streaming.c

   1 /*
   2  * Copyright (c) 2011, Google Inc.
   3  */
   4 #include "cache.h"
   5 #include "streaming.h"
   6
   7 enum input_source {
   8         stream_error = -1,
   9         incore = 0,
  10         loose = 1,
  11         pack_non_delta = 2
  12 };
  13
  14 typedef int (*open_istream_fn)(struct git_istream *,
  15                                struct object_info *,
  16                                const unsigned char *,
  17                                enum object_type *);
  18 typedef int (*close_istream_fn)(struct git_istream *);
  19 typedef ssize_t (*read_istream_fn)(struct git_istream *, char *, size_t);
  20
  21 struct stream_vtbl {
  22         close_istream_fn close;
  23         read_istream_fn read;
  24 };
  25
  26 #define open_method_decl(name) \
  27         int open_istream_ ##name \
  28         (struct git_istream *st, struct object_info *oi, \
  29          const unsigned char *sha1, \
  30          enum object_type *type)
  31
  32 #define close_method_decl(name) \
  33         int close_istream_ ##name \
  34         (struct git_istream *st)
  35
  36 #define read_method_decl(name) \
  37         ssize_t read_istream_ ##name \
  38         (struct git_istream *st, char *buf, size_t sz)
  39
  40 /* forward declaration */
  41 static open_method_decl(incore);
  42 static open_method_decl(loose);
  43 static open_method_decl(pack_non_delta);
  44 static struct git_istream *attach_stream_filter(struct git_istream *st,
  45                                                 struct stream_filter *filter);
  46
  47
  48 static open_istream_fn open_istream_tbl[] = {
  49         open_istream_incore,
  50         open_istream_loose,
  51         open_istream_pack_non_delta,
  52 };
  53
  54 #define FILTER_BUFFER (1024*16)
  55
  56 struct filtered_istream {
  57         struct git_istream *upstream;
  58         struct stream_filter *filter;
  59         char ibuf[FILTER_BUFFER];
  60         char obuf[FILTER_BUFFER];
  61         int i_end, i_ptr;
  62         int o_end, o_ptr;
  63         int input_finished;
  64 };
  65
  66 struct git_istream {
  67         const struct stream_vtbl *vtbl;
  68         unsigned long size; /* inflated size of full object */
  69         git_zstream z;
  70         enum { z_unused, z_used, z_done, z_error } z_state;
  71
  72         union {
  73                 struct {
  74                         char *buf; /* from read_object() */
  75                         unsigned long read_ptr;
  76                 } incore;
  77
  78                 struct {
  79                         void *mapped;
  80                         unsigned long mapsize;
  81                         char hdr[32];
  82                         int hdr_avail;
  83                         int hdr_used;
  84                 } loose;
  85
  86                 struct {
  87                         struct packed_git *pack;
  88                         off_t pos;
  89                 } in_pack;
  90
  91                 struct filtered_istream filtered;
  92         } u;
  93 };
  94
  95 int close_istream(struct git_istream *st)
  96 {
  97         int r = st->vtbl->close(st);
  98         free(st);
  99         return r;
 100 }
 101
 102 ssize_t read_istream(struct git_istream *st, void *buf, size_t sz)
 103 {
 104         return st->vtbl->read(st, buf, sz);
 105 }
 106
 107 static enum input_source istream_source(const unsigned char *sha1,
 108                                         enum object_type *type,
 109                                         struct object_info *oi)
 110 {
 111         unsigned long size;
 112         int status;
 113
 114         oi->sizep = &size;
 115         status = sha1_object_info_extended(sha1, oi);
 116         if (status < 0)
 117                 return stream_error;
 118         *type = status;
 119
 120         switch (oi->whence) {
 121         case OI_LOOSE:
 122                 return loose;
 123         case OI_PACKED:
 124                 if (!oi->u.packed.is_delta && big_file_threshold < size)
 125                         return pack_non_delta;
 126                 /* fallthru */
 127         default:
 128                 return incore;
 129         }
 130 }
 131
 132 struct git_istream *open_istream(const unsigned char *sha1,
 133                                  enum object_type *type,
 134                                  unsigned long *size,
 135                                  struct stream_filter *filter)
 136 {
 137         struct git_istream *st;
 138         struct object_info oi;
 139         const unsigned char *real = lookup_replace_object(sha1);
 140         enum input_source src = istream_source(real, type, &oi);
 141
 142         if (src < 0)
 143                 return NULL;
 144
 145         st = xmalloc(sizeof(*st));
 146         if (open_istream_tbl[src](st, &oi, real, type)) {
 147                 if (open_istream_incore(st, &oi, real, type)) {
 148                         free(st);
 149                         return NULL;
 150                 }
 151         }
 152         if (st && filter) {
 153                 /* Add "&& !is_null_stream_filter(filter)" for performance */
 154                 struct git_istream *nst = attach_stream_filter(st, filter);
 155                 if (!nst)
 156                         close_istream(st);
 157                 st = nst;
 158         }
 159
 160         *size = st->size;
 161         return st;
 162 }
 163
 164
 165 /*****************************************************************
 166  *
 167  * Common helpers
 168  *
 169  *****************************************************************/
 170
 171 static void close_deflated_stream(struct git_istream *st)
 172 {
 173         if (st->z_state == z_used)
 174                 git_inflate_end(&st->z);
 175 }
 176
 177
 178 /*****************************************************************
 179  *
 180  * Filtered stream
 181  *
 182  *****************************************************************/
 183
 184 static close_method_decl(filtered)
 185 {
 186         free_stream_filter(st->u.filtered.filter);
 187         return close_istream(st->u.filtered.upstream);
 188 }
 189
 190 static read_method_decl(filtered)
 191 {
 192         struct filtered_istream *fs = &(st->u.filtered);
 193         size_t filled = 0;
 194
 195         while (sz) {
 196                 /* do we already have filtered output? */
 197                 if (fs->o_ptr < fs->o_end) {
 198                         size_t to_move = fs->o_end - fs->o_ptr;
 199                         if (sz < to_move)
 200                                 to_move = sz;
 201                         memcpy(buf + filled, fs->obuf + fs->o_ptr, to_move);
 202                         fs->o_ptr += to_move;
 203                         sz -= to_move;
 204                         filled += to_move;
 205                         continue;
 206                 }
 207                 fs->o_end = fs->o_ptr = 0;
 208
 209                 /* do we have anything to feed the filter with? */
 210                 if (fs->i_ptr < fs->i_end) {
 211                         size_t to_feed = fs->i_end - fs->i_ptr;
 212                         size_t to_receive = FILTER_BUFFER;
 213                         if (stream_filter(fs->filter,
 214                                           fs->ibuf + fs->i_ptr, &to_feed,
 215                                           fs->obuf, &to_receive))
 216                                 return -1;
 217                         fs->i_ptr = fs->i_end - to_feed;
 218                         fs->o_end = FILTER_BUFFER - to_receive;
 219                         continue;
 220                 }
 221
 222                 /* tell the filter to drain upon no more input */
 223                 if (fs->input_finished) {
 224                         size_t to_receive = FILTER_BUFFER;
 225                         if (stream_filter(fs->filter,
 226                                           NULL, NULL,
 227                                           fs->obuf, &to_receive))
 228                                 return -1;
 229                         fs->o_end = FILTER_BUFFER - to_receive;
 230                         if (!fs->o_end)
 231                                 break;
 232                         continue;
 233                 }
 234                 fs->i_end = fs->i_ptr = 0;
 235
 236                 /* refill the input from the upstream */
 237                 if (!fs->input_finished) {
 238                         fs->i_end = read_istream(fs->upstream, fs->ibuf, FILTER_BUFFER);
 239                         if (fs->i_end < 0)
 240                                 return -1;
 241                         if (fs->i_end)
 242                                 continue;
 243                 }
 244                 fs->input_finished = 1;
 245         }
 246         return filled;
 247 }
 248
 249 static struct stream_vtbl filtered_vtbl = {
 250         close_istream_filtered,
 251         read_istream_filtered,
 252 };
 253
 254 static struct git_istream *attach_stream_filter(struct git_istream *st,
 255                                                 struct stream_filter *filter)
 256 {
 257         struct git_istream *ifs = xmalloc(sizeof(*ifs));
 258         struct filtered_istream *fs = &(ifs->u.filtered);
 259
 260         ifs->vtbl = &filtered_vtbl;
 261         fs->upstream = st;
 262         fs->filter = filter;
 263         fs->i_end = fs->i_ptr = 0;
 264         fs->o_end = fs->o_ptr = 0;
 265         fs->input_finished = 0;
 266         ifs->size = -1; /* unknown */
 267         return ifs;
 268 }
 269
 270 /*****************************************************************
 271  *
 272  * Loose object stream
 273  *
 274  *****************************************************************/
 275
 276 static read_method_decl(loose)
 277 {
 278         size_t total_read = 0;
 279
 280         switch (st->z_state) {
 281         case z_done:
 282                 return 0;
 283         case z_error:
 284                 return -1;
 285         default:
 286                 break;
 287         }
 288
 289         if (st->u.loose.hdr_used < st->u.loose.hdr_avail) {
 290                 size_t to_copy = st->u.loose.hdr_avail - st->u.loose.hdr_used;
 291                 if (sz < to_copy)
 292                         to_copy = sz;
 293                 memcpy(buf, st->u.loose.hdr + st->u.loose.hdr_used, to_copy);
 294                 st->u.loose.hdr_used += to_copy;
 295                 total_read += to_copy;
 296         }
 297
 298         while (total_read < sz) {
 299                 int status;
 300
 301                 st->z.next_out = (unsigned char *)buf + total_read;
 302                 st->z.avail_out = sz - total_read;
 303                 status = git_inflate(&st->z, Z_FINISH);
 304
 305                 total_read = st->z.next_out - (unsigned char *)buf;
 306
 307                 if (status == Z_STREAM_END) {
 308                         git_inflate_end(&st->z);
 309                         st->z_state = z_done;
 310                         break;
 311                 }
 312                 if (status != Z_OK && (status != Z_BUF_ERROR || total_read < sz)) {
 313                         git_inflate_end(&st->z);
 314                         st->z_state = z_error;
 315                         return -1;
 316                 }
 317         }
 318         return total_read;
 319 }
 320
 321 static close_method_decl(loose)
 322 {
 323         close_deflated_stream(st);
 324         munmap(st->u.loose.mapped, st->u.loose.mapsize);
 325         return 0;
 326 }
 327
 328 static struct stream_vtbl loose_vtbl = {
 329         close_istream_loose,
 330         read_istream_loose,
 331 };
 332
 333 static open_method_decl(loose)
 334 {
 335         st->u.loose.mapped = map_sha1_file(sha1, &st->u.loose.mapsize);
 336         if (!st->u.loose.mapped)
 337                 return -1;
 338         if (unpack_sha1_header(&st->z,
 339                                st->u.loose.mapped,
 340                                st->u.loose.mapsize,
 341                                st->u.loose.hdr,
 342                                sizeof(st->u.loose.hdr)) < 0) {
 343                 git_inflate_end(&st->z);
 344                 munmap(st->u.loose.mapped, st->u.loose.mapsize);
 345                 return -1;
 346         }
 347
 348         parse_sha1_header(st->u.loose.hdr, &st->size);
 349         st->u.loose.hdr_used = strlen(st->u.loose.hdr) + 1;
 350         st->u.loose.hdr_avail = st->z.total_out;
 351         st->z_state = z_used;
 352
 353         st->vtbl = &loose_vtbl;
 354         return 0;
 355 }
 356
 357
 358 /*****************************************************************
 359  *
 360  * Non-delta packed object stream
 361  *
 362  *****************************************************************/
 363
 364 static read_method_decl(pack_non_delta)
 365 {
 366         size_t total_read = 0;
 367
 368         switch (st->z_state) {
 369         case z_unused:
 370                 memset(&st->z, 0, sizeof(st->z));
 371                 git_inflate_init(&st->z);
 372                 st->z_state = z_used;
 373                 break;
 374         case z_done:
 375                 return 0;
 376         case z_error:
 377                 return -1;
 378         case z_used:
 379                 break;
 380         }
 381
 382         while (total_read < sz) {
 383                 int status;
 384                 struct pack_window *window = NULL;
 385                 unsigned char *mapped;
 386
 387                 mapped = use_pack(st->u.in_pack.pack, &window,
 388                                   st->u.in_pack.pos, &st->z.avail_in);
 389
 390                 st->z.next_out = (unsigned char *)buf + total_read;
 391                 st->z.avail_out = sz - total_read;
 392                 st->z.next_in = mapped;
 393                 status = git_inflate(&st->z, Z_FINISH);
 394
 395                 st->u.in_pack.pos += st->z.next_in - mapped;
 396                 total_read = st->z.next_out - (unsigned char *)buf;
 397                 unuse_pack(&window);
 398
 399                 if (status == Z_STREAM_END) {
 400                         git_inflate_end(&st->z);
 401                         st->z_state = z_done;
 402                         break;
 403                 }
 404                 if (status != Z_OK && status != Z_BUF_ERROR) {
 405                         git_inflate_end(&st->z);
 406                         st->z_state = z_error;
 407                         return -1;
 408                 }
 409         }
 410         return total_read;
 411 }
 412
 413 static close_method_decl(pack_non_delta)
 414 {
 415         close_deflated_stream(st);
 416         return 0;
 417 }
 418
 419 static struct stream_vtbl pack_non_delta_vtbl = {
 420         close_istream_pack_non_delta,
 421         read_istream_pack_non_delta,
 422 };
 423
 424 static open_method_decl(pack_non_delta)
 425 {
 426         struct pack_window *window;
 427         enum object_type in_pack_type;
 428
 429         st->u.in_pack.pack = oi->u.packed.pack;
 430         st->u.in_pack.pos = oi->u.packed.offset;
 431         window = NULL;
 432
 433         in_pack_type = unpack_object_header(st->u.in_pack.pack,
 434                                             &window,
 435                                             &st->u.in_pack.pos,
 436                                             &st->size);
 437         unuse_pack(&window);
 438         switch (in_pack_type) {
 439         default:
 440                 return -1; /* we do not do deltas for now */
 441         case OBJ_COMMIT:
 442         case OBJ_TREE:
 443         case OBJ_BLOB:
 444         case OBJ_TAG:
 445                 break;
 446         }
 447         st->z_state = z_unused;
 448         st->vtbl = &pack_non_delta_vtbl;
 449         return 0;
 450 }
 451
 452
 453 /*****************************************************************
 454  *
 455  * In-core stream
 456  *
 457  *****************************************************************/
 458
 459 static close_method_decl(incore)
 460 {
 461         free(st->u.incore.buf);
 462         return 0;
 463 }
 464
 465 static read_method_decl(incore)
 466 {
 467         size_t read_size = sz;
 468         size_t remainder = st->size - st->u.incore.read_ptr;
 469
 470         if (remainder <= read_size)
 471                 read_size = remainder;
 472         if (read_size) {
 473                 memcpy(buf, st->u.incore.buf + st->u.incore.read_ptr, read_size);
 474                 st->u.incore.read_ptr += read_size;
 475         }
 476         return read_size;
 477 }
 478
 479 static struct stream_vtbl incore_vtbl = {
 480         close_istream_incore,
 481         read_istream_incore,
 482 };
 483
 484 static open_method_decl(incore)
 485 {
 486         st->u.incore.buf = read_sha1_file_extended(sha1, type, &st->size, 0);
 487         st->u.incore.read_ptr = 0;
 488         st->vtbl = &incore_vtbl;
 489
 490         return st->u.incore.buf ? 0 : -1;
 491 }
 492
 493
 494 /****************************************************************
 495  * Users of streaming interface
 496  ****************************************************************/
 497
 498 int stream_blob_to_fd(int fd, unsigned const char *sha1, struct stream_filter *filter,
 499                       int can_seek)
 500 {
 501         struct git_istream *st;
 502         enum object_type type;
 503         unsigned long sz;
 504         ssize_t kept = 0;
 505         int result = -1;
 506
 507         st = open_istream(sha1, &type, &sz, filter);
 508         if (!st)
 509                 return result;
 510         if (type != OBJ_BLOB)
 511                 goto close_and_exit;
 512         for (;;) {
 513                 char buf[1024 * 16];
 514                 ssize_t wrote, holeto;
 515                 ssize_t readlen = read_istream(st, buf, sizeof(buf));
 516
 517                 if (readlen < 0)
 518                         goto close_and_exit;
 519                 if (!readlen)
 520                         break;
 521                 if (can_seek && sizeof(buf) == readlen) {
 522                         for (holeto = 0; holeto < readlen; holeto++)
 523                                 if (buf[holeto])
 524                                         break;
 525                         if (readlen == holeto) {
 526                                 kept += holeto;
 527                                 continue;
 528                         }
 529                 }
 530
 531                 if (kept && lseek(fd, kept, SEEK_CUR) == (off_t) -1)
 532                         goto close_and_exit;
 533                 else
 534                         kept = 0;
 535                 wrote = write_in_full(fd, buf, readlen);
 536
 537                 if (wrote != readlen)
 538                         goto close_and_exit;
 539         }
 540         if (kept && (lseek(fd, kept - 1, SEEK_CUR) == (off_t) -1 ||
 541                      write(fd, "", 1) != 1))
 542                 goto close_and_exit;
 543         result = 0;
 544
 545  close_and_exit:
 546         close_istream(st);
 547         return result;
 548 }