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