Merge branch 'cc/fetch-error-message-fix'
[git] / streaming.c
1 /*
2  * Copyright (c) 2011, Google Inc.
3  */
4 #include "cache.h"
5 #include "streaming.h"
6 #include "repository.h"
7 #include "object-store.h"
8 #include "replace-object.h"
9 #include "packfile.h"
10
11 enum input_source {
12         stream_error = -1,
13         incore = 0,
14         loose = 1,
15         pack_non_delta = 2
16 };
17
18 typedef int (*open_istream_fn)(struct git_istream *,
19                                struct object_info *,
20                                const struct object_id *,
21                                enum object_type *);
22 typedef int (*close_istream_fn)(struct git_istream *);
23 typedef ssize_t (*read_istream_fn)(struct git_istream *, char *, size_t);
24
25 struct stream_vtbl {
26         close_istream_fn close;
27         read_istream_fn read;
28 };
29
30 #define open_method_decl(name) \
31         int open_istream_ ##name \
32         (struct git_istream *st, struct object_info *oi, \
33          const struct object_id *oid, \
34          enum object_type *type)
35
36 #define close_method_decl(name) \
37         int close_istream_ ##name \
38         (struct git_istream *st)
39
40 #define read_method_decl(name) \
41         ssize_t read_istream_ ##name \
42         (struct git_istream *st, char *buf, size_t sz)
43
44 /* forward declaration */
45 static open_method_decl(incore);
46 static open_method_decl(loose);
47 static open_method_decl(pack_non_delta);
48 static struct git_istream *attach_stream_filter(struct git_istream *st,
49                                                 struct stream_filter *filter);
50
51
52 static open_istream_fn open_istream_tbl[] = {
53         open_istream_incore,
54         open_istream_loose,
55         open_istream_pack_non_delta,
56 };
57
58 #define FILTER_BUFFER (1024*16)
59
60 struct filtered_istream {
61         struct git_istream *upstream;
62         struct stream_filter *filter;
63         char ibuf[FILTER_BUFFER];
64         char obuf[FILTER_BUFFER];
65         int i_end, i_ptr;
66         int o_end, o_ptr;
67         int input_finished;
68 };
69
70 struct git_istream {
71         const struct stream_vtbl *vtbl;
72         unsigned long size; /* inflated size of full object */
73         git_zstream z;
74         enum { z_unused, z_used, z_done, z_error } z_state;
75
76         union {
77                 struct {
78                         char *buf; /* from read_object() */
79                         unsigned long read_ptr;
80                 } incore;
81
82                 struct {
83                         void *mapped;
84                         unsigned long mapsize;
85                         char hdr[32];
86                         int hdr_avail;
87                         int hdr_used;
88                 } loose;
89
90                 struct {
91                         struct packed_git *pack;
92                         off_t pos;
93                 } in_pack;
94
95                 struct filtered_istream filtered;
96         } u;
97 };
98
99 int close_istream(struct git_istream *st)
100 {
101         int r = st->vtbl->close(st);
102         free(st);
103         return r;
104 }
105
106 ssize_t read_istream(struct git_istream *st, void *buf, size_t sz)
107 {
108         return st->vtbl->read(st, buf, sz);
109 }
110
111 static enum input_source istream_source(const struct object_id *oid,
112                                         enum object_type *type,
113                                         struct object_info *oi)
114 {
115         unsigned long size;
116         int status;
117
118         oi->typep = type;
119         oi->sizep = &size;
120         status = oid_object_info_extended(the_repository, oid, oi, 0);
121         if (status < 0)
122                 return stream_error;
123
124         switch (oi->whence) {
125         case OI_LOOSE:
126                 return loose;
127         case OI_PACKED:
128                 if (!oi->u.packed.is_delta && big_file_threshold < size)
129                         return pack_non_delta;
130                 /* fallthru */
131         default:
132                 return incore;
133         }
134 }
135
136 struct git_istream *open_istream(const struct object_id *oid,
137                                  enum object_type *type,
138                                  unsigned long *size,
139                                  struct stream_filter *filter)
140 {
141         struct git_istream *st;
142         struct object_info oi = OBJECT_INFO_INIT;
143         const struct object_id *real = lookup_replace_object(the_repository, oid);
144         enum input_source src = istream_source(real, type, &oi);
145
146         if (src < 0)
147                 return NULL;
148
149         st = xmalloc(sizeof(*st));
150         if (open_istream_tbl[src](st, &oi, real, type)) {
151                 if (open_istream_incore(st, &oi, real, type)) {
152                         free(st);
153                         return NULL;
154                 }
155         }
156         if (filter) {
157                 /* Add "&& !is_null_stream_filter(filter)" for performance */
158                 struct git_istream *nst = attach_stream_filter(st, filter);
159                 if (!nst) {
160                         close_istream(st);
161                         return NULL;
162                 }
163                 st = nst;
164         }
165
166         *size = st->size;
167         return st;
168 }
169
170
171 /*****************************************************************
172  *
173  * Common helpers
174  *
175  *****************************************************************/
176
177 static void close_deflated_stream(struct git_istream *st)
178 {
179         if (st->z_state == z_used)
180                 git_inflate_end(&st->z);
181 }
182
183
184 /*****************************************************************
185  *
186  * Filtered stream
187  *
188  *****************************************************************/
189
190 static close_method_decl(filtered)
191 {
192         free_stream_filter(st->u.filtered.filter);
193         return close_istream(st->u.filtered.upstream);
194 }
195
196 static read_method_decl(filtered)
197 {
198         struct filtered_istream *fs = &(st->u.filtered);
199         size_t filled = 0;
200
201         while (sz) {
202                 /* do we already have filtered output? */
203                 if (fs->o_ptr < fs->o_end) {
204                         size_t to_move = fs->o_end - fs->o_ptr;
205                         if (sz < to_move)
206                                 to_move = sz;
207                         memcpy(buf + filled, fs->obuf + fs->o_ptr, to_move);
208                         fs->o_ptr += to_move;
209                         sz -= to_move;
210                         filled += to_move;
211                         continue;
212                 }
213                 fs->o_end = fs->o_ptr = 0;
214
215                 /* do we have anything to feed the filter with? */
216                 if (fs->i_ptr < fs->i_end) {
217                         size_t to_feed = fs->i_end - fs->i_ptr;
218                         size_t to_receive = FILTER_BUFFER;
219                         if (stream_filter(fs->filter,
220                                           fs->ibuf + fs->i_ptr, &to_feed,
221                                           fs->obuf, &to_receive))
222                                 return -1;
223                         fs->i_ptr = fs->i_end - to_feed;
224                         fs->o_end = FILTER_BUFFER - to_receive;
225                         continue;
226                 }
227
228                 /* tell the filter to drain upon no more input */
229                 if (fs->input_finished) {
230                         size_t to_receive = FILTER_BUFFER;
231                         if (stream_filter(fs->filter,
232                                           NULL, NULL,
233                                           fs->obuf, &to_receive))
234                                 return -1;
235                         fs->o_end = FILTER_BUFFER - to_receive;
236                         if (!fs->o_end)
237                                 break;
238                         continue;
239                 }
240                 fs->i_end = fs->i_ptr = 0;
241
242                 /* refill the input from the upstream */
243                 if (!fs->input_finished) {
244                         fs->i_end = read_istream(fs->upstream, fs->ibuf, FILTER_BUFFER);
245                         if (fs->i_end < 0)
246                                 return -1;
247                         if (fs->i_end)
248                                 continue;
249                 }
250                 fs->input_finished = 1;
251         }
252         return filled;
253 }
254
255 static struct stream_vtbl filtered_vtbl = {
256         close_istream_filtered,
257         read_istream_filtered,
258 };
259
260 static struct git_istream *attach_stream_filter(struct git_istream *st,
261                                                 struct stream_filter *filter)
262 {
263         struct git_istream *ifs = xmalloc(sizeof(*ifs));
264         struct filtered_istream *fs = &(ifs->u.filtered);
265
266         ifs->vtbl = &filtered_vtbl;
267         fs->upstream = st;
268         fs->filter = filter;
269         fs->i_end = fs->i_ptr = 0;
270         fs->o_end = fs->o_ptr = 0;
271         fs->input_finished = 0;
272         ifs->size = -1; /* unknown */
273         return ifs;
274 }
275
276 /*****************************************************************
277  *
278  * Loose object stream
279  *
280  *****************************************************************/
281
282 static read_method_decl(loose)
283 {
284         size_t total_read = 0;
285
286         switch (st->z_state) {
287         case z_done:
288                 return 0;
289         case z_error:
290                 return -1;
291         default:
292                 break;
293         }
294
295         if (st->u.loose.hdr_used < st->u.loose.hdr_avail) {
296                 size_t to_copy = st->u.loose.hdr_avail - st->u.loose.hdr_used;
297                 if (sz < to_copy)
298                         to_copy = sz;
299                 memcpy(buf, st->u.loose.hdr + st->u.loose.hdr_used, to_copy);
300                 st->u.loose.hdr_used += to_copy;
301                 total_read += to_copy;
302         }
303
304         while (total_read < sz) {
305                 int status;
306
307                 st->z.next_out = (unsigned char *)buf + total_read;
308                 st->z.avail_out = sz - total_read;
309                 status = git_inflate(&st->z, Z_FINISH);
310
311                 total_read = st->z.next_out - (unsigned char *)buf;
312
313                 if (status == Z_STREAM_END) {
314                         git_inflate_end(&st->z);
315                         st->z_state = z_done;
316                         break;
317                 }
318                 if (status != Z_OK && (status != Z_BUF_ERROR || total_read < sz)) {
319                         git_inflate_end(&st->z);
320                         st->z_state = z_error;
321                         return -1;
322                 }
323         }
324         return total_read;
325 }
326
327 static close_method_decl(loose)
328 {
329         close_deflated_stream(st);
330         munmap(st->u.loose.mapped, st->u.loose.mapsize);
331         return 0;
332 }
333
334 static struct stream_vtbl loose_vtbl = {
335         close_istream_loose,
336         read_istream_loose,
337 };
338
339 static open_method_decl(loose)
340 {
341         st->u.loose.mapped = map_sha1_file(the_repository,
342                                            oid->hash, &st->u.loose.mapsize);
343         if (!st->u.loose.mapped)
344                 return -1;
345         if ((unpack_sha1_header(&st->z,
346                                 st->u.loose.mapped,
347                                 st->u.loose.mapsize,
348                                 st->u.loose.hdr,
349                                 sizeof(st->u.loose.hdr)) < 0) ||
350             (parse_sha1_header(st->u.loose.hdr, &st->size) < 0)) {
351                 git_inflate_end(&st->z);
352                 munmap(st->u.loose.mapped, st->u.loose.mapsize);
353                 return -1;
354         }
355
356         st->u.loose.hdr_used = strlen(st->u.loose.hdr) + 1;
357         st->u.loose.hdr_avail = st->z.total_out;
358         st->z_state = z_used;
359
360         st->vtbl = &loose_vtbl;
361         return 0;
362 }
363
364
365 /*****************************************************************
366  *
367  * Non-delta packed object stream
368  *
369  *****************************************************************/
370
371 static read_method_decl(pack_non_delta)
372 {
373         size_t total_read = 0;
374
375         switch (st->z_state) {
376         case z_unused:
377                 memset(&st->z, 0, sizeof(st->z));
378                 git_inflate_init(&st->z);
379                 st->z_state = z_used;
380                 break;
381         case z_done:
382                 return 0;
383         case z_error:
384                 return -1;
385         case z_used:
386                 break;
387         }
388
389         while (total_read < sz) {
390                 int status;
391                 struct pack_window *window = NULL;
392                 unsigned char *mapped;
393
394                 mapped = use_pack(st->u.in_pack.pack, &window,
395                                   st->u.in_pack.pos, &st->z.avail_in);
396
397                 st->z.next_out = (unsigned char *)buf + total_read;
398                 st->z.avail_out = sz - total_read;
399                 st->z.next_in = mapped;
400                 status = git_inflate(&st->z, Z_FINISH);
401
402                 st->u.in_pack.pos += st->z.next_in - mapped;
403                 total_read = st->z.next_out - (unsigned char *)buf;
404                 unuse_pack(&window);
405
406                 if (status == Z_STREAM_END) {
407                         git_inflate_end(&st->z);
408                         st->z_state = z_done;
409                         break;
410                 }
411
412                 /*
413                  * Unlike the loose object case, we do not have to worry here
414                  * about running out of input bytes and spinning infinitely. If
415                  * we get Z_BUF_ERROR due to too few input bytes, then we'll
416                  * replenish them in the next use_pack() call when we loop. If
417                  * we truly hit the end of the pack (i.e., because it's corrupt
418                  * or truncated), then use_pack() catches that and will die().
419                  */
420                 if (status != Z_OK && status != Z_BUF_ERROR) {
421                         git_inflate_end(&st->z);
422                         st->z_state = z_error;
423                         return -1;
424                 }
425         }
426         return total_read;
427 }
428
429 static close_method_decl(pack_non_delta)
430 {
431         close_deflated_stream(st);
432         return 0;
433 }
434
435 static struct stream_vtbl pack_non_delta_vtbl = {
436         close_istream_pack_non_delta,
437         read_istream_pack_non_delta,
438 };
439
440 static open_method_decl(pack_non_delta)
441 {
442         struct pack_window *window;
443         enum object_type in_pack_type;
444
445         st->u.in_pack.pack = oi->u.packed.pack;
446         st->u.in_pack.pos = oi->u.packed.offset;
447         window = NULL;
448
449         in_pack_type = unpack_object_header(st->u.in_pack.pack,
450                                             &window,
451                                             &st->u.in_pack.pos,
452                                             &st->size);
453         unuse_pack(&window);
454         switch (in_pack_type) {
455         default:
456                 return -1; /* we do not do deltas for now */
457         case OBJ_COMMIT:
458         case OBJ_TREE:
459         case OBJ_BLOB:
460         case OBJ_TAG:
461                 break;
462         }
463         st->z_state = z_unused;
464         st->vtbl = &pack_non_delta_vtbl;
465         return 0;
466 }
467
468
469 /*****************************************************************
470  *
471  * In-core stream
472  *
473  *****************************************************************/
474
475 static close_method_decl(incore)
476 {
477         free(st->u.incore.buf);
478         return 0;
479 }
480
481 static read_method_decl(incore)
482 {
483         size_t read_size = sz;
484         size_t remainder = st->size - st->u.incore.read_ptr;
485
486         if (remainder <= read_size)
487                 read_size = remainder;
488         if (read_size) {
489                 memcpy(buf, st->u.incore.buf + st->u.incore.read_ptr, read_size);
490                 st->u.incore.read_ptr += read_size;
491         }
492         return read_size;
493 }
494
495 static struct stream_vtbl incore_vtbl = {
496         close_istream_incore,
497         read_istream_incore,
498 };
499
500 static open_method_decl(incore)
501 {
502         st->u.incore.buf = read_object_file_extended(oid, type, &st->size, 0);
503         st->u.incore.read_ptr = 0;
504         st->vtbl = &incore_vtbl;
505
506         return st->u.incore.buf ? 0 : -1;
507 }
508
509
510 /****************************************************************
511  * Users of streaming interface
512  ****************************************************************/
513
514 int stream_blob_to_fd(int fd, const struct object_id *oid, struct stream_filter *filter,
515                       int can_seek)
516 {
517         struct git_istream *st;
518         enum object_type type;
519         unsigned long sz;
520         ssize_t kept = 0;
521         int result = -1;
522
523         st = open_istream(oid, &type, &sz, filter);
524         if (!st) {
525                 if (filter)
526                         free_stream_filter(filter);
527                 return result;
528         }
529         if (type != OBJ_BLOB)
530                 goto close_and_exit;
531         for (;;) {
532                 char buf[1024 * 16];
533                 ssize_t wrote, holeto;
534                 ssize_t readlen = read_istream(st, buf, sizeof(buf));
535
536                 if (readlen < 0)
537                         goto close_and_exit;
538                 if (!readlen)
539                         break;
540                 if (can_seek && sizeof(buf) == readlen) {
541                         for (holeto = 0; holeto < readlen; holeto++)
542                                 if (buf[holeto])
543                                         break;
544                         if (readlen == holeto) {
545                                 kept += holeto;
546                                 continue;
547                         }
548                 }
549
550                 if (kept && lseek(fd, kept, SEEK_CUR) == (off_t) -1)
551                         goto close_and_exit;
552                 else
553                         kept = 0;
554                 wrote = write_in_full(fd, buf, readlen);
555
556                 if (wrote < 0)
557                         goto close_and_exit;
558         }
559         if (kept && (lseek(fd, kept - 1, SEEK_CUR) == (off_t) -1 ||
560                      xwrite(fd, "", 1) != 1))
561                 goto close_and_exit;
562         result = 0;
563
564  close_and_exit:
565         close_istream(st);
566         return result;
567 }