Merge branch 'np/delta' into next
[git] / http-fetch.c
1 #include "cache.h"
2 #include "commit.h"
3 #include "pack.h"
4 #include "fetch.h"
5 #include "http.h"
6
7 #define PREV_BUF_SIZE 4096
8 #define RANGE_HEADER_SIZE 30
9
10 static int got_alternates = -1;
11
12 static struct curl_slist *no_pragma_header;
13
14 struct alt_base
15 {
16         char *base;
17         int got_indices;
18         struct packed_git *packs;
19         struct alt_base *next;
20 };
21
22 static struct alt_base *alt = NULL;
23
24 enum object_request_state {
25         WAITING,
26         ABORTED,
27         ACTIVE,
28         COMPLETE,
29 };
30
31 struct object_request
32 {
33         unsigned char sha1[20];
34         struct alt_base *repo;
35         char *url;
36         char filename[PATH_MAX];
37         char tmpfile[PATH_MAX];
38         int local;
39         enum object_request_state state;
40         CURLcode curl_result;
41         char errorstr[CURL_ERROR_SIZE];
42         long http_code;
43         unsigned char real_sha1[20];
44         SHA_CTX c;
45         z_stream stream;
46         int zret;
47         int rename;
48         struct active_request_slot *slot;
49         struct object_request *next;
50 };
51
52 struct alternates_request {
53         char *base;
54         char *url;
55         struct buffer *buffer;
56         struct active_request_slot *slot;
57         int http_specific;
58 };
59
60 static struct object_request *object_queue_head = NULL;
61
62 static size_t fwrite_sha1_file(void *ptr, size_t eltsize, size_t nmemb,
63                                void *data)
64 {
65         unsigned char expn[4096];
66         size_t size = eltsize * nmemb;
67         int posn = 0;
68         struct object_request *obj_req = (struct object_request *)data;
69         do {
70                 ssize_t retval = write(obj_req->local,
71                                        ptr + posn, size - posn);
72                 if (retval < 0)
73                         return posn;
74                 posn += retval;
75         } while (posn < size);
76
77         obj_req->stream.avail_in = size;
78         obj_req->stream.next_in = ptr;
79         do {
80                 obj_req->stream.next_out = expn;
81                 obj_req->stream.avail_out = sizeof(expn);
82                 obj_req->zret = inflate(&obj_req->stream, Z_SYNC_FLUSH);
83                 SHA1_Update(&obj_req->c, expn,
84                             sizeof(expn) - obj_req->stream.avail_out);
85         } while (obj_req->stream.avail_in && obj_req->zret == Z_OK);
86         data_received++;
87         return size;
88 }
89
90 static void fetch_alternates(char *base);
91
92 static void process_object_response(void *callback_data);
93
94 static void start_object_request(struct object_request *obj_req)
95 {
96         char *hex = sha1_to_hex(obj_req->sha1);
97         char prevfile[PATH_MAX];
98         char *url;
99         char *posn;
100         int prevlocal;
101         unsigned char prev_buf[PREV_BUF_SIZE];
102         ssize_t prev_read = 0;
103         long prev_posn = 0;
104         char range[RANGE_HEADER_SIZE];
105         struct curl_slist *range_header = NULL;
106         struct active_request_slot *slot;
107
108         snprintf(prevfile, sizeof(prevfile), "%s.prev", obj_req->filename);
109         unlink(prevfile);
110         rename(obj_req->tmpfile, prevfile);
111         unlink(obj_req->tmpfile);
112
113         if (obj_req->local != -1)
114                 error("fd leakage in start: %d", obj_req->local);
115         obj_req->local = open(obj_req->tmpfile,
116                               O_WRONLY | O_CREAT | O_EXCL, 0666);
117         /* This could have failed due to the "lazy directory creation";
118          * try to mkdir the last path component.
119          */
120         if (obj_req->local < 0 && errno == ENOENT) {
121                 char *dir = strrchr(obj_req->tmpfile, '/');
122                 if (dir) {
123                         *dir = 0;
124                         mkdir(obj_req->tmpfile, 0777);
125                         *dir = '/';
126                 }
127                 obj_req->local = open(obj_req->tmpfile,
128                                       O_WRONLY | O_CREAT | O_EXCL, 0666);
129         }
130
131         if (obj_req->local < 0) {
132                 obj_req->state = ABORTED;
133                 error("Couldn't create temporary file %s for %s: %s",
134                       obj_req->tmpfile, obj_req->filename, strerror(errno));
135                 return;
136         }
137
138         memset(&obj_req->stream, 0, sizeof(obj_req->stream));
139
140         inflateInit(&obj_req->stream);
141
142         SHA1_Init(&obj_req->c);
143
144         url = xmalloc(strlen(obj_req->repo->base) + 50);
145         obj_req->url = xmalloc(strlen(obj_req->repo->base) + 50);
146         strcpy(url, obj_req->repo->base);
147         posn = url + strlen(obj_req->repo->base);
148         strcpy(posn, "objects/");
149         posn += 8;
150         memcpy(posn, hex, 2);
151         posn += 2;
152         *(posn++) = '/';
153         strcpy(posn, hex + 2);
154         strcpy(obj_req->url, url);
155
156         /* If a previous temp file is present, process what was already
157            fetched. */
158         prevlocal = open(prevfile, O_RDONLY);
159         if (prevlocal != -1) {
160                 do {
161                         prev_read = read(prevlocal, prev_buf, PREV_BUF_SIZE);
162                         if (prev_read>0) {
163                                 if (fwrite_sha1_file(prev_buf,
164                                                      1,
165                                                      prev_read,
166                                                      obj_req) == prev_read) {
167                                         prev_posn += prev_read;
168                                 } else {
169                                         prev_read = -1;
170                                 }
171                         }
172                 } while (prev_read > 0);
173                 close(prevlocal);
174         }
175         unlink(prevfile);
176
177         /* Reset inflate/SHA1 if there was an error reading the previous temp
178            file; also rewind to the beginning of the local file. */
179         if (prev_read == -1) {
180                 memset(&obj_req->stream, 0, sizeof(obj_req->stream));
181                 inflateInit(&obj_req->stream);
182                 SHA1_Init(&obj_req->c);
183                 if (prev_posn>0) {
184                         prev_posn = 0;
185                         lseek(obj_req->local, SEEK_SET, 0);
186                         ftruncate(obj_req->local, 0);
187                 }
188         }
189
190         slot = get_active_slot();
191         slot->callback_func = process_object_response;
192         slot->callback_data = obj_req;
193         obj_req->slot = slot;
194
195         curl_easy_setopt(slot->curl, CURLOPT_FILE, obj_req);
196         curl_easy_setopt(slot->curl, CURLOPT_WRITEFUNCTION, fwrite_sha1_file);
197         curl_easy_setopt(slot->curl, CURLOPT_ERRORBUFFER, obj_req->errorstr);
198         curl_easy_setopt(slot->curl, CURLOPT_URL, url);
199         curl_easy_setopt(slot->curl, CURLOPT_HTTPHEADER, no_pragma_header);
200
201         /* If we have successfully processed data from a previous fetch
202            attempt, only fetch the data we don't already have. */
203         if (prev_posn>0) {
204                 if (get_verbosely)
205                         fprintf(stderr,
206                                 "Resuming fetch of object %s at byte %ld\n",
207                                 hex, prev_posn);
208                 sprintf(range, "Range: bytes=%ld-", prev_posn);
209                 range_header = curl_slist_append(range_header, range);
210                 curl_easy_setopt(slot->curl,
211                                  CURLOPT_HTTPHEADER, range_header);
212         }
213
214         /* Try to get the request started, abort the request on error */
215         obj_req->state = ACTIVE;
216         if (!start_active_slot(slot)) {
217                 obj_req->state = ABORTED;
218                 obj_req->slot = NULL;
219                 close(obj_req->local); obj_req->local = -1;
220                 free(obj_req->url);
221                 return;
222         }
223 }
224
225 static void finish_object_request(struct object_request *obj_req)
226 {
227         struct stat st;
228
229         fchmod(obj_req->local, 0444);
230         close(obj_req->local); obj_req->local = -1;
231
232         if (obj_req->http_code == 416) {
233                 fprintf(stderr, "Warning: requested range invalid; we may already have all the data.\n");
234         } else if (obj_req->curl_result != CURLE_OK) {
235                 if (stat(obj_req->tmpfile, &st) == 0)
236                         if (st.st_size == 0)
237                                 unlink(obj_req->tmpfile);
238                 return;
239         }
240
241         inflateEnd(&obj_req->stream);
242         SHA1_Final(obj_req->real_sha1, &obj_req->c);
243         if (obj_req->zret != Z_STREAM_END) {
244                 unlink(obj_req->tmpfile);
245                 return;
246         }
247         if (memcmp(obj_req->sha1, obj_req->real_sha1, 20)) {
248                 unlink(obj_req->tmpfile);
249                 return;
250         }
251         obj_req->rename =
252                 move_temp_to_file(obj_req->tmpfile, obj_req->filename);
253
254         if (obj_req->rename == 0)
255                 pull_say("got %s\n", sha1_to_hex(obj_req->sha1));
256 }
257
258 static void process_object_response(void *callback_data)
259 {
260         struct object_request *obj_req =
261                 (struct object_request *)callback_data;
262
263         obj_req->curl_result = obj_req->slot->curl_result;
264         obj_req->http_code = obj_req->slot->http_code;
265         obj_req->slot = NULL;
266         obj_req->state = COMPLETE;
267
268         /* Use alternates if necessary */
269         if (obj_req->http_code == 404 ||
270             obj_req->curl_result == CURLE_FILE_COULDNT_READ_FILE) {
271                 fetch_alternates(alt->base);
272                 if (obj_req->repo->next != NULL) {
273                         obj_req->repo =
274                                 obj_req->repo->next;
275                         close(obj_req->local);
276                         obj_req->local = -1;
277                         start_object_request(obj_req);
278                         return;
279                 }
280         }
281
282         finish_object_request(obj_req);
283 }
284
285 static void release_object_request(struct object_request *obj_req)
286 {
287         struct object_request *entry = object_queue_head;
288
289         if (obj_req->local != -1)
290                 error("fd leakage in release: %d", obj_req->local);
291         if (obj_req == object_queue_head) {
292                 object_queue_head = obj_req->next;
293         } else {
294                 while (entry->next != NULL && entry->next != obj_req)
295                         entry = entry->next;
296                 if (entry->next == obj_req)
297                         entry->next = entry->next->next;
298         }
299
300         free(obj_req->url);
301         free(obj_req);
302 }
303
304 #ifdef USE_CURL_MULTI
305 void fill_active_slots(void)
306 {
307         struct object_request *obj_req = object_queue_head;
308         struct active_request_slot *slot = active_queue_head;
309         int num_transfers;
310
311         while (active_requests < max_requests && obj_req != NULL) {
312                 if (obj_req->state == WAITING) {
313                         if (has_sha1_file(obj_req->sha1))
314                                 obj_req->state = COMPLETE;
315                         else
316                                 start_object_request(obj_req);
317                         curl_multi_perform(curlm, &num_transfers);
318                 }
319                 obj_req = obj_req->next;
320         }
321
322         while (slot != NULL) {
323                 if (!slot->in_use && slot->curl != NULL) {
324                         curl_easy_cleanup(slot->curl);
325                         slot->curl = NULL;
326                 }
327                 slot = slot->next;
328         }
329 }
330 #endif
331
332 void prefetch(unsigned char *sha1)
333 {
334         struct object_request *newreq;
335         struct object_request *tail;
336         char *filename = sha1_file_name(sha1);
337
338         newreq = xmalloc(sizeof(*newreq));
339         memcpy(newreq->sha1, sha1, 20);
340         newreq->repo = 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->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 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
375         FILE *indexfile;
376         struct active_request_slot *slot;
377         struct slot_results results;
378
379         if (has_pack_index(sha1))
380                 return 0;
381
382         if (get_verbosely)
383                 fprintf(stderr, "Getting index for pack %s\n", hex);
384
385         url = xmalloc(strlen(repo->base) + 64);
386         sprintf(url, "%s/objects/pack/pack-%s.idx", repo->base, hex);
387
388         filename = sha1_pack_index_name(sha1);
389         snprintf(tmpfile, sizeof(tmpfile), "%s.temp", filename);
390         indexfile = fopen(tmpfile, "a");
391         if (!indexfile)
392                 return error("Unable to open local file %s for pack index",
393                              filename);
394
395         slot = get_active_slot();
396         slot->results = &results;
397         curl_easy_setopt(slot->curl, CURLOPT_FILE, indexfile);
398         curl_easy_setopt(slot->curl, CURLOPT_WRITEFUNCTION, fwrite);
399         curl_easy_setopt(slot->curl, CURLOPT_URL, url);
400         curl_easy_setopt(slot->curl, CURLOPT_HTTPHEADER, no_pragma_header);
401         slot->local = indexfile;
402
403         /* If there is data present from a previous transfer attempt,
404            resume where it left off */
405         prev_posn = ftell(indexfile);
406         if (prev_posn>0) {
407                 if (get_verbosely)
408                         fprintf(stderr,
409                                 "Resuming fetch of index for pack %s at byte %ld\n",
410                                 hex, prev_posn);
411                 sprintf(range, "Range: bytes=%ld-", prev_posn);
412                 range_header = curl_slist_append(range_header, range);
413                 curl_easy_setopt(slot->curl, CURLOPT_HTTPHEADER, range_header);
414         }
415
416         if (start_active_slot(slot)) {
417                 run_active_slot(slot);
418                 if (results.curl_result != CURLE_OK) {
419                         fclose(indexfile);
420                         return error("Unable to get pack index %s\n%s", url,
421                                      curl_errorstr);
422                 }
423         } else {
424                 fclose(indexfile);
425                 return error("Unable to start request");
426         }
427
428         fclose(indexfile);
429
430         return move_temp_to_file(tmpfile, filename);
431 }
432
433 static int setup_index(struct alt_base *repo, unsigned char *sha1)
434 {
435         struct packed_git *new_pack;
436         if (has_pack_file(sha1))
437                 return 0; // don't list this as something we can get
438
439         if (fetch_index(repo, sha1))
440                 return -1;
441
442         new_pack = parse_pack_index(sha1);
443         new_pack->next = repo->packs;
444         repo->packs = new_pack;
445         return 0;
446 }
447
448 static void process_alternates_response(void *callback_data)
449 {
450         struct alternates_request *alt_req =
451                 (struct alternates_request *)callback_data;
452         struct active_request_slot *slot = alt_req->slot;
453         struct alt_base *tail = alt;
454         char *base = alt_req->base;
455         static const char null_byte = '\0';
456         char *data;
457         int i = 0;
458
459         if (alt_req->http_specific) {
460                 if (slot->curl_result != CURLE_OK ||
461                     !alt_req->buffer->posn) {
462
463                         /* Try reusing the slot to get non-http alternates */
464                         alt_req->http_specific = 0;
465                         sprintf(alt_req->url, "%s/objects/info/alternates",
466                                 base);
467                         curl_easy_setopt(slot->curl, CURLOPT_URL,
468                                          alt_req->url);
469                         active_requests++;
470                         slot->in_use = 1;
471                         if (!start_active_slot(slot)) {
472                                 got_alternates = -1;
473                                 slot->in_use = 0;
474                         }
475                         return;
476                 }
477         } else if (slot->curl_result != CURLE_OK) {
478                 if (slot->http_code != 404 &&
479                     slot->curl_result != CURLE_FILE_COULDNT_READ_FILE) {
480                         got_alternates = -1;
481                         return;
482                 }
483         }
484
485         fwrite_buffer(&null_byte, 1, 1, alt_req->buffer);
486         alt_req->buffer->posn--;
487         data = alt_req->buffer->buffer;
488
489         while (i < alt_req->buffer->posn) {
490                 int posn = i;
491                 while (posn < alt_req->buffer->posn && data[posn] != '\n')
492                         posn++;
493                 if (data[posn] == '\n') {
494                         int okay = 0;
495                         int serverlen = 0;
496                         struct alt_base *newalt;
497                         char *target = NULL;
498                         if (data[i] == '/') {
499                                 serverlen = strchr(base + 8, '/') - base;
500                                 okay = 1;
501                         } else if (!memcmp(data + i, "../", 3)) {
502                                 i += 3;
503                                 serverlen = strlen(base);
504                                 while (i + 2 < posn &&
505                                        !memcmp(data + i, "../", 3)) {
506                                         do {
507                                                 serverlen--;
508                                         } while (serverlen &&
509                                                  base[serverlen - 1] != '/');
510                                         i += 3;
511                                 }
512                                 // If the server got removed, give up.
513                                 okay = strchr(base, ':') - base + 3 <
514                                         serverlen;
515                         } else if (alt_req->http_specific) {
516                                 char *colon = strchr(data + i, ':');
517                                 char *slash = strchr(data + i, '/');
518                                 if (colon && slash && colon < data + posn &&
519                                     slash < data + posn && colon < slash) {
520                                         okay = 1;
521                                 }
522                         }
523                         // skip 'objects' at end
524                         if (okay) {
525                                 target = xmalloc(serverlen + posn - i - 6);
526                                 strncpy(target, base, serverlen);
527                                 strncpy(target + serverlen, data + i,
528                                         posn - i - 7);
529                                 target[serverlen + posn - i - 7] = '\0';
530                                 if (get_verbosely)
531                                         fprintf(stderr,
532                                                 "Also look at %s\n", target);
533                                 newalt = xmalloc(sizeof(*newalt));
534                                 newalt->next = NULL;
535                                 newalt->base = target;
536                                 newalt->got_indices = 0;
537                                 newalt->packs = NULL;
538                                 while (tail->next != NULL)
539                                         tail = tail->next;
540                                 tail->next = newalt;
541                         }
542                 }
543                 i = posn + 1;
544         }
545
546         got_alternates = 1;
547 }
548
549 static void fetch_alternates(char *base)
550 {
551         struct buffer buffer;
552         char *url;
553         char *data;
554         struct active_request_slot *slot;
555         struct alternates_request alt_req;
556
557         /* If another request has already started fetching alternates,
558            wait for them to arrive and return to processing this request's
559            curl message */
560 #ifdef USE_CURL_MULTI
561         while (got_alternates == 0) {
562                 step_active_slots();
563         }
564 #endif
565
566         /* Nothing to do if they've already been fetched */
567         if (got_alternates == 1)
568                 return;
569
570         /* Start the fetch */
571         got_alternates = 0;
572
573         data = xmalloc(4096);
574         buffer.size = 4096;
575         buffer.posn = 0;
576         buffer.buffer = data;
577
578         if (get_verbosely)
579                 fprintf(stderr, "Getting alternates list for %s\n", base);
580
581         url = xmalloc(strlen(base) + 31);
582         sprintf(url, "%s/objects/info/http-alternates", base);
583
584         /* Use a callback to process the result, since another request
585            may fail and need to have alternates loaded before continuing */
586         slot = get_active_slot();
587         slot->callback_func = process_alternates_response;
588         slot->callback_data = &alt_req;
589
590         curl_easy_setopt(slot->curl, CURLOPT_FILE, &buffer);
591         curl_easy_setopt(slot->curl, CURLOPT_WRITEFUNCTION, fwrite_buffer);
592         curl_easy_setopt(slot->curl, CURLOPT_URL, url);
593
594         alt_req.base = base;
595         alt_req.url = url;
596         alt_req.buffer = &buffer;
597         alt_req.http_specific = 1;
598         alt_req.slot = slot;
599
600         if (start_active_slot(slot))
601                 run_active_slot(slot);
602         else
603                 got_alternates = -1;
604
605         free(data);
606         free(url);
607 }
608
609 static int fetch_indices(struct alt_base *repo)
610 {
611         unsigned char sha1[20];
612         char *url;
613         struct buffer buffer;
614         char *data;
615         int i = 0;
616
617         struct active_request_slot *slot;
618         struct slot_results results;
619
620         if (repo->got_indices)
621                 return 0;
622
623         data = xmalloc(4096);
624         buffer.size = 4096;
625         buffer.posn = 0;
626         buffer.buffer = data;
627
628         if (get_verbosely)
629                 fprintf(stderr, "Getting pack list for %s\n", repo->base);
630
631         url = xmalloc(strlen(repo->base) + 21);
632         sprintf(url, "%s/objects/info/packs", repo->base);
633
634         slot = get_active_slot();
635         slot->results = &results;
636         curl_easy_setopt(slot->curl, CURLOPT_FILE, &buffer);
637         curl_easy_setopt(slot->curl, CURLOPT_WRITEFUNCTION, fwrite_buffer);
638         curl_easy_setopt(slot->curl, CURLOPT_URL, url);
639         curl_easy_setopt(slot->curl, CURLOPT_HTTPHEADER, NULL);
640         if (start_active_slot(slot)) {
641                 run_active_slot(slot);
642                 if (results.curl_result != CURLE_OK) {
643                         if (results.http_code == 404 ||
644                             results.curl_result == CURLE_FILE_COULDNT_READ_FILE) {
645                                 repo->got_indices = 1;
646                                 free(buffer.buffer);
647                                 return 0;
648                         } else {
649                                 repo->got_indices = 0;
650                                 free(buffer.buffer);
651                                 return error("%s", curl_errorstr);
652                         }
653                 }
654         } else {
655                 repo->got_indices = 0;
656                 free(buffer.buffer);
657                 return error("Unable to start request");
658         }
659
660         data = buffer.buffer;
661         while (i < buffer.posn) {
662                 switch (data[i]) {
663                 case 'P':
664                         i++;
665                         if (i + 52 <= buffer.posn &&
666                             !strncmp(data + i, " pack-", 6) &&
667                             !strncmp(data + i + 46, ".pack\n", 6)) {
668                                 get_sha1_hex(data + i + 6, sha1);
669                                 setup_index(repo, sha1);
670                                 i += 51;
671                                 break;
672                         }
673                 default:
674                         while (i < buffer.posn && data[i] != '\n')
675                                 i++;
676                 }
677                 i++;
678         }
679
680         free(buffer.buffer);
681         repo->got_indices = 1;
682         return 0;
683 }
684
685 static int fetch_pack(struct alt_base *repo, unsigned char *sha1)
686 {
687         char *url;
688         struct packed_git *target;
689         struct packed_git **lst;
690         FILE *packfile;
691         char *filename;
692         char tmpfile[PATH_MAX];
693         int ret;
694         long prev_posn = 0;
695         char range[RANGE_HEADER_SIZE];
696         struct curl_slist *range_header = NULL;
697
698         struct active_request_slot *slot;
699         struct slot_results results;
700
701         if (fetch_indices(repo))
702                 return -1;
703         target = find_sha1_pack(sha1, repo->packs);
704         if (!target)
705                 return -1;
706
707         if (get_verbosely) {
708                 fprintf(stderr, "Getting pack %s\n",
709                         sha1_to_hex(target->sha1));
710                 fprintf(stderr, " which contains %s\n",
711                         sha1_to_hex(sha1));
712         }
713
714         url = xmalloc(strlen(repo->base) + 65);
715         sprintf(url, "%s/objects/pack/pack-%s.pack",
716                 repo->base, sha1_to_hex(target->sha1));
717
718         filename = sha1_pack_name(target->sha1);
719         snprintf(tmpfile, sizeof(tmpfile), "%s.temp", filename);
720         packfile = fopen(tmpfile, "a");
721         if (!packfile)
722                 return error("Unable to open local file %s for pack",
723                              filename);
724
725         slot = get_active_slot();
726         slot->results = &results;
727         curl_easy_setopt(slot->curl, CURLOPT_FILE, packfile);
728         curl_easy_setopt(slot->curl, CURLOPT_WRITEFUNCTION, fwrite);
729         curl_easy_setopt(slot->curl, CURLOPT_URL, url);
730         curl_easy_setopt(slot->curl, CURLOPT_HTTPHEADER, no_pragma_header);
731         slot->local = packfile;
732
733         /* If there is data present from a previous transfer attempt,
734            resume where it left off */
735         prev_posn = ftell(packfile);
736         if (prev_posn>0) {
737                 if (get_verbosely)
738                         fprintf(stderr,
739                                 "Resuming fetch of pack %s at byte %ld\n",
740                                 sha1_to_hex(target->sha1), prev_posn);
741                 sprintf(range, "Range: bytes=%ld-", prev_posn);
742                 range_header = curl_slist_append(range_header, range);
743                 curl_easy_setopt(slot->curl, CURLOPT_HTTPHEADER, range_header);
744         }
745
746         if (start_active_slot(slot)) {
747                 run_active_slot(slot);
748                 if (results.curl_result != CURLE_OK) {
749                         fclose(packfile);
750                         return error("Unable to get pack file %s\n%s", url,
751                                      curl_errorstr);
752                 }
753         } else {
754                 fclose(packfile);
755                 return error("Unable to start request");
756         }
757
758         fclose(packfile);
759
760         ret = move_temp_to_file(tmpfile, filename);
761         if (ret)
762                 return ret;
763
764         lst = &repo->packs;
765         while (*lst != target)
766                 lst = &((*lst)->next);
767         *lst = (*lst)->next;
768
769         if (verify_pack(target, 0))
770                 return -1;
771         install_packed_git(target);
772
773         return 0;
774 }
775
776 static void abort_object_request(struct object_request *obj_req)
777 {
778         if (obj_req->local >= 0) {
779                 close(obj_req->local);
780                 obj_req->local = -1;
781         }
782         unlink(obj_req->tmpfile);
783         if (obj_req->slot) {
784                 release_active_slot(obj_req->slot);
785                 obj_req->slot = NULL;
786         }
787         release_object_request(obj_req);
788 }
789
790 static int fetch_object(struct alt_base *repo, unsigned char *sha1)
791 {
792         char *hex = sha1_to_hex(sha1);
793         int ret = 0;
794         struct object_request *obj_req = object_queue_head;
795
796         while (obj_req != NULL && memcmp(obj_req->sha1, sha1, 20))
797                 obj_req = obj_req->next;
798         if (obj_req == NULL)
799                 return error("Couldn't find request for %s in the queue", hex);
800
801         if (has_sha1_file(obj_req->sha1)) {
802                 abort_object_request(obj_req);
803                 return 0;
804         }
805
806 #ifdef USE_CURL_MULTI
807         while (obj_req->state == WAITING) {
808                 step_active_slots();
809         }
810 #else
811         start_object_request(obj_req);
812 #endif
813
814         while (obj_req->state == ACTIVE) {
815                 run_active_slot(obj_req->slot);
816         }
817         if (obj_req->local != -1) {
818                 close(obj_req->local); obj_req->local = -1;
819         }
820
821         if (obj_req->state == ABORTED) {
822                 ret = error("Request for %s aborted", hex);
823         } else if (obj_req->curl_result != CURLE_OK &&
824                    obj_req->http_code != 416) {
825                 if (obj_req->http_code == 404 ||
826                     obj_req->curl_result == CURLE_FILE_COULDNT_READ_FILE)
827                         ret = -1; /* Be silent, it is probably in a pack. */
828                 else
829                         ret = error("%s (curl_result = %d, http_code = %ld, sha1 = %s)",
830                                     obj_req->errorstr, obj_req->curl_result,
831                                     obj_req->http_code, hex);
832         } else if (obj_req->zret != Z_STREAM_END) {
833                 ret = error("File %s (%s) corrupt", hex, obj_req->url);
834         } else if (memcmp(obj_req->sha1, obj_req->real_sha1, 20)) {
835                 ret = error("File %s has bad hash", hex);
836         } else if (obj_req->rename < 0) {
837                 ret = error("unable to write sha1 filename %s",
838                             obj_req->filename);
839         }
840
841         release_object_request(obj_req);
842         return ret;
843 }
844
845 int fetch(unsigned char *sha1)
846 {
847         struct alt_base *altbase = alt;
848
849         if (!fetch_object(altbase, sha1))
850                 return 0;
851         while (altbase) {
852                 if (!fetch_pack(altbase, sha1))
853                         return 0;
854                 fetch_alternates(alt->base);
855                 altbase = altbase->next;
856         }
857         return error("Unable to find %s under %s", sha1_to_hex(sha1),
858                      alt->base);
859 }
860
861 static inline int needs_quote(int ch)
862 {
863         switch (ch) {
864         case '/': case '-': case '.':
865         case 'A'...'Z': case 'a'...'z': case '0'...'9':
866                 return 0;
867         default:
868                 return 1;
869         }
870 }
871
872 static inline int hex(int v)
873 {
874         if (v < 10) return '0' + v;
875         else return 'A' + v - 10;
876 }
877
878 static char *quote_ref_url(const char *base, const char *ref)
879 {
880         const char *cp;
881         char *dp, *qref;
882         int len, baselen, ch;
883
884         baselen = strlen(base);
885         len = baselen + 6; /* "refs/" + NUL */
886         for (cp = ref; (ch = *cp) != 0; cp++, len++)
887                 if (needs_quote(ch))
888                         len += 2; /* extra two hex plus replacement % */
889         qref = xmalloc(len);
890         memcpy(qref, base, baselen);
891         memcpy(qref + baselen, "refs/", 5);
892         for (cp = ref, dp = qref + baselen + 5; (ch = *cp) != 0; cp++) {
893                 if (needs_quote(ch)) {
894                         *dp++ = '%';
895                         *dp++ = hex((ch >> 4) & 0xF);
896                         *dp++ = hex(ch & 0xF);
897                 }
898                 else
899                         *dp++ = ch;
900         }
901         *dp = 0;
902
903         return qref;
904 }
905
906 int fetch_ref(char *ref, unsigned char *sha1)
907 {
908         char *url;
909         char hex[42];
910         struct buffer buffer;
911         char *base = alt->base;
912         struct active_request_slot *slot;
913         struct slot_results results;
914         buffer.size = 41;
915         buffer.posn = 0;
916         buffer.buffer = hex;
917         hex[41] = '\0';
918
919         url = quote_ref_url(base, ref);
920         slot = get_active_slot();
921         slot->results = &results;
922         curl_easy_setopt(slot->curl, CURLOPT_FILE, &buffer);
923         curl_easy_setopt(slot->curl, CURLOPT_WRITEFUNCTION, fwrite_buffer);
924         curl_easy_setopt(slot->curl, CURLOPT_HTTPHEADER, NULL);
925         curl_easy_setopt(slot->curl, CURLOPT_URL, url);
926         if (start_active_slot(slot)) {
927                 run_active_slot(slot);
928                 if (results.curl_result != CURLE_OK)
929                         return error("Couldn't get %s for %s\n%s",
930                                      url, ref, curl_errorstr);
931         } else {
932                 return error("Unable to start request");
933         }
934
935         hex[40] = '\0';
936         get_sha1_hex(hex, sha1);
937         return 0;
938 }
939
940 int main(int argc, char **argv)
941 {
942         char *commit_id;
943         char *url;
944         int arg = 1;
945         int rc = 0;
946
947         setup_git_directory();
948
949         while (arg < argc && argv[arg][0] == '-') {
950                 if (argv[arg][1] == 't') {
951                         get_tree = 1;
952                 } else if (argv[arg][1] == 'c') {
953                         get_history = 1;
954                 } else if (argv[arg][1] == 'a') {
955                         get_all = 1;
956                         get_tree = 1;
957                         get_history = 1;
958                 } else if (argv[arg][1] == 'v') {
959                         get_verbosely = 1;
960                 } else if (argv[arg][1] == 'w') {
961                         write_ref = argv[arg + 1];
962                         arg++;
963                 } else if (!strcmp(argv[arg], "--recover")) {
964                         get_recover = 1;
965                 }
966                 arg++;
967         }
968         if (argc < arg + 2) {
969                 usage("git-http-fetch [-c] [-t] [-a] [-d] [-v] [--recover] [-w ref] commit-id url");
970                 return 1;
971         }
972         commit_id = argv[arg];
973         url = argv[arg + 1];
974
975         http_init();
976
977         no_pragma_header = curl_slist_append(no_pragma_header, "Pragma:");
978
979         alt = xmalloc(sizeof(*alt));
980         alt->base = url;
981         alt->got_indices = 0;
982         alt->packs = NULL;
983         alt->next = NULL;
984
985         if (pull(commit_id))
986                 rc = 1;
987
988         curl_slist_free_all(no_pragma_header);
989
990         http_cleanup();
991
992         return rc;
993 }