convert.c

   1 #define NO_THE_INDEX_COMPATIBILITY_MACROS
   2 #include "cache.h"
   3 #include "config.h"
   4 #include "attr.h"
   5 #include "run-command.h"
   6 #include "quote.h"
   7 #include "sigchain.h"
   8 #include "pkt-line.h"
   9 #include "sub-process.h"
  10
  11 /*
  12  * convert.c - convert a file when checking it out and checking it in.
  13  *
  14  * This should use the pathname to decide on whether it wants to do some
  15  * more interesting conversions (automatic gzip/unzip, general format
  16  * conversions etc etc), but by default it just does automatic CRLF<->LF
  17  * translation when the "text" attribute or "auto_crlf" option is set.
  18  */
  19
  20 /* Stat bits: When BIN is set, the txt bits are unset */
  21 #define CONVERT_STAT_BITS_TXT_LF    0x1
  22 #define CONVERT_STAT_BITS_TXT_CRLF  0x2
  23 #define CONVERT_STAT_BITS_BIN       0x4
  24
  25 enum crlf_action {
  26         CRLF_UNDEFINED,
  27         CRLF_BINARY,
  28         CRLF_TEXT,
  29         CRLF_TEXT_INPUT,
  30         CRLF_TEXT_CRLF,
  31         CRLF_AUTO,
  32         CRLF_AUTO_INPUT,
  33         CRLF_AUTO_CRLF
  34 };
  35
  36 struct text_stat {
  37         /* NUL, CR, LF and CRLF counts */
  38         unsigned nul, lonecr, lonelf, crlf;
  39
  40         /* These are just approximations! */
  41         unsigned printable, nonprintable;
  42 };
  43
  44 static void gather_stats(const char *buf, unsigned long size, struct text_stat *stats)
  45 {
  46         unsigned long i;
  47
  48         memset(stats, 0, sizeof(*stats));
  49
  50         for (i = 0; i < size; i++) {
  51                 unsigned char c = buf[i];
  52                 if (c == '\r') {
  53                         if (i+1 < size && buf[i+1] == '\n') {
  54                                 stats->crlf++;
  55                                 i++;
  56                         } else
  57                                 stats->lonecr++;
  58                         continue;
  59                 }
  60                 if (c == '\n') {
  61                         stats->lonelf++;
  62                         continue;
  63                 }
  64                 if (c == 127)
  65                         /* DEL */
  66                         stats->nonprintable++;
  67                 else if (c < 32) {
  68                         switch (c) {
  69                                 /* BS, HT, ESC and FF */
  70                         case '\b': case '\t': case '\033': case '\014':
  71                                 stats->printable++;
  72                                 break;
  73                         case 0:
  74                                 stats->nul++;
  75                                 /* fall through */
  76                         default:
  77                                 stats->nonprintable++;
  78                         }
  79                 }
  80                 else
  81                         stats->printable++;
  82         }
  83
  84         /* If file ends with EOF then don't count this EOF as non-printable. */
  85         if (size >= 1 && buf[size-1] == '\032')
  86                 stats->nonprintable--;
  87 }
  88
  89 /*
  90  * The same heuristics as diff.c::mmfile_is_binary()
  91  * We treat files with bare CR as binary
  92  */
  93 static int convert_is_binary(unsigned long size, const struct text_stat *stats)
  94 {
  95         if (stats->lonecr)
  96                 return 1;
  97         if (stats->nul)
  98                 return 1;
  99         if ((stats->printable >> 7) < stats->nonprintable)
 100                 return 1;
 101         return 0;
 102 }
 103
 104 static unsigned int gather_convert_stats(const char *data, unsigned long size)
 105 {
 106         struct text_stat stats;
 107         int ret = 0;
 108         if (!data || !size)
 109                 return 0;
 110         gather_stats(data, size, &stats);
 111         if (convert_is_binary(size, &stats))
 112                 ret |= CONVERT_STAT_BITS_BIN;
 113         if (stats.crlf)
 114                 ret |= CONVERT_STAT_BITS_TXT_CRLF;
 115         if (stats.lonelf)
 116                 ret |=  CONVERT_STAT_BITS_TXT_LF;
 117
 118         return ret;
 119 }
 120
 121 static const char *gather_convert_stats_ascii(const char *data, unsigned long size)
 122 {
 123         unsigned int convert_stats = gather_convert_stats(data, size);
 124
 125         if (convert_stats & CONVERT_STAT_BITS_BIN)
 126                 return "-text";
 127         switch (convert_stats) {
 128         case CONVERT_STAT_BITS_TXT_LF:
 129                 return "lf";
 130         case CONVERT_STAT_BITS_TXT_CRLF:
 131                 return "crlf";
 132         case CONVERT_STAT_BITS_TXT_LF | CONVERT_STAT_BITS_TXT_CRLF:
 133                 return "mixed";
 134         default:
 135                 return "none";
 136         }
 137 }
 138
 139 const char *get_cached_convert_stats_ascii(const struct index_state *istate,
 140                                            const char *path)
 141 {
 142         const char *ret;
 143         unsigned long sz;
 144         void *data = read_blob_data_from_index(istate, path, &sz);
 145         ret = gather_convert_stats_ascii(data, sz);
 146         free(data);
 147         return ret;
 148 }
 149
 150 const char *get_wt_convert_stats_ascii(const char *path)
 151 {
 152         const char *ret = "";
 153         struct strbuf sb = STRBUF_INIT;
 154         if (strbuf_read_file(&sb, path, 0) >= 0)
 155                 ret = gather_convert_stats_ascii(sb.buf, sb.len);
 156         strbuf_release(&sb);
 157         return ret;
 158 }
 159
 160 static int text_eol_is_crlf(void)
 161 {
 162         if (auto_crlf == AUTO_CRLF_TRUE)
 163                 return 1;
 164         else if (auto_crlf == AUTO_CRLF_INPUT)
 165                 return 0;
 166         if (core_eol == EOL_CRLF)
 167                 return 1;
 168         if (core_eol == EOL_UNSET && EOL_NATIVE == EOL_CRLF)
 169                 return 1;
 170         return 0;
 171 }
 172
 173 static enum eol output_eol(enum crlf_action crlf_action)
 174 {
 175         switch (crlf_action) {
 176         case CRLF_BINARY:
 177                 return EOL_UNSET;
 178         case CRLF_TEXT_CRLF:
 179                 return EOL_CRLF;
 180         case CRLF_TEXT_INPUT:
 181                 return EOL_LF;
 182         case CRLF_UNDEFINED:
 183         case CRLF_AUTO_CRLF:
 184                 return EOL_CRLF;
 185         case CRLF_AUTO_INPUT:
 186                 return EOL_LF;
 187         case CRLF_TEXT:
 188         case CRLF_AUTO:
 189                 /* fall through */
 190                 return text_eol_is_crlf() ? EOL_CRLF : EOL_LF;
 191         }
 192         warning("Illegal crlf_action %d\n", (int)crlf_action);
 193         return core_eol;
 194 }
 195
 196 static void check_safe_crlf(const char *path, enum crlf_action crlf_action,
 197                             struct text_stat *old_stats, struct text_stat *new_stats,
 198                             enum safe_crlf checksafe)
 199 {
 200         if (old_stats->crlf && !new_stats->crlf ) {
 201                 /*
 202                  * CRLFs would not be restored by checkout
 203                  */
 204                 if (checksafe == SAFE_CRLF_WARN)
 205                         warning(_("CRLF will be replaced by LF in %s.\n"
 206                                   "The file will have its original line"
 207                                   " endings in your working directory."), path);
 208                 else /* i.e. SAFE_CRLF_FAIL */
 209                         die(_("CRLF would be replaced by LF in %s."), path);
 210         } else if (old_stats->lonelf && !new_stats->lonelf ) {
 211                 /*
 212                  * CRLFs would be added by checkout
 213                  */
 214                 if (checksafe == SAFE_CRLF_WARN)
 215                         warning(_("LF will be replaced by CRLF in %s.\n"
 216                                   "The file will have its original line"
 217                                   " endings in your working directory."), path);
 218                 else /* i.e. SAFE_CRLF_FAIL */
 219                         die(_("LF would be replaced by CRLF in %s"), path);
 220         }
 221 }
 222
 223 static int has_cr_in_index(const struct index_state *istate, const char *path)
 224 {
 225         unsigned long sz;
 226         void *data;
 227         int has_cr;
 228
 229         data = read_blob_data_from_index(istate, path, &sz);
 230         if (!data)
 231                 return 0;
 232         has_cr = memchr(data, '\r', sz) != NULL;
 233         free(data);
 234         return has_cr;
 235 }
 236
 237 static int will_convert_lf_to_crlf(size_t len, struct text_stat *stats,
 238                                    enum crlf_action crlf_action)
 239 {
 240         if (output_eol(crlf_action) != EOL_CRLF)
 241                 return 0;
 242         /* No "naked" LF? Nothing to convert, regardless. */
 243         if (!stats->lonelf)
 244                 return 0;
 245
 246         if (crlf_action == CRLF_AUTO || crlf_action == CRLF_AUTO_INPUT || crlf_action == CRLF_AUTO_CRLF) {
 247                 /* If we have any CR or CRLF line endings, we do not touch it */
 248                 /* This is the new safer autocrlf-handling */
 249                 if (stats->lonecr || stats->crlf)
 250                         return 0;
 251
 252                 if (convert_is_binary(len, stats))
 253                         return 0;
 254         }
 255         return 1;
 256
 257 }
 258
 259 static int crlf_to_git(const struct index_state *istate,
 260                        const char *path, const char *src, size_t len,
 261                        struct strbuf *buf,
 262                        enum crlf_action crlf_action, enum safe_crlf checksafe)
 263 {
 264         struct text_stat stats;
 265         char *dst;
 266         int convert_crlf_into_lf;
 267
 268         if (crlf_action == CRLF_BINARY ||
 269             (src && !len))
 270                 return 0;
 271
 272         /*
 273          * If we are doing a dry-run and have no source buffer, there is
 274          * nothing to analyze; we must assume we would convert.
 275          */
 276         if (!buf && !src)
 277                 return 1;
 278
 279         gather_stats(src, len, &stats);
 280         /* Optimization: No CRLF? Nothing to convert, regardless. */
 281         convert_crlf_into_lf = !!stats.crlf;
 282
 283         if (crlf_action == CRLF_AUTO || crlf_action == CRLF_AUTO_INPUT || crlf_action == CRLF_AUTO_CRLF) {
 284                 if (convert_is_binary(len, &stats))
 285                         return 0;
 286                 /*
 287                  * If the file in the index has any CR in it, do not
 288                  * convert.  This is the new safer autocrlf handling,
 289                  * unless we want to renormalize in a merge or
 290                  * cherry-pick.
 291                  */
 292                 if ((checksafe != SAFE_CRLF_RENORMALIZE) &&
 293                     has_cr_in_index(istate, path))
 294                         convert_crlf_into_lf = 0;
 295         }
 296         if ((checksafe == SAFE_CRLF_WARN ||
 297             (checksafe == SAFE_CRLF_FAIL)) && len) {
 298                 struct text_stat new_stats;
 299                 memcpy(&new_stats, &stats, sizeof(new_stats));
 300                 /* simulate "git add" */
 301                 if (convert_crlf_into_lf) {
 302                         new_stats.lonelf += new_stats.crlf;
 303                         new_stats.crlf = 0;
 304                 }
 305                 /* simulate "git checkout" */
 306                 if (will_convert_lf_to_crlf(len, &new_stats, crlf_action)) {
 307                         new_stats.crlf += new_stats.lonelf;
 308                         new_stats.lonelf = 0;
 309                 }
 310                 check_safe_crlf(path, crlf_action, &stats, &new_stats, checksafe);
 311         }
 312         if (!convert_crlf_into_lf)
 313                 return 0;
 314
 315         /*
 316          * At this point all of our source analysis is done, and we are sure we
 317          * would convert. If we are in dry-run mode, we can give an answer.
 318          */
 319         if (!buf)
 320                 return 1;
 321
 322         /* only grow if not in place */
 323         if (strbuf_avail(buf) + buf->len < len)
 324                 strbuf_grow(buf, len - buf->len);
 325         dst = buf->buf;
 326         if (crlf_action == CRLF_AUTO || crlf_action == CRLF_AUTO_INPUT || crlf_action == CRLF_AUTO_CRLF) {
 327                 /*
 328                  * If we guessed, we already know we rejected a file with
 329                  * lone CR, and we can strip a CR without looking at what
 330                  * follow it.
 331                  */
 332                 do {
 333                         unsigned char c = *src++;
 334                         if (c != '\r')
 335                                 *dst++ = c;
 336                 } while (--len);
 337         } else {
 338                 do {
 339                         unsigned char c = *src++;
 340                         if (! (c == '\r' && (1 < len && *src == '\n')))
 341                                 *dst++ = c;
 342                 } while (--len);
 343         }
 344         strbuf_setlen(buf, dst - buf->buf);
 345         return 1;
 346 }
 347
 348 static int crlf_to_worktree(const char *path, const char *src, size_t len,
 349                             struct strbuf *buf, enum crlf_action crlf_action)
 350 {
 351         char *to_free = NULL;
 352         struct text_stat stats;
 353
 354         if (!len || output_eol(crlf_action) != EOL_CRLF)
 355                 return 0;
 356
 357         gather_stats(src, len, &stats);
 358         if (!will_convert_lf_to_crlf(len, &stats, crlf_action))
 359                 return 0;
 360
 361         /* are we "faking" in place editing ? */
 362         if (src == buf->buf)
 363                 to_free = strbuf_detach(buf, NULL);
 364
 365         strbuf_grow(buf, len + stats.lonelf);
 366         for (;;) {
 367                 const char *nl = memchr(src, '\n', len);
 368                 if (!nl)
 369                         break;
 370                 if (nl > src && nl[-1] == '\r') {
 371                         strbuf_add(buf, src, nl + 1 - src);
 372                 } else {
 373                         strbuf_add(buf, src, nl - src);
 374                         strbuf_addstr(buf, "\r\n");
 375                 }
 376                 len -= nl + 1 - src;
 377                 src  = nl + 1;
 378         }
 379         strbuf_add(buf, src, len);
 380
 381         free(to_free);
 382         return 1;
 383 }
 384
 385 struct filter_params {
 386         const char *src;
 387         unsigned long size;
 388         int fd;
 389         const char *cmd;
 390         const char *path;
 391 };
 392
 393 static int filter_buffer_or_fd(int in, int out, void *data)
 394 {
 395         /*
 396          * Spawn cmd and feed the buffer contents through its stdin.
 397          */
 398         struct child_process child_process = CHILD_PROCESS_INIT;
 399         struct filter_params *params = (struct filter_params *)data;
 400         int write_err, status;
 401         const char *argv[] = { NULL, NULL };
 402
 403         /* apply % substitution to cmd */
 404         struct strbuf cmd = STRBUF_INIT;
 405         struct strbuf path = STRBUF_INIT;
 406         struct strbuf_expand_dict_entry dict[] = {
 407                 { "f", NULL, },
 408                 { NULL, NULL, },
 409         };
 410
 411         /* quote the path to preserve spaces, etc. */
 412         sq_quote_buf(&path, params->path);
 413         dict[0].value = path.buf;
 414
 415         /* expand all %f with the quoted path */
 416         strbuf_expand(&cmd, params->cmd, strbuf_expand_dict_cb, &dict);
 417         strbuf_release(&path);
 418
 419         argv[0] = cmd.buf;
 420
 421         child_process.argv = argv;
 422         child_process.use_shell = 1;
 423         child_process.in = -1;
 424         child_process.out = out;
 425
 426         if (start_command(&child_process))
 427                 return error("cannot fork to run external filter '%s'", params->cmd);
 428
 429         sigchain_push(SIGPIPE, SIG_IGN);
 430
 431         if (params->src) {
 432                 write_err = (write_in_full(child_process.in,
 433                                            params->src, params->size) < 0);
 434                 if (errno == EPIPE)
 435                         write_err = 0;
 436         } else {
 437                 write_err = copy_fd(params->fd, child_process.in);
 438                 if (write_err == COPY_WRITE_ERROR && errno == EPIPE)
 439                         write_err = 0;
 440         }
 441
 442         if (close(child_process.in))
 443                 write_err = 1;
 444         if (write_err)
 445                 error("cannot feed the input to external filter '%s'", params->cmd);
 446
 447         sigchain_pop(SIGPIPE);
 448
 449         status = finish_command(&child_process);
 450         if (status)
 451                 error("external filter '%s' failed %d", params->cmd, status);
 452
 453         strbuf_release(&cmd);
 454         return (write_err || status);
 455 }
 456
 457 static int apply_single_file_filter(const char *path, const char *src, size_t len, int fd,
 458                         struct strbuf *dst, const char *cmd)
 459 {
 460         /*
 461          * Create a pipeline to have the command filter the buffer's
 462          * contents.
 463          *
 464          * (child --> cmd) --> us
 465          */
 466         int err = 0;
 467         struct strbuf nbuf = STRBUF_INIT;
 468         struct async async;
 469         struct filter_params params;
 470
 471         memset(&async, 0, sizeof(async));
 472         async.proc = filter_buffer_or_fd;
 473         async.data = &params;
 474         async.out = -1;
 475         params.src = src;
 476         params.size = len;
 477         params.fd = fd;
 478         params.cmd = cmd;
 479         params.path = path;
 480
 481         fflush(NULL);
 482         if (start_async(&async))
 483                 return 0;       /* error was already reported */
 484
 485         if (strbuf_read(&nbuf, async.out, len) < 0) {
 486                 err = error("read from external filter '%s' failed", cmd);
 487         }
 488         if (close(async.out)) {
 489                 err = error("read from external filter '%s' failed", cmd);
 490         }
 491         if (finish_async(&async)) {
 492                 err = error("external filter '%s' failed", cmd);
 493         }
 494
 495         if (!err) {
 496                 strbuf_swap(dst, &nbuf);
 497         }
 498         strbuf_release(&nbuf);
 499         return !err;
 500 }
 501
 502 #define CAP_CLEAN    (1u<<0)
 503 #define CAP_SMUDGE   (1u<<1)
 504 #define CAP_DELAY    (1u<<2)
 505
 506 struct cmd2process {
 507         struct subprocess_entry subprocess; /* must be the first member! */
 508         unsigned int supported_capabilities;
 509 };
 510
 511 static int subprocess_map_initialized;
 512 static struct hashmap subprocess_map;
 513
 514 static int start_multi_file_filter_fn(struct subprocess_entry *subprocess)
 515 {
 516         static int versions[] = {2, 0};
 517         static struct subprocess_capability capabilities[] = {
 518                 { "clean",  CAP_CLEAN  },
 519                 { "smudge", CAP_SMUDGE },
 520                 { "delay",  CAP_DELAY  },
 521                 { NULL, 0 }
 522         };
 523         struct cmd2process *entry = (struct cmd2process *)subprocess;
 524         return subprocess_handshake(subprocess, "git-filter", versions, NULL,
 525                                     capabilities,
 526                                     &entry->supported_capabilities);
 527 }
 528
 529 static void handle_filter_error(const struct strbuf *filter_status,
 530                                 struct cmd2process *entry,
 531                                 const unsigned int wanted_capability) {
 532         if (!strcmp(filter_status->buf, "error"))
 533                 ; /* The filter signaled a problem with the file. */
 534         else if (!strcmp(filter_status->buf, "abort") && wanted_capability) {
 535                 /*
 536                  * The filter signaled a permanent problem. Don't try to filter
 537                  * files with the same command for the lifetime of the current
 538                  * Git process.
 539                  */
 540                  entry->supported_capabilities &= ~wanted_capability;
 541         } else {
 542                 /*
 543                  * Something went wrong with the protocol filter.
 544                  * Force shutdown and restart if another blob requires filtering.
 545                  */
 546                 error("external filter '%s' failed", entry->subprocess.cmd);
 547                 subprocess_stop(&subprocess_map, &entry->subprocess);
 548                 free(entry);
 549         }
 550 }
 551
 552 static int apply_multi_file_filter(const char *path, const char *src, size_t len,
 553                                    int fd, struct strbuf *dst, const char *cmd,
 554                                    const unsigned int wanted_capability,
 555                                    struct delayed_checkout *dco)
 556 {
 557         int err;
 558         int can_delay = 0;
 559         struct cmd2process *entry;
 560         struct child_process *process;
 561         struct strbuf nbuf = STRBUF_INIT;
 562         struct strbuf filter_status = STRBUF_INIT;
 563         const char *filter_type;
 564
 565         if (!subprocess_map_initialized) {
 566                 subprocess_map_initialized = 1;
 567                 hashmap_init(&subprocess_map, (hashmap_cmp_fn) cmd2process_cmp,
 568                              NULL, 0);
 569                 entry = NULL;
 570         } else {
 571                 entry = (struct cmd2process *)subprocess_find_entry(&subprocess_map, cmd);
 572         }
 573
 574         fflush(NULL);
 575
 576         if (!entry) {
 577                 entry = xmalloc(sizeof(*entry));
 578                 entry->supported_capabilities = 0;
 579
 580                 if (subprocess_start(&subprocess_map, &entry->subprocess, cmd, start_multi_file_filter_fn)) {
 581                         free(entry);
 582                         return 0;
 583                 }
 584         }
 585         process = &entry->subprocess.process;
 586
 587         if (!(entry->supported_capabilities & wanted_capability))
 588                 return 0;
 589
 590         if (wanted_capability & CAP_CLEAN)
 591                 filter_type = "clean";
 592         else if (wanted_capability & CAP_SMUDGE)
 593                 filter_type = "smudge";
 594         else
 595                 die("unexpected filter type");
 596
 597         sigchain_push(SIGPIPE, SIG_IGN);
 598
 599         assert(strlen(filter_type) < LARGE_PACKET_DATA_MAX - strlen("command=\n"));
 600         err = packet_write_fmt_gently(process->in, "command=%s\n", filter_type);
 601         if (err)
 602                 goto done;
 603
 604         err = strlen(path) > LARGE_PACKET_DATA_MAX - strlen("pathname=\n");
 605         if (err) {
 606                 error("path name too long for external filter");
 607                 goto done;
 608         }
 609
 610         err = packet_write_fmt_gently(process->in, "pathname=%s\n", path);
 611         if (err)
 612                 goto done;
 613
 614         if ((entry->supported_capabilities & CAP_DELAY) &&
 615             dco && dco->state == CE_CAN_DELAY) {
 616                 can_delay = 1;
 617                 err = packet_write_fmt_gently(process->in, "can-delay=1\n");
 618                 if (err)
 619                         goto done;
 620         }
 621
 622         err = packet_flush_gently(process->in);
 623         if (err)
 624                 goto done;
 625
 626         if (fd >= 0)
 627                 err = write_packetized_from_fd(fd, process->in);
 628         else
 629                 err = write_packetized_from_buf(src, len, process->in);
 630         if (err)
 631                 goto done;
 632
 633         err = subprocess_read_status(process->out, &filter_status);
 634         if (err)
 635                 goto done;
 636
 637         if (can_delay && !strcmp(filter_status.buf, "delayed")) {
 638                 string_list_insert(&dco->filters, cmd);
 639                 string_list_insert(&dco->paths, path);
 640         } else {
 641                 /* The filter got the blob and wants to send us a response. */
 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
 657 done:
 658         sigchain_pop(SIGPIPE);
 659
 660         if (err)
 661                 handle_filter_error(&filter_status, entry, wanted_capability);
 662         else
 663                 strbuf_swap(dst, &nbuf);
 664         strbuf_release(&nbuf);
 665         return !err;
 666 }
 667
 668
 669 int async_query_available_blobs(const char *cmd, struct string_list *available_paths)
 670 {
 671         int err;
 672         char *line;
 673         struct cmd2process *entry;
 674         struct child_process *process;
 675         struct strbuf filter_status = STRBUF_INIT;
 676
 677         assert(subprocess_map_initialized);
 678         entry = (struct cmd2process *)subprocess_find_entry(&subprocess_map, cmd);
 679         if (!entry) {
 680                 error("external filter '%s' is not available anymore although "
 681                       "not all paths have been filtered", cmd);
 682                 return 0;
 683         }
 684         process = &entry->subprocess.process;
 685         sigchain_push(SIGPIPE, SIG_IGN);
 686
 687         err = packet_write_fmt_gently(
 688                 process->in, "command=list_available_blobs\n");
 689         if (err)
 690                 goto done;
 691
 692         err = packet_flush_gently(process->in);
 693         if (err)
 694                 goto done;
 695
 696         while ((line = packet_read_line(process->out, NULL))) {
 697                 const char *path;
 698                 if (skip_prefix(line, "pathname=", &path))
 699                         string_list_insert(available_paths, xstrdup(path));
 700                 else
 701                         ; /* ignore unknown keys */
 702         }
 703
 704         err = subprocess_read_status(process->out, &filter_status);
 705         if (err)
 706                 goto done;
 707
 708         err = strcmp(filter_status.buf, "success");
 709
 710 done:
 711         sigchain_pop(SIGPIPE);
 712
 713         if (err)
 714                 handle_filter_error(&filter_status, entry, 0);
 715         return !err;
 716 }
 717
 718 static struct convert_driver {
 719         const char *name;
 720         struct convert_driver *next;
 721         const char *smudge;
 722         const char *clean;
 723         const char *process;
 724         int required;
 725 } *user_convert, **user_convert_tail;
 726
 727 static int apply_filter(const char *path, const char *src, size_t len,
 728                         int fd, struct strbuf *dst, struct convert_driver *drv,
 729                         const unsigned int wanted_capability,
 730                         struct delayed_checkout *dco)
 731 {
 732         const char *cmd = NULL;
 733
 734         if (!drv)
 735                 return 0;
 736
 737         if (!dst)
 738                 return 1;
 739
 740         if ((wanted_capability & CAP_CLEAN) && !drv->process && drv->clean)
 741                 cmd = drv->clean;
 742         else if ((wanted_capability & CAP_SMUDGE) && !drv->process && drv->smudge)
 743                 cmd = drv->smudge;
 744
 745         if (cmd && *cmd)
 746                 return apply_single_file_filter(path, src, len, fd, dst, cmd);
 747         else if (drv->process && *drv->process)
 748                 return apply_multi_file_filter(path, src, len, fd, dst,
 749                         drv->process, wanted_capability, dco);
 750
 751         return 0;
 752 }
 753
 754 static int read_convert_config(const char *var, const char *value, void *cb)
 755 {
 756         const char *key, *name;
 757         int namelen;
 758         struct convert_driver *drv;
 759
 760         /*
 761          * External conversion drivers are configured using
 762          * "filter.<name>.variable".
 763          */
 764         if (parse_config_key(var, "filter", &name, &namelen, &key) < 0 || !name)
 765                 return 0;
 766         for (drv = user_convert; drv; drv = drv->next)
 767                 if (!strncmp(drv->name, name, namelen) && !drv->name[namelen])
 768                         break;
 769         if (!drv) {
 770                 drv = xcalloc(1, sizeof(struct convert_driver));
 771                 drv->name = xmemdupz(name, namelen);
 772                 *user_convert_tail = drv;
 773                 user_convert_tail = &(drv->next);
 774         }
 775
 776         /*
 777          * filter.<name>.smudge and filter.<name>.clean specifies
 778          * the command line:
 779          *
 780          *      command-line
 781          *
 782          * The command-line will not be interpolated in any way.
 783          */
 784
 785         if (!strcmp("smudge", key))
 786                 return git_config_string(&drv->smudge, var, value);
 787
 788         if (!strcmp("clean", key))
 789                 return git_config_string(&drv->clean, var, value);
 790
 791         if (!strcmp("process", key))
 792                 return git_config_string(&drv->process, var, value);
 793
 794         if (!strcmp("required", key)) {
 795                 drv->required = git_config_bool(var, value);
 796                 return 0;
 797         }
 798
 799         return 0;
 800 }
 801
 802 static int count_ident(const char *cp, unsigned long size)
 803 {
 804         /*
 805          * "$Id: 0000000000000000000000000000000000000000 $" <=> "$Id$"
 806          */
 807         int cnt = 0;
 808         char ch;
 809
 810         while (size) {
 811                 ch = *cp++;
 812                 size--;
 813                 if (ch != '$')
 814                         continue;
 815                 if (size < 3)
 816                         break;
 817                 if (memcmp("Id", cp, 2))
 818                         continue;
 819                 ch = cp[2];
 820                 cp += 3;
 821                 size -= 3;
 822                 if (ch == '$')
 823                         cnt++; /* $Id$ */
 824                 if (ch != ':')
 825                         continue;
 826
 827                 /*
 828                  * "$Id: ... "; scan up to the closing dollar sign and discard.
 829                  */
 830                 while (size) {
 831                         ch = *cp++;
 832                         size--;
 833                         if (ch == '$') {
 834                                 cnt++;
 835                                 break;
 836                         }
 837                         if (ch == '\n')
 838                                 break;
 839                 }
 840         }
 841         return cnt;
 842 }
 843
 844 static int ident_to_git(const char *path, const char *src, size_t len,
 845                         struct strbuf *buf, int ident)
 846 {
 847         char *dst, *dollar;
 848
 849         if (!ident || (src && !count_ident(src, len)))
 850                 return 0;
 851
 852         if (!buf)
 853                 return 1;
 854
 855         /* only grow if not in place */
 856         if (strbuf_avail(buf) + buf->len < len)
 857                 strbuf_grow(buf, len - buf->len);
 858         dst = buf->buf;
 859         for (;;) {
 860                 dollar = memchr(src, '$', len);
 861                 if (!dollar)
 862                         break;
 863                 memmove(dst, src, dollar + 1 - src);
 864                 dst += dollar + 1 - src;
 865                 len -= dollar + 1 - src;
 866                 src  = dollar + 1;
 867
 868                 if (len > 3 && !memcmp(src, "Id:", 3)) {
 869                         dollar = memchr(src + 3, '$', len - 3);
 870                         if (!dollar)
 871                                 break;
 872                         if (memchr(src + 3, '\n', dollar - src - 3)) {
 873                                 /* Line break before the next dollar. */
 874                                 continue;
 875                         }
 876
 877                         memcpy(dst, "Id$", 3);
 878                         dst += 3;
 879                         len -= dollar + 1 - src;
 880                         src  = dollar + 1;
 881                 }
 882         }
 883         memmove(dst, src, len);
 884         strbuf_setlen(buf, dst + len - buf->buf);
 885         return 1;
 886 }
 887
 888 static int ident_to_worktree(const char *path, const char *src, size_t len,
 889                              struct strbuf *buf, int ident)
 890 {
 891         unsigned char sha1[20];
 892         char *to_free = NULL, *dollar, *spc;
 893         int cnt;
 894
 895         if (!ident)
 896                 return 0;
 897
 898         cnt = count_ident(src, len);
 899         if (!cnt)
 900                 return 0;
 901
 902         /* are we "faking" in place editing ? */
 903         if (src == buf->buf)
 904                 to_free = strbuf_detach(buf, NULL);
 905         hash_sha1_file(src, len, "blob", sha1);
 906
 907         strbuf_grow(buf, len + cnt * 43);
 908         for (;;) {
 909                 /* step 1: run to the next '$' */
 910                 dollar = memchr(src, '$', len);
 911                 if (!dollar)
 912                         break;
 913                 strbuf_add(buf, src, dollar + 1 - src);
 914                 len -= dollar + 1 - src;
 915                 src  = dollar + 1;
 916
 917                 /* step 2: does it looks like a bit like Id:xxx$ or Id$ ? */
 918                 if (len < 3 || memcmp("Id", src, 2))
 919                         continue;
 920
 921                 /* step 3: skip over Id$ or Id:xxxxx$ */
 922                 if (src[2] == '$') {
 923                         src += 3;
 924                         len -= 3;
 925                 } else if (src[2] == ':') {
 926                         /*
 927                          * It's possible that an expanded Id has crept its way into the
 928                          * repository, we cope with that by stripping the expansion out.
 929                          * This is probably not a good idea, since it will cause changes
 930                          * on checkout, which won't go away by stash, but let's keep it
 931                          * for git-style ids.
 932                          */
 933                         dollar = memchr(src + 3, '$', len - 3);
 934                         if (!dollar) {
 935                                 /* incomplete keyword, no more '$', so just quit the loop */
 936                                 break;
 937                         }
 938
 939                         if (memchr(src + 3, '\n', dollar - src - 3)) {
 940                                 /* Line break before the next dollar. */
 941                                 continue;
 942                         }
 943
 944                         spc = memchr(src + 4, ' ', dollar - src - 4);
 945                         if (spc && spc < dollar-1) {
 946                                 /* There are spaces in unexpected places.
 947                                  * This is probably an id from some other
 948                                  * versioning system. Keep it for now.
 949                                  */
 950                                 continue;
 951                         }
 952
 953                         len -= dollar + 1 - src;
 954                         src  = dollar + 1;
 955                 } else {
 956                         /* it wasn't a "Id$" or "Id:xxxx$" */
 957                         continue;
 958                 }
 959
 960                 /* step 4: substitute */
 961                 strbuf_addstr(buf, "Id: ");
 962                 strbuf_add(buf, sha1_to_hex(sha1), 40);
 963                 strbuf_addstr(buf, " $");
 964         }
 965         strbuf_add(buf, src, len);
 966
 967         free(to_free);
 968         return 1;
 969 }
 970
 971 static enum crlf_action git_path_check_crlf(struct attr_check_item *check)
 972 {
 973         const char *value = check->value;
 974
 975         if (ATTR_TRUE(value))
 976                 return CRLF_TEXT;
 977         else if (ATTR_FALSE(value))
 978                 return CRLF_BINARY;
 979         else if (ATTR_UNSET(value))
 980                 ;
 981         else if (!strcmp(value, "input"))
 982                 return CRLF_TEXT_INPUT;
 983         else if (!strcmp(value, "auto"))
 984                 return CRLF_AUTO;
 985         return CRLF_UNDEFINED;
 986 }
 987
 988 static enum eol git_path_check_eol(struct attr_check_item *check)
 989 {
 990         const char *value = check->value;
 991
 992         if (ATTR_UNSET(value))
 993                 ;
 994         else if (!strcmp(value, "lf"))
 995                 return EOL_LF;
 996         else if (!strcmp(value, "crlf"))
 997                 return EOL_CRLF;
 998         return EOL_UNSET;
 999 }
1000
1001 static struct convert_driver *git_path_check_convert(struct attr_check_item *check)
1002 {
1003         const char *value = check->value;
1004         struct convert_driver *drv;
1005
1006         if (ATTR_TRUE(value) || ATTR_FALSE(value) || ATTR_UNSET(value))
1007                 return NULL;
1008         for (drv = user_convert; drv; drv = drv->next)
1009                 if (!strcmp(value, drv->name))
1010                         return drv;
1011         return NULL;
1012 }
1013
1014 static int git_path_check_ident(struct attr_check_item *check)
1015 {
1016         const char *value = check->value;
1017
1018         return !!ATTR_TRUE(value);
1019 }
1020
1021 struct conv_attrs {
1022         struct convert_driver *drv;
1023         enum crlf_action attr_action; /* What attr says */
1024         enum crlf_action crlf_action; /* When no attr is set, use core.autocrlf */
1025         int ident;
1026 };
1027
1028 static void convert_attrs(struct conv_attrs *ca, const char *path)
1029 {
1030         static struct attr_check *check;
1031
1032         if (!check) {
1033                 check = attr_check_initl("crlf", "ident", "filter",
1034                                          "eol", "text", NULL);
1035                 user_convert_tail = &user_convert;
1036                 git_config(read_convert_config, NULL);
1037         }
1038
1039         if (!git_check_attr(path, check)) {
1040                 struct attr_check_item *ccheck = check->items;
1041                 ca->crlf_action = git_path_check_crlf(ccheck + 4);
1042                 if (ca->crlf_action == CRLF_UNDEFINED)
1043                         ca->crlf_action = git_path_check_crlf(ccheck + 0);
1044                 ca->attr_action = ca->crlf_action;
1045                 ca->ident = git_path_check_ident(ccheck + 1);
1046                 ca->drv = git_path_check_convert(ccheck + 2);
1047                 if (ca->crlf_action != CRLF_BINARY) {
1048                         enum eol eol_attr = git_path_check_eol(ccheck + 3);
1049                         if (ca->crlf_action == CRLF_AUTO && eol_attr == EOL_LF)
1050                                 ca->crlf_action = CRLF_AUTO_INPUT;
1051                         else if (ca->crlf_action == CRLF_AUTO && eol_attr == EOL_CRLF)
1052                                 ca->crlf_action = CRLF_AUTO_CRLF;
1053                         else if (eol_attr == EOL_LF)
1054                                 ca->crlf_action = CRLF_TEXT_INPUT;
1055                         else if (eol_attr == EOL_CRLF)
1056                                 ca->crlf_action = CRLF_TEXT_CRLF;
1057                 }
1058                 ca->attr_action = ca->crlf_action;
1059         } else {
1060                 ca->drv = NULL;
1061                 ca->crlf_action = CRLF_UNDEFINED;
1062                 ca->ident = 0;
1063         }
1064         if (ca->crlf_action == CRLF_TEXT)
1065                 ca->crlf_action = text_eol_is_crlf() ? CRLF_TEXT_CRLF : CRLF_TEXT_INPUT;
1066         if (ca->crlf_action == CRLF_UNDEFINED && auto_crlf == AUTO_CRLF_FALSE)
1067                 ca->crlf_action = CRLF_BINARY;
1068         if (ca->crlf_action == CRLF_UNDEFINED && auto_crlf == AUTO_CRLF_TRUE)
1069                 ca->crlf_action = CRLF_AUTO_CRLF;
1070         if (ca->crlf_action == CRLF_UNDEFINED && auto_crlf == AUTO_CRLF_INPUT)
1071                 ca->crlf_action = CRLF_AUTO_INPUT;
1072 }
1073
1074 int would_convert_to_git_filter_fd(const char *path)
1075 {
1076         struct conv_attrs ca;
1077
1078         convert_attrs(&ca, path);
1079         if (!ca.drv)
1080                 return 0;
1081
1082         /*
1083          * Apply a filter to an fd only if the filter is required to succeed.
1084          * We must die if the filter fails, because the original data before
1085          * filtering is not available.
1086          */
1087         if (!ca.drv->required)
1088                 return 0;
1089
1090         return apply_filter(path, NULL, 0, -1, NULL, ca.drv, CAP_CLEAN, NULL);
1091 }
1092
1093 const char *get_convert_attr_ascii(const char *path)
1094 {
1095         struct conv_attrs ca;
1096
1097         convert_attrs(&ca, path);
1098         switch (ca.attr_action) {
1099         case CRLF_UNDEFINED:
1100                 return "";
1101         case CRLF_BINARY:
1102                 return "-text";
1103         case CRLF_TEXT:
1104                 return "text";
1105         case CRLF_TEXT_INPUT:
1106                 return "text eol=lf";
1107         case CRLF_TEXT_CRLF:
1108                 return "text eol=crlf";
1109         case CRLF_AUTO:
1110                 return "text=auto";
1111         case CRLF_AUTO_CRLF:
1112                 return "text=auto eol=crlf";
1113         case CRLF_AUTO_INPUT:
1114                 return "text=auto eol=lf";
1115         }
1116         return "";
1117 }
1118
1119 int convert_to_git(const struct index_state *istate,
1120                    const char *path, const char *src, size_t len,
1121                    struct strbuf *dst, enum safe_crlf checksafe)
1122 {
1123         int ret = 0;
1124         struct conv_attrs ca;
1125
1126         convert_attrs(&ca, path);
1127
1128         ret |= apply_filter(path, src, len, -1, dst, ca.drv, CAP_CLEAN, NULL);
1129         if (!ret && ca.drv && ca.drv->required)
1130                 die("%s: clean filter '%s' failed", path, ca.drv->name);
1131
1132         if (ret && dst) {
1133                 src = dst->buf;
1134                 len = dst->len;
1135         }
1136         if (checksafe != SAFE_CRLF_KEEP_CRLF) {
1137                 ret |= crlf_to_git(istate, path, src, len, dst, ca.crlf_action, checksafe);
1138                 if (ret && dst) {
1139                         src = dst->buf;
1140                         len = dst->len;
1141                 }
1142         }
1143         return ret | ident_to_git(path, src, len, dst, ca.ident);
1144 }
1145
1146 void convert_to_git_filter_fd(const struct index_state *istate,
1147                               const char *path, int fd, struct strbuf *dst,
1148                               enum safe_crlf checksafe)
1149 {
1150         struct conv_attrs ca;
1151         convert_attrs(&ca, path);
1152
1153         assert(ca.drv);
1154         assert(ca.drv->clean || ca.drv->process);
1155
1156         if (!apply_filter(path, NULL, 0, fd, dst, ca.drv, CAP_CLEAN, NULL))
1157                 die("%s: clean filter '%s' failed", path, ca.drv->name);
1158
1159         crlf_to_git(istate, path, dst->buf, dst->len, dst, ca.crlf_action, checksafe);
1160         ident_to_git(path, dst->buf, dst->len, dst, ca.ident);
1161 }
1162
1163 static int convert_to_working_tree_internal(const char *path, const char *src,
1164                                             size_t len, struct strbuf *dst,
1165                                             int normalizing, struct delayed_checkout *dco)
1166 {
1167         int ret = 0, ret_filter = 0;
1168         struct conv_attrs ca;
1169
1170         convert_attrs(&ca, path);
1171
1172         ret |= ident_to_worktree(path, src, len, dst, ca.ident);
1173         if (ret) {
1174                 src = dst->buf;
1175                 len = dst->len;
1176         }
1177         /*
1178          * CRLF conversion can be skipped if normalizing, unless there
1179          * is a smudge or process filter (even if the process filter doesn't
1180          * support smudge).  The filters might expect CRLFs.
1181          */
1182         if ((ca.drv && (ca.drv->smudge || ca.drv->process)) || !normalizing) {
1183                 ret |= crlf_to_worktree(path, src, len, dst, ca.crlf_action);
1184                 if (ret) {
1185                         src = dst->buf;
1186                         len = dst->len;
1187                 }
1188         }
1189
1190         ret_filter = apply_filter(
1191                 path, src, len, -1, dst, ca.drv, CAP_SMUDGE, dco);
1192         if (!ret_filter && ca.drv && ca.drv->required)
1193                 die("%s: smudge filter %s failed", path, ca.drv->name);
1194
1195         return ret | ret_filter;
1196 }
1197
1198 int async_convert_to_working_tree(const char *path, const char *src,
1199                                   size_t len, struct strbuf *dst,
1200                                   void *dco)
1201 {
1202         return convert_to_working_tree_internal(path, src, len, dst, 0, dco);
1203 }
1204
1205 int convert_to_working_tree(const char *path, const char *src, size_t len, struct strbuf *dst)
1206 {
1207         return convert_to_working_tree_internal(path, src, len, dst, 0, NULL);
1208 }
1209
1210 int renormalize_buffer(const struct index_state *istate, const char *path,
1211                        const char *src, size_t len, struct strbuf *dst)
1212 {
1213         int ret = convert_to_working_tree_internal(path, src, len, dst, 1, NULL);
1214         if (ret) {
1215                 src = dst->buf;
1216                 len = dst->len;
1217         }
1218         return ret | convert_to_git(istate, path, src, len, dst, SAFE_CRLF_RENORMALIZE);
1219 }
1220
1221 /*****************************************************************
1222  *
1223  * Streaming conversion support
1224  *
1225  *****************************************************************/
1226
1227 typedef int (*filter_fn)(struct stream_filter *,
1228                          const char *input, size_t *isize_p,
1229                          char *output, size_t *osize_p);
1230 typedef void (*free_fn)(struct stream_filter *);
1231
1232 struct stream_filter_vtbl {
1233         filter_fn filter;
1234         free_fn free;
1235 };
1236
1237 struct stream_filter {
1238         struct stream_filter_vtbl *vtbl;
1239 };
1240
1241 static int null_filter_fn(struct stream_filter *filter,
1242                           const char *input, size_t *isize_p,
1243                           char *output, size_t *osize_p)
1244 {
1245         size_t count;
1246
1247         if (!input)
1248                 return 0; /* we do not keep any states */
1249         count = *isize_p;
1250         if (*osize_p < count)
1251                 count = *osize_p;
1252         if (count) {
1253                 memmove(output, input, count);
1254                 *isize_p -= count;
1255                 *osize_p -= count;
1256         }
1257         return 0;
1258 }
1259
1260 static void null_free_fn(struct stream_filter *filter)
1261 {
1262         ; /* nothing -- null instances are shared */
1263 }
1264
1265 static struct stream_filter_vtbl null_vtbl = {
1266         null_filter_fn,
1267         null_free_fn,
1268 };
1269
1270 static struct stream_filter null_filter_singleton = {
1271         &null_vtbl,
1272 };
1273
1274 int is_null_stream_filter(struct stream_filter *filter)
1275 {
1276         return filter == &null_filter_singleton;
1277 }
1278
1279
1280 /*
1281  * LF-to-CRLF filter
1282  */
1283
1284 struct lf_to_crlf_filter {
1285         struct stream_filter filter;
1286         unsigned has_held:1;
1287         char held;
1288 };
1289
1290 static int lf_to_crlf_filter_fn(struct stream_filter *filter,
1291                                 const char *input, size_t *isize_p,
1292                                 char *output, size_t *osize_p)
1293 {
1294         size_t count, o = 0;
1295         struct lf_to_crlf_filter *lf_to_crlf = (struct lf_to_crlf_filter *)filter;
1296
1297         /*
1298          * We may be holding onto the CR to see if it is followed by a
1299          * LF, in which case we would need to go to the main loop.
1300          * Otherwise, just emit it to the output stream.
1301          */
1302         if (lf_to_crlf->has_held && (lf_to_crlf->held != '\r' || !input)) {
1303                 output[o++] = lf_to_crlf->held;
1304                 lf_to_crlf->has_held = 0;
1305         }
1306
1307         /* We are told to drain */
1308         if (!input) {
1309                 *osize_p -= o;
1310                 return 0;
1311         }
1312
1313         count = *isize_p;
1314         if (count || lf_to_crlf->has_held) {
1315                 size_t i;
1316                 int was_cr = 0;
1317
1318                 if (lf_to_crlf->has_held) {
1319                         was_cr = 1;
1320                         lf_to_crlf->has_held = 0;
1321                 }
1322
1323                 for (i = 0; o < *osize_p && i < count; i++) {
1324                         char ch = input[i];
1325
1326                         if (ch == '\n') {
1327                                 output[o++] = '\r';
1328                         } else if (was_cr) {
1329                                 /*
1330                                  * Previous round saw CR and it is not followed
1331                                  * by a LF; emit the CR before processing the
1332                                  * current character.
1333                                  */
1334                                 output[o++] = '\r';
1335                         }
1336
1337                         /*
1338                          * We may have consumed the last output slot,
1339                          * in which case we need to break out of this
1340                          * loop; hold the current character before
1341                          * returning.
1342                          */
1343                         if (*osize_p <= o) {
1344                                 lf_to_crlf->has_held = 1;
1345                                 lf_to_crlf->held = ch;
1346                                 continue; /* break but increment i */
1347                         }
1348
1349                         if (ch == '\r') {
1350                                 was_cr = 1;
1351                                 continue;
1352                         }
1353
1354                         was_cr = 0;
1355                         output[o++] = ch;
1356                 }
1357
1358                 *osize_p -= o;
1359                 *isize_p -= i;
1360
1361                 if (!lf_to_crlf->has_held && was_cr) {
1362                         lf_to_crlf->has_held = 1;
1363                         lf_to_crlf->held = '\r';
1364                 }
1365         }
1366         return 0;
1367 }
1368
1369 static void lf_to_crlf_free_fn(struct stream_filter *filter)
1370 {
1371         free(filter);
1372 }
1373
1374 static struct stream_filter_vtbl lf_to_crlf_vtbl = {
1375         lf_to_crlf_filter_fn,
1376         lf_to_crlf_free_fn,
1377 };
1378
1379 static struct stream_filter *lf_to_crlf_filter(void)
1380 {
1381         struct lf_to_crlf_filter *lf_to_crlf = xcalloc(1, sizeof(*lf_to_crlf));
1382
1383         lf_to_crlf->filter.vtbl = &lf_to_crlf_vtbl;
1384         return (struct stream_filter *)lf_to_crlf;
1385 }
1386
1387 /*
1388  * Cascade filter
1389  */
1390 #define FILTER_BUFFER 1024
1391 struct cascade_filter {
1392         struct stream_filter filter;
1393         struct stream_filter *one;
1394         struct stream_filter *two;
1395         char buf[FILTER_BUFFER];
1396         int end, ptr;
1397 };
1398
1399 static int cascade_filter_fn(struct stream_filter *filter,
1400                              const char *input, size_t *isize_p,
1401                              char *output, size_t *osize_p)
1402 {
1403         struct cascade_filter *cas = (struct cascade_filter *) filter;
1404         size_t filled = 0;
1405         size_t sz = *osize_p;
1406         size_t to_feed, remaining;
1407
1408         /*
1409          * input -- (one) --> buf -- (two) --> output
1410          */
1411         while (filled < sz) {
1412                 remaining = sz - filled;
1413
1414                 /* do we already have something to feed two with? */
1415                 if (cas->ptr < cas->end) {
1416                         to_feed = cas->end - cas->ptr;
1417                         if (stream_filter(cas->two,
1418                                           cas->buf + cas->ptr, &to_feed,
1419                                           output + filled, &remaining))
1420                                 return -1;
1421                         cas->ptr += (cas->end - cas->ptr) - to_feed;
1422                         filled = sz - remaining;
1423                         continue;
1424                 }
1425
1426                 /* feed one from upstream and have it emit into our buffer */
1427                 to_feed = input ? *isize_p : 0;
1428                 if (input && !to_feed)
1429                         break;
1430                 remaining = sizeof(cas->buf);
1431                 if (stream_filter(cas->one,
1432                                   input, &to_feed,
1433                                   cas->buf, &remaining))
1434                         return -1;
1435                 cas->end = sizeof(cas->buf) - remaining;
1436                 cas->ptr = 0;
1437                 if (input) {
1438                         size_t fed = *isize_p - to_feed;
1439                         *isize_p -= fed;
1440                         input += fed;
1441                 }
1442
1443                 /* do we know that we drained one completely? */
1444                 if (input || cas->end)
1445                         continue;
1446
1447                 /* tell two to drain; we have nothing more to give it */
1448                 to_feed = 0;
1449                 remaining = sz - filled;
1450                 if (stream_filter(cas->two,
1451                                   NULL, &to_feed,
1452                                   output + filled, &remaining))
1453                         return -1;
1454                 if (remaining == (sz - filled))
1455                         break; /* completely drained two */
1456                 filled = sz - remaining;
1457         }
1458         *osize_p -= filled;
1459         return 0;
1460 }
1461
1462 static void cascade_free_fn(struct stream_filter *filter)
1463 {
1464         struct cascade_filter *cas = (struct cascade_filter *)filter;
1465         free_stream_filter(cas->one);
1466         free_stream_filter(cas->two);
1467         free(filter);
1468 }
1469
1470 static struct stream_filter_vtbl cascade_vtbl = {
1471         cascade_filter_fn,
1472         cascade_free_fn,
1473 };
1474
1475 static struct stream_filter *cascade_filter(struct stream_filter *one,
1476                                             struct stream_filter *two)
1477 {
1478         struct cascade_filter *cascade;
1479
1480         if (!one || is_null_stream_filter(one))
1481                 return two;
1482         if (!two || is_null_stream_filter(two))
1483                 return one;
1484
1485         cascade = xmalloc(sizeof(*cascade));
1486         cascade->one = one;
1487         cascade->two = two;
1488         cascade->end = cascade->ptr = 0;
1489         cascade->filter.vtbl = &cascade_vtbl;
1490         return (struct stream_filter *)cascade;
1491 }
1492
1493 /*
1494  * ident filter
1495  */
1496 #define IDENT_DRAINING (-1)
1497 #define IDENT_SKIPPING (-2)
1498 struct ident_filter {
1499         struct stream_filter filter;
1500         struct strbuf left;
1501         int state;
1502         char ident[45]; /* ": x40 $" */
1503 };
1504
1505 static int is_foreign_ident(const char *str)
1506 {
1507         int i;
1508
1509         if (!skip_prefix(str, "$Id: ", &str))
1510                 return 0;
1511         for (i = 0; str[i]; i++) {
1512                 if (isspace(str[i]) && str[i+1] != '$')
1513                         return 1;
1514         }
1515         return 0;
1516 }
1517
1518 static void ident_drain(struct ident_filter *ident, char **output_p, size_t *osize_p)
1519 {
1520         size_t to_drain = ident->left.len;
1521
1522         if (*osize_p < to_drain)
1523                 to_drain = *osize_p;
1524         if (to_drain) {
1525                 memcpy(*output_p, ident->left.buf, to_drain);
1526                 strbuf_remove(&ident->left, 0, to_drain);
1527                 *output_p += to_drain;
1528                 *osize_p -= to_drain;
1529         }
1530         if (!ident->left.len)
1531                 ident->state = 0;
1532 }
1533
1534 static int ident_filter_fn(struct stream_filter *filter,
1535                            const char *input, size_t *isize_p,
1536                            char *output, size_t *osize_p)
1537 {
1538         struct ident_filter *ident = (struct ident_filter *)filter;
1539         static const char head[] = "$Id";
1540
1541         if (!input) {
1542                 /* drain upon eof */
1543                 switch (ident->state) {
1544                 default:
1545                         strbuf_add(&ident->left, head, ident->state);
1546                 case IDENT_SKIPPING:
1547                         /* fallthru */
1548                 case IDENT_DRAINING:
1549                         ident_drain(ident, &output, osize_p);
1550                 }
1551                 return 0;
1552         }
1553
1554         while (*isize_p || (ident->state == IDENT_DRAINING)) {
1555                 int ch;
1556
1557                 if (ident->state == IDENT_DRAINING) {
1558                         ident_drain(ident, &output, osize_p);
1559                         if (!*osize_p)
1560                                 break;
1561                         continue;
1562                 }
1563
1564                 ch = *(input++);
1565                 (*isize_p)--;
1566
1567                 if (ident->state == IDENT_SKIPPING) {
1568                         /*
1569                          * Skipping until '$' or LF, but keeping them
1570                          * in case it is a foreign ident.
1571                          */
1572                         strbuf_addch(&ident->left, ch);
1573                         if (ch != '\n' && ch != '$')
1574                                 continue;
1575                         if (ch == '$' && !is_foreign_ident(ident->left.buf)) {
1576                                 strbuf_setlen(&ident->left, sizeof(head) - 1);
1577                                 strbuf_addstr(&ident->left, ident->ident);
1578                         }
1579                         ident->state = IDENT_DRAINING;
1580                         continue;
1581                 }
1582
1583                 if (ident->state < sizeof(head) &&
1584                     head[ident->state] == ch) {
1585                         ident->state++;
1586                         continue;
1587                 }
1588
1589                 if (ident->state)
1590                         strbuf_add(&ident->left, head, ident->state);
1591                 if (ident->state == sizeof(head) - 1) {
1592                         if (ch != ':' && ch != '$') {
1593                                 strbuf_addch(&ident->left, ch);
1594                                 ident->state = 0;
1595                                 continue;
1596                         }
1597
1598                         if (ch == ':') {
1599                                 strbuf_addch(&ident->left, ch);
1600                                 ident->state = IDENT_SKIPPING;
1601                         } else {
1602                                 strbuf_addstr(&ident->left, ident->ident);
1603                                 ident->state = IDENT_DRAINING;
1604                         }
1605                         continue;
1606                 }
1607
1608                 strbuf_addch(&ident->left, ch);
1609                 ident->state = IDENT_DRAINING;
1610         }
1611         return 0;
1612 }
1613
1614 static void ident_free_fn(struct stream_filter *filter)
1615 {
1616         struct ident_filter *ident = (struct ident_filter *)filter;
1617         strbuf_release(&ident->left);
1618         free(filter);
1619 }
1620
1621 static struct stream_filter_vtbl ident_vtbl = {
1622         ident_filter_fn,
1623         ident_free_fn,
1624 };
1625
1626 static struct stream_filter *ident_filter(const unsigned char *sha1)
1627 {
1628         struct ident_filter *ident = xmalloc(sizeof(*ident));
1629
1630         xsnprintf(ident->ident, sizeof(ident->ident),
1631                   ": %s $", sha1_to_hex(sha1));
1632         strbuf_init(&ident->left, 0);
1633         ident->filter.vtbl = &ident_vtbl;
1634         ident->state = 0;
1635         return (struct stream_filter *)ident;
1636 }
1637
1638 /*
1639  * Return an appropriately constructed filter for the path, or NULL if
1640  * the contents cannot be filtered without reading the whole thing
1641  * in-core.
1642  *
1643  * Note that you would be crazy to set CRLF, smuge/clean or ident to a
1644  * large binary blob you would want us not to slurp into the memory!
1645  */
1646 struct stream_filter *get_stream_filter(const char *path, const unsigned char *sha1)
1647 {
1648         struct conv_attrs ca;
1649         struct stream_filter *filter = NULL;
1650
1651         convert_attrs(&ca, path);
1652         if (ca.drv && (ca.drv->process || ca.drv->smudge || ca.drv->clean))
1653                 return NULL;
1654
1655         if (ca.crlf_action == CRLF_AUTO || ca.crlf_action == CRLF_AUTO_CRLF)
1656                 return NULL;
1657
1658         if (ca.ident)
1659                 filter = ident_filter(sha1);
1660
1661         if (output_eol(ca.crlf_action) == EOL_CRLF)
1662                 filter = cascade_filter(filter, lf_to_crlf_filter());
1663         else
1664                 filter = cascade_filter(filter, &null_filter_singleton);
1665
1666         return filter;
1667 }
1668
1669 void free_stream_filter(struct stream_filter *filter)
1670 {
1671         filter->vtbl->free(filter);
1672 }
1673
1674 int stream_filter(struct stream_filter *filter,
1675                   const char *input, size_t *isize_p,
1676                   char *output, size_t *osize_p)
1677 {
1678         return filter->vtbl->filter(filter, input, isize_p, output, osize_p);
1679 }