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_object_file_extended(oid, 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 }