git.oblomov.eu Git - git/blob - 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
   8 /*
   9  * convert.c - convert a file when checking it out and checking it in.
  10  *
  11  * This should use the pathname to decide on whether it wants to do some
  12  * more interesting conversions (automatic gzip/unzip, general format
  13  * conversions etc etc), but by default it just does automatic CRLF<->LF
  14  * translation when the "text" attribute or "auto_crlf" option is set.
  15  */
  16
  17 /* Stat bits: When BIN is set, the txt bits are unset */
  18 #define CONVERT_STAT_BITS_TXT_LF    0x1
  19 #define CONVERT_STAT_BITS_TXT_CRLF  0x2
  20 #define CONVERT_STAT_BITS_BIN       0x4
  21
  22 enum crlf_action {
  23         CRLF_UNDEFINED,
  24         CRLF_BINARY,
  25         CRLF_TEXT,
  26         CRLF_TEXT_INPUT,
  27         CRLF_TEXT_CRLF,
  28         CRLF_AUTO,
  29         CRLF_AUTO_INPUT,
  30         CRLF_AUTO_CRLF
  31 };
  32
  33 struct text_stat {
  34         /* NUL, CR, LF and CRLF counts */
  35         unsigned nul, lonecr, lonelf, crlf;
  36
  37         /* These are just approximations! */
  38         unsigned printable, nonprintable;
  39 };
  40
  41 static void gather_stats(const char *buf, unsigned long size, struct text_stat *stats)
  42 {
  43         unsigned long i;
  44
  45         memset(stats, 0, sizeof(*stats));
  46
  47         for (i = 0; i < size; i++) {
  48                 unsigned char c = buf[i];
  49                 if (c == '\r') {
  50                         if (i+1 < size && buf[i+1] == '\n') {
  51                                 stats->crlf++;
  52                                 i++;
  53                         } else
  54                                 stats->lonecr++;
  55                         continue;
  56                 }
  57                 if (c == '\n') {
  58                         stats->lonelf++;
  59                         continue;
  60                 }
  61                 if (c == 127)
  62                         /* DEL */
  63                         stats->nonprintable++;
  64                 else if (c < 32) {
  65                         switch (c) {
  66                                 /* BS, HT, ESC and FF */
  67                         case '\b': case '\t': case '\033': case '\014':
  68                                 stats->printable++;
  69                                 break;
  70                         case 0:
  71                                 stats->nul++;
  72                                 /* fall through */
  73                         default:
  74                                 stats->nonprintable++;
  75                         }
  76                 }
  77                 else
  78                         stats->printable++;
  79         }
  80
  81         /* If file ends with EOF then don't count this EOF as non-printable. */
  82         if (size >= 1 && buf[size-1] == '\032')
  83                 stats->nonprintable--;
  84 }
  85
  86 /*
  87  * The same heuristics as diff.c::mmfile_is_binary()
  88  * We treat files with bare CR as binary
  89  */
  90 static int convert_is_binary(unsigned long size, const struct text_stat *stats)
  91 {
  92         if (stats->lonecr)
  93                 return 1;
  94         if (stats->nul)
  95                 return 1;
  96         if ((stats->printable >> 7) < stats->nonprintable)
  97                 return 1;
  98         return 0;
  99 }
 100
 101 static unsigned int gather_convert_stats(const char *data, unsigned long size)
 102 {
 103         struct text_stat stats;
 104         int ret = 0;
 105         if (!data || !size)
 106                 return 0;
 107         gather_stats(data, size, &stats);
 108         if (convert_is_binary(size, &stats))
 109                 ret |= CONVERT_STAT_BITS_BIN;
 110         if (stats.crlf)
 111                 ret |= CONVERT_STAT_BITS_TXT_CRLF;
 112         if (stats.lonelf)
 113                 ret |=  CONVERT_STAT_BITS_TXT_LF;
 114
 115         return ret;
 116 }
 117
 118 static const char *gather_convert_stats_ascii(const char *data, unsigned long size)
 119 {
 120         unsigned int convert_stats = gather_convert_stats(data, size);
 121
 122         if (convert_stats & CONVERT_STAT_BITS_BIN)
 123                 return "-text";
 124         switch (convert_stats) {
 125         case CONVERT_STAT_BITS_TXT_LF:
 126                 return "lf";
 127         case CONVERT_STAT_BITS_TXT_CRLF:
 128                 return "crlf";
 129         case CONVERT_STAT_BITS_TXT_LF | CONVERT_STAT_BITS_TXT_CRLF:
 130                 return "mixed";
 131         default:
 132                 return "none";
 133         }
 134 }
 135
 136 const char *get_cached_convert_stats_ascii(const char *path)
 137 {
 138         const char *ret;
 139         unsigned long sz;
 140         void *data = read_blob_data_from_cache(path, &sz);
 141         ret = gather_convert_stats_ascii(data, sz);
 142         free(data);
 143         return ret;
 144 }
 145
 146 const char *get_wt_convert_stats_ascii(const char *path)
 147 {
 148         const char *ret = "";
 149         struct strbuf sb = STRBUF_INIT;
 150         if (strbuf_read_file(&sb, path, 0) >= 0)
 151                 ret = gather_convert_stats_ascii(sb.buf, sb.len);
 152         strbuf_release(&sb);
 153         return ret;
 154 }
 155
 156 static int text_eol_is_crlf(void)
 157 {
 158         if (auto_crlf == AUTO_CRLF_TRUE)
 159                 return 1;
 160         else if (auto_crlf == AUTO_CRLF_INPUT)
 161                 return 0;
 162         if (core_eol == EOL_CRLF)
 163                 return 1;
 164         if (core_eol == EOL_UNSET && EOL_NATIVE == EOL_CRLF)
 165                 return 1;
 166         return 0;
 167 }
 168
 169 static enum eol output_eol(enum crlf_action crlf_action)
 170 {
 171         switch (crlf_action) {
 172         case CRLF_BINARY:
 173                 return EOL_UNSET;
 174         case CRLF_TEXT_CRLF:
 175                 return EOL_CRLF;
 176         case CRLF_TEXT_INPUT:
 177                 return EOL_LF;
 178         case CRLF_UNDEFINED:
 179         case CRLF_AUTO_CRLF:
 180                 return EOL_CRLF;
 181         case CRLF_AUTO_INPUT:
 182                 return EOL_LF;
 183         case CRLF_TEXT:
 184         case CRLF_AUTO:
 185                 /* fall through */
 186                 return text_eol_is_crlf() ? EOL_CRLF : EOL_LF;
 187         }
 188         warning("Illegal crlf_action %d\n", (int)crlf_action);
 189         return core_eol;
 190 }
 191
 192 static void check_safe_crlf(const char *path, enum crlf_action crlf_action,
 193                             struct text_stat *old_stats, struct text_stat *new_stats,
 194                             enum safe_crlf checksafe)
 195 {
 196         if (old_stats->crlf && !new_stats->crlf ) {
 197                 /*
 198                  * CRLFs would not be restored by checkout
 199                  */
 200                 if (checksafe == SAFE_CRLF_WARN)
 201                         warning(_("CRLF will be replaced by LF in %s.\n"
 202                                   "The file will have its original line"
 203                                   " endings in your working directory."), path);
 204                 else /* i.e. SAFE_CRLF_FAIL */
 205                         die(_("CRLF would be replaced by LF in %s."), path);
 206         } else if (old_stats->lonelf && !new_stats->lonelf ) {
 207                 /*
 208                  * CRLFs would be added by checkout
 209                  */
 210                 if (checksafe == SAFE_CRLF_WARN)
 211                         warning(_("LF will be replaced by CRLF in %s.\n"
 212                                   "The file will have its original line"
 213                                   " endings in your working directory."), path);
 214                 else /* i.e. SAFE_CRLF_FAIL */
 215                         die(_("LF would be replaced by CRLF in %s"), path);
 216         }
 217 }
 218
 219 static int has_cr_in_index(const char *path)
 220 {
 221         unsigned long sz;
 222         void *data;
 223         int has_cr;
 224
 225         data = read_blob_data_from_cache(path, &sz);
 226         if (!data)
 227                 return 0;
 228         has_cr = memchr(data, '\r', sz) != NULL;
 229         free(data);
 230         return has_cr;
 231 }
 232
 233 static int will_convert_lf_to_crlf(size_t len, struct text_stat *stats,
 234                                    enum crlf_action crlf_action)
 235 {
 236         if (output_eol(crlf_action) != EOL_CRLF)
 237                 return 0;
 238         /* No "naked" LF? Nothing to convert, regardless. */
 239         if (!stats->lonelf)
 240                 return 0;
 241
 242         if (crlf_action == CRLF_AUTO || crlf_action == CRLF_AUTO_INPUT || crlf_action == CRLF_AUTO_CRLF) {
 243                 /* If we have any CR or CRLF line endings, we do not touch it */
 244                 /* This is the new safer autocrlf-handling */
 245                 if (stats->lonecr || stats->crlf)
 246                         return 0;
 247
 248                 if (convert_is_binary(len, stats))
 249                         return 0;
 250         }
 251         return 1;
 252
 253 }
 254
 255 static int crlf_to_git(const char *path, const char *src, size_t len,
 256                        struct strbuf *buf,
 257                        enum crlf_action crlf_action, enum safe_crlf checksafe)
 258 {
 259         struct text_stat stats;
 260         char *dst;
 261         int convert_crlf_into_lf;
 262
 263         if (crlf_action == CRLF_BINARY ||
 264             (src && !len))
 265                 return 0;
 266
 267         /*
 268          * If we are doing a dry-run and have no source buffer, there is
 269          * nothing to analyze; we must assume we would convert.
 270          */
 271         if (!buf && !src)
 272                 return 1;
 273
 274         gather_stats(src, len, &stats);
 275         /* Optimization: No CRLF? Nothing to convert, regardless. */
 276         convert_crlf_into_lf = !!stats.crlf;
 277
 278         if (crlf_action == CRLF_AUTO || crlf_action == CRLF_AUTO_INPUT || crlf_action == CRLF_AUTO_CRLF) {
 279                 if (convert_is_binary(len, &stats))
 280                         return 0;
 281                 /*
 282                  * If the file in the index has any CR in it, do not
 283                  * convert.  This is the new safer autocrlf handling,
 284                  * unless we want to renormalize in a merge or
 285                  * cherry-pick.
 286                  */
 287                 if ((checksafe != SAFE_CRLF_RENORMALIZE) && has_cr_in_index(path))
 288                         convert_crlf_into_lf = 0;
 289         }
 290         if ((checksafe == SAFE_CRLF_WARN ||
 291             (checksafe == SAFE_CRLF_FAIL)) && len) {
 292                 struct text_stat new_stats;
 293                 memcpy(&new_stats, &stats, sizeof(new_stats));
 294                 /* simulate "git add" */
 295                 if (convert_crlf_into_lf) {
 296                         new_stats.lonelf += new_stats.crlf;
 297                         new_stats.crlf = 0;
 298                 }
 299                 /* simulate "git checkout" */
 300                 if (will_convert_lf_to_crlf(len, &new_stats, crlf_action)) {
 301                         new_stats.crlf += new_stats.lonelf;
 302                         new_stats.lonelf = 0;
 303                 }
 304                 check_safe_crlf(path, crlf_action, &stats, &new_stats, checksafe);
 305         }
 306         if (!convert_crlf_into_lf)
 307                 return 0;
 308
 309         /*
 310          * At this point all of our source analysis is done, and we are sure we
 311          * would convert. If we are in dry-run mode, we can give an answer.
 312          */
 313         if (!buf)
 314                 return 1;
 315
 316         /* only grow if not in place */
 317         if (strbuf_avail(buf) + buf->len < len)
 318                 strbuf_grow(buf, len - buf->len);
 319         dst = buf->buf;
 320         if (crlf_action == CRLF_AUTO || crlf_action == CRLF_AUTO_INPUT || crlf_action == CRLF_AUTO_CRLF) {
 321                 /*
 322                  * If we guessed, we already know we rejected a file with
 323                  * lone CR, and we can strip a CR without looking at what
 324                  * follow it.
 325                  */
 326                 do {
 327                         unsigned char c = *src++;
 328                         if (c != '\r')
 329                                 *dst++ = c;
 330                 } while (--len);
 331         } else {
 332                 do {
 333                         unsigned char c = *src++;
 334                         if (! (c == '\r' && (1 < len && *src == '\n')))
 335                                 *dst++ = c;
 336                 } while (--len);
 337         }
 338         strbuf_setlen(buf, dst - buf->buf);
 339         return 1;
 340 }
 341
 342 static int crlf_to_worktree(const char *path, const char *src, size_t len,
 343                             struct strbuf *buf, enum crlf_action crlf_action)
 344 {
 345         char *to_free = NULL;
 346         struct text_stat stats;
 347
 348         if (!len || output_eol(crlf_action) != EOL_CRLF)
 349                 return 0;
 350
 351         gather_stats(src, len, &stats);
 352         if (!will_convert_lf_to_crlf(len, &stats, crlf_action))
 353                 return 0;
 354
 355         /* are we "faking" in place editing ? */
 356         if (src == buf->buf)
 357                 to_free = strbuf_detach(buf, NULL);
 358
 359         strbuf_grow(buf, len + stats.lonelf);
 360         for (;;) {
 361                 const char *nl = memchr(src, '\n', len);
 362                 if (!nl)
 363                         break;
 364                 if (nl > src && nl[-1] == '\r') {
 365                         strbuf_add(buf, src, nl + 1 - src);
 366                 } else {
 367                         strbuf_add(buf, src, nl - src);
 368                         strbuf_addstr(buf, "\r\n");
 369                 }
 370                 len -= nl + 1 - src;
 371                 src  = nl + 1;
 372         }
 373         strbuf_add(buf, src, len);
 374
 375         free(to_free);
 376         return 1;
 377 }
 378
 379 struct filter_params {
 380         const char *src;
 381         unsigned long size;
 382         int fd;
 383         const char *cmd;
 384         const char *path;
 385 };
 386
 387 static int filter_buffer_or_fd(int in, int out, void *data)
 388 {
 389         /*
 390          * Spawn cmd and feed the buffer contents through its stdin.
 391          */
 392         struct child_process child_process = CHILD_PROCESS_INIT;
 393         struct filter_params *params = (struct filter_params *)data;
 394         int write_err, status;
 395         const char *argv[] = { NULL, NULL };
 396
 397         /* apply % substitution to cmd */
 398         struct strbuf cmd = STRBUF_INIT;
 399         struct strbuf path = STRBUF_INIT;
 400         struct strbuf_expand_dict_entry dict[] = {
 401                 { "f", NULL, },
 402                 { NULL, NULL, },
 403         };
 404
 405         /* quote the path to preserve spaces, etc. */
 406         sq_quote_buf(&path, params->path);
 407         dict[0].value = path.buf;
 408
 409         /* expand all %f with the quoted path */
 410         strbuf_expand(&cmd, params->cmd, strbuf_expand_dict_cb, &dict);
 411         strbuf_release(&path);
 412
 413         argv[0] = cmd.buf;
 414
 415         child_process.argv = argv;
 416         child_process.use_shell = 1;
 417         child_process.in = -1;
 418         child_process.out = out;
 419
 420         if (start_command(&child_process))
 421                 return error("cannot fork to run external filter '%s'", params->cmd);
 422
 423         sigchain_push(SIGPIPE, SIG_IGN);
 424
 425         if (params->src) {
 426                 write_err = (write_in_full(child_process.in,
 427                                            params->src, params->size) < 0);
 428                 if (errno == EPIPE)
 429                         write_err = 0;
 430         } else {
 431                 write_err = copy_fd(params->fd, child_process.in);
 432                 if (write_err == COPY_WRITE_ERROR && errno == EPIPE)
 433                         write_err = 0;
 434         }
 435
 436         if (close(child_process.in))
 437                 write_err = 1;
 438         if (write_err)
 439                 error("cannot feed the input to external filter '%s'", params->cmd);
 440
 441         sigchain_pop(SIGPIPE);
 442
 443         status = finish_command(&child_process);
 444         if (status)
 445                 error("external filter '%s' failed %d", params->cmd, status);
 446
 447         strbuf_release(&cmd);
 448         return (write_err || status);
 449 }
 450
 451 static int apply_single_file_filter(const char *path, const char *src, size_t len, int fd,
 452                         struct strbuf *dst, const char *cmd)
 453 {
 454         /*
 455          * Create a pipeline to have the command filter the buffer's
 456          * contents.
 457          *
 458          * (child --> cmd) --> us
 459          */
 460         int err = 0;
 461         struct strbuf nbuf = STRBUF_INIT;
 462         struct async async;
 463         struct filter_params params;
 464
 465         memset(&async, 0, sizeof(async));
 466         async.proc = filter_buffer_or_fd;
 467         async.data = &params;
 468         async.out = -1;
 469         params.src = src;
 470         params.size = len;
 471         params.fd = fd;
 472         params.cmd = cmd;
 473         params.path = path;
 474
 475         fflush(NULL);
 476         if (start_async(&async))
 477                 return 0;       /* error was already reported */
 478
 479         if (strbuf_read(&nbuf, async.out, len) < 0) {
 480                 err = error("read from external filter '%s' failed", cmd);
 481         }
 482         if (close(async.out)) {
 483                 err = error("read from external filter '%s' failed", cmd);
 484         }
 485         if (finish_async(&async)) {
 486                 err = error("external filter '%s' failed", cmd);
 487         }
 488
 489         if (!err) {
 490                 strbuf_swap(dst, &nbuf);
 491         }
 492         strbuf_release(&nbuf);
 493         return !err;
 494 }
 495
 496 #define CAP_CLEAN    (1u<<0)
 497 #define CAP_SMUDGE   (1u<<1)
 498
 499 struct subprocess_entry {
 500         struct hashmap_entry ent; /* must be the first member! */
 501         const char *cmd;
 502         struct child_process process;
 503 };
 504
 505 struct cmd2process {
 506         struct subprocess_entry subprocess; /* must be the first member! */
 507         unsigned int supported_capabilities;
 508 };
 509
 510 static int cmd_process_map_initialized;
 511 static struct hashmap cmd_process_map;
 512
 513 static int cmd2process_cmp(const struct subprocess_entry *e1,
 514                            const struct subprocess_entry *e2,
 515                            const void *unused)
 516 {
 517         return strcmp(e1->cmd, e2->cmd);
 518 }
 519
 520 static struct subprocess_entry *find_multi_file_filter_entry(struct hashmap *hashmap, const char *cmd)
 521 {
 522         struct subprocess_entry key;
 523
 524         hashmap_entry_init(&key, strhash(cmd));
 525         key.cmd = cmd;
 526         return hashmap_get(hashmap, &key, NULL);
 527 }
 528
 529 static void read_multi_file_filter_status(int fd, struct strbuf *status)
 530 {
 531         struct strbuf **pair;
 532         char *line;
 533         for (;;) {
 534                 line = packet_read_line(fd, NULL);
 535                 if (!line)
 536                         break;
 537                 pair = strbuf_split_str(line, '=', 2);
 538                 if (pair[0] && pair[0]->len && pair[1]) {
 539                         /* the last "status=<foo>" line wins */
 540                         if (!strcmp(pair[0]->buf, "status=")) {
 541                                 strbuf_reset(status);
 542                                 strbuf_addbuf(status, pair[1]);
 543                         }
 544                 }
 545                 strbuf_list_free(pair);
 546         }
 547 }
 548
 549 static void kill_multi_file_filter(struct hashmap *hashmap, struct subprocess_entry *entry)
 550 {
 551         if (!entry)
 552                 return;
 553
 554         entry->process.clean_on_exit = 0;
 555         kill(entry->process.pid, SIGTERM);
 556         finish_command(&entry->process);
 557
 558         hashmap_remove(hashmap, entry, NULL);
 559         free(entry);
 560 }
 561
 562 static void stop_multi_file_filter(struct child_process *process)
 563 {
 564         sigchain_push(SIGPIPE, SIG_IGN);
 565         /* Closing the pipe signals the filter to initiate a shutdown. */
 566         close(process->in);
 567         close(process->out);
 568         sigchain_pop(SIGPIPE);
 569         /* Finish command will wait until the shutdown is complete. */
 570         finish_command(process);
 571 }
 572
 573 static int start_multi_file_filter_fn(struct cmd2process *entry)
 574 {
 575         int err;
 576         struct string_list cap_list = STRING_LIST_INIT_NODUP;
 577         char *cap_buf;
 578         const char *cap_name;
 579         struct child_process *process = &entry->subprocess.process;
 580         const char *cmd = entry->subprocess.cmd;
 581
 582         sigchain_push(SIGPIPE, SIG_IGN);
 583
 584         err = packet_writel(process->in, "git-filter-client", "version=2", NULL);
 585         if (err)
 586                 goto done;
 587
 588         err = strcmp(packet_read_line(process->out, NULL), "git-filter-server");
 589         if (err) {
 590                 error("external filter '%s' does not support filter protocol version 2", cmd);
 591                 goto done;
 592         }
 593         err = strcmp(packet_read_line(process->out, NULL), "version=2");
 594         if (err)
 595                 goto done;
 596         err = packet_read_line(process->out, NULL) != NULL;
 597         if (err)
 598                 goto done;
 599
 600         err = packet_writel(process->in, "capability=clean", "capability=smudge", NULL);
 601
 602         for (;;) {
 603                 cap_buf = packet_read_line(process->out, NULL);
 604                 if (!cap_buf)
 605                         break;
 606                 string_list_split_in_place(&cap_list, cap_buf, '=', 1);
 607
 608                 if (cap_list.nr != 2 || strcmp(cap_list.items[0].string, "capability"))
 609                         continue;
 610
 611                 cap_name = cap_list.items[1].string;
 612                 if (!strcmp(cap_name, "clean")) {
 613                         entry->supported_capabilities |= CAP_CLEAN;
 614                 } else if (!strcmp(cap_name, "smudge")) {
 615                         entry->supported_capabilities |= CAP_SMUDGE;
 616                 } else {
 617                         warning(
 618                                 "external filter '%s' requested unsupported filter capability '%s'",
 619                                 cmd, cap_name
 620                         );
 621                 }
 622
 623                 string_list_clear(&cap_list, 0);
 624         }
 625
 626 done:
 627         sigchain_pop(SIGPIPE);
 628
 629         return err;
 630 }
 631
 632 static struct cmd2process *start_multi_file_filter(struct hashmap *hashmap, const char *cmd)
 633 {
 634         int err;
 635         struct cmd2process *entry;
 636         struct child_process *process;
 637         const char *argv[] = { cmd, NULL };
 638
 639         entry = xmalloc(sizeof(*entry));
 640         entry->subprocess.cmd = cmd;
 641         entry->supported_capabilities = 0;
 642         process = &entry->subprocess.process;
 643
 644         child_process_init(process);
 645         process->argv = argv;
 646         process->use_shell = 1;
 647         process->in = -1;
 648         process->out = -1;
 649         process->clean_on_exit = 1;
 650         process->clean_on_exit_handler = stop_multi_file_filter;
 651
 652         if (start_command(process)) {
 653                 error("cannot fork to run external filter '%s'", cmd);
 654                 return NULL;
 655         }
 656
 657         hashmap_entry_init(entry, strhash(cmd));
 658
 659         err = start_multi_file_filter_fn(entry);
 660         if (err) {
 661                 error("initialization for external filter '%s' failed", cmd);
 662                 kill_multi_file_filter(hashmap, &entry->subprocess);
 663                 return NULL;
 664         }
 665
 666         hashmap_add(hashmap, entry);
 667         return entry;
 668 }
 669
 670 static int apply_multi_file_filter(const char *path, const char *src, size_t len,
 671                                    int fd, struct strbuf *dst, const char *cmd,
 672                                    const unsigned int wanted_capability)
 673 {
 674         int err;
 675         struct cmd2process *entry;
 676         struct child_process *process;
 677         struct strbuf nbuf = STRBUF_INIT;
 678         struct strbuf filter_status = STRBUF_INIT;
 679         const char *filter_type;
 680
 681         if (!cmd_process_map_initialized) {
 682                 cmd_process_map_initialized = 1;
 683                 hashmap_init(&cmd_process_map, (hashmap_cmp_fn) cmd2process_cmp, 0);
 684                 entry = NULL;
 685         } else {
 686                 entry = (struct cmd2process *)find_multi_file_filter_entry(&cmd_process_map, cmd);
 687         }
 688
 689         fflush(NULL);
 690
 691         if (!entry) {
 692                 entry = start_multi_file_filter(&cmd_process_map, cmd);
 693                 if (!entry)
 694                         return 0;
 695         }
 696         process = &entry->subprocess.process;
 697
 698         if (!(wanted_capability & entry->supported_capabilities))
 699                 return 0;
 700
 701         if (CAP_CLEAN & wanted_capability)
 702                 filter_type = "clean";
 703         else if (CAP_SMUDGE & wanted_capability)
 704                 filter_type = "smudge";
 705         else
 706                 die("unexpected filter type");
 707
 708         sigchain_push(SIGPIPE, SIG_IGN);
 709
 710         assert(strlen(filter_type) < LARGE_PACKET_DATA_MAX - strlen("command=\n"));
 711         err = packet_write_fmt_gently(process->in, "command=%s\n", filter_type);
 712         if (err)
 713                 goto done;
 714
 715         err = strlen(path) > LARGE_PACKET_DATA_MAX - strlen("pathname=\n");
 716         if (err) {
 717                 error("path name too long for external filter");
 718                 goto done;
 719         }
 720
 721         err = packet_write_fmt_gently(process->in, "pathname=%s\n", path);
 722         if (err)
 723                 goto done;
 724
 725         err = packet_flush_gently(process->in);
 726         if (err)
 727                 goto done;
 728
 729         if (fd >= 0)
 730                 err = write_packetized_from_fd(fd, process->in);
 731         else
 732                 err = write_packetized_from_buf(src, len, process->in);
 733         if (err)
 734                 goto done;
 735
 736         read_multi_file_filter_status(process->out, &filter_status);
 737         err = strcmp(filter_status.buf, "success");
 738         if (err)
 739                 goto done;
 740
 741         err = read_packetized_to_strbuf(process->out, &nbuf) < 0;
 742         if (err)
 743                 goto done;
 744
 745         read_multi_file_filter_status(process->out, &filter_status);
 746         err = strcmp(filter_status.buf, "success");
 747
 748 done:
 749         sigchain_pop(SIGPIPE);
 750
 751         if (err) {
 752                 if (!strcmp(filter_status.buf, "error")) {
 753                         /* The filter signaled a problem with the file. */
 754                 } else if (!strcmp(filter_status.buf, "abort")) {
 755                         /*
 756                          * The filter signaled a permanent problem. Don't try to filter
 757                          * files with the same command for the lifetime of the current
 758                          * Git process.
 759                          */
 760                          entry->supported_capabilities &= ~wanted_capability;
 761                 } else {
 762                         /*
 763                          * Something went wrong with the protocol filter.
 764                          * Force shutdown and restart if another blob requires filtering.
 765                          */
 766                         error("external filter '%s' failed", cmd);
 767                         kill_multi_file_filter(&cmd_process_map, &entry->subprocess);
 768                 }
 769         } else {
 770                 strbuf_swap(dst, &nbuf);
 771         }
 772         strbuf_release(&nbuf);
 773         return !err;
 774 }
 775
 776 static struct convert_driver {
 777         const char *name;
 778         struct convert_driver *next;
 779         const char *smudge;
 780         const char *clean;
 781         const char *process;
 782         int required;
 783 } *user_convert, **user_convert_tail;
 784
 785 static int apply_filter(const char *path, const char *src, size_t len,
 786                         int fd, struct strbuf *dst, struct convert_driver *drv,
 787                         const unsigned int wanted_capability)
 788 {
 789         const char *cmd = NULL;
 790
 791         if (!drv)
 792                 return 0;
 793
 794         if (!dst)
 795                 return 1;
 796
 797         if ((CAP_CLEAN & wanted_capability) && !drv->process && drv->clean)
 798                 cmd = drv->clean;
 799         else if ((CAP_SMUDGE & wanted_capability) && !drv->process && drv->smudge)
 800                 cmd = drv->smudge;
 801
 802         if (cmd && *cmd)
 803                 return apply_single_file_filter(path, src, len, fd, dst, cmd);
 804         else if (drv->process && *drv->process)
 805                 return apply_multi_file_filter(path, src, len, fd, dst, drv->process, wanted_capability);
 806
 807         return 0;
 808 }
 809
 810 static int read_convert_config(const char *var, const char *value, void *cb)
 811 {
 812         const char *key, *name;
 813         int namelen;
 814         struct convert_driver *drv;
 815
 816         /*
 817          * External conversion drivers are configured using
 818          * "filter.<name>.variable".
 819          */
 820         if (parse_config_key(var, "filter", &name, &namelen, &key) < 0 || !name)
 821                 return 0;
 822         for (drv = user_convert; drv; drv = drv->next)
 823                 if (!strncmp(drv->name, name, namelen) && !drv->name[namelen])
 824                         break;
 825         if (!drv) {
 826                 drv = xcalloc(1, sizeof(struct convert_driver));
 827                 drv->name = xmemdupz(name, namelen);
 828                 *user_convert_tail = drv;
 829                 user_convert_tail = &(drv->next);
 830         }
 831
 832         /*
 833          * filter.<name>.smudge and filter.<name>.clean specifies
 834          * the command line:
 835          *
 836          *      command-line
 837          *
 838          * The command-line will not be interpolated in any way.
 839          */
 840
 841         if (!strcmp("smudge", key))
 842                 return git_config_string(&drv->smudge, var, value);
 843
 844         if (!strcmp("clean", key))
 845                 return git_config_string(&drv->clean, var, value);
 846
 847         if (!strcmp("process", key))
 848                 return git_config_string(&drv->process, var, value);
 849
 850         if (!strcmp("required", key)) {
 851                 drv->required = git_config_bool(var, value);
 852                 return 0;
 853         }
 854
 855         return 0;
 856 }
 857
 858 static int count_ident(const char *cp, unsigned long size)
 859 {
 860         /*
 861          * "$Id: 0000000000000000000000000000000000000000 $" <=> "$Id$"
 862          */
 863         int cnt = 0;
 864         char ch;
 865
 866         while (size) {
 867                 ch = *cp++;
 868                 size--;
 869                 if (ch != '$')
 870                         continue;
 871                 if (size < 3)
 872                         break;
 873                 if (memcmp("Id", cp, 2))
 874                         continue;
 875                 ch = cp[2];
 876                 cp += 3;
 877                 size -= 3;
 878                 if (ch == '$')
 879                         cnt++; /* $Id$ */
 880                 if (ch != ':')
 881                         continue;
 882
 883                 /*
 884                  * "$Id: ... "; scan up to the closing dollar sign and discard.
 885                  */
 886                 while (size) {
 887                         ch = *cp++;
 888                         size--;
 889                         if (ch == '$') {
 890                                 cnt++;
 891                                 break;
 892                         }
 893                         if (ch == '\n')
 894                                 break;
 895                 }
 896         }
 897         return cnt;
 898 }
 899
 900 static int ident_to_git(const char *path, const char *src, size_t len,
 901                         struct strbuf *buf, int ident)
 902 {
 903         char *dst, *dollar;
 904
 905         if (!ident || (src && !count_ident(src, len)))
 906                 return 0;
 907
 908         if (!buf)
 909                 return 1;
 910
 911         /* only grow if not in place */
 912         if (strbuf_avail(buf) + buf->len < len)
 913                 strbuf_grow(buf, len - buf->len);
 914         dst = buf->buf;
 915         for (;;) {
 916                 dollar = memchr(src, '$', len);
 917                 if (!dollar)
 918                         break;
 919                 memmove(dst, src, dollar + 1 - src);
 920                 dst += dollar + 1 - src;
 921                 len -= dollar + 1 - src;
 922                 src  = dollar + 1;
 923
 924                 if (len > 3 && !memcmp(src, "Id:", 3)) {
 925                         dollar = memchr(src + 3, '$', len - 3);
 926                         if (!dollar)
 927                                 break;
 928                         if (memchr(src + 3, '\n', dollar - src - 3)) {
 929                                 /* Line break before the next dollar. */
 930                                 continue;
 931                         }
 932
 933                         memcpy(dst, "Id$", 3);
 934                         dst += 3;
 935                         len -= dollar + 1 - src;
 936                         src  = dollar + 1;
 937                 }
 938         }
 939         memmove(dst, src, len);
 940         strbuf_setlen(buf, dst + len - buf->buf);
 941         return 1;
 942 }
 943
 944 static int ident_to_worktree(const char *path, const char *src, size_t len,
 945                              struct strbuf *buf, int ident)
 946 {
 947         unsigned char sha1[20];
 948         char *to_free = NULL, *dollar, *spc;
 949         int cnt;
 950
 951         if (!ident)
 952                 return 0;
 953
 954         cnt = count_ident(src, len);
 955         if (!cnt)
 956                 return 0;
 957
 958         /* are we "faking" in place editing ? */
 959         if (src == buf->buf)
 960                 to_free = strbuf_detach(buf, NULL);
 961         hash_sha1_file(src, len, "blob", sha1);
 962
 963         strbuf_grow(buf, len + cnt * 43);
 964         for (;;) {
 965                 /* step 1: run to the next '$' */
 966                 dollar = memchr(src, '$', len);
 967                 if (!dollar)
 968                         break;
 969                 strbuf_add(buf, src, dollar + 1 - src);
 970                 len -= dollar + 1 - src;
 971                 src  = dollar + 1;
 972
 973                 /* step 2: does it looks like a bit like Id:xxx$ or Id$ ? */
 974                 if (len < 3 || memcmp("Id", src, 2))
 975                         continue;
 976
 977                 /* step 3: skip over Id$ or Id:xxxxx$ */
 978                 if (src[2] == '$') {
 979                         src += 3;
 980                         len -= 3;
 981                 } else if (src[2] == ':') {
 982                         /*
 983                          * It's possible that an expanded Id has crept its way into the
 984                          * repository, we cope with that by stripping the expansion out.
 985                          * This is probably not a good idea, since it will cause changes
 986                          * on checkout, which won't go away by stash, but let's keep it
 987                          * for git-style ids.
 988                          */
 989                         dollar = memchr(src + 3, '$', len - 3);
 990                         if (!dollar) {
 991                                 /* incomplete keyword, no more '$', so just quit the loop */
 992                                 break;
 993                         }
 994
 995                         if (memchr(src + 3, '\n', dollar - src - 3)) {
 996                                 /* Line break before the next dollar. */
 997                                 continue;
 998                         }
 999
1000                         spc = memchr(src + 4, ' ', dollar - src - 4);
1001                         if (spc && spc < dollar-1) {
1002                                 /* There are spaces in unexpected places.
1003                                  * This is probably an id from some other
1004                                  * versioning system. Keep it for now.
1005                                  */
1006                                 continue;
1007                         }
1008
1009                         len -= dollar + 1 - src;
1010                         src  = dollar + 1;
1011                 } else {
1012                         /* it wasn't a "Id$" or "Id:xxxx$" */
1013                         continue;
1014                 }
1015
1016                 /* step 4: substitute */
1017                 strbuf_addstr(buf, "Id: ");
1018                 strbuf_add(buf, sha1_to_hex(sha1), 40);
1019                 strbuf_addstr(buf, " $");
1020         }
1021         strbuf_add(buf, src, len);
1022
1023         free(to_free);
1024         return 1;
1025 }
1026
1027 static enum crlf_action git_path_check_crlf(struct attr_check_item *check)
1028 {
1029         const char *value = check->value;
1030
1031         if (ATTR_TRUE(value))
1032                 return CRLF_TEXT;
1033         else if (ATTR_FALSE(value))
1034                 return CRLF_BINARY;
1035         else if (ATTR_UNSET(value))
1036                 ;
1037         else if (!strcmp(value, "input"))
1038                 return CRLF_TEXT_INPUT;
1039         else if (!strcmp(value, "auto"))
1040                 return CRLF_AUTO;
1041         return CRLF_UNDEFINED;
1042 }
1043
1044 static enum eol git_path_check_eol(struct attr_check_item *check)
1045 {
1046         const char *value = check->value;
1047
1048         if (ATTR_UNSET(value))
1049                 ;
1050         else if (!strcmp(value, "lf"))
1051                 return EOL_LF;
1052         else if (!strcmp(value, "crlf"))
1053                 return EOL_CRLF;
1054         return EOL_UNSET;
1055 }
1056
1057 static struct convert_driver *git_path_check_convert(struct attr_check_item *check)
1058 {
1059         const char *value = check->value;
1060         struct convert_driver *drv;
1061
1062         if (ATTR_TRUE(value) || ATTR_FALSE(value) || ATTR_UNSET(value))
1063                 return NULL;
1064         for (drv = user_convert; drv; drv = drv->next)
1065                 if (!strcmp(value, drv->name))
1066                         return drv;
1067         return NULL;
1068 }
1069
1070 static int git_path_check_ident(struct attr_check_item *check)
1071 {
1072         const char *value = check->value;
1073
1074         return !!ATTR_TRUE(value);
1075 }
1076
1077 struct conv_attrs {
1078         struct convert_driver *drv;
1079         enum crlf_action attr_action; /* What attr says */
1080         enum crlf_action crlf_action; /* When no attr is set, use core.autocrlf */
1081         int ident;
1082 };
1083
1084 static void convert_attrs(struct conv_attrs *ca, const char *path)
1085 {
1086         static struct attr_check *check;
1087
1088         if (!check) {
1089                 check = attr_check_initl("crlf", "ident", "filter",
1090                                          "eol", "text", NULL);
1091                 user_convert_tail = &user_convert;
1092                 git_config(read_convert_config, NULL);
1093         }
1094
1095         if (!git_check_attr(path, check)) {
1096                 struct attr_check_item *ccheck = check->items;
1097                 ca->crlf_action = git_path_check_crlf(ccheck + 4);
1098                 if (ca->crlf_action == CRLF_UNDEFINED)
1099                         ca->crlf_action = git_path_check_crlf(ccheck + 0);
1100                 ca->attr_action = ca->crlf_action;
1101                 ca->ident = git_path_check_ident(ccheck + 1);
1102                 ca->drv = git_path_check_convert(ccheck + 2);
1103                 if (ca->crlf_action != CRLF_BINARY) {
1104                         enum eol eol_attr = git_path_check_eol(ccheck + 3);
1105                         if (ca->crlf_action == CRLF_AUTO && eol_attr == EOL_LF)
1106                                 ca->crlf_action = CRLF_AUTO_INPUT;
1107                         else if (ca->crlf_action == CRLF_AUTO && eol_attr == EOL_CRLF)
1108                                 ca->crlf_action = CRLF_AUTO_CRLF;
1109                         else if (eol_attr == EOL_LF)
1110                                 ca->crlf_action = CRLF_TEXT_INPUT;
1111                         else if (eol_attr == EOL_CRLF)
1112                                 ca->crlf_action = CRLF_TEXT_CRLF;
1113                 }
1114                 ca->attr_action = ca->crlf_action;
1115         } else {
1116                 ca->drv = NULL;
1117                 ca->crlf_action = CRLF_UNDEFINED;
1118                 ca->ident = 0;
1119         }
1120         if (ca->crlf_action == CRLF_TEXT)
1121                 ca->crlf_action = text_eol_is_crlf() ? CRLF_TEXT_CRLF : CRLF_TEXT_INPUT;
1122         if (ca->crlf_action == CRLF_UNDEFINED && auto_crlf == AUTO_CRLF_FALSE)
1123                 ca->crlf_action = CRLF_BINARY;
1124         if (ca->crlf_action == CRLF_UNDEFINED && auto_crlf == AUTO_CRLF_TRUE)
1125                 ca->crlf_action = CRLF_AUTO_CRLF;
1126         if (ca->crlf_action == CRLF_UNDEFINED && auto_crlf == AUTO_CRLF_INPUT)
1127                 ca->crlf_action = CRLF_AUTO_INPUT;
1128 }
1129
1130 int would_convert_to_git_filter_fd(const char *path)
1131 {
1132         struct conv_attrs ca;
1133
1134         convert_attrs(&ca, path);
1135         if (!ca.drv)
1136                 return 0;
1137
1138         /*
1139          * Apply a filter to an fd only if the filter is required to succeed.
1140          * We must die if the filter fails, because the original data before
1141          * filtering is not available.
1142          */
1143         if (!ca.drv->required)
1144                 return 0;
1145
1146         return apply_filter(path, NULL, 0, -1, NULL, ca.drv, CAP_CLEAN);
1147 }
1148
1149 const char *get_convert_attr_ascii(const char *path)
1150 {
1151         struct conv_attrs ca;
1152
1153         convert_attrs(&ca, path);
1154         switch (ca.attr_action) {
1155         case CRLF_UNDEFINED:
1156                 return "";
1157         case CRLF_BINARY:
1158                 return "-text";
1159         case CRLF_TEXT:
1160                 return "text";
1161         case CRLF_TEXT_INPUT:
1162                 return "text eol=lf";
1163         case CRLF_TEXT_CRLF:
1164                 return "text eol=crlf";
1165         case CRLF_AUTO:
1166                 return "text=auto";
1167         case CRLF_AUTO_CRLF:
1168                 return "text=auto eol=crlf";
1169         case CRLF_AUTO_INPUT:
1170                 return "text=auto eol=lf";
1171         }
1172         return "";
1173 }
1174
1175 int convert_to_git(const char *path, const char *src, size_t len,
1176                    struct strbuf *dst, enum safe_crlf checksafe)
1177 {
1178         int ret = 0;
1179         struct conv_attrs ca;
1180
1181         convert_attrs(&ca, path);
1182
1183         ret |= apply_filter(path, src, len, -1, dst, ca.drv, CAP_CLEAN);
1184         if (!ret && ca.drv && ca.drv->required)
1185                 die("%s: clean filter '%s' failed", path, ca.drv->name);
1186
1187         if (ret && dst) {
1188                 src = dst->buf;
1189                 len = dst->len;
1190         }
1191         ret |= crlf_to_git(path, src, len, dst, ca.crlf_action, checksafe);
1192         if (ret && dst) {
1193                 src = dst->buf;
1194                 len = dst->len;
1195         }
1196         return ret | ident_to_git(path, src, len, dst, ca.ident);
1197 }
1198
1199 void convert_to_git_filter_fd(const char *path, int fd, struct strbuf *dst,
1200                               enum safe_crlf checksafe)
1201 {
1202         struct conv_attrs ca;
1203         convert_attrs(&ca, path);
1204
1205         assert(ca.drv);
1206         assert(ca.drv->clean || ca.drv->process);
1207
1208         if (!apply_filter(path, NULL, 0, fd, dst, ca.drv, CAP_CLEAN))
1209                 die("%s: clean filter '%s' failed", path, ca.drv->name);
1210
1211         crlf_to_git(path, dst->buf, dst->len, dst, ca.crlf_action, checksafe);
1212         ident_to_git(path, dst->buf, dst->len, dst, ca.ident);
1213 }
1214
1215 static int convert_to_working_tree_internal(const char *path, const char *src,
1216                                             size_t len, struct strbuf *dst,
1217                                             int normalizing)
1218 {
1219         int ret = 0, ret_filter = 0;
1220         struct conv_attrs ca;
1221
1222         convert_attrs(&ca, path);
1223
1224         ret |= ident_to_worktree(path, src, len, dst, ca.ident);
1225         if (ret) {
1226                 src = dst->buf;
1227                 len = dst->len;
1228         }
1229         /*
1230          * CRLF conversion can be skipped if normalizing, unless there
1231          * is a smudge or process filter (even if the process filter doesn't
1232          * support smudge).  The filters might expect CRLFs.
1233          */
1234         if ((ca.drv && (ca.drv->smudge || ca.drv->process)) || !normalizing) {
1235                 ret |= crlf_to_worktree(path, src, len, dst, ca.crlf_action);
1236                 if (ret) {
1237                         src = dst->buf;
1238                         len = dst->len;
1239                 }
1240         }
1241
1242         ret_filter = apply_filter(path, src, len, -1, dst, ca.drv, CAP_SMUDGE);
1243         if (!ret_filter && ca.drv && ca.drv->required)
1244                 die("%s: smudge filter %s failed", path, ca.drv->name);
1245
1246         return ret | ret_filter;
1247 }
1248
1249 int convert_to_working_tree(const char *path, const char *src, size_t len, struct strbuf *dst)
1250 {
1251         return convert_to_working_tree_internal(path, src, len, dst, 0);
1252 }
1253
1254 int renormalize_buffer(const char *path, const char *src, size_t len, struct strbuf *dst)
1255 {
1256         int ret = convert_to_working_tree_internal(path, src, len, dst, 1);
1257         if (ret) {
1258                 src = dst->buf;
1259                 len = dst->len;
1260         }
1261         return ret | convert_to_git(path, src, len, dst, SAFE_CRLF_RENORMALIZE);
1262 }
1263
1264 /*****************************************************************
1265  *
1266  * Streaming conversion support
1267  *
1268  *****************************************************************/
1269
1270 typedef int (*filter_fn)(struct stream_filter *,
1271                          const char *input, size_t *isize_p,
1272                          char *output, size_t *osize_p);
1273 typedef void (*free_fn)(struct stream_filter *);
1274
1275 struct stream_filter_vtbl {
1276         filter_fn filter;
1277         free_fn free;
1278 };
1279
1280 struct stream_filter {
1281         struct stream_filter_vtbl *vtbl;
1282 };
1283
1284 static int null_filter_fn(struct stream_filter *filter,
1285                           const char *input, size_t *isize_p,
1286                           char *output, size_t *osize_p)
1287 {
1288         size_t count;
1289
1290         if (!input)
1291                 return 0; /* we do not keep any states */
1292         count = *isize_p;
1293         if (*osize_p < count)
1294                 count = *osize_p;
1295         if (count) {
1296                 memmove(output, input, count);
1297                 *isize_p -= count;
1298                 *osize_p -= count;
1299         }
1300         return 0;
1301 }
1302
1303 static void null_free_fn(struct stream_filter *filter)
1304 {
1305         ; /* nothing -- null instances are shared */
1306 }
1307
1308 static struct stream_filter_vtbl null_vtbl = {
1309         null_filter_fn,
1310         null_free_fn,
1311 };
1312
1313 static struct stream_filter null_filter_singleton = {
1314         &null_vtbl,
1315 };
1316
1317 int is_null_stream_filter(struct stream_filter *filter)
1318 {
1319         return filter == &null_filter_singleton;
1320 }
1321
1322
1323 /*
1324  * LF-to-CRLF filter
1325  */
1326
1327 struct lf_to_crlf_filter {
1328         struct stream_filter filter;
1329         unsigned has_held:1;
1330         char held;
1331 };
1332
1333 static int lf_to_crlf_filter_fn(struct stream_filter *filter,
1334                                 const char *input, size_t *isize_p,
1335                                 char *output, size_t *osize_p)
1336 {
1337         size_t count, o = 0;
1338         struct lf_to_crlf_filter *lf_to_crlf = (struct lf_to_crlf_filter *)filter;
1339
1340         /*
1341          * We may be holding onto the CR to see if it is followed by a
1342          * LF, in which case we would need to go to the main loop.
1343          * Otherwise, just emit it to the output stream.
1344          */
1345         if (lf_to_crlf->has_held && (lf_to_crlf->held != '\r' || !input)) {
1346                 output[o++] = lf_to_crlf->held;
1347                 lf_to_crlf->has_held = 0;
1348         }
1349
1350         /* We are told to drain */
1351         if (!input) {
1352                 *osize_p -= o;
1353                 return 0;
1354         }
1355
1356         count = *isize_p;
1357         if (count || lf_to_crlf->has_held) {
1358                 size_t i;
1359                 int was_cr = 0;
1360
1361                 if (lf_to_crlf->has_held) {
1362                         was_cr = 1;
1363                         lf_to_crlf->has_held = 0;
1364                 }
1365
1366                 for (i = 0; o < *osize_p && i < count; i++) {
1367                         char ch = input[i];
1368
1369                         if (ch == '\n') {
1370                                 output[o++] = '\r';
1371                         } else if (was_cr) {
1372                                 /*
1373                                  * Previous round saw CR and it is not followed
1374                                  * by a LF; emit the CR before processing the
1375                                  * current character.
1376                                  */
1377                                 output[o++] = '\r';
1378                         }
1379
1380                         /*
1381                          * We may have consumed the last output slot,
1382                          * in which case we need to break out of this
1383                          * loop; hold the current character before
1384                          * returning.
1385                          */
1386                         if (*osize_p <= o) {
1387                                 lf_to_crlf->has_held = 1;
1388                                 lf_to_crlf->held = ch;
1389                                 continue; /* break but increment i */
1390                         }
1391
1392                         if (ch == '\r') {
1393                                 was_cr = 1;
1394                                 continue;
1395                         }
1396
1397                         was_cr = 0;
1398                         output[o++] = ch;
1399                 }
1400
1401                 *osize_p -= o;
1402                 *isize_p -= i;
1403
1404                 if (!lf_to_crlf->has_held && was_cr) {
1405                         lf_to_crlf->has_held = 1;
1406                         lf_to_crlf->held = '\r';
1407                 }
1408         }
1409         return 0;
1410 }
1411
1412 static void lf_to_crlf_free_fn(struct stream_filter *filter)
1413 {
1414         free(filter);
1415 }
1416
1417 static struct stream_filter_vtbl lf_to_crlf_vtbl = {
1418         lf_to_crlf_filter_fn,
1419         lf_to_crlf_free_fn,
1420 };
1421
1422 static struct stream_filter *lf_to_crlf_filter(void)
1423 {
1424         struct lf_to_crlf_filter *lf_to_crlf = xcalloc(1, sizeof(*lf_to_crlf));
1425
1426         lf_to_crlf->filter.vtbl = &lf_to_crlf_vtbl;
1427         return (struct stream_filter *)lf_to_crlf;
1428 }
1429
1430 /*
1431  * Cascade filter
1432  */
1433 #define FILTER_BUFFER 1024
1434 struct cascade_filter {
1435         struct stream_filter filter;
1436         struct stream_filter *one;
1437         struct stream_filter *two;
1438         char buf[FILTER_BUFFER];
1439         int end, ptr;
1440 };
1441
1442 static int cascade_filter_fn(struct stream_filter *filter,
1443                              const char *input, size_t *isize_p,
1444                              char *output, size_t *osize_p)
1445 {
1446         struct cascade_filter *cas = (struct cascade_filter *) filter;
1447         size_t filled = 0;
1448         size_t sz = *osize_p;
1449         size_t to_feed, remaining;
1450
1451         /*
1452          * input -- (one) --> buf -- (two) --> output
1453          */
1454         while (filled < sz) {
1455                 remaining = sz - filled;
1456
1457                 /* do we already have something to feed two with? */
1458                 if (cas->ptr < cas->end) {
1459                         to_feed = cas->end - cas->ptr;
1460                         if (stream_filter(cas->two,
1461                                           cas->buf + cas->ptr, &to_feed,
1462                                           output + filled, &remaining))
1463                                 return -1;
1464                         cas->ptr += (cas->end - cas->ptr) - to_feed;
1465                         filled = sz - remaining;
1466                         continue;
1467                 }
1468
1469                 /* feed one from upstream and have it emit into our buffer */
1470                 to_feed = input ? *isize_p : 0;
1471                 if (input && !to_feed)
1472                         break;
1473                 remaining = sizeof(cas->buf);
1474                 if (stream_filter(cas->one,
1475                                   input, &to_feed,
1476                                   cas->buf, &remaining))
1477                         return -1;
1478                 cas->end = sizeof(cas->buf) - remaining;
1479                 cas->ptr = 0;
1480                 if (input) {
1481                         size_t fed = *isize_p - to_feed;
1482                         *isize_p -= fed;
1483                         input += fed;
1484                 }
1485
1486                 /* do we know that we drained one completely? */
1487                 if (input || cas->end)
1488                         continue;
1489
1490                 /* tell two to drain; we have nothing more to give it */
1491                 to_feed = 0;
1492                 remaining = sz - filled;
1493                 if (stream_filter(cas->two,
1494                                   NULL, &to_feed,
1495                                   output + filled, &remaining))
1496                         return -1;
1497                 if (remaining == (sz - filled))
1498                         break; /* completely drained two */
1499                 filled = sz - remaining;
1500         }
1501         *osize_p -= filled;
1502         return 0;
1503 }
1504
1505 static void cascade_free_fn(struct stream_filter *filter)
1506 {
1507         struct cascade_filter *cas = (struct cascade_filter *)filter;
1508         free_stream_filter(cas->one);
1509         free_stream_filter(cas->two);
1510         free(filter);
1511 }
1512
1513 static struct stream_filter_vtbl cascade_vtbl = {
1514         cascade_filter_fn,
1515         cascade_free_fn,
1516 };
1517
1518 static struct stream_filter *cascade_filter(struct stream_filter *one,
1519                                             struct stream_filter *two)
1520 {
1521         struct cascade_filter *cascade;
1522
1523         if (!one || is_null_stream_filter(one))
1524                 return two;
1525         if (!two || is_null_stream_filter(two))
1526                 return one;
1527
1528         cascade = xmalloc(sizeof(*cascade));
1529         cascade->one = one;
1530         cascade->two = two;
1531         cascade->end = cascade->ptr = 0;
1532         cascade->filter.vtbl = &cascade_vtbl;
1533         return (struct stream_filter *)cascade;
1534 }
1535
1536 /*
1537  * ident filter
1538  */
1539 #define IDENT_DRAINING (-1)
1540 #define IDENT_SKIPPING (-2)
1541 struct ident_filter {
1542         struct stream_filter filter;
1543         struct strbuf left;
1544         int state;
1545         char ident[45]; /* ": x40 $" */
1546 };
1547
1548 static int is_foreign_ident(const char *str)
1549 {
1550         int i;
1551
1552         if (!skip_prefix(str, "$Id: ", &str))
1553                 return 0;
1554         for (i = 0; str[i]; i++) {
1555                 if (isspace(str[i]) && str[i+1] != '$')
1556                         return 1;
1557         }
1558         return 0;
1559 }
1560
1561 static void ident_drain(struct ident_filter *ident, char **output_p, size_t *osize_p)
1562 {
1563         size_t to_drain = ident->left.len;
1564
1565         if (*osize_p < to_drain)
1566                 to_drain = *osize_p;
1567         if (to_drain) {
1568                 memcpy(*output_p, ident->left.buf, to_drain);
1569                 strbuf_remove(&ident->left, 0, to_drain);
1570                 *output_p += to_drain;
1571                 *osize_p -= to_drain;
1572         }
1573         if (!ident->left.len)
1574                 ident->state = 0;
1575 }
1576
1577 static int ident_filter_fn(struct stream_filter *filter,
1578                            const char *input, size_t *isize_p,
1579                            char *output, size_t *osize_p)
1580 {
1581         struct ident_filter *ident = (struct ident_filter *)filter;
1582         static const char head[] = "$Id";
1583
1584         if (!input) {
1585                 /* drain upon eof */
1586                 switch (ident->state) {
1587                 default:
1588                         strbuf_add(&ident->left, head, ident->state);
1589                 case IDENT_SKIPPING:
1590                         /* fallthru */
1591                 case IDENT_DRAINING:
1592                         ident_drain(ident, &output, osize_p);
1593                 }
1594                 return 0;
1595         }
1596
1597         while (*isize_p || (ident->state == IDENT_DRAINING)) {
1598                 int ch;
1599
1600                 if (ident->state == IDENT_DRAINING) {
1601                         ident_drain(ident, &output, osize_p);
1602                         if (!*osize_p)
1603                                 break;
1604                         continue;
1605                 }
1606
1607                 ch = *(input++);
1608                 (*isize_p)--;
1609
1610                 if (ident->state == IDENT_SKIPPING) {
1611                         /*
1612                          * Skipping until '$' or LF, but keeping them
1613                          * in case it is a foreign ident.
1614                          */
1615                         strbuf_addch(&ident->left, ch);
1616                         if (ch != '\n' && ch != '$')
1617                                 continue;
1618                         if (ch == '$' && !is_foreign_ident(ident->left.buf)) {
1619                                 strbuf_setlen(&ident->left, sizeof(head) - 1);
1620                                 strbuf_addstr(&ident->left, ident->ident);
1621                         }
1622                         ident->state = IDENT_DRAINING;
1623                         continue;
1624                 }
1625
1626                 if (ident->state < sizeof(head) &&
1627                     head[ident->state] == ch) {
1628                         ident->state++;
1629                         continue;
1630                 }
1631
1632                 if (ident->state)
1633                         strbuf_add(&ident->left, head, ident->state);
1634                 if (ident->state == sizeof(head) - 1) {
1635                         if (ch != ':' && ch != '$') {
1636                                 strbuf_addch(&ident->left, ch);
1637                                 ident->state = 0;
1638                                 continue;
1639                         }
1640
1641                         if (ch == ':') {
1642                                 strbuf_addch(&ident->left, ch);
1643                                 ident->state = IDENT_SKIPPING;
1644                         } else {
1645                                 strbuf_addstr(&ident->left, ident->ident);
1646                                 ident->state = IDENT_DRAINING;
1647                         }
1648                         continue;
1649                 }
1650
1651                 strbuf_addch(&ident->left, ch);
1652                 ident->state = IDENT_DRAINING;
1653         }
1654         return 0;
1655 }
1656
1657 static void ident_free_fn(struct stream_filter *filter)
1658 {
1659         struct ident_filter *ident = (struct ident_filter *)filter;
1660         strbuf_release(&ident->left);
1661         free(filter);
1662 }
1663
1664 static struct stream_filter_vtbl ident_vtbl = {
1665         ident_filter_fn,
1666         ident_free_fn,
1667 };
1668
1669 static struct stream_filter *ident_filter(const unsigned char *sha1)
1670 {
1671         struct ident_filter *ident = xmalloc(sizeof(*ident));
1672
1673         xsnprintf(ident->ident, sizeof(ident->ident),
1674                   ": %s $", sha1_to_hex(sha1));
1675         strbuf_init(&ident->left, 0);
1676         ident->filter.vtbl = &ident_vtbl;
1677         ident->state = 0;
1678         return (struct stream_filter *)ident;
1679 }
1680
1681 /*
1682  * Return an appropriately constructed filter for the path, or NULL if
1683  * the contents cannot be filtered without reading the whole thing
1684  * in-core.
1685  *
1686  * Note that you would be crazy to set CRLF, smuge/clean or ident to a
1687  * large binary blob you would want us not to slurp into the memory!
1688  */
1689 struct stream_filter *get_stream_filter(const char *path, const unsigned char *sha1)
1690 {
1691         struct conv_attrs ca;
1692         struct stream_filter *filter = NULL;
1693
1694         convert_attrs(&ca, path);
1695         if (ca.drv && (ca.drv->process || ca.drv->smudge || ca.drv->clean))
1696                 return NULL;
1697
1698         if (ca.crlf_action == CRLF_AUTO || ca.crlf_action == CRLF_AUTO_CRLF)
1699                 return NULL;
1700
1701         if (ca.ident)
1702                 filter = ident_filter(sha1);
1703
1704         if (output_eol(ca.crlf_action) == EOL_CRLF)
1705                 filter = cascade_filter(filter, lf_to_crlf_filter());
1706         else
1707                 filter = cascade_filter(filter, &null_filter_singleton);
1708
1709         return filter;
1710 }
1711
1712 void free_stream_filter(struct stream_filter *filter)
1713 {
1714         filter->vtbl->free(filter);
1715 }
1716
1717 int stream_filter(struct stream_filter *filter,
1718                   const char *input, size_t *isize_p,
1719                   char *output, size_t *osize_p)
1720 {
1721         return filter->vtbl->filter(filter, input, isize_p, output, osize_p);
1722 }