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 unsigned char *,
  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 unsigned char *sha1, \
  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
 115         oi->typep = type;
 116         oi->sizep = &size;
 117         status = sha1_object_info_extended(sha1, oi, 0);
 118         if (status < 0)
 119                 return stream_error;
 120
 121         switch (oi->whence) {
 122         case OI_LOOSE:
 123                 return loose;
 124         case OI_PACKED:
 125                 if (!oi->u.packed.is_delta && big_file_threshold < size)
 126                         return pack_non_delta;
 127                 /* fallthru */
 128         default:
 129                 return incore;
 130         }
 131 }
 132
 133 struct git_istream *open_istream(const unsigned char *sha1,
 134                                  enum object_type *type,
 135                                  unsigned long *size,
 136                                  struct stream_filter *filter)
 137 {
 138         struct git_istream *st;
 139         struct object_info oi = OBJECT_INFO_INIT;
 140         const unsigned char *real = lookup_replace_object(sha1);
 141         enum input_source src = istream_source(real, type, &oi);
 142
 143         if (src < 0)
 144                 return NULL;
 145
 146         st = xmalloc(sizeof(*st));
 147         if (open_istream_tbl[src](st, &oi, real, type)) {
 148                 if (open_istream_incore(st, &oi, real, type)) {
 149                         free(st);
 150                         return NULL;
 151                 }
 152         }
 153         if (filter) {
 154                 /* Add "&& !is_null_stream_filter(filter)" for performance */
 155                 struct git_istream *nst = attach_stream_filter(st, filter);
 156                 if (!nst) {
 157                         close_istream(st);
 158                         return NULL;
 159                 }
 160                 st = nst;
 161         }
 162
 163         *size = st->size;
 164         return st;
 165 }
 166
 167
 168 /*****************************************************************
 169  *
 170  * Common helpers
 171  *
 172  *****************************************************************/
 173
 174 static void close_deflated_stream(struct git_istream *st)
 175 {
 176         if (st->z_state == z_used)
 177                 git_inflate_end(&st->z);
 178 }
 179
 180
 181 /*****************************************************************
 182  *
 183  * Filtered stream
 184  *
 185  *****************************************************************/
 186
 187 static close_method_decl(filtered)
 188 {
 189         free_stream_filter(st->u.filtered.filter);
 190         return close_istream(st->u.filtered.upstream);
 191 }
 192
 193 static read_method_decl(filtered)
 194 {
 195         struct filtered_istream *fs = &(st->u.filtered);
 196         size_t filled = 0;
 197
 198         while (sz) {
 199                 /* do we already have filtered output? */
 200                 if (fs->o_ptr < fs->o_end) {
 201                         size_t to_move = fs->o_end - fs->o_ptr;
 202                         if (sz < to_move)
 203                                 to_move = sz;
 204                         memcpy(buf + filled, fs->obuf + fs->o_ptr, to_move);
 205                         fs->o_ptr += to_move;
 206                         sz -= to_move;
 207                         filled += to_move;
 208                         continue;
 209                 }
 210                 fs->o_end = fs->o_ptr = 0;
 211
 212                 /* do we have anything to feed the filter with? */
 213                 if (fs->i_ptr < fs->i_end) {
 214                         size_t to_feed = fs->i_end - fs->i_ptr;
 215                         size_t to_receive = FILTER_BUFFER;
 216                         if (stream_filter(fs->filter,
 217                                           fs->ibuf + fs->i_ptr, &to_feed,
 218                                           fs->obuf, &to_receive))
 219                                 return -1;
 220                         fs->i_ptr = fs->i_end - to_feed;
 221                         fs->o_end = FILTER_BUFFER - to_receive;
 222                         continue;
 223                 }
 224
 225                 /* tell the filter to drain upon no more input */
 226                 if (fs->input_finished) {
 227                         size_t to_receive = FILTER_BUFFER;
 228                         if (stream_filter(fs->filter,
 229                                           NULL, NULL,
 230                                           fs->obuf, &to_receive))
 231                                 return -1;
 232                         fs->o_end = FILTER_BUFFER - to_receive;
 233                         if (!fs->o_end)
 234                                 break;
 235                         continue;
 236                 }
 237                 fs->i_end = fs->i_ptr = 0;
 238
 239                 /* refill the input from the upstream */
 240                 if (!fs->input_finished) {
 241                         fs->i_end = read_istream(fs->upstream, fs->ibuf, FILTER_BUFFER);
 242                         if (fs->i_end < 0)
 243                                 return -1;
 244                         if (fs->i_end)
 245                                 continue;
 246                 }
 247                 fs->input_finished = 1;
 248         }
 249         return filled;
 250 }
 251
 252 static struct stream_vtbl filtered_vtbl = {
 253         close_istream_filtered,
 254         read_istream_filtered,
 255 };
 256
 257 static struct git_istream *attach_stream_filter(struct git_istream *st,
 258                                                 struct stream_filter *filter)
 259 {
 260         struct git_istream *ifs = xmalloc(sizeof(*ifs));
 261         struct filtered_istream *fs = &(ifs->u.filtered);
 262
 263         ifs->vtbl = &filtered_vtbl;
 264         fs->upstream = st;
 265         fs->filter = filter;
 266         fs->i_end = fs->i_ptr = 0;
 267         fs->o_end = fs->o_ptr = 0;
 268         fs->input_finished = 0;
 269         ifs->size = -1; /* unknown */
 270         return ifs;
 271 }
 272
 273 /*****************************************************************
 274  *
 275  * Loose object stream
 276  *
 277  *****************************************************************/
 278
 279 static read_method_decl(loose)
 280 {
 281         size_t total_read = 0;
 282
 283         switch (st->z_state) {
 284         case z_done:
 285                 return 0;
 286         case z_error:
 287                 return -1;
 288         default:
 289                 break;
 290         }
 291
 292         if (st->u.loose.hdr_used < st->u.loose.hdr_avail) {
 293                 size_t to_copy = st->u.loose.hdr_avail - st->u.loose.hdr_used;
 294                 if (sz < to_copy)
 295                         to_copy = sz;
 296                 memcpy(buf, st->u.loose.hdr + st->u.loose.hdr_used, to_copy);
 297                 st->u.loose.hdr_used += to_copy;
 298                 total_read += to_copy;
 299         }
 300
 301         while (total_read < sz) {
 302                 int status;
 303
 304                 st->z.next_out = (unsigned char *)buf + total_read;
 305                 st->z.avail_out = sz - total_read;
 306                 status = git_inflate(&st->z, Z_FINISH);
 307
 308                 total_read = st->z.next_out - (unsigned char *)buf;
 309
 310                 if (status == Z_STREAM_END) {
 311                         git_inflate_end(&st->z);
 312                         st->z_state = z_done;
 313                         break;
 314                 }
 315                 if (status != Z_OK && (status != Z_BUF_ERROR || total_read < sz)) {
 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 close_method_decl(loose)
 325 {
 326         close_deflated_stream(st);
 327         munmap(st->u.loose.mapped, st->u.loose.mapsize);
 328         return 0;
 329 }
 330
 331 static struct stream_vtbl loose_vtbl = {
 332         close_istream_loose,
 333         read_istream_loose,
 334 };
 335
 336 static open_method_decl(loose)
 337 {
 338         st->u.loose.mapped = map_sha1_file(sha1, &st->u.loose.mapsize);
 339         if (!st->u.loose.mapped)
 340                 return -1;
 341         if ((unpack_sha1_header(&st->z,
 342                                 st->u.loose.mapped,
 343                                 st->u.loose.mapsize,
 344                                 st->u.loose.hdr,
 345                                 sizeof(st->u.loose.hdr)) < 0) ||
 346             (parse_sha1_header(st->u.loose.hdr, &st->size) < 0)) {
 347                 git_inflate_end(&st->z);
 348                 munmap(st->u.loose.mapped, st->u.loose.mapsize);
 349                 return -1;
 350         }
 351
 352         st->u.loose.hdr_used = strlen(st->u.loose.hdr) + 1;
 353         st->u.loose.hdr_avail = st->z.total_out;
 354         st->z_state = z_used;
 355
 356         st->vtbl = &loose_vtbl;
 357         return 0;
 358 }
 359
 360
 361 /*****************************************************************
 362  *
 363  * Non-delta packed object stream
 364  *
 365  *****************************************************************/
 366
 367 static read_method_decl(pack_non_delta)
 368 {
 369         size_t total_read = 0;
 370
 371         switch (st->z_state) {
 372         case z_unused:
 373                 memset(&st->z, 0, sizeof(st->z));
 374                 git_inflate_init(&st->z);
 375                 st->z_state = z_used;
 376                 break;
 377         case z_done:
 378                 return 0;
 379         case z_error:
 380                 return -1;
 381         case z_used:
 382                 break;
 383         }
 384
 385         while (total_read < sz) {
 386                 int status;
 387                 struct pack_window *window = NULL;
 388                 unsigned char *mapped;
 389
 390                 mapped = use_pack(st->u.in_pack.pack, &window,
 391                                   st->u.in_pack.pos, &st->z.avail_in);
 392
 393                 st->z.next_out = (unsigned char *)buf + total_read;
 394                 st->z.avail_out = sz - total_read;
 395                 st->z.next_in = mapped;
 396                 status = git_inflate(&st->z, Z_FINISH);
 397
 398                 st->u.in_pack.pos += st->z.next_in - mapped;
 399                 total_read = st->z.next_out - (unsigned char *)buf;
 400                 unuse_pack(&window);
 401
 402                 if (status == Z_STREAM_END) {
 403                         git_inflate_end(&st->z);
 404                         st->z_state = z_done;
 405                         break;
 406                 }
 407                 if (status != Z_OK && status != Z_BUF_ERROR) {
 408                         git_inflate_end(&st->z);
 409                         st->z_state = z_error;
 410                         return -1;
 411                 }
 412         }
 413         return total_read;
 414 }
 415
 416 static close_method_decl(pack_non_delta)
 417 {
 418         close_deflated_stream(st);
 419         return 0;
 420 }
 421
 422 static struct stream_vtbl pack_non_delta_vtbl = {
 423         close_istream_pack_non_delta,
 424         read_istream_pack_non_delta,
 425 };
 426
 427 static open_method_decl(pack_non_delta)
 428 {
 429         struct pack_window *window;
 430         enum object_type in_pack_type;
 431
 432         st->u.in_pack.pack = oi->u.packed.pack;
 433         st->u.in_pack.pos = oi->u.packed.offset;
 434         window = NULL;
 435
 436         in_pack_type = unpack_object_header(st->u.in_pack.pack,
 437                                             &window,
 438                                             &st->u.in_pack.pos,
 439                                             &st->size);
 440         unuse_pack(&window);
 441         switch (in_pack_type) {
 442         default:
 443                 return -1; /* we do not do deltas for now */
 444         case OBJ_COMMIT:
 445         case OBJ_TREE:
 446         case OBJ_BLOB:
 447         case OBJ_TAG:
 448                 break;
 449         }
 450         st->z_state = z_unused;
 451         st->vtbl = &pack_non_delta_vtbl;
 452         return 0;
 453 }
 454
 455
 456 /*****************************************************************
 457  *
 458  * In-core stream
 459  *
 460  *****************************************************************/
 461
 462 static close_method_decl(incore)
 463 {
 464         free(st->u.incore.buf);
 465         return 0;
 466 }
 467
 468 static read_method_decl(incore)
 469 {
 470         size_t read_size = sz;
 471         size_t remainder = st->size - st->u.incore.read_ptr;
 472
 473         if (remainder <= read_size)
 474                 read_size = remainder;
 475         if (read_size) {
 476                 memcpy(buf, st->u.incore.buf + st->u.incore.read_ptr, read_size);
 477                 st->u.incore.read_ptr += read_size;
 478         }
 479         return read_size;
 480 }
 481
 482 static struct stream_vtbl incore_vtbl = {
 483         close_istream_incore,
 484         read_istream_incore,
 485 };
 486
 487 static open_method_decl(incore)
 488 {
 489         st->u.incore.buf = read_sha1_file_extended(sha1, type, &st->size, 0);
 490         st->u.incore.read_ptr = 0;
 491         st->vtbl = &incore_vtbl;
 492
 493         return st->u.incore.buf ? 0 : -1;
 494 }
 495
 496
 497 /****************************************************************
 498  * Users of streaming interface
 499  ****************************************************************/
 500
 501 int stream_blob_to_fd(int fd, const struct object_id *oid, struct stream_filter *filter,
 502                       int can_seek)
 503 {
 504         struct git_istream *st;
 505         enum object_type type;
 506         unsigned long sz;
 507         ssize_t kept = 0;
 508         int result = -1;
 509
 510         st = open_istream(oid->hash, &type, &sz, filter);
 511         if (!st) {
 512                 if (filter)
 513                         free_stream_filter(filter);
 514                 return result;
 515         }
 516         if (type != OBJ_BLOB)
 517                 goto close_and_exit;
 518         for (;;) {
 519                 char buf[1024 * 16];
 520                 ssize_t wrote, holeto;
 521                 ssize_t readlen = read_istream(st, buf, sizeof(buf));
 522
 523                 if (readlen < 0)
 524                         goto close_and_exit;
 525                 if (!readlen)
 526                         break;
 527                 if (can_seek && sizeof(buf) == readlen) {
 528                         for (holeto = 0; holeto < readlen; holeto++)
 529                                 if (buf[holeto])
 530                                         break;
 531                         if (readlen == holeto) {
 532                                 kept += holeto;
 533                                 continue;
 534                         }
 535                 }
 536
 537                 if (kept && lseek(fd, kept, SEEK_CUR) == (off_t) -1)
 538                         goto close_and_exit;
 539                 else
 540                         kept = 0;
 541                 wrote = write_in_full(fd, buf, readlen);
 542
 543                 if (wrote < 0)
 544                         goto close_and_exit;
 545         }
 546         if (kept && (lseek(fd, kept - 1, SEEK_CUR) == (off_t) -1 ||
 547                      xwrite(fd, "", 1) != 1))
 548                 goto close_and_exit;
 549         result = 0;
 550
 551  close_and_exit:
 552         close_istream(st);
 553         return result;
 554 }