convert.c

   1 #include "cache.h"
   2 #include "attr.h"
   3 #include "run-command.h"
   4 #include "quote.h"
   5 #include "sigchain.h"
   6 #include "pkt-line.h"
   7 #include "sub-process.h"
   8
   9 /*
  10  * convert.c - convert a file when checking it out and checking it in.
  11  *
  12  * This should use the pathname to decide on whether it wants to do some
  13  * more interesting conversions (automatic gzip/unzip, general format
  14  * conversions etc etc), but by default it just does automatic CRLF<->LF
  15  * translation when the "text" attribute or "auto_crlf" option is set.
  16  */
  17
  18 /* Stat bits: When BIN is set, the txt bits are unset */
  19 #define CONVERT_STAT_BITS_TXT_LF    0x1
  20 #define CONVERT_STAT_BITS_TXT_CRLF  0x2
  21 #define CONVERT_STAT_BITS_BIN       0x4
  22
  23 enum crlf_action {
  24         CRLF_UNDEFINED,
  25         CRLF_BINARY,
  26         CRLF_TEXT,
  27         CRLF_TEXT_INPUT,
  28         CRLF_TEXT_CRLF,
  29         CRLF_AUTO,
  30         CRLF_AUTO_INPUT,
  31         CRLF_AUTO_CRLF
  32 };
  33
  34 struct text_stat {
  35         /* NUL, CR, LF and CRLF counts */
  36         unsigned nul, lonecr, lonelf, crlf;
  37
  38         /* These are just approximations! */
  39         unsigned printable, nonprintable;
  40 };
  41
  42 static void gather_stats(const char *buf, unsigned long size, struct text_stat *stats)
  43 {
  44         unsigned long i;
  45
  46         memset(stats, 0, sizeof(*stats));
  47
  48         for (i = 0; i < size; i++) {
  49                 unsigned char c = buf[i];
  50                 if (c == '\r') {
  51                         if (i+1 < size && buf[i+1] == '\n') {
  52                                 stats->crlf++;
  53                                 i++;
  54                         } else
  55                                 stats->lonecr++;
  56                         continue;
  57                 }
  58                 if (c == '\n') {
  59                         stats->lonelf++;
  60                         continue;
  61                 }
  62                 if (c == 127)
  63                         /* DEL */
  64                         stats->nonprintable++;
  65                 else if (c < 32) {
  66                         switch (c) {
  67                                 /* BS, HT, ESC and FF */
  68                         case '\b': case '\t': case '\033': case '\014':
  69                                 stats->printable++;
  70                                 break;
  71                         case 0:
  72                                 stats->nul++;
  73                                 /* fall through */
  74                         default:
  75                                 stats->nonprintable++;
  76                         }
  77                 }
  78                 else
  79                         stats->printable++;
  80         }
  81
  82         /* If file ends with EOF then don't count this EOF as non-printable. */
  83         if (size >= 1 && buf[size-1] == '\032')
  84                 stats->nonprintable--;
  85 }
  86
  87 /*
  88  * The same heuristics as diff.c::mmfile_is_binary()
  89  * We treat files with bare CR as binary
  90  */
  91 static int convert_is_binary(unsigned long size, const struct text_stat *stats)
  92 {
  93         if (stats->lonecr)
  94                 return 1;
  95         if (stats->nul)
  96                 return 1;
  97         if ((stats->printable >> 7) < stats->nonprintable)
  98                 return 1;
  99         return 0;
 100 }
 101
 102 static unsigned int gather_convert_stats(const char *data, unsigned long size)
 103 {
 104         struct text_stat stats;
 105         int ret = 0;
 106         if (!data || !size)
 107                 return 0;
 108         gather_stats(data, size, &stats);
 109         if (convert_is_binary(size, &stats))
 110                 ret |= CONVERT_STAT_BITS_BIN;
 111         if (stats.crlf)
 112                 ret |= CONVERT_STAT_BITS_TXT_CRLF;
 113         if (stats.lonelf)
 114                 ret |=  CONVERT_STAT_BITS_TXT_LF;
 115
 116         return ret;
 117 }
 118
 119 static const char *gather_convert_stats_ascii(const char *data, unsigned long size)
 120 {
 121         unsigned int convert_stats = gather_convert_stats(data, size);
 122
 123         if (convert_stats & CONVERT_STAT_BITS_BIN)
 124                 return "-text";
 125         switch (convert_stats) {
 126         case CONVERT_STAT_BITS_TXT_LF:
 127                 return "lf";
 128         case CONVERT_STAT_BITS_TXT_CRLF:
 129                 return "crlf";
 130         case CONVERT_STAT_BITS_TXT_LF | CONVERT_STAT_BITS_TXT_CRLF:
 131                 return "mixed";
 132         default:
 133                 return "none";
 134         }
 135 }
 136
 137 const char *get_cached_convert_stats_ascii(const char *path)
 138 {
 139         const char *ret;
 140         unsigned long sz;
 141         void *data = read_blob_data_from_cache(path, &sz);
 142         ret = gather_convert_stats_ascii(data, sz);
 143         free(data);
 144         return ret;
 145 }
 146
 147 const char *get_wt_convert_stats_ascii(const char *path)
 148 {
 149         const char *ret = "";
 150         struct strbuf sb = STRBUF_INIT;
 151         if (strbuf_read_file(&sb, path, 0) >= 0)
 152                 ret = gather_convert_stats_ascii(sb.buf, sb.len);
 153         strbuf_release(&sb);
 154         return ret;
 155 }
 156
 157 static int text_eol_is_crlf(void)
 158 {
 159         if (auto_crlf == AUTO_CRLF_TRUE)
 160                 return 1;
 161         else if (auto_crlf == AUTO_CRLF_INPUT)
 162                 return 0;
 163         if (core_eol == EOL_CRLF)
 164                 return 1;
 165         if (core_eol == EOL_UNSET && EOL_NATIVE == EOL_CRLF)
 166                 return 1;
 167         return 0;
 168 }
 169
 170 static enum eol output_eol(enum crlf_action crlf_action)
 171 {
 172         switch (crlf_action) {
 173         case CRLF_BINARY:
 174                 return EOL_UNSET;
 175         case CRLF_TEXT_CRLF:
 176                 return EOL_CRLF;
 177         case CRLF_TEXT_INPUT:
 178                 return EOL_LF;
 179         case CRLF_UNDEFINED:
 180         case CRLF_AUTO_CRLF:
 181                 return EOL_CRLF;
 182         case CRLF_AUTO_INPUT:
 183                 return EOL_LF;
 184         case CRLF_TEXT:
 185         case CRLF_AUTO:
 186                 /* fall through */
 187                 return text_eol_is_crlf() ? EOL_CRLF : EOL_LF;
 188         }
 189         warning("Illegal crlf_action %d\n", (int)crlf_action);
 190         return core_eol;
 191 }
 192
 193 static void check_safe_crlf(const char *path, enum crlf_action crlf_action,
 194                             struct text_stat *old_stats, struct text_stat *new_stats,
 195                             enum safe_crlf checksafe)
 196 {
 197         if (old_stats->crlf && !new_stats->crlf ) {
 198                 /*
 199                  * CRLFs would not be restored by checkout
 200                  */
 201                 if (checksafe == SAFE_CRLF_WARN)
 202                         warning(_("CRLF will be replaced by LF in %s.\n"
 203                                   "The file will have its original line"
 204                                   " endings in your working directory."), path);
 205                 else /* i.e. SAFE_CRLF_FAIL */
 206                         die(_("CRLF would be replaced by LF in %s."), path);
 207         } else if (old_stats->lonelf && !new_stats->lonelf ) {
 208                 /*
 209                  * CRLFs would be added by checkout
 210                  */
 211                 if (checksafe == SAFE_CRLF_WARN)
 212                         warning(_("LF will be replaced by CRLF in %s.\n"
 213                                   "The file will have its original line"
 214                                   " endings in your working directory."), path);
 215                 else /* i.e. SAFE_CRLF_FAIL */
 216                         die(_("LF would be replaced by CRLF in %s"), path);
 217         }
 218 }
 219
 220 static int has_cr_in_index(const char *path)
 221 {
 222         unsigned long sz;
 223         void *data;
 224         int has_cr;
 225
 226         data = read_blob_data_from_cache(path, &sz);
 227         if (!data)
 228                 return 0;
 229         has_cr = memchr(data, '\r', sz) != NULL;
 230         free(data);
 231         return has_cr;
 232 }
 233
 234 static int will_convert_lf_to_crlf(size_t len, struct text_stat *stats,
 235                                    enum crlf_action crlf_action)
 236 {
 237         if (output_eol(crlf_action) != EOL_CRLF)
 238                 return 0;
 239         /* No "naked" LF? Nothing to convert, regardless. */
 240         if (!stats->lonelf)
 241                 return 0;
 242
 243         if (crlf_action == CRLF_AUTO || crlf_action == CRLF_AUTO_INPUT || crlf_action == CRLF_AUTO_CRLF) {
 244                 /* If we have any CR or CRLF line endings, we do not touch it */
 245                 /* This is the new safer autocrlf-handling */
 246                 if (stats->lonecr || stats->crlf)
 247                         return 0;
 248
 249                 if (convert_is_binary(len, stats))
 250                         return 0;
 251         }
 252         return 1;
 253
 254 }
 255
 256 static int crlf_to_git(const char *path, const char *src, size_t len,
 257                        struct strbuf *buf,
 258                        enum crlf_action crlf_action, enum safe_crlf checksafe)
 259 {
 260         struct text_stat stats;
 261         char *dst;
 262         int convert_crlf_into_lf;
 263
 264         if (crlf_action == CRLF_BINARY ||
 265             (src && !len))
 266                 return 0;
 267
 268         /*
 269          * If we are doing a dry-run and have no source buffer, there is
 270          * nothing to analyze; we must assume we would convert.
 271          */
 272         if (!buf && !src)
 273                 return 1;
 274
 275         gather_stats(src, len, &stats);
 276         /* Optimization: No CRLF? Nothing to convert, regardless. */
 277         convert_crlf_into_lf = !!stats.crlf;
 278
 279         if (crlf_action == CRLF_AUTO || crlf_action == CRLF_AUTO_INPUT || crlf_action == CRLF_AUTO_CRLF) {
 280                 if (convert_is_binary(len, &stats))
 281                         return 0;
 282                 /*
 283                  * If the file in the index has any CR in it, do not
 284                  * convert.  This is the new safer autocrlf handling,
 285                  * unless we want to renormalize in a merge or
 286                  * cherry-pick.
 287                  */
 288                 if ((checksafe != SAFE_CRLF_RENORMALIZE) && has_cr_in_index(path))
 289                         convert_crlf_into_lf = 0;
 290         }
 291         if ((checksafe == SAFE_CRLF_WARN ||
 292             (checksafe == SAFE_CRLF_FAIL)) && len) {
 293                 struct text_stat new_stats;
 294                 memcpy(&new_stats, &stats, sizeof(new_stats));
 295                 /* simulate "git add" */
 296                 if (convert_crlf_into_lf) {
 297                         new_stats.lonelf += new_stats.crlf;
 298                         new_stats.crlf = 0;
 299                 }
 300                 /* simulate "git checkout" */
 301                 if (will_convert_lf_to_crlf(len, &new_stats, crlf_action)) {
 302                         new_stats.crlf += new_stats.lonelf;
 303                         new_stats.lonelf = 0;
 304                 }
 305                 check_safe_crlf(path, crlf_action, &stats, &new_stats, checksafe);
 306         }
 307         if (!convert_crlf_into_lf)
 308                 return 0;
 309
 310         /*
 311          * At this point all of our source analysis is done, and we are sure we
 312          * would convert. If we are in dry-run mode, we can give an answer.
 313          */
 314         if (!buf)
 315                 return 1;
 316
 317         /* only grow if not in place */
 318         if (strbuf_avail(buf) + buf->len < len)
 319                 strbuf_grow(buf, len - buf->len);
 320         dst = buf->buf;
 321         if (crlf_action == CRLF_AUTO || crlf_action == CRLF_AUTO_INPUT || crlf_action == CRLF_AUTO_CRLF) {
 322                 /*
 323                  * If we guessed, we already know we rejected a file with
 324                  * lone CR, and we can strip a CR without looking at what
 325                  * follow it.
 326                  */
 327                 do {
 328                         unsigned char c = *src++;
 329                         if (c != '\r')
 330                                 *dst++ = c;
 331                 } while (--len);
 332         } else {
 333                 do {
 334                         unsigned char c = *src++;
 335                         if (! (c == '\r' && (1 < len && *src == '\n')))
 336                                 *dst++ = c;
 337                 } while (--len);
 338         }
 339         strbuf_setlen(buf, dst - buf->buf);
 340         return 1;
 341 }
 342
 343 static int crlf_to_worktree(const char *path, const char *src, size_t len,
 344                             struct strbuf *buf, enum crlf_action crlf_action)
 345 {
 346         char *to_free = NULL;
 347         struct text_stat stats;
 348
 349         if (!len || output_eol(crlf_action) != EOL_CRLF)
 350                 return 0;
 351
 352         gather_stats(src, len, &stats);
 353         if (!will_convert_lf_to_crlf(len, &stats, crlf_action))
 354                 return 0;
 355
 356         /* are we "faking" in place editing ? */
 357         if (src == buf->buf)
 358                 to_free = strbuf_detach(buf, NULL);
 359
 360         strbuf_grow(buf, len + stats.lonelf);
 361         for (;;) {
 362                 const char *nl = memchr(src, '\n', len);
 363                 if (!nl)
 364                         break;
 365                 if (nl > src && nl[-1] == '\r') {
 366                         strbuf_add(buf, src, nl + 1 - src);
 367                 } else {
 368                         strbuf_add(buf, src, nl - src);
 369                         strbuf_addstr(buf, "\r\n");
 370                 }
 371                 len -= nl + 1 - src;
 372                 src  = nl + 1;
 373         }
 374         strbuf_add(buf, src, len);
 375
 376         free(to_free);
 377         return 1;
 378 }
 379
 380 struct filter_params {
 381         const char *src;
 382         unsigned long size;
 383         int fd;
 384         const char *cmd;
 385         const char *path;
 386 };
 387
 388 static int filter_buffer_or_fd(int in, int out, void *data)
 389 {
 390         /*
 391          * Spawn cmd and feed the buffer contents through its stdin.
 392          */
 393         struct child_process child_process = CHILD_PROCESS_INIT;
 394         struct filter_params *params = (struct filter_params *)data;
 395         int write_err, status;
 396         const char *argv[] = { NULL, NULL };
 397
 398         /* apply % substitution to cmd */
 399         struct strbuf cmd = STRBUF_INIT;
 400         struct strbuf path = STRBUF_INIT;
 401         struct strbuf_expand_dict_entry dict[] = {
 402                 { "f", NULL, },
 403                 { NULL, NULL, },
 404         };
 405
 406         /* quote the path to preserve spaces, etc. */
 407         sq_quote_buf(&path, params->path);
 408         dict[0].value = path.buf;
 409
 410         /* expand all %f with the quoted path */
 411         strbuf_expand(&cmd, params->cmd, strbuf_expand_dict_cb, &dict);
 412         strbuf_release(&path);
 413
 414         argv[0] = cmd.buf;
 415
 416         child_process.argv = argv;
 417         child_process.use_shell = 1;
 418         child_process.in = -1;
 419         child_process.out = out;
 420
 421         if (start_command(&child_process))
 422                 return error("cannot fork to run external filter '%s'", params->cmd);
 423
 424         sigchain_push(SIGPIPE, SIG_IGN);
 425
 426         if (params->src) {
 427                 write_err = (write_in_full(child_process.in,
 428                                            params->src, params->size) < 0);
 429                 if (errno == EPIPE)
 430                         write_err = 0;
 431         } else {
 432                 write_err = copy_fd(params->fd, child_process.in);
 433                 if (write_err == COPY_WRITE_ERROR && errno == EPIPE)
 434                         write_err = 0;
 435         }
 436
 437         if (close(child_process.in))
 438                 write_err = 1;
 439         if (write_err)
 440                 error("cannot feed the input to external filter '%s'", params->cmd);
 441
 442         sigchain_pop(SIGPIPE);
 443
 444         status = finish_command(&child_process);
 445         if (status)
 446                 error("external filter '%s' failed %d", params->cmd, status);
 447
 448         strbuf_release(&cmd);
 449         return (write_err || status);
 450 }
 451
 452 static int apply_single_file_filter(const char *path, const char *src, size_t len, int fd,
 453                         struct strbuf *dst, const char *cmd)
 454 {
 455         /*
 456          * Create a pipeline to have the command filter the buffer's
 457          * contents.
 458          *
 459          * (child --> cmd) --> us
 460          */
 461         int err = 0;
 462         struct strbuf nbuf = STRBUF_INIT;
 463         struct async async;
 464         struct filter_params params;
 465
 466         memset(&async, 0, sizeof(async));
 467         async.proc = filter_buffer_or_fd;
 468         async.data = &params;
 469         async.out = -1;
 470         params.src = src;
 471         params.size = len;
 472         params.fd = fd;
 473         params.cmd = cmd;
 474         params.path = path;
 475
 476         fflush(NULL);
 477         if (start_async(&async))
 478                 return 0;       /* error was already reported */
 479
 480         if (strbuf_read(&nbuf, async.out, len) < 0) {
 481                 err = error("read from external filter '%s' failed", cmd);
 482         }
 483         if (close(async.out)) {
 484                 err = error("read from external filter '%s' failed", cmd);
 485         }
 486         if (finish_async(&async)) {
 487                 err = error("external filter '%s' failed", cmd);
 488         }
 489
 490         if (!err) {
 491                 strbuf_swap(dst, &nbuf);
 492         }
 493         strbuf_release(&nbuf);
 494         return !err;
 495 }
 496
 497 #define CAP_CLEAN    (1u<<0)
 498 #define CAP_SMUDGE   (1u<<1)
 499
 500 struct cmd2process {
 501         struct subprocess_entry subprocess; /* must be the first member! */
 502         unsigned int supported_capabilities;
 503 };
 504
 505 static int subprocess_map_initialized;
 506 static struct hashmap subprocess_map;
 507
 508 static int start_multi_file_filter_fn(struct subprocess_entry *subprocess)
 509 {
 510         int err;
 511         struct cmd2process *entry = (struct cmd2process *)subprocess;
 512         struct string_list cap_list = STRING_LIST_INIT_NODUP;
 513         char *cap_buf;
 514         const char *cap_name;
 515         struct child_process *process = &subprocess->process;
 516         const char *cmd = subprocess->cmd;
 517
 518         sigchain_push(SIGPIPE, SIG_IGN);
 519
 520         err = packet_writel(process->in, "git-filter-client", "version=2", NULL);
 521         if (err)
 522                 goto done;
 523
 524         err = strcmp(packet_read_line(process->out, NULL), "git-filter-server");
 525         if (err) {
 526                 error("external filter '%s' does not support filter protocol version 2", cmd);
 527                 goto done;
 528         }
 529         err = strcmp(packet_read_line(process->out, NULL), "version=2");
 530         if (err)
 531                 goto done;
 532         err = packet_read_line(process->out, NULL) != NULL;
 533         if (err)
 534                 goto done;
 535
 536         err = packet_writel(process->in, "capability=clean", "capability=smudge", NULL);
 537
 538         for (;;) {
 539                 cap_buf = packet_read_line(process->out, NULL);
 540                 if (!cap_buf)
 541                         break;
 542                 string_list_split_in_place(&cap_list, cap_buf, '=', 1);
 543
 544                 if (cap_list.nr != 2 || strcmp(cap_list.items[0].string, "capability"))
 545                         continue;
 546
 547                 cap_name = cap_list.items[1].string;
 548                 if (!strcmp(cap_name, "clean")) {
 549                         entry->supported_capabilities |= CAP_CLEAN;
 550                 } else if (!strcmp(cap_name, "smudge")) {
 551                         entry->supported_capabilities |= CAP_SMUDGE;
 552                 } else {
 553                         warning(
 554                                 "external filter '%s' requested unsupported filter capability '%s'",
 555                                 cmd, cap_name
 556                         );
 557                 }
 558
 559                 string_list_clear(&cap_list, 0);
 560         }
 561
 562 done:
 563         sigchain_pop(SIGPIPE);
 564
 565         return err;
 566 }
 567
 568 static int apply_multi_file_filter(const char *path, const char *src, size_t len,
 569                                    int fd, struct strbuf *dst, const char *cmd,
 570                                    const unsigned int wanted_capability)
 571 {
 572         int err;
 573         struct cmd2process *entry;
 574         struct child_process *process;
 575         struct strbuf nbuf = STRBUF_INIT;
 576         struct strbuf filter_status = STRBUF_INIT;
 577         const char *filter_type;
 578
 579         if (!subprocess_map_initialized) {
 580                 subprocess_map_initialized = 1;
 581                 hashmap_init(&subprocess_map, (hashmap_cmp_fn) cmd2process_cmp, 0);
 582                 entry = NULL;
 583         } else {
 584                 entry = (struct cmd2process *)subprocess_find_entry(&subprocess_map, cmd);
 585         }
 586
 587         fflush(NULL);
 588
 589         if (!entry) {
 590                 entry = xmalloc(sizeof(*entry));
 591                 entry->supported_capabilities = 0;
 592
 593                 if (subprocess_start(&subprocess_map, &entry->subprocess, cmd, start_multi_file_filter_fn)) {
 594                         free(entry);
 595                         return 0;
 596                 }
 597         }
 598         process = &entry->subprocess.process;
 599
 600         if (!(wanted_capability & entry->supported_capabilities))
 601                 return 0;
 602
 603         if (CAP_CLEAN & wanted_capability)
 604                 filter_type = "clean";
 605         else if (CAP_SMUDGE & wanted_capability)
 606                 filter_type = "smudge";
 607         else
 608                 die("unexpected filter type");
 609
 610         sigchain_push(SIGPIPE, SIG_IGN);
 611
 612         assert(strlen(filter_type) < LARGE_PACKET_DATA_MAX - strlen("command=\n"));
 613         err = packet_write_fmt_gently(process->in, "command=%s\n", filter_type);
 614         if (err)
 615                 goto done;
 616
 617         err = strlen(path) > LARGE_PACKET_DATA_MAX - strlen("pathname=\n");
 618         if (err) {
 619                 error("path name too long for external filter");
 620                 goto done;
 621         }
 622
 623         err = packet_write_fmt_gently(process->in, "pathname=%s\n", path);
 624         if (err)
 625                 goto done;
 626
 627         err = packet_flush_gently(process->in);
 628         if (err)
 629                 goto done;
 630
 631         if (fd >= 0)
 632                 err = write_packetized_from_fd(fd, process->in);
 633         else
 634                 err = write_packetized_from_buf(src, len, process->in);
 635         if (err)
 636                 goto done;
 637
 638         err = subprocess_read_status(process->out, &filter_status);
 639         if (err)
 640                 goto done;
 641
 642         err = strcmp(filter_status.buf, "success");
 643         if (err)
 644                 goto done;
 645
 646         err = read_packetized_to_strbuf(process->out, &nbuf) < 0;
 647         if (err)
 648                 goto done;
 649
 650         err = subprocess_read_status(process->out, &filter_status);
 651         if (err)
 652                 goto done;
 653
 654         err = strcmp(filter_status.buf, "success");
 655
 656 done:
 657         sigchain_pop(SIGPIPE);
 658
 659         if (err) {
 660                 if (!strcmp(filter_status.buf, "error")) {
 661                         /* The filter signaled a problem with the file. */
 662                 } else if (!strcmp(filter_status.buf, "abort")) {
 663                         /*
 664                          * The filter signaled a permanent problem. Don't try to filter
 665                          * files with the same command for the lifetime of the current
 666                          * Git process.
 667                          */
 668                          entry->supported_capabilities &= ~wanted_capability;
 669                 } else {
 670                         /*
 671                          * Something went wrong with the protocol filter.
 672                          * Force shutdown and restart if another blob requires filtering.
 673                          */
 674                         error("external filter '%s' failed", cmd);
 675                         subprocess_stop(&subprocess_map, &entry->subprocess);
 676                         free(entry);
 677                 }
 678         } else {
 679                 strbuf_swap(dst, &nbuf);
 680         }
 681         strbuf_release(&nbuf);
 682         return !err;
 683 }
 684
 685 static struct convert_driver {
 686         const char *name;
 687         struct convert_driver *next;
 688         const char *smudge;
 689         const char *clean;
 690         const char *process;
 691         int required;
 692 } *user_convert, **user_convert_tail;
 693
 694 static int apply_filter(const char *path, const char *src, size_t len,
 695                         int fd, struct strbuf *dst, struct convert_driver *drv,
 696                         const unsigned int wanted_capability)
 697 {
 698         const char *cmd = NULL;
 699
 700         if (!drv)
 701                 return 0;
 702
 703         if (!dst)
 704                 return 1;
 705
 706         if ((CAP_CLEAN & wanted_capability) && !drv->process && drv->clean)
 707                 cmd = drv->clean;
 708         else if ((CAP_SMUDGE & wanted_capability) && !drv->process && drv->smudge)
 709                 cmd = drv->smudge;
 710
 711         if (cmd && *cmd)
 712                 return apply_single_file_filter(path, src, len, fd, dst, cmd);
 713         else if (drv->process && *drv->process)
 714                 return apply_multi_file_filter(path, src, len, fd, dst, drv->process, wanted_capability);
 715
 716         return 0;
 717 }
 718
 719 static int read_convert_config(const char *var, const char *value, void *cb)
 720 {
 721         const char *key, *name;
 722         int namelen;
 723         struct convert_driver *drv;
 724
 725         /*
 726          * External conversion drivers are configured using
 727          * "filter.<name>.variable".
 728          */
 729         if (parse_config_key(var, "filter", &name, &namelen, &key) < 0 || !name)
 730                 return 0;
 731         for (drv = user_convert; drv; drv = drv->next)
 732                 if (!strncmp(drv->name, name, namelen) && !drv->name[namelen])
 733                         break;
 734         if (!drv) {
 735                 drv = xcalloc(1, sizeof(struct convert_driver));
 736                 drv->name = xmemdupz(name, namelen);
 737                 *user_convert_tail = drv;
 738                 user_convert_tail = &(drv->next);
 739         }
 740
 741         /*
 742          * filter.<name>.smudge and filter.<name>.clean specifies
 743          * the command line:
 744          *
 745          *      command-line
 746          *
 747          * The command-line will not be interpolated in any way.
 748          */
 749
 750         if (!strcmp("smudge", key))
 751                 return git_config_string(&drv->smudge, var, value);
 752
 753         if (!strcmp("clean", key))
 754                 return git_config_string(&drv->clean, var, value);
 755
 756         if (!strcmp("process", key))
 757                 return git_config_string(&drv->process, var, value);
 758
 759         if (!strcmp("required", key)) {
 760                 drv->required = git_config_bool(var, value);
 761                 return 0;
 762         }
 763
 764         return 0;
 765 }
 766
 767 static int count_ident(const char *cp, unsigned long size)
 768 {
 769         /*
 770          * "$Id: 0000000000000000000000000000000000000000 $" <=> "$Id$"
 771          */
 772         int cnt = 0;
 773         char ch;
 774
 775         while (size) {
 776                 ch = *cp++;
 777                 size--;
 778                 if (ch != '$')
 779                         continue;
 780                 if (size < 3)
 781                         break;
 782                 if (memcmp("Id", cp, 2))
 783                         continue;
 784                 ch = cp[2];
 785                 cp += 3;
 786                 size -= 3;
 787                 if (ch == '$')
 788                         cnt++; /* $Id$ */
 789                 if (ch != ':')
 790                         continue;
 791
 792                 /*
 793                  * "$Id: ... "; scan up to the closing dollar sign and discard.
 794                  */
 795                 while (size) {
 796                         ch = *cp++;
 797                         size--;
 798                         if (ch == '$') {
 799                                 cnt++;
 800                                 break;
 801                         }
 802                         if (ch == '\n')
 803                                 break;
 804                 }
 805         }
 806         return cnt;
 807 }
 808
 809 static int ident_to_git(const char *path, const char *src, size_t len,
 810                         struct strbuf *buf, int ident)
 811 {
 812         char *dst, *dollar;
 813
 814         if (!ident || (src && !count_ident(src, len)))
 815                 return 0;
 816
 817         if (!buf)
 818                 return 1;
 819
 820         /* only grow if not in place */
 821         if (strbuf_avail(buf) + buf->len < len)
 822                 strbuf_grow(buf, len - buf->len);
 823         dst = buf->buf;
 824         for (;;) {
 825                 dollar = memchr(src, '$', len);
 826                 if (!dollar)
 827                         break;
 828                 memmove(dst, src, dollar + 1 - src);
 829                 dst += dollar + 1 - src;
 830                 len -= dollar + 1 - src;
 831                 src  = dollar + 1;
 832
 833                 if (len > 3 && !memcmp(src, "Id:", 3)) {
 834                         dollar = memchr(src + 3, '$', len - 3);
 835                         if (!dollar)
 836                                 break;
 837                         if (memchr(src + 3, '\n', dollar - src - 3)) {
 838                                 /* Line break before the next dollar. */
 839                                 continue;
 840                         }
 841
 842                         memcpy(dst, "Id$", 3);
 843                         dst += 3;
 844                         len -= dollar + 1 - src;
 845                         src  = dollar + 1;
 846                 }
 847         }
 848         memmove(dst, src, len);
 849         strbuf_setlen(buf, dst + len - buf->buf);
 850         return 1;
 851 }
 852
 853 static int ident_to_worktree(const char *path, const char *src, size_t len,
 854                              struct strbuf *buf, int ident)
 855 {
 856         unsigned char sha1[20];
 857         char *to_free = NULL, *dollar, *spc;
 858         int cnt;
 859
 860         if (!ident)
 861                 return 0;
 862
 863         cnt = count_ident(src, len);
 864         if (!cnt)
 865                 return 0;
 866
 867         /* are we "faking" in place editing ? */
 868         if (src == buf->buf)
 869                 to_free = strbuf_detach(buf, NULL);
 870         hash_sha1_file(src, len, "blob", sha1);
 871
 872         strbuf_grow(buf, len + cnt * 43);
 873         for (;;) {
 874                 /* step 1: run to the next '$' */
 875                 dollar = memchr(src, '$', len);
 876                 if (!dollar)
 877                         break;
 878                 strbuf_add(buf, src, dollar + 1 - src);
 879                 len -= dollar + 1 - src;
 880                 src  = dollar + 1;
 881
 882                 /* step 2: does it looks like a bit like Id:xxx$ or Id$ ? */
 883                 if (len < 3 || memcmp("Id", src, 2))
 884                         continue;
 885
 886                 /* step 3: skip over Id$ or Id:xxxxx$ */
 887                 if (src[2] == '$') {
 888                         src += 3;
 889                         len -= 3;
 890                 } else if (src[2] == ':') {
 891                         /*
 892                          * It's possible that an expanded Id has crept its way into the
 893                          * repository, we cope with that by stripping the expansion out.
 894                          * This is probably not a good idea, since it will cause changes
 895                          * on checkout, which won't go away by stash, but let's keep it
 896                          * for git-style ids.
 897                          */
 898                         dollar = memchr(src + 3, '$', len - 3);
 899                         if (!dollar) {
 900                                 /* incomplete keyword, no more '$', so just quit the loop */
 901                                 break;
 902                         }
 903
 904                         if (memchr(src + 3, '\n', dollar - src - 3)) {
 905                                 /* Line break before the next dollar. */
 906                                 continue;
 907                         }
 908
 909                         spc = memchr(src + 4, ' ', dollar - src - 4);
 910                         if (spc && spc < dollar-1) {
 911                                 /* There are spaces in unexpected places.
 912                                  * This is probably an id from some other
 913                                  * versioning system. Keep it for now.
 914                                  */
 915                                 continue;
 916                         }
 917
 918                         len -= dollar + 1 - src;
 919                         src  = dollar + 1;
 920                 } else {
 921                         /* it wasn't a "Id$" or "Id:xxxx$" */
 922                         continue;
 923                 }
 924
 925                 /* step 4: substitute */
 926                 strbuf_addstr(buf, "Id: ");
 927                 strbuf_add(buf, sha1_to_hex(sha1), 40);
 928                 strbuf_addstr(buf, " $");
 929         }
 930         strbuf_add(buf, src, len);
 931
 932         free(to_free);
 933         return 1;
 934 }
 935
 936 static enum crlf_action git_path_check_crlf(struct attr_check_item *check)
 937 {
 938         const char *value = check->value;
 939
 940         if (ATTR_TRUE(value))
 941                 return CRLF_TEXT;
 942         else if (ATTR_FALSE(value))
 943                 return CRLF_BINARY;
 944         else if (ATTR_UNSET(value))
 945                 ;
 946         else if (!strcmp(value, "input"))
 947                 return CRLF_TEXT_INPUT;
 948         else if (!strcmp(value, "auto"))
 949                 return CRLF_AUTO;
 950         return CRLF_UNDEFINED;
 951 }
 952
 953 static enum eol git_path_check_eol(struct attr_check_item *check)
 954 {
 955         const char *value = check->value;
 956
 957         if (ATTR_UNSET(value))
 958                 ;
 959         else if (!strcmp(value, "lf"))
 960                 return EOL_LF;
 961         else if (!strcmp(value, "crlf"))
 962                 return EOL_CRLF;
 963         return EOL_UNSET;
 964 }
 965
 966 static struct convert_driver *git_path_check_convert(struct attr_check_item *check)
 967 {
 968         const char *value = check->value;
 969         struct convert_driver *drv;
 970
 971         if (ATTR_TRUE(value) || ATTR_FALSE(value) || ATTR_UNSET(value))
 972                 return NULL;
 973         for (drv = user_convert; drv; drv = drv->next)
 974                 if (!strcmp(value, drv->name))
 975                         return drv;
 976         return NULL;
 977 }
 978
 979 static int git_path_check_ident(struct attr_check_item *check)
 980 {
 981         const char *value = check->value;
 982
 983         return !!ATTR_TRUE(value);
 984 }
 985
 986 struct conv_attrs {
 987         struct convert_driver *drv;
 988         enum crlf_action attr_action; /* What attr says */
 989         enum crlf_action crlf_action; /* When no attr is set, use core.autocrlf */
 990         int ident;
 991 };
 992
 993 static void convert_attrs(struct conv_attrs *ca, const char *path)
 994 {
 995         static struct attr_check *check;
 996
 997         if (!check) {
 998                 check = attr_check_initl("crlf", "ident", "filter",
 999                                          "eol", "text", NULL);
1000                 user_convert_tail = &user_convert;
1001                 git_config(read_convert_config, NULL);
1002         }
1003
1004         if (!git_check_attr(path, check)) {
1005                 struct attr_check_item *ccheck = check->items;
1006                 ca->crlf_action = git_path_check_crlf(ccheck + 4);
1007                 if (ca->crlf_action == CRLF_UNDEFINED)
1008                         ca->crlf_action = git_path_check_crlf(ccheck + 0);
1009                 ca->attr_action = ca->crlf_action;
1010                 ca->ident = git_path_check_ident(ccheck + 1);
1011                 ca->drv = git_path_check_convert(ccheck + 2);
1012                 if (ca->crlf_action != CRLF_BINARY) {
1013                         enum eol eol_attr = git_path_check_eol(ccheck + 3);
1014                         if (ca->crlf_action == CRLF_AUTO && eol_attr == EOL_LF)
1015                                 ca->crlf_action = CRLF_AUTO_INPUT;
1016                         else if (ca->crlf_action == CRLF_AUTO && eol_attr == EOL_CRLF)
1017                                 ca->crlf_action = CRLF_AUTO_CRLF;
1018                         else if (eol_attr == EOL_LF)
1019                                 ca->crlf_action = CRLF_TEXT_INPUT;
1020                         else if (eol_attr == EOL_CRLF)
1021                                 ca->crlf_action = CRLF_TEXT_CRLF;
1022                 }
1023                 ca->attr_action = ca->crlf_action;
1024         } else {
1025                 ca->drv = NULL;
1026                 ca->crlf_action = CRLF_UNDEFINED;
1027                 ca->ident = 0;
1028         }
1029         if (ca->crlf_action == CRLF_TEXT)
1030                 ca->crlf_action = text_eol_is_crlf() ? CRLF_TEXT_CRLF : CRLF_TEXT_INPUT;
1031         if (ca->crlf_action == CRLF_UNDEFINED && auto_crlf == AUTO_CRLF_FALSE)
1032                 ca->crlf_action = CRLF_BINARY;
1033         if (ca->crlf_action == CRLF_UNDEFINED && auto_crlf == AUTO_CRLF_TRUE)
1034                 ca->crlf_action = CRLF_AUTO_CRLF;
1035         if (ca->crlf_action == CRLF_UNDEFINED && auto_crlf == AUTO_CRLF_INPUT)
1036                 ca->crlf_action = CRLF_AUTO_INPUT;
1037 }
1038
1039 int would_convert_to_git_filter_fd(const char *path)
1040 {
1041         struct conv_attrs ca;
1042
1043         convert_attrs(&ca, path);
1044         if (!ca.drv)
1045                 return 0;
1046
1047         /*
1048          * Apply a filter to an fd only if the filter is required to succeed.
1049          * We must die if the filter fails, because the original data before
1050          * filtering is not available.
1051          */
1052         if (!ca.drv->required)
1053                 return 0;
1054
1055         return apply_filter(path, NULL, 0, -1, NULL, ca.drv, CAP_CLEAN);
1056 }
1057
1058 const char *get_convert_attr_ascii(const char *path)
1059 {
1060         struct conv_attrs ca;
1061
1062         convert_attrs(&ca, path);
1063         switch (ca.attr_action) {
1064         case CRLF_UNDEFINED:
1065                 return "";
1066         case CRLF_BINARY:
1067                 return "-text";
1068         case CRLF_TEXT:
1069                 return "text";
1070         case CRLF_TEXT_INPUT:
1071                 return "text eol=lf";
1072         case CRLF_TEXT_CRLF:
1073                 return "text eol=crlf";
1074         case CRLF_AUTO:
1075                 return "text=auto";
1076         case CRLF_AUTO_CRLF:
1077                 return "text=auto eol=crlf";
1078         case CRLF_AUTO_INPUT:
1079                 return "text=auto eol=lf";
1080         }
1081         return "";
1082 }
1083
1084 int convert_to_git(const char *path, const char *src, size_t len,
1085                    struct strbuf *dst, enum safe_crlf checksafe)
1086 {
1087         int ret = 0;
1088         struct conv_attrs ca;
1089
1090         convert_attrs(&ca, path);
1091
1092         ret |= apply_filter(path, src, len, -1, dst, ca.drv, CAP_CLEAN);
1093         if (!ret && ca.drv && ca.drv->required)
1094                 die("%s: clean filter '%s' failed", path, ca.drv->name);
1095
1096         if (ret && dst) {
1097                 src = dst->buf;
1098                 len = dst->len;
1099         }
1100         ret |= crlf_to_git(path, src, len, dst, ca.crlf_action, checksafe);
1101         if (ret && dst) {
1102                 src = dst->buf;
1103                 len = dst->len;
1104         }
1105         return ret | ident_to_git(path, src, len, dst, ca.ident);
1106 }
1107
1108 void convert_to_git_filter_fd(const char *path, int fd, struct strbuf *dst,
1109                               enum safe_crlf checksafe)
1110 {
1111         struct conv_attrs ca;
1112         convert_attrs(&ca, path);
1113
1114         assert(ca.drv);
1115         assert(ca.drv->clean || ca.drv->process);
1116
1117         if (!apply_filter(path, NULL, 0, fd, dst, ca.drv, CAP_CLEAN))
1118                 die("%s: clean filter '%s' failed", path, ca.drv->name);
1119
1120         crlf_to_git(path, dst->buf, dst->len, dst, ca.crlf_action, checksafe);
1121         ident_to_git(path, dst->buf, dst->len, dst, ca.ident);
1122 }
1123
1124 static int convert_to_working_tree_internal(const char *path, const char *src,
1125                                             size_t len, struct strbuf *dst,
1126                                             int normalizing)
1127 {
1128         int ret = 0, ret_filter = 0;
1129         struct conv_attrs ca;
1130
1131         convert_attrs(&ca, path);
1132
1133         ret |= ident_to_worktree(path, src, len, dst, ca.ident);
1134         if (ret) {
1135                 src = dst->buf;
1136                 len = dst->len;
1137         }
1138         /*
1139          * CRLF conversion can be skipped if normalizing, unless there
1140          * is a smudge or process filter (even if the process filter doesn't
1141          * support smudge).  The filters might expect CRLFs.
1142          */
1143         if ((ca.drv && (ca.drv->smudge || ca.drv->process)) || !normalizing) {
1144                 ret |= crlf_to_worktree(path, src, len, dst, ca.crlf_action);
1145                 if (ret) {
1146                         src = dst->buf;
1147                         len = dst->len;
1148                 }
1149         }
1150
1151         ret_filter = apply_filter(path, src, len, -1, dst, ca.drv, CAP_SMUDGE);
1152         if (!ret_filter && ca.drv && ca.drv->required)
1153                 die("%s: smudge filter %s failed", path, ca.drv->name);
1154
1155         return ret | ret_filter;
1156 }
1157
1158 int convert_to_working_tree(const char *path, const char *src, size_t len, struct strbuf *dst)
1159 {
1160         return convert_to_working_tree_internal(path, src, len, dst, 0);
1161 }
1162
1163 int renormalize_buffer(const char *path, const char *src, size_t len, struct strbuf *dst)
1164 {
1165         int ret = convert_to_working_tree_internal(path, src, len, dst, 1);
1166         if (ret) {
1167                 src = dst->buf;
1168                 len = dst->len;
1169         }
1170         return ret | convert_to_git(path, src, len, dst, SAFE_CRLF_RENORMALIZE);
1171 }
1172
1173 /*****************************************************************
1174  *
1175  * Streaming conversion support
1176  *
1177  *****************************************************************/
1178
1179 typedef int (*filter_fn)(struct stream_filter *,
1180                          const char *input, size_t *isize_p,
1181                          char *output, size_t *osize_p);
1182 typedef void (*free_fn)(struct stream_filter *);
1183
1184 struct stream_filter_vtbl {
1185         filter_fn filter;
1186         free_fn free;
1187 };
1188
1189 struct stream_filter {
1190         struct stream_filter_vtbl *vtbl;
1191 };
1192
1193 static int null_filter_fn(struct stream_filter *filter,
1194                           const char *input, size_t *isize_p,
1195                           char *output, size_t *osize_p)
1196 {
1197         size_t count;
1198
1199         if (!input)
1200                 return 0; /* we do not keep any states */
1201         count = *isize_p;
1202         if (*osize_p < count)
1203                 count = *osize_p;
1204         if (count) {
1205                 memmove(output, input, count);
1206                 *isize_p -= count;
1207                 *osize_p -= count;
1208         }
1209         return 0;
1210 }
1211
1212 static void null_free_fn(struct stream_filter *filter)
1213 {
1214         ; /* nothing -- null instances are shared */
1215 }
1216
1217 static struct stream_filter_vtbl null_vtbl = {
1218         null_filter_fn,
1219         null_free_fn,
1220 };
1221
1222 static struct stream_filter null_filter_singleton = {
1223         &null_vtbl,
1224 };
1225
1226 int is_null_stream_filter(struct stream_filter *filter)
1227 {
1228         return filter == &null_filter_singleton;
1229 }
1230
1231
1232 /*
1233  * LF-to-CRLF filter
1234  */
1235
1236 struct lf_to_crlf_filter {
1237         struct stream_filter filter;
1238         unsigned has_held:1;
1239         char held;
1240 };
1241
1242 static int lf_to_crlf_filter_fn(struct stream_filter *filter,
1243                                 const char *input, size_t *isize_p,
1244                                 char *output, size_t *osize_p)
1245 {
1246         size_t count, o = 0;
1247         struct lf_to_crlf_filter *lf_to_crlf = (struct lf_to_crlf_filter *)filter;
1248
1249         /*
1250          * We may be holding onto the CR to see if it is followed by a
1251          * LF, in which case we would need to go to the main loop.
1252          * Otherwise, just emit it to the output stream.
1253          */
1254         if (lf_to_crlf->has_held && (lf_to_crlf->held != '\r' || !input)) {
1255                 output[o++] = lf_to_crlf->held;
1256                 lf_to_crlf->has_held = 0;
1257         }
1258
1259         /* We are told to drain */
1260         if (!input) {
1261                 *osize_p -= o;
1262                 return 0;
1263         }
1264
1265         count = *isize_p;
1266         if (count || lf_to_crlf->has_held) {
1267                 size_t i;
1268                 int was_cr = 0;
1269
1270                 if (lf_to_crlf->has_held) {
1271                         was_cr = 1;
1272                         lf_to_crlf->has_held = 0;
1273                 }
1274
1275                 for (i = 0; o < *osize_p && i < count; i++) {
1276                         char ch = input[i];
1277
1278                         if (ch == '\n') {
1279                                 output[o++] = '\r';
1280                         } else if (was_cr) {
1281                                 /*
1282                                  * Previous round saw CR and it is not followed
1283                                  * by a LF; emit the CR before processing the
1284                                  * current character.
1285                                  */
1286                                 output[o++] = '\r';
1287                         }
1288
1289                         /*
1290                          * We may have consumed the last output slot,
1291                          * in which case we need to break out of this
1292                          * loop; hold the current character before
1293                          * returning.
1294                          */
1295                         if (*osize_p <= o) {
1296                                 lf_to_crlf->has_held = 1;
1297                                 lf_to_crlf->held = ch;
1298                                 continue; /* break but increment i */
1299                         }
1300
1301                         if (ch == '\r') {
1302                                 was_cr = 1;
1303                                 continue;
1304                         }
1305
1306                         was_cr = 0;
1307                         output[o++] = ch;
1308                 }
1309
1310                 *osize_p -= o;
1311                 *isize_p -= i;
1312
1313                 if (!lf_to_crlf->has_held && was_cr) {
1314                         lf_to_crlf->has_held = 1;
1315                         lf_to_crlf->held = '\r';
1316                 }
1317         }
1318         return 0;
1319 }
1320
1321 static void lf_to_crlf_free_fn(struct stream_filter *filter)
1322 {
1323         free(filter);
1324 }
1325
1326 static struct stream_filter_vtbl lf_to_crlf_vtbl = {
1327         lf_to_crlf_filter_fn,
1328         lf_to_crlf_free_fn,
1329 };
1330
1331 static struct stream_filter *lf_to_crlf_filter(void)
1332 {
1333         struct lf_to_crlf_filter *lf_to_crlf = xcalloc(1, sizeof(*lf_to_crlf));
1334
1335         lf_to_crlf->filter.vtbl = &lf_to_crlf_vtbl;
1336         return (struct stream_filter *)lf_to_crlf;
1337 }
1338
1339 /*
1340  * Cascade filter
1341  */
1342 #define FILTER_BUFFER 1024
1343 struct cascade_filter {
1344         struct stream_filter filter;
1345         struct stream_filter *one;
1346         struct stream_filter *two;
1347         char buf[FILTER_BUFFER];
1348         int end, ptr;
1349 };
1350
1351 static int cascade_filter_fn(struct stream_filter *filter,
1352                              const char *input, size_t *isize_p,
1353                              char *output, size_t *osize_p)
1354 {
1355         struct cascade_filter *cas = (struct cascade_filter *) filter;
1356         size_t filled = 0;
1357         size_t sz = *osize_p;
1358         size_t to_feed, remaining;
1359
1360         /*
1361          * input -- (one) --> buf -- (two) --> output
1362          */
1363         while (filled < sz) {
1364                 remaining = sz - filled;
1365
1366                 /* do we already have something to feed two with? */
1367                 if (cas->ptr < cas->end) {
1368                         to_feed = cas->end - cas->ptr;
1369                         if (stream_filter(cas->two,
1370                                           cas->buf + cas->ptr, &to_feed,
1371                                           output + filled, &remaining))
1372                                 return -1;
1373                         cas->ptr += (cas->end - cas->ptr) - to_feed;
1374                         filled = sz - remaining;
1375                         continue;
1376                 }
1377
1378                 /* feed one from upstream and have it emit into our buffer */
1379                 to_feed = input ? *isize_p : 0;
1380                 if (input && !to_feed)
1381                         break;
1382                 remaining = sizeof(cas->buf);
1383                 if (stream_filter(cas->one,
1384                                   input, &to_feed,
1385                                   cas->buf, &remaining))
1386                         return -1;
1387                 cas->end = sizeof(cas->buf) - remaining;
1388                 cas->ptr = 0;
1389                 if (input) {
1390                         size_t fed = *isize_p - to_feed;
1391                         *isize_p -= fed;
1392                         input += fed;
1393                 }
1394
1395                 /* do we know that we drained one completely? */
1396                 if (input || cas->end)
1397                         continue;
1398
1399                 /* tell two to drain; we have nothing more to give it */
1400                 to_feed = 0;
1401                 remaining = sz - filled;
1402                 if (stream_filter(cas->two,
1403                                   NULL, &to_feed,
1404                                   output + filled, &remaining))
1405                         return -1;
1406                 if (remaining == (sz - filled))
1407                         break; /* completely drained two */
1408                 filled = sz - remaining;
1409         }
1410         *osize_p -= filled;
1411         return 0;
1412 }
1413
1414 static void cascade_free_fn(struct stream_filter *filter)
1415 {
1416         struct cascade_filter *cas = (struct cascade_filter *)filter;
1417         free_stream_filter(cas->one);
1418         free_stream_filter(cas->two);
1419         free(filter);
1420 }
1421
1422 static struct stream_filter_vtbl cascade_vtbl = {
1423         cascade_filter_fn,
1424         cascade_free_fn,
1425 };
1426
1427 static struct stream_filter *cascade_filter(struct stream_filter *one,
1428                                             struct stream_filter *two)
1429 {
1430         struct cascade_filter *cascade;
1431
1432         if (!one || is_null_stream_filter(one))
1433                 return two;
1434         if (!two || is_null_stream_filter(two))
1435                 return one;
1436
1437         cascade = xmalloc(sizeof(*cascade));
1438         cascade->one = one;
1439         cascade->two = two;
1440         cascade->end = cascade->ptr = 0;
1441         cascade->filter.vtbl = &cascade_vtbl;
1442         return (struct stream_filter *)cascade;
1443 }
1444
1445 /*
1446  * ident filter
1447  */
1448 #define IDENT_DRAINING (-1)
1449 #define IDENT_SKIPPING (-2)
1450 struct ident_filter {
1451         struct stream_filter filter;
1452         struct strbuf left;
1453         int state;
1454         char ident[45]; /* ": x40 $" */
1455 };
1456
1457 static int is_foreign_ident(const char *str)
1458 {
1459         int i;
1460
1461         if (!skip_prefix(str, "$Id: ", &str))
1462                 return 0;
1463         for (i = 0; str[i]; i++) {
1464                 if (isspace(str[i]) && str[i+1] != '$')
1465                         return 1;
1466         }
1467         return 0;
1468 }
1469
1470 static void ident_drain(struct ident_filter *ident, char **output_p, size_t *osize_p)
1471 {
1472         size_t to_drain = ident->left.len;
1473
1474         if (*osize_p < to_drain)
1475                 to_drain = *osize_p;
1476         if (to_drain) {
1477                 memcpy(*output_p, ident->left.buf, to_drain);
1478                 strbuf_remove(&ident->left, 0, to_drain);
1479                 *output_p += to_drain;
1480                 *osize_p -= to_drain;
1481         }
1482         if (!ident->left.len)
1483                 ident->state = 0;
1484 }
1485
1486 static int ident_filter_fn(struct stream_filter *filter,
1487                            const char *input, size_t *isize_p,
1488                            char *output, size_t *osize_p)
1489 {
1490         struct ident_filter *ident = (struct ident_filter *)filter;
1491         static const char head[] = "$Id";
1492
1493         if (!input) {
1494                 /* drain upon eof */
1495                 switch (ident->state) {
1496                 default:
1497                         strbuf_add(&ident->left, head, ident->state);
1498                 case IDENT_SKIPPING:
1499                         /* fallthru */
1500                 case IDENT_DRAINING:
1501                         ident_drain(ident, &output, osize_p);
1502                 }
1503                 return 0;
1504         }
1505
1506         while (*isize_p || (ident->state == IDENT_DRAINING)) {
1507                 int ch;
1508
1509                 if (ident->state == IDENT_DRAINING) {
1510                         ident_drain(ident, &output, osize_p);
1511                         if (!*osize_p)
1512                                 break;
1513                         continue;
1514                 }
1515
1516                 ch = *(input++);
1517                 (*isize_p)--;
1518
1519                 if (ident->state == IDENT_SKIPPING) {
1520                         /*
1521                          * Skipping until '$' or LF, but keeping them
1522                          * in case it is a foreign ident.
1523                          */
1524                         strbuf_addch(&ident->left, ch);
1525                         if (ch != '\n' && ch != '$')
1526                                 continue;
1527                         if (ch == '$' && !is_foreign_ident(ident->left.buf)) {
1528                                 strbuf_setlen(&ident->left, sizeof(head) - 1);
1529                                 strbuf_addstr(&ident->left, ident->ident);
1530                         }
1531                         ident->state = IDENT_DRAINING;
1532                         continue;
1533                 }
1534
1535                 if (ident->state < sizeof(head) &&
1536                     head[ident->state] == ch) {
1537                         ident->state++;
1538                         continue;
1539                 }
1540
1541                 if (ident->state)
1542                         strbuf_add(&ident->left, head, ident->state);
1543                 if (ident->state == sizeof(head) - 1) {
1544                         if (ch != ':' && ch != '$') {
1545                                 strbuf_addch(&ident->left, ch);
1546                                 ident->state = 0;
1547                                 continue;
1548                         }
1549
1550                         if (ch == ':') {
1551                                 strbuf_addch(&ident->left, ch);
1552                                 ident->state = IDENT_SKIPPING;
1553                         } else {
1554                                 strbuf_addstr(&ident->left, ident->ident);
1555                                 ident->state = IDENT_DRAINING;
1556                         }
1557                         continue;
1558                 }
1559
1560                 strbuf_addch(&ident->left, ch);
1561                 ident->state = IDENT_DRAINING;
1562         }
1563         return 0;
1564 }
1565
1566 static void ident_free_fn(struct stream_filter *filter)
1567 {
1568         struct ident_filter *ident = (struct ident_filter *)filter;
1569         strbuf_release(&ident->left);
1570         free(filter);
1571 }
1572
1573 static struct stream_filter_vtbl ident_vtbl = {
1574         ident_filter_fn,
1575         ident_free_fn,
1576 };
1577
1578 static struct stream_filter *ident_filter(const unsigned char *sha1)
1579 {
1580         struct ident_filter *ident = xmalloc(sizeof(*ident));
1581
1582         xsnprintf(ident->ident, sizeof(ident->ident),
1583                   ": %s $", sha1_to_hex(sha1));
1584         strbuf_init(&ident->left, 0);
1585         ident->filter.vtbl = &ident_vtbl;
1586         ident->state = 0;
1587         return (struct stream_filter *)ident;
1588 }
1589
1590 /*
1591  * Return an appropriately constructed filter for the path, or NULL if
1592  * the contents cannot be filtered without reading the whole thing
1593  * in-core.
1594  *
1595  * Note that you would be crazy to set CRLF, smuge/clean or ident to a
1596  * large binary blob you would want us not to slurp into the memory!
1597  */
1598 struct stream_filter *get_stream_filter(const char *path, const unsigned char *sha1)
1599 {
1600         struct conv_attrs ca;
1601         struct stream_filter *filter = NULL;
1602
1603         convert_attrs(&ca, path);
1604         if (ca.drv && (ca.drv->process || ca.drv->smudge || ca.drv->clean))
1605                 return NULL;
1606
1607         if (ca.crlf_action == CRLF_AUTO || ca.crlf_action == CRLF_AUTO_CRLF)
1608                 return NULL;
1609
1610         if (ca.ident)
1611                 filter = ident_filter(sha1);
1612
1613         if (output_eol(ca.crlf_action) == EOL_CRLF)
1614                 filter = cascade_filter(filter, lf_to_crlf_filter());
1615         else
1616                 filter = cascade_filter(filter, &null_filter_singleton);
1617
1618         return filter;
1619 }
1620
1621 void free_stream_filter(struct stream_filter *filter)
1622 {
1623         filter->vtbl->free(filter);
1624 }
1625
1626 int stream_filter(struct stream_filter *filter,
1627                   const char *input, size_t *isize_p,
1628                   char *output, size_t *osize_p)
1629 {
1630         return filter->vtbl->filter(filter, input, isize_p, output, osize_p);
1631 }