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_loose_object(the_repository,
 342                                               oid, &st->u.loose.mapsize);
 343         if (!st->u.loose.mapped)
 344                 return -1;
 345         if ((unpack_loose_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_loose_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(the_repository, 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 }