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 };
  64
  65 struct git_istream {
  66         const struct stream_vtbl *vtbl;
  67         unsigned long size; /* inflated size of full object */
  68         z_stream z;
  69         enum { z_unused, z_used, z_done, z_error } z_state;
  70
  71         union {
  72                 struct {
  73                         char *buf; /* from read_object() */
  74                         unsigned long read_ptr;
  75                 } incore;
  76
  77                 struct {
  78                         void *mapped;
  79                         unsigned long mapsize;
  80                         char hdr[32];
  81                         int hdr_avail;
  82                         int hdr_used;
  83                 } loose;
  84
  85                 struct {
  86                         struct packed_git *pack;
  87                         off_t pos;
  88                 } in_pack;
  89
  90                 struct filtered_istream filtered;
  91         } u;
  92 };
  93
  94 int close_istream(struct git_istream *st)
  95 {
  96         return st->vtbl->close(st);
  97 }
  98
  99 ssize_t read_istream(struct git_istream *st, char *buf, size_t sz)
 100 {
 101         return st->vtbl->read(st, buf, sz);
 102 }
 103
 104 static enum input_source istream_source(const unsigned char *sha1,
 105                                         enum object_type *type,
 106                                         struct object_info *oi)
 107 {
 108         unsigned long size;
 109         int status;
 110
 111         oi->sizep = &size;
 112         status = sha1_object_info_extended(sha1, oi);
 113         if (status < 0)
 114                 return stream_error;
 115         *type = status;
 116
 117         switch (oi->whence) {
 118         case OI_LOOSE:
 119                 return loose;
 120         case OI_PACKED:
 121                 if (!oi->u.packed.is_delta && big_file_threshold <= size)
 122                         return pack_non_delta;
 123                 /* fallthru */
 124         default:
 125                 return incore;
 126         }
 127 }
 128
 129 struct git_istream *open_istream(const unsigned char *sha1,
 130                                  enum object_type *type,
 131                                  unsigned long *size,
 132                                  struct stream_filter *filter)
 133 {
 134         struct git_istream *st;
 135         struct object_info oi;
 136         const unsigned char *real = lookup_replace_object(sha1);
 137         enum input_source src = istream_source(real, type, &oi);
 138
 139         if (src < 0)
 140                 return NULL;
 141
 142         st = xmalloc(sizeof(*st));
 143         if (open_istream_tbl[src](st, &oi, real, type)) {
 144                 if (open_istream_incore(st, &oi, real, type)) {
 145                         free(st);
 146                         return NULL;
 147                 }
 148         }
 149         if (st && filter) {
 150                 /* Add "&& !is_null_stream_filter(filter)" for performance */
 151                 struct git_istream *nst = attach_stream_filter(st, filter);
 152                 if (!nst)
 153                         close_istream(st);
 154                 st = nst;
 155         }
 156
 157         *size = st->size;
 158         return st;
 159 }
 160
 161
 162 /*****************************************************************
 163  *
 164  * Common helpers
 165  *
 166  *****************************************************************/
 167
 168 static void close_deflated_stream(struct git_istream *st)
 169 {
 170         if (st->z_state == z_used)
 171                 git_inflate_end(&st->z);
 172 }
 173
 174
 175 /*****************************************************************
 176  *
 177  * Filtered stream
 178  *
 179  *****************************************************************/
 180
 181 static close_method_decl(filtered)
 182 {
 183         free_stream_filter(st->u.filtered.filter);
 184         return close_istream(st->u.filtered.upstream);
 185 }
 186
 187 static read_method_decl(filtered)
 188 {
 189         struct filtered_istream *fs = &(st->u.filtered);
 190         size_t filled = 0;
 191
 192         while (sz) {
 193                 /* do we already have filtered output? */
 194                 if (fs->o_ptr < fs->o_end) {
 195                         size_t to_move = fs->o_end - fs->o_ptr;
 196                         if (sz < to_move)
 197                                 to_move = sz;
 198                         memcpy(buf + filled, fs->obuf + fs->o_ptr, to_move);
 199                         fs->o_ptr += to_move;
 200                         sz -= to_move;
 201                         filled += to_move;
 202                         continue;
 203                 }
 204                 fs->o_end = fs->o_ptr = 0;
 205
 206                 /* do we have anything to feed the filter with? */
 207                 if (fs->i_ptr < fs->i_end) {
 208                         size_t to_feed = fs->i_end - fs->i_ptr;
 209                         size_t to_receive = FILTER_BUFFER;
 210                         if (stream_filter(fs->filter,
 211                                           fs->ibuf + fs->i_ptr, &to_feed,
 212                                           fs->obuf, &to_receive))
 213                                 return -1;
 214                         fs->i_ptr = fs->i_end - to_feed;
 215                         fs->o_end = FILTER_BUFFER - to_receive;
 216                         continue;
 217                 }
 218                 fs->i_end = fs->i_ptr = 0;
 219
 220                 /* refill the input from the upstream */
 221                 fs->i_end = read_istream(fs->upstream, fs->ibuf, FILTER_BUFFER);
 222                 if (fs->i_end <= 0)
 223                         break;
 224         }
 225         return filled;
 226 }
 227
 228 static struct stream_vtbl filtered_vtbl = {
 229         close_istream_filtered,
 230         read_istream_filtered,
 231 };
 232
 233 static struct git_istream *attach_stream_filter(struct git_istream *st,
 234                                                 struct stream_filter *filter)
 235 {
 236         struct git_istream *ifs = xmalloc(sizeof(*ifs));
 237         struct filtered_istream *fs = &(ifs->u.filtered);
 238
 239         ifs->vtbl = &filtered_vtbl;
 240         fs->upstream = st;
 241         fs->filter = filter;
 242         fs->i_end = fs->i_ptr = 0;
 243         fs->o_end = fs->o_ptr = 0;
 244         ifs->size = -1; /* unknown */
 245         return ifs;
 246 }
 247
 248 /*****************************************************************
 249  *
 250  * Loose object stream
 251  *
 252  *****************************************************************/
 253
 254 static read_method_decl(loose)
 255 {
 256         size_t total_read = 0;
 257
 258         switch (st->z_state) {
 259         case z_done:
 260                 return 0;
 261         case z_error:
 262                 return -1;
 263         default:
 264                 break;
 265         }
 266
 267         if (st->u.loose.hdr_used < st->u.loose.hdr_avail) {
 268                 size_t to_copy = st->u.loose.hdr_avail - st->u.loose.hdr_used;
 269                 if (sz < to_copy)
 270                         to_copy = sz;
 271                 memcpy(buf, st->u.loose.hdr + st->u.loose.hdr_used, to_copy);
 272                 st->u.loose.hdr_used += to_copy;
 273                 total_read += to_copy;
 274         }
 275
 276         while (total_read < sz) {
 277                 int status;
 278
 279                 st->z.next_out = (unsigned char *)buf + total_read;
 280                 st->z.avail_out = sz - total_read;
 281                 status = git_inflate(&st->z, Z_FINISH);
 282
 283                 total_read = st->z.next_out - (unsigned char *)buf;
 284
 285                 if (status == Z_STREAM_END) {
 286                         git_inflate_end(&st->z);
 287                         st->z_state = z_done;
 288                         break;
 289                 }
 290                 if (status != Z_OK && status != Z_BUF_ERROR) {
 291                         git_inflate_end(&st->z);
 292                         st->z_state = z_error;
 293                         return -1;
 294                 }
 295         }
 296         return total_read;
 297 }
 298
 299 static close_method_decl(loose)
 300 {
 301         close_deflated_stream(st);
 302         munmap(st->u.loose.mapped, st->u.loose.mapsize);
 303         return 0;
 304 }
 305
 306 static struct stream_vtbl loose_vtbl = {
 307         close_istream_loose,
 308         read_istream_loose,
 309 };
 310
 311 static open_method_decl(loose)
 312 {
 313         st->u.loose.mapped = map_sha1_file(sha1, &st->u.loose.mapsize);
 314         if (!st->u.loose.mapped)
 315                 return -1;
 316         if (unpack_sha1_header(&st->z,
 317                                st->u.loose.mapped,
 318                                st->u.loose.mapsize,
 319                                st->u.loose.hdr,
 320                                sizeof(st->u.loose.hdr)) < 0) {
 321                 git_inflate_end(&st->z);
 322                 munmap(st->u.loose.mapped, st->u.loose.mapsize);
 323                 return -1;
 324         }
 325
 326         parse_sha1_header(st->u.loose.hdr, &st->size);
 327         st->u.loose.hdr_used = strlen(st->u.loose.hdr) + 1;
 328         st->u.loose.hdr_avail = st->z.total_out;
 329         st->z_state = z_used;
 330
 331         st->vtbl = &loose_vtbl;
 332         return 0;
 333 }
 334
 335
 336 /*****************************************************************
 337  *
 338  * Non-delta packed object stream
 339  *
 340  *****************************************************************/
 341
 342 static read_method_decl(pack_non_delta)
 343 {
 344         size_t total_read = 0;
 345
 346         switch (st->z_state) {
 347         case z_unused:
 348                 memset(&st->z, 0, sizeof(st->z));
 349                 git_inflate_init(&st->z);
 350                 st->z_state = z_used;
 351                 break;
 352         case z_done:
 353                 return 0;
 354         case z_error:
 355                 return -1;
 356         case z_used:
 357                 break;
 358         }
 359
 360         while (total_read < sz) {
 361                 int status;
 362                 struct pack_window *window = NULL;
 363                 unsigned char *mapped;
 364
 365                 mapped = use_pack(st->u.in_pack.pack, &window,
 366                                   st->u.in_pack.pos, &st->z.avail_in);
 367
 368                 st->z.next_out = (unsigned char *)buf + total_read;
 369                 st->z.avail_out = sz - total_read;
 370                 st->z.next_in = mapped;
 371                 status = git_inflate(&st->z, Z_FINISH);
 372
 373                 st->u.in_pack.pos += st->z.next_in - mapped;
 374                 total_read = st->z.next_out - (unsigned char *)buf;
 375                 unuse_pack(&window);
 376
 377                 if (status == Z_STREAM_END) {
 378                         git_inflate_end(&st->z);
 379                         st->z_state = z_done;
 380                         break;
 381                 }
 382                 if (status != Z_OK && status != Z_BUF_ERROR) {
 383                         git_inflate_end(&st->z);
 384                         st->z_state = z_error;
 385                         return -1;
 386                 }
 387         }
 388         return total_read;
 389 }
 390
 391 static close_method_decl(pack_non_delta)
 392 {
 393         close_deflated_stream(st);
 394         return 0;
 395 }
 396
 397 static struct stream_vtbl pack_non_delta_vtbl = {
 398         close_istream_pack_non_delta,
 399         read_istream_pack_non_delta,
 400 };
 401
 402 static open_method_decl(pack_non_delta)
 403 {
 404         struct pack_window *window;
 405         enum object_type in_pack_type;
 406
 407         st->u.in_pack.pack = oi->u.packed.pack;
 408         st->u.in_pack.pos = oi->u.packed.offset;
 409         window = NULL;
 410
 411         in_pack_type = unpack_object_header(st->u.in_pack.pack,
 412                                             &window,
 413                                             &st->u.in_pack.pos,
 414                                             &st->size);
 415         unuse_pack(&window);
 416         switch (in_pack_type) {
 417         default:
 418                 return -1; /* we do not do deltas for now */
 419         case OBJ_COMMIT:
 420         case OBJ_TREE:
 421         case OBJ_BLOB:
 422         case OBJ_TAG:
 423                 break;
 424         }
 425         st->z_state = z_unused;
 426         st->vtbl = &pack_non_delta_vtbl;
 427         return 0;
 428 }
 429
 430
 431 /*****************************************************************
 432  *
 433  * In-core stream
 434  *
 435  *****************************************************************/
 436
 437 static close_method_decl(incore)
 438 {
 439         free(st->u.incore.buf);
 440         return 0;
 441 }
 442
 443 static read_method_decl(incore)
 444 {
 445         size_t read_size = sz;
 446         size_t remainder = st->size - st->u.incore.read_ptr;
 447
 448         if (remainder <= read_size)
 449                 read_size = remainder;
 450         if (read_size) {
 451                 memcpy(buf, st->u.incore.buf + st->u.incore.read_ptr, read_size);
 452                 st->u.incore.read_ptr += read_size;
 453         }
 454         return read_size;
 455 }
 456
 457 static struct stream_vtbl incore_vtbl = {
 458         close_istream_incore,
 459         read_istream_incore,
 460 };
 461
 462 static open_method_decl(incore)
 463 {
 464         st->u.incore.buf = read_sha1_file_extended(sha1, type, &st->size, 0);
 465         st->u.incore.read_ptr = 0;
 466         st->vtbl = &incore_vtbl;
 467
 468         return st->u.incore.buf ? 0 : -1;
 469 }