streaming: convert istream internals to struct object_id
[git/git.git] / streaming.c
1 /*
2 * Copyright (c) 2011, Google Inc.
3 */
4 #include "cache.h"
5 #include "streaming.h"
6 #include "packfile.h"
7
8 enum input_source {
9 stream_error = -1,
10 incore = 0,
11 loose = 1,
12 pack_non_delta = 2
13 };
14
15 typedef int (*open_istream_fn)(struct git_istream *,
16 struct object_info *,
17 const struct object_id *,
18 enum object_type *);
19 typedef int (*close_istream_fn)(struct git_istream *);
20 typedef ssize_t (*read_istream_fn)(struct git_istream *, char *, size_t);
21
22 struct stream_vtbl {
23 close_istream_fn close;
24 read_istream_fn read;
25 };
26
27 #define open_method_decl(name) \
28 int open_istream_ ##name \
29 (struct git_istream *st, struct object_info *oi, \
30 const struct object_id *oid, \
31 enum object_type *type)
32
33 #define close_method_decl(name) \
34 int close_istream_ ##name \
35 (struct git_istream *st)
36
37 #define read_method_decl(name) \
38 ssize_t read_istream_ ##name \
39 (struct git_istream *st, char *buf, size_t sz)
40
41 /* forward declaration */
42 static open_method_decl(incore);
43 static open_method_decl(loose);
44 static open_method_decl(pack_non_delta);
45 static struct git_istream *attach_stream_filter(struct git_istream *st,
46 struct stream_filter *filter);
47
48
49 static open_istream_fn open_istream_tbl[] = {
50 open_istream_incore,
51 open_istream_loose,
52 open_istream_pack_non_delta,
53 };
54
55 #define FILTER_BUFFER (1024*16)
56
57 struct filtered_istream {
58 struct git_istream *upstream;
59 struct stream_filter *filter;
60 char ibuf[FILTER_BUFFER];
61 char obuf[FILTER_BUFFER];
62 int i_end, i_ptr;
63 int o_end, o_ptr;
64 int input_finished;
65 };
66
67 struct git_istream {
68 const struct stream_vtbl *vtbl;
69 unsigned long size; /* inflated size of full object */
70 git_zstream z;
71 enum { z_unused, z_used, z_done, z_error } z_state;
72
73 union {
74 struct {
75 char *buf; /* from read_object() */
76 unsigned long read_ptr;
77 } incore;
78
79 struct {
80 void *mapped;
81 unsigned long mapsize;
82 char hdr[32];
83 int hdr_avail;
84 int hdr_used;
85 } loose;
86
87 struct {
88 struct packed_git *pack;
89 off_t pos;
90 } in_pack;
91
92 struct filtered_istream filtered;
93 } u;
94 };
95
96 int close_istream(struct git_istream *st)
97 {
98 int r = st->vtbl->close(st);
99 free(st);
100 return r;
101 }
102
103 ssize_t read_istream(struct git_istream *st, void *buf, size_t sz)
104 {
105 return st->vtbl->read(st, buf, sz);
106 }
107
108 static enum input_source istream_source(const unsigned char *sha1,
109 enum object_type *type,
110 struct object_info *oi)
111 {
112 unsigned long size;
113 int status;
114 struct object_id oid;
115
116 hashcpy(oid.hash, sha1);
117
118 oi->typep = type;
119 oi->sizep = &size;
120 status = oid_object_info_extended(&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 unsigned char *real = lookup_replace_object(oid->hash);
144 enum input_source src = istream_source(real, type, &oi);
145 struct object_id realoid;
146
147 hashcpy(realoid.hash, real);
148
149 if (src < 0)
150 return NULL;
151
152 st = xmalloc(sizeof(*st));
153 if (open_istream_tbl[src](st, &oi, &realoid, type)) {
154 if (open_istream_incore(st, &oi, &realoid, type)) {
155 free(st);
156 return NULL;
157 }
158 }
159 if (filter) {
160 /* Add "&& !is_null_stream_filter(filter)" for performance */
161 struct git_istream *nst = attach_stream_filter(st, filter);
162 if (!nst) {
163 close_istream(st);
164 return NULL;
165 }
166 st = nst;
167 }
168
169 *size = st->size;
170 return st;
171 }
172
173
174 /*****************************************************************
175 *
176 * Common helpers
177 *
178 *****************************************************************/
179
180 static void close_deflated_stream(struct git_istream *st)
181 {
182 if (st->z_state == z_used)
183 git_inflate_end(&st->z);
184 }
185
186
187 /*****************************************************************
188 *
189 * Filtered stream
190 *
191 *****************************************************************/
192
193 static close_method_decl(filtered)
194 {
195 free_stream_filter(st->u.filtered.filter);
196 return close_istream(st->u.filtered.upstream);
197 }
198
199 static read_method_decl(filtered)
200 {
201 struct filtered_istream *fs = &(st->u.filtered);
202 size_t filled = 0;
203
204 while (sz) {
205 /* do we already have filtered output? */
206 if (fs->o_ptr < fs->o_end) {
207 size_t to_move = fs->o_end - fs->o_ptr;
208 if (sz < to_move)
209 to_move = sz;
210 memcpy(buf + filled, fs->obuf + fs->o_ptr, to_move);
211 fs->o_ptr += to_move;
212 sz -= to_move;
213 filled += to_move;
214 continue;
215 }
216 fs->o_end = fs->o_ptr = 0;
217
218 /* do we have anything to feed the filter with? */
219 if (fs->i_ptr < fs->i_end) {
220 size_t to_feed = fs->i_end - fs->i_ptr;
221 size_t to_receive = FILTER_BUFFER;
222 if (stream_filter(fs->filter,
223 fs->ibuf + fs->i_ptr, &to_feed,
224 fs->obuf, &to_receive))
225 return -1;
226 fs->i_ptr = fs->i_end - to_feed;
227 fs->o_end = FILTER_BUFFER - to_receive;
228 continue;
229 }
230
231 /* tell the filter to drain upon no more input */
232 if (fs->input_finished) {
233 size_t to_receive = FILTER_BUFFER;
234 if (stream_filter(fs->filter,
235 NULL, NULL,
236 fs->obuf, &to_receive))
237 return -1;
238 fs->o_end = FILTER_BUFFER - to_receive;
239 if (!fs->o_end)
240 break;
241 continue;
242 }
243 fs->i_end = fs->i_ptr = 0;
244
245 /* refill the input from the upstream */
246 if (!fs->input_finished) {
247 fs->i_end = read_istream(fs->upstream, fs->ibuf, FILTER_BUFFER);
248 if (fs->i_end < 0)
249 return -1;
250 if (fs->i_end)
251 continue;
252 }
253 fs->input_finished = 1;
254 }
255 return filled;
256 }
257
258 static struct stream_vtbl filtered_vtbl = {
259 close_istream_filtered,
260 read_istream_filtered,
261 };
262
263 static struct git_istream *attach_stream_filter(struct git_istream *st,
264 struct stream_filter *filter)
265 {
266 struct git_istream *ifs = xmalloc(sizeof(*ifs));
267 struct filtered_istream *fs = &(ifs->u.filtered);
268
269 ifs->vtbl = &filtered_vtbl;
270 fs->upstream = st;
271 fs->filter = filter;
272 fs->i_end = fs->i_ptr = 0;
273 fs->o_end = fs->o_ptr = 0;
274 fs->input_finished = 0;
275 ifs->size = -1; /* unknown */
276 return ifs;
277 }
278
279 /*****************************************************************
280 *
281 * Loose object stream
282 *
283 *****************************************************************/
284
285 static read_method_decl(loose)
286 {
287 size_t total_read = 0;
288
289 switch (st->z_state) {
290 case z_done:
291 return 0;
292 case z_error:
293 return -1;
294 default:
295 break;
296 }
297
298 if (st->u.loose.hdr_used < st->u.loose.hdr_avail) {
299 size_t to_copy = st->u.loose.hdr_avail - st->u.loose.hdr_used;
300 if (sz < to_copy)
301 to_copy = sz;
302 memcpy(buf, st->u.loose.hdr + st->u.loose.hdr_used, to_copy);
303 st->u.loose.hdr_used += to_copy;
304 total_read += to_copy;
305 }
306
307 while (total_read < sz) {
308 int status;
309
310 st->z.next_out = (unsigned char *)buf + total_read;
311 st->z.avail_out = sz - total_read;
312 status = git_inflate(&st->z, Z_FINISH);
313
314 total_read = st->z.next_out - (unsigned char *)buf;
315
316 if (status == Z_STREAM_END) {
317 git_inflate_end(&st->z);
318 st->z_state = z_done;
319 break;
320 }
321 if (status != Z_OK && (status != Z_BUF_ERROR || total_read < sz)) {
322 git_inflate_end(&st->z);
323 st->z_state = z_error;
324 return -1;
325 }
326 }
327 return total_read;
328 }
329
330 static close_method_decl(loose)
331 {
332 close_deflated_stream(st);
333 munmap(st->u.loose.mapped, st->u.loose.mapsize);
334 return 0;
335 }
336
337 static struct stream_vtbl loose_vtbl = {
338 close_istream_loose,
339 read_istream_loose,
340 };
341
342 static open_method_decl(loose)
343 {
344 st->u.loose.mapped = map_sha1_file(oid->hash, &st->u.loose.mapsize);
345 if (!st->u.loose.mapped)
346 return -1;
347 if ((unpack_sha1_header(&st->z,
348 st->u.loose.mapped,
349 st->u.loose.mapsize,
350 st->u.loose.hdr,
351 sizeof(st->u.loose.hdr)) < 0) ||
352 (parse_sha1_header(st->u.loose.hdr, &st->size) < 0)) {
353 git_inflate_end(&st->z);
354 munmap(st->u.loose.mapped, st->u.loose.mapsize);
355 return -1;
356 }
357
358 st->u.loose.hdr_used = strlen(st->u.loose.hdr) + 1;
359 st->u.loose.hdr_avail = st->z.total_out;
360 st->z_state = z_used;
361
362 st->vtbl = &loose_vtbl;
363 return 0;
364 }
365
366
367 /*****************************************************************
368 *
369 * Non-delta packed object stream
370 *
371 *****************************************************************/
372
373 static read_method_decl(pack_non_delta)
374 {
375 size_t total_read = 0;
376
377 switch (st->z_state) {
378 case z_unused:
379 memset(&st->z, 0, sizeof(st->z));
380 git_inflate_init(&st->z);
381 st->z_state = z_used;
382 break;
383 case z_done:
384 return 0;
385 case z_error:
386 return -1;
387 case z_used:
388 break;
389 }
390
391 while (total_read < sz) {
392 int status;
393 struct pack_window *window = NULL;
394 unsigned char *mapped;
395
396 mapped = use_pack(st->u.in_pack.pack, &window,
397 st->u.in_pack.pos, &st->z.avail_in);
398
399 st->z.next_out = (unsigned char *)buf + total_read;
400 st->z.avail_out = sz - total_read;
401 st->z.next_in = mapped;
402 status = git_inflate(&st->z, Z_FINISH);
403
404 st->u.in_pack.pos += st->z.next_in - mapped;
405 total_read = st->z.next_out - (unsigned char *)buf;
406 unuse_pack(&window);
407
408 if (status == Z_STREAM_END) {
409 git_inflate_end(&st->z);
410 st->z_state = z_done;
411 break;
412 }
413 if (status != Z_OK && status != Z_BUF_ERROR) {
414 git_inflate_end(&st->z);
415 st->z_state = z_error;
416 return -1;
417 }
418 }
419 return total_read;
420 }
421
422 static close_method_decl(pack_non_delta)
423 {
424 close_deflated_stream(st);
425 return 0;
426 }
427
428 static struct stream_vtbl pack_non_delta_vtbl = {
429 close_istream_pack_non_delta,
430 read_istream_pack_non_delta,
431 };
432
433 static open_method_decl(pack_non_delta)
434 {
435 struct pack_window *window;
436 enum object_type in_pack_type;
437
438 st->u.in_pack.pack = oi->u.packed.pack;
439 st->u.in_pack.pos = oi->u.packed.offset;
440 window = NULL;
441
442 in_pack_type = unpack_object_header(st->u.in_pack.pack,
443 &window,
444 &st->u.in_pack.pos,
445 &st->size);
446 unuse_pack(&window);
447 switch (in_pack_type) {
448 default:
449 return -1; /* we do not do deltas for now */
450 case OBJ_COMMIT:
451 case OBJ_TREE:
452 case OBJ_BLOB:
453 case OBJ_TAG:
454 break;
455 }
456 st->z_state = z_unused;
457 st->vtbl = &pack_non_delta_vtbl;
458 return 0;
459 }
460
461
462 /*****************************************************************
463 *
464 * In-core stream
465 *
466 *****************************************************************/
467
468 static close_method_decl(incore)
469 {
470 free(st->u.incore.buf);
471 return 0;
472 }
473
474 static read_method_decl(incore)
475 {
476 size_t read_size = sz;
477 size_t remainder = st->size - st->u.incore.read_ptr;
478
479 if (remainder <= read_size)
480 read_size = remainder;
481 if (read_size) {
482 memcpy(buf, st->u.incore.buf + st->u.incore.read_ptr, read_size);
483 st->u.incore.read_ptr += read_size;
484 }
485 return read_size;
486 }
487
488 static struct stream_vtbl incore_vtbl = {
489 close_istream_incore,
490 read_istream_incore,
491 };
492
493 static open_method_decl(incore)
494 {
495 st->u.incore.buf = read_sha1_file_extended(oid->hash, type, &st->size, 0);
496 st->u.incore.read_ptr = 0;
497 st->vtbl = &incore_vtbl;
498
499 return st->u.incore.buf ? 0 : -1;
500 }
501
502
503 /****************************************************************
504 * Users of streaming interface
505 ****************************************************************/
506
507 int stream_blob_to_fd(int fd, const struct object_id *oid, struct stream_filter *filter,
508 int can_seek)
509 {
510 struct git_istream *st;
511 enum object_type type;
512 unsigned long sz;
513 ssize_t kept = 0;
514 int result = -1;
515
516 st = open_istream(oid, &type, &sz, filter);
517 if (!st) {
518 if (filter)
519 free_stream_filter(filter);
520 return result;
521 }
522 if (type != OBJ_BLOB)
523 goto close_and_exit;
524 for (;;) {
525 char buf[1024 * 16];
526 ssize_t wrote, holeto;
527 ssize_t readlen = read_istream(st, buf, sizeof(buf));
528
529 if (readlen < 0)
530 goto close_and_exit;
531 if (!readlen)
532 break;
533 if (can_seek && sizeof(buf) == readlen) {
534 for (holeto = 0; holeto < readlen; holeto++)
535 if (buf[holeto])
536 break;
537 if (readlen == holeto) {
538 kept += holeto;
539 continue;
540 }
541 }
542
543 if (kept && lseek(fd, kept, SEEK_CUR) == (off_t) -1)
544 goto close_and_exit;
545 else
546 kept = 0;
547 wrote = write_in_full(fd, buf, readlen);
548
549 if (wrote < 0)
550 goto close_and_exit;
551 }
552 if (kept && (lseek(fd, kept - 1, SEEK_CUR) == (off_t) -1 ||
553 xwrite(fd, "", 1) != 1))
554 goto close_and_exit;
555 result = 0;
556
557 close_and_exit:
558 close_istream(st);
559 return result;
560 }