objects/info/packs", repo->base);
662
663         slot = get_active_slot();
664         slot->results = &results;
665         curl_easy_setopt(slot->curl, CURLOPT_FILE, &buffer);
666         curl_easy_setopt(slot->curl, CURLOPT_WRITEFUNCTION, fwrite_buffer);
667         curl_easy_setopt(slot->curl, CURLOPT_URL, url);
668         curl_easy_setopt(slot->curl, CURLOPT_HTTPHEADER, NULL);
669         if (start_active_slot(slot)) {
670                 run_active_slot(slot);
671                 if (results.curl_result != CURLE_OK) {
672                         if (missing_target(&results)) {
673                                 repo->got_indices = 1;
674                                 goto cleanup;
675                         } else {
676                                 repo->got_indices = 0;
677                                 ret = error("%s", curl_errorstr);
678                                 goto cleanup;
679                         }
680                 }
681         } else {
682                 repo->got_indices = 0;
683                 ret = error("Unable to start request");
684                 goto cleanup;
685         }
686
687         data = buffer.buf;
688         while (i < buffer.len) {
689                 switch (data[i]) {
690                 case 'P':
691                         i++;
692                         if (i + 52 <= buffer.len &&
693                             !prefixcmp(data + i, " pack-") &&
694                             !prefixcmp(data + i + 46, ".pack\n")) {
695                                 get_sha1_hex(data + i + 6, sha1);
696                                 setup_index(walker, repo, sha1);
697                                 i += 51;
698                                 break;
699                         }
700                 default:
701                         while (i < buffer.len && data[i] != '\n')
702                                 i++;
703                 }
704                 i++;
705         }
706
707         repo->got_indices = 1;
708 cleanup:
709         strbuf_release(&buffer);
710         free(url);
711         return ret;
712 }
713
714 static int fetch_pack(struct walker *walker, struct alt_base *repo, unsigned char *sha1)
715 {
716         char *url;
717         struct packed_git *target;
718         struct packed_git **lst;
719         FILE *packfile;
720         char *filename;
721         char tmpfile[PATH_MAX];
722         int ret;
723         long prev_posn = 0;
724         char range[RANGE_HEADER_SIZE];
725         struct curl_slist *range_header = NULL;
726         struct walker_data *data = walker->data;
727
728         struct active_request_slot *slot;
729         struct slot_results results;
730
731         if (fetch_indices(walker, repo))
732                 return -1;
733         target = find_sha1_pack(sha1, repo->packs);
734         if (!target)
735                 return -1;
736
737         if (walker->get_verbosely) {
738                 fprintf(stderr, "Getting pack %s\n",
739                         sha1_to_hex(target->sha1));
740                 fprintf(stderr, " which contains %s\n",
741                         sha1_to_hex(sha1));
742         }
743
744         url = xmalloc(strlen(repo->base) + 65);
745         sprintf(url, "%s/objects/pack/pack-%s.pack",
746                 repo->base, sha1_to_hex(target->sha1));
747
748         filename = sha1_pack_name(target->sha1);
749         snprintf(tmpfile, sizeof(tmpfile), "%s.temp", filename);
750         packfile = fopen(tmpfile, "a");
751         if (!packfile)
752                 return error("Unable to open local file %s for pack",
753                              tmpfile);
754
755         slot = get_active_slot();
756         slot->results = &results;
757         curl_easy_setopt(slot->curl, CURLOPT_FILE, packfile);
758         curl_easy_setopt(slot->curl, CURLOPT_WRITEFUNCTION, fwrite);
759         curl_easy_setopt(slot->curl, CURLOPT_URL, url);
760         curl_easy_setopt(slot->curl, CURLOPT_HTTPHEADER, data->no_pragma_header);
761         slot->local = packfile;
762
763         /* If there is data present from a previous transfer attempt,
764            resume where it left off */
765         prev_posn = ftell(packfile);
766         if (prev_posn>0) {
767                 if (walker->get_verbosely)
768                         fprintf(stderr,
769                                 "Resuming fetch of pack %s at byte %ld\n",
770                                 sha1_to_hex(target->sha1), prev_posn);
771                 sprintf(range, "Range: bytes=%ld-", prev_posn);
772                 range_header = curl_slist_append(range_header, range);
773                 curl_easy_setopt(slot->curl, CURLOPT_HTTPHEADER, range_header);
774         }
775
776         if (start_active_slot(slot)) {
777                 run_active_slot(slot);
778                 if (results.curl_result != CURLE_OK) {
779                         fclose(packfile);
780                         return error("Unable to get pack file %s\n%s", url,
781                                      curl_errorstr);
782                 }
783         } else {
784                 fclose(packfile);
785                 return error("Unable to start request");
786         }
787
788         target->pack_size = ftell(packfile);
789         fclose(packfile);
790
791         ret = move_temp_to_file(tmpfile, filename);
792         if (ret)
793                 return ret;
794
795         lst = &repo->packs;
796         while (*lst != target)
797                 lst = &((*lst)->next);
798         *lst = (*lst)->next;
799
800         if (verify_pack(target))
801                 return -1;
802         install_packed_git(target);
803
804         return 0;
805 }
806
807 static void abort_object_request(struct object_request *obj_req)
808 {
809         if (obj_req->local >= 0) {
810                 close(obj_req->local);
811                 obj_req->local = -1;
812         }
813         unlink(obj_req->tmpfile);
814         if (obj_req->slot) {
815                 release_active_slot(obj_req->slot);
816                 obj_req->slot = NULL;
817         }
818         release_object_request(obj_req);
819 }
820
821 static int fetch_object(struct walker *walker, struct alt_base *repo, unsigned char *sha1)
822 {
823         char *hex = sha1_to_hex(sha1);
824         int ret = 0;
825         struct object_request *obj_req = object_queue_head;
826
827         while (obj_req != NULL && hashcmp(obj_req->sha1, sha1))
828                 obj_req = obj_req->next;
829         if (obj_req == NULL)
830                 return error("Couldn't find request for %s in the queue", hex);
831
832         if (has_sha1_file(obj_req->sha1)) {
833                 abort_object_request(obj_req);
834                 return 0;
835         }
836
837 #ifdef USE_CURL_MULTI
838         while (obj_req->state == WAITING) {
839                 step_active_slots();
840         }
841 #else
842         start_object_request(walker, obj_req);
843 #endif
844
845         while (obj_req->state == ACTIVE) {
846                 run_active_slot(obj_req->slot);
847         }
848         if (obj_req->local != -1) {
849                 close(obj_req->local); obj_req->local = -1;
850         }
851
852         if (obj_req->state == ABORTED) {
853                 ret = error("Request for %s aborted", hex);
854         } else if (obj_req->curl_result != CURLE_OK &&
855                    obj_req->http_code != 416) {
856                 if (missing_target(obj_req))
857                         ret = -1; /* Be silent, it is probably in a pack. */
858                 else
859                         ret = error("%s (curl_result = %d, http_code = %ld, sha1 = %s)",
860                                     obj_req->errorstr, obj_req->curl_result,
861                                     obj_req->http_code, hex);
862         } else if (obj_req->zret != Z_STREAM_END) {
863                 walker->corrupt_object_found++;
864                 ret = error("File %s (%s) corrupt", hex, obj_req->url);
865         } else if (hashcmp(obj_req->sha1, obj_req->real_sha1)) {
866                 ret = error("File %s has bad hash", hex);
867         } else if (obj_req->rename < 0) {
868                 ret = error("unable to write sha1 filename %s",
869                             obj_req->filename);
870         }
871
872         release_object_request(obj_req);
873         return ret;
874 }
875
876 static int fetch(struct walker *walker, unsigned char *sha1)
877 {
878         struct walker_data *data = walker->data;
879         struct alt_base *altbase = data->alt;
880
881         if (!fetch_object(walker, altbase, sha1))
882                 return 0;
883         while (altbase) {
884                 if (!fetch_pack(walker, altbase, sha1))
885                         return 0;
886                 fetch_alternates(walker, data->alt->base);
887                 altbase = altbase->next;
888         }
889         return error("Unable to find %s under %s", sha1_to_hex(sha1),
890                      data->alt->base);
891 }
892
893 static int fetch_ref(struct walker *walker, struct ref *ref)
894 {
895         struct walker_data *data = walker->data;
896         return http_fetch_ref(data->alt->base, ref);
897 }
898
899 static void cleanup(struct walker *walker)
900 {
901         struct walker_data *data = walker->data;
902         http_cleanup();
903
904         curl_slist_free_all(data->no_pragma_header);
905 }
906
907 struct walker *get_http_walker(const char *url, struct remote *remote)
908 {
909         char *s;
910         struct walker_data *data = xmalloc(sizeof(struct walker_data));
911         struct walker *walker = xmalloc(sizeof(struct walker));
912
913         http_init(remote);
914
915         data->no_pragma_header = curl_slist_append(NULL, "Pragma:");
916
917         data->alt = xmalloc(sizeof(*data->alt));
918         data->alt->base = xmalloc(strlen(url) + 1);
919         strcpy(data->alt->base, url);
920         for (s = data->alt->base + strlen(data->alt->base) - 1; *s == '/'; --s)
921                 *s = 0;
922
923         data->alt->got_indices = 0;
924         data->alt->packs = NULL;
925         data->alt->next = NULL;
926         data->got_alternates = -1;
927
928         walker->corrupt_object_found = 0;
929         walker->fetch = fetch;
930         walker->fetch_ref = fetch_ref;
931         walker->prefetch = prefetch;
932         walker->cleanup = cleanup;
933         walker->data = data;
934
935 #ifdef USE_CURL_MULTI
936         add_fill_function(walker, (int (*)(void *)) fill_active_slot);
937 #endif
938
939         return walker;
940 }