convert.c

   1 #include "cache.h"
   2 #include "attr.h"
   3 #include "run-command.h"
   4 #include "quote.h"
   5 #include "sigchain.h"
   6
   7 /*
   8  * convert.c - convert a file when checking it out and checking it in.
   9  *
  10  * This should use the pathname to decide on whether it wants to do some
  11  * more interesting conversions (automatic gzip/unzip, general format
  12  * conversions etc etc), but by default it just does automatic CRLF<->LF
  13  * translation when the "text" attribute or "auto_crlf" option is set.
  14  */
  15
  16 enum crlf_action {
  17         CRLF_GUESS = -1,
  18         CRLF_BINARY = 0,
  19         CRLF_TEXT,
  20         CRLF_INPUT,
  21         CRLF_CRLF,
  22         CRLF_AUTO
  23 };
  24
  25 struct text_stat {
  26         /* NUL, CR, LF and CRLF counts */
  27         unsigned nul, cr, lf, crlf;
  28
  29         /* These are just approximations! */
  30         unsigned printable, nonprintable;
  31 };
  32
  33 static void gather_stats(const char *buf, unsigned long size, struct text_stat *stats)
  34 {
  35         unsigned long i;
  36
  37         memset(stats, 0, sizeof(*stats));
  38
  39         for (i = 0; i < size; i++) {
  40                 unsigned char c = buf[i];
  41                 if (c == '\r') {
  42                         stats->cr++;
  43                         if (i+1 < size && buf[i+1] == '\n')
  44                                 stats->crlf++;
  45                         continue;
  46                 }
  47                 if (c == '\n') {
  48                         stats->lf++;
  49                         continue;
  50                 }
  51                 if (c == 127)
  52                         /* DEL */
  53                         stats->nonprintable++;
  54                 else if (c < 32) {
  55                         switch (c) {
  56                                 /* BS, HT, ESC and FF */
  57                         case '\b': case '\t': case '\033': case '\014':
  58                                 stats->printable++;
  59                                 break;
  60                         case 0:
  61                                 stats->nul++;
  62                                 /* fall through */
  63                         default:
  64                                 stats->nonprintable++;
  65                         }
  66                 }
  67                 else
  68                         stats->printable++;
  69         }
  70
  71         /* If file ends with EOF then don't count this EOF as non-printable. */
  72         if (size >= 1 && buf[size-1] == '\032')
  73                 stats->nonprintable--;
  74 }
  75
  76 /*
  77  * The same heuristics as diff.c::mmfile_is_binary()
  78  */
  79 static int is_binary(unsigned long size, struct text_stat *stats)
  80 {
  81
  82         if (stats->nul)
  83                 return 1;
  84         if ((stats->printable >> 7) < stats->nonprintable)
  85                 return 1;
  86         /*
  87          * Other heuristics? Average line length might be relevant,
  88          * as might LF vs CR vs CRLF counts..
  89          *
  90          * NOTE! It might be normal to have a low ratio of CRLF to LF
  91          * (somebody starts with a LF-only file and edits it with an editor
  92          * that adds CRLF only to lines that are added..). But do  we
  93          * want to support CR-only? Probably not.
  94          */
  95         return 0;
  96 }
  97
  98 static enum eol output_eol(enum crlf_action crlf_action)
  99 {
 100         switch (crlf_action) {
 101         case CRLF_BINARY:
 102                 return EOL_UNSET;
 103         case CRLF_CRLF:
 104                 return EOL_CRLF;
 105         case CRLF_INPUT:
 106                 return EOL_LF;
 107         case CRLF_GUESS:
 108                 if (!auto_crlf)
 109                         return EOL_UNSET;
 110                 /* fall through */
 111         case CRLF_TEXT:
 112         case CRLF_AUTO:
 113                 if (auto_crlf == AUTO_CRLF_TRUE)
 114                         return EOL_CRLF;
 115                 else if (auto_crlf == AUTO_CRLF_INPUT)
 116                         return EOL_LF;
 117                 else if (core_eol == EOL_UNSET)
 118                         return EOL_NATIVE;
 119         }
 120         return core_eol;
 121 }
 122
 123 static void check_safe_crlf(const char *path, enum crlf_action crlf_action,
 124                             struct text_stat *stats, enum safe_crlf checksafe)
 125 {
 126         if (!checksafe)
 127                 return;
 128
 129         if (output_eol(crlf_action) == EOL_LF) {
 130                 /*
 131                  * CRLFs would not be restored by checkout:
 132                  * check if we'd remove CRLFs
 133                  */
 134                 if (stats->crlf) {
 135                         if (checksafe == SAFE_CRLF_WARN)
 136                                 warning("CRLF will be replaced by LF in %s.\nThe file will have its original line endings in your working directory.", path);
 137                         else /* i.e. SAFE_CRLF_FAIL */
 138                                 die("CRLF would be replaced by LF in %s.", path);
 139                 }
 140         } else if (output_eol(crlf_action) == EOL_CRLF) {
 141                 /*
 142                  * CRLFs would be added by checkout:
 143                  * check if we have "naked" LFs
 144                  */
 145                 if (stats->lf != stats->crlf) {
 146                         if (checksafe == SAFE_CRLF_WARN)
 147                                 warning("LF will be replaced by CRLF in %s.\nThe file will have its original line endings in your working directory.", path);
 148                         else /* i.e. SAFE_CRLF_FAIL */
 149                                 die("LF would be replaced by CRLF in %s", path);
 150                 }
 151         }
 152 }
 153
 154 static int has_cr_in_index(const char *path)
 155 {
 156         unsigned long sz;
 157         void *data;
 158         int has_cr;
 159
 160         data = read_blob_data_from_cache(path, &sz);
 161         if (!data)
 162                 return 0;
 163         has_cr = memchr(data, '\r', sz) != NULL;
 164         free(data);
 165         return has_cr;
 166 }
 167
 168 static int crlf_to_git(const char *path, const char *src, size_t len,
 169                        struct strbuf *buf,
 170                        enum crlf_action crlf_action, enum safe_crlf checksafe)
 171 {
 172         struct text_stat stats;
 173         char *dst;
 174
 175         if (crlf_action == CRLF_BINARY ||
 176             (crlf_action == CRLF_GUESS && auto_crlf == AUTO_CRLF_FALSE) ||
 177             (src && !len))
 178                 return 0;
 179
 180         /*
 181          * If we are doing a dry-run and have no source buffer, there is
 182          * nothing to analyze; we must assume we would convert.
 183          */
 184         if (!buf && !src)
 185                 return 1;
 186
 187         gather_stats(src, len, &stats);
 188
 189         if (crlf_action == CRLF_AUTO || crlf_action == CRLF_GUESS) {
 190                 /*
 191                  * We're currently not going to even try to convert stuff
 192                  * that has bare CR characters. Does anybody do that crazy
 193                  * stuff?
 194                  */
 195                 if (stats.cr != stats.crlf)
 196                         return 0;
 197
 198                 /*
 199                  * And add some heuristics for binary vs text, of course...
 200                  */
 201                 if (is_binary(len, &stats))
 202                         return 0;
 203
 204                 if (crlf_action == CRLF_GUESS) {
 205                         /*
 206                          * If the file in the index has any CR in it, do not convert.
 207                          * This is the new safer autocrlf handling.
 208                          */
 209                         if (has_cr_in_index(path))
 210                                 return 0;
 211                 }
 212         }
 213
 214         check_safe_crlf(path, crlf_action, &stats, checksafe);
 215
 216         /* Optimization: No CR? Nothing to convert, regardless. */
 217         if (!stats.cr)
 218                 return 0;
 219
 220         /*
 221          * At this point all of our source analysis is done, and we are sure we
 222          * would convert. If we are in dry-run mode, we can give an answer.
 223          */
 224         if (!buf)
 225                 return 1;
 226
 227         /* only grow if not in place */
 228         if (strbuf_avail(buf) + buf->len < len)
 229                 strbuf_grow(buf, len - buf->len);
 230         dst = buf->buf;
 231         if (crlf_action == CRLF_AUTO || crlf_action == CRLF_GUESS) {
 232                 /*
 233                  * If we guessed, we already know we rejected a file with
 234                  * lone CR, and we can strip a CR without looking at what
 235                  * follow it.
 236                  */
 237                 do {
 238                         unsigned char c = *src++;
 239                         if (c != '\r')
 240                                 *dst++ = c;
 241                 } while (--len);
 242         } else {
 243                 do {
 244                         unsigned char c = *src++;
 245                         if (! (c == '\r' && (1 < len && *src == '\n')))
 246                                 *dst++ = c;
 247                 } while (--len);
 248         }
 249         strbuf_setlen(buf, dst - buf->buf);
 250         return 1;
 251 }
 252
 253 static int crlf_to_worktree(const char *path, const char *src, size_t len,
 254                             struct strbuf *buf, enum crlf_action crlf_action)
 255 {
 256         char *to_free = NULL;
 257         struct text_stat stats;
 258
 259         if (!len || output_eol(crlf_action) != EOL_CRLF)
 260                 return 0;
 261
 262         gather_stats(src, len, &stats);
 263
 264         /* No LF? Nothing to convert, regardless. */
 265         if (!stats.lf)
 266                 return 0;
 267
 268         /* Was it already in CRLF format? */
 269         if (stats.lf == stats.crlf)
 270                 return 0;
 271
 272         if (crlf_action == CRLF_AUTO || crlf_action == CRLF_GUESS) {
 273                 if (crlf_action == CRLF_GUESS) {
 274                         /* If we have any CR or CRLF line endings, we do not touch it */
 275                         /* This is the new safer autocrlf-handling */
 276                         if (stats.cr > 0 || stats.crlf > 0)
 277                                 return 0;
 278                 }
 279
 280                 /* If we have any bare CR characters, we're not going to touch it */
 281                 if (stats.cr != stats.crlf)
 282                         return 0;
 283
 284                 if (is_binary(len, &stats))
 285                         return 0;
 286         }
 287
 288         /* are we "faking" in place editing ? */
 289         if (src == buf->buf)
 290                 to_free = strbuf_detach(buf, NULL);
 291
 292         strbuf_grow(buf, len + stats.lf - stats.crlf);
 293         for (;;) {
 294                 const char *nl = memchr(src, '\n', len);
 295                 if (!nl)
 296                         break;
 297                 if (nl > src && nl[-1] == '\r') {
 298                         strbuf_add(buf, src, nl + 1 - src);
 299                 } else {
 300                         strbuf_add(buf, src, nl - src);
 301                         strbuf_addstr(buf, "\r\n");
 302                 }
 303                 len -= nl + 1 - src;
 304                 src  = nl + 1;
 305         }
 306         strbuf_add(buf, src, len);
 307
 308         free(to_free);
 309         return 1;
 310 }
 311
 312 struct filter_params {
 313         const char *src;
 314         unsigned long size;
 315         const char *cmd;
 316         const char *path;
 317 };
 318
 319 static int filter_buffer(int in, int out, void *data)
 320 {
 321         /*
 322          * Spawn cmd and feed the buffer contents through its stdin.
 323          */
 324         struct child_process child_process;
 325         struct filter_params *params = (struct filter_params *)data;
 326         int write_err, status;
 327         const char *argv[] = { NULL, NULL };
 328
 329         /* apply % substitution to cmd */
 330         struct strbuf cmd = STRBUF_INIT;
 331         struct strbuf path = STRBUF_INIT;
 332         struct strbuf_expand_dict_entry dict[] = {
 333                 { "f", NULL, },
 334                 { NULL, NULL, },
 335         };
 336
 337         /* quote the path to preserve spaces, etc. */
 338         sq_quote_buf(&path, params->path);
 339         dict[0].value = path.buf;
 340
 341         /* expand all %f with the quoted path */
 342         strbuf_expand(&cmd, params->cmd, strbuf_expand_dict_cb, &dict);
 343         strbuf_release(&path);
 344
 345         argv[0] = cmd.buf;
 346
 347         memset(&child_process, 0, sizeof(child_process));
 348         child_process.argv = argv;
 349         child_process.use_shell = 1;
 350         child_process.in = -1;
 351         child_process.out = out;
 352
 353         if (start_command(&child_process))
 354                 return error("cannot fork to run external filter %s", params->cmd);
 355
 356         sigchain_push(SIGPIPE, SIG_IGN);
 357
 358         write_err = (write_in_full(child_process.in, params->src, params->size) < 0);
 359         if (close(child_process.in))
 360                 write_err = 1;
 361         if (write_err)
 362                 error("cannot feed the input to external filter %s", params->cmd);
 363
 364         sigchain_pop(SIGPIPE);
 365
 366         status = finish_command(&child_process);
 367         if (status)
 368                 error("external filter %s failed %d", params->cmd, status);
 369
 370         strbuf_release(&cmd);
 371         return (write_err || status);
 372 }
 373
 374 static int apply_filter(const char *path, const char *src, size_t len,
 375                         struct strbuf *dst, const char *cmd)
 376 {
 377         /*
 378          * Create a pipeline to have the command filter the buffer's
 379          * contents.
 380          *
 381          * (child --> cmd) --> us
 382          */
 383         int ret = 1;
 384         struct strbuf nbuf = STRBUF_INIT;
 385         struct async async;
 386         struct filter_params params;
 387
 388         if (!cmd)
 389                 return 0;
 390
 391         if (!dst)
 392                 return 1;
 393
 394         memset(&async, 0, sizeof(async));
 395         async.proc = filter_buffer;
 396         async.data = &params;
 397         async.out = -1;
 398         params.src = src;
 399         params.size = len;
 400         params.cmd = cmd;
 401         params.path = path;
 402
 403         fflush(NULL);
 404         if (start_async(&async))
 405                 return 0;       /* error was already reported */
 406
 407         if (strbuf_read(&nbuf, async.out, len) < 0) {
 408                 error("read from external filter %s failed", cmd);
 409                 ret = 0;
 410         }
 411         if (close(async.out)) {
 412                 error("read from external filter %s failed", cmd);
 413                 ret = 0;
 414         }
 415         if (finish_async(&async)) {
 416                 error("external filter %s failed", cmd);
 417                 ret = 0;
 418         }
 419
 420         if (ret) {
 421                 strbuf_swap(dst, &nbuf);
 422         }
 423         strbuf_release(&nbuf);
 424         return ret;
 425 }
 426
 427 static struct convert_driver {
 428         const char *name;
 429         struct convert_driver *next;
 430         const char *smudge;
 431         const char *clean;
 432         int required;
 433 } *user_convert, **user_convert_tail;
 434
 435 static int read_convert_config(const char *var, const char *value, void *cb)
 436 {
 437         const char *key, *name;
 438         int namelen;
 439         struct convert_driver *drv;
 440
 441         /*
 442          * External conversion drivers are configured using
 443          * "filter.<name>.variable".
 444          */
 445         if (parse_config_key(var, "filter", &name, &namelen, &key) < 0 || !name)
 446                 return 0;
 447         for (drv = user_convert; drv; drv = drv->next)
 448                 if (!strncmp(drv->name, name, namelen) && !drv->name[namelen])
 449                         break;
 450         if (!drv) {
 451                 drv = xcalloc(1, sizeof(struct convert_driver));
 452                 drv->name = xmemdupz(name, namelen);
 453                 *user_convert_tail = drv;
 454                 user_convert_tail = &(drv->next);
 455         }
 456
 457         /*
 458          * filter.<name>.smudge and filter.<name>.clean specifies
 459          * the command line:
 460          *
 461          *      command-line
 462          *
 463          * The command-line will not be interpolated in any way.
 464          */
 465
 466         if (!strcmp("smudge", key))
 467                 return git_config_string(&drv->smudge, var, value);
 468
 469         if (!strcmp("clean", key))
 470                 return git_config_string(&drv->clean, var, value);
 471
 472         if (!strcmp("required", key)) {
 473                 drv->required = git_config_bool(var, value);
 474                 return 0;
 475         }
 476
 477         return 0;
 478 }
 479
 480 static int count_ident(const char *cp, unsigned long size)
 481 {
 482         /*
 483          * "$Id: 0000000000000000000000000000000000000000 $" <=> "$Id$"
 484          */
 485         int cnt = 0;
 486         char ch;
 487
 488         while (size) {
 489                 ch = *cp++;
 490                 size--;
 491                 if (ch != '$')
 492                         continue;
 493                 if (size < 3)
 494                         break;
 495                 if (memcmp("Id", cp, 2))
 496                         continue;
 497                 ch = cp[2];
 498                 cp += 3;
 499                 size -= 3;
 500                 if (ch == '$')
 501                         cnt++; /* $Id$ */
 502                 if (ch != ':')
 503                         continue;
 504
 505                 /*
 506                  * "$Id: ... "; scan up to the closing dollar sign and discard.
 507                  */
 508                 while (size) {
 509                         ch = *cp++;
 510                         size--;
 511                         if (ch == '$') {
 512                                 cnt++;
 513                                 break;
 514                         }
 515                         if (ch == '\n')
 516                                 break;
 517                 }
 518         }
 519         return cnt;
 520 }
 521
 522 static int ident_to_git(const char *path, const char *src, size_t len,
 523                         struct strbuf *buf, int ident)
 524 {
 525         char *dst, *dollar;
 526
 527         if (!ident || (src && !count_ident(src, len)))
 528                 return 0;
 529
 530         if (!buf)
 531                 return 1;
 532
 533         /* only grow if not in place */
 534         if (strbuf_avail(buf) + buf->len < len)
 535                 strbuf_grow(buf, len - buf->len);
 536         dst = buf->buf;
 537         for (;;) {
 538                 dollar = memchr(src, '$', len);
 539                 if (!dollar)
 540                         break;
 541                 memmove(dst, src, dollar + 1 - src);
 542                 dst += dollar + 1 - src;
 543                 len -= dollar + 1 - src;
 544                 src  = dollar + 1;
 545
 546                 if (len > 3 && !memcmp(src, "Id:", 3)) {
 547                         dollar = memchr(src + 3, '$', len - 3);
 548                         if (!dollar)
 549                                 break;
 550                         if (memchr(src + 3, '\n', dollar - src - 3)) {
 551                                 /* Line break before the next dollar. */
 552                                 continue;
 553                         }
 554
 555                         memcpy(dst, "Id$", 3);
 556                         dst += 3;
 557                         len -= dollar + 1 - src;
 558                         src  = dollar + 1;
 559                 }
 560         }
 561         memmove(dst, src, len);
 562         strbuf_setlen(buf, dst + len - buf->buf);
 563         return 1;
 564 }
 565
 566 static int ident_to_worktree(const char *path, const char *src, size_t len,
 567                              struct strbuf *buf, int ident)
 568 {
 569         unsigned char sha1[20];
 570         char *to_free = NULL, *dollar, *spc;
 571         int cnt;
 572
 573         if (!ident)
 574                 return 0;
 575
 576         cnt = count_ident(src, len);
 577         if (!cnt)
 578                 return 0;
 579
 580         /* are we "faking" in place editing ? */
 581         if (src == buf->buf)
 582                 to_free = strbuf_detach(buf, NULL);
 583         hash_sha1_file(src, len, "blob", sha1);
 584
 585         strbuf_grow(buf, len + cnt * 43);
 586         for (;;) {
 587                 /* step 1: run to the next '$' */
 588                 dollar = memchr(src, '$', len);
 589                 if (!dollar)
 590                         break;
 591                 strbuf_add(buf, src, dollar + 1 - src);
 592                 len -= dollar + 1 - src;
 593                 src  = dollar + 1;
 594
 595                 /* step 2: does it looks like a bit like Id:xxx$ or Id$ ? */
 596                 if (len < 3 || memcmp("Id", src, 2))
 597                         continue;
 598
 599                 /* step 3: skip over Id$ or Id:xxxxx$ */
 600                 if (src[2] == '$') {
 601                         src += 3;
 602                         len -= 3;
 603                 } else if (src[2] == ':') {
 604                         /*
 605                          * It's possible that an expanded Id has crept its way into the
 606                          * repository, we cope with that by stripping the expansion out.
 607                          * This is probably not a good idea, since it will cause changes
 608                          * on checkout, which won't go away by stash, but let's keep it
 609                          * for git-style ids.
 610                          */
 611                         dollar = memchr(src + 3, '$', len - 3);
 612                         if (!dollar) {
 613                                 /* incomplete keyword, no more '$', so just quit the loop */
 614                                 break;
 615                         }
 616
 617                         if (memchr(src + 3, '\n', dollar - src - 3)) {
 618                                 /* Line break before the next dollar. */
 619                                 continue;
 620                         }
 621
 622                         spc = memchr(src + 4, ' ', dollar - src - 4);
 623                         if (spc && spc < dollar-1) {
 624                                 /* There are spaces in unexpected places.
 625                                  * This is probably an id from some other
 626                                  * versioning system. Keep it for now.
 627                                  */
 628                                 continue;
 629                         }
 630
 631                         len -= dollar + 1 - src;
 632                         src  = dollar + 1;
 633                 } else {
 634                         /* it wasn't a "Id$" or "Id:xxxx$" */
 635                         continue;
 636                 }
 637
 638                 /* step 4: substitute */
 639                 strbuf_addstr(buf, "Id: ");
 640                 strbuf_add(buf, sha1_to_hex(sha1), 40);
 641                 strbuf_addstr(buf, " $");
 642         }
 643         strbuf_add(buf, src, len);
 644
 645         free(to_free);
 646         return 1;
 647 }
 648
 649 static enum crlf_action git_path_check_crlf(const char *path, struct git_attr_check *check)
 650 {
 651         const char *value = check->value;
 652
 653         if (ATTR_TRUE(value))
 654                 return CRLF_TEXT;
 655         else if (ATTR_FALSE(value))
 656                 return CRLF_BINARY;
 657         else if (ATTR_UNSET(value))
 658                 ;
 659         else if (!strcmp(value, "input"))
 660                 return CRLF_INPUT;
 661         else if (!strcmp(value, "auto"))
 662                 return CRLF_AUTO;
 663         return CRLF_GUESS;
 664 }
 665
 666 static enum eol git_path_check_eol(const char *path, struct git_attr_check *check)
 667 {
 668         const char *value = check->value;
 669
 670         if (ATTR_UNSET(value))
 671                 ;
 672         else if (!strcmp(value, "lf"))
 673                 return EOL_LF;
 674         else if (!strcmp(value, "crlf"))
 675                 return EOL_CRLF;
 676         return EOL_UNSET;
 677 }
 678
 679 static struct convert_driver *git_path_check_convert(const char *path,
 680                                              struct git_attr_check *check)
 681 {
 682         const char *value = check->value;
 683         struct convert_driver *drv;
 684
 685         if (ATTR_TRUE(value) || ATTR_FALSE(value) || ATTR_UNSET(value))
 686                 return NULL;
 687         for (drv = user_convert; drv; drv = drv->next)
 688                 if (!strcmp(value, drv->name))
 689                         return drv;
 690         return NULL;
 691 }
 692
 693 static int git_path_check_ident(const char *path, struct git_attr_check *check)
 694 {
 695         const char *value = check->value;
 696
 697         return !!ATTR_TRUE(value);
 698 }
 699
 700 static enum crlf_action input_crlf_action(enum crlf_action text_attr, enum eol eol_attr)
 701 {
 702         if (text_attr == CRLF_BINARY)
 703                 return CRLF_BINARY;
 704         if (eol_attr == EOL_LF)
 705                 return CRLF_INPUT;
 706         if (eol_attr == EOL_CRLF)
 707                 return CRLF_CRLF;
 708         return text_attr;
 709 }
 710
 711 struct conv_attrs {
 712         struct convert_driver *drv;
 713         enum crlf_action crlf_action;
 714         enum eol eol_attr;
 715         int ident;
 716 };
 717
 718 static const char *conv_attr_name[] = {
 719         "crlf", "ident", "filter", "eol", "text",
 720 };
 721 #define NUM_CONV_ATTRS ARRAY_SIZE(conv_attr_name)
 722
 723 static void convert_attrs(struct conv_attrs *ca, const char *path)
 724 {
 725         int i;
 726         static struct git_attr_check ccheck[NUM_CONV_ATTRS];
 727
 728         if (!ccheck[0].attr) {
 729                 for (i = 0; i < NUM_CONV_ATTRS; i++)
 730                         ccheck[i].attr = git_attr(conv_attr_name[i]);
 731                 user_convert_tail = &user_convert;
 732                 git_config(read_convert_config, NULL);
 733         }
 734
 735         if (!git_check_attr(path, NUM_CONV_ATTRS, ccheck)) {
 736                 ca->crlf_action = git_path_check_crlf(path, ccheck + 4);
 737                 if (ca->crlf_action == CRLF_GUESS)
 738                         ca->crlf_action = git_path_check_crlf(path, ccheck + 0);
 739                 ca->ident = git_path_check_ident(path, ccheck + 1);
 740                 ca->drv = git_path_check_convert(path, ccheck + 2);
 741                 ca->eol_attr = git_path_check_eol(path, ccheck + 3);
 742         } else {
 743                 ca->drv = NULL;
 744                 ca->crlf_action = CRLF_GUESS;
 745                 ca->eol_attr = EOL_UNSET;
 746                 ca->ident = 0;
 747         }
 748 }
 749
 750 int convert_to_git(const char *path, const char *src, size_t len,
 751                    struct strbuf *dst, enum safe_crlf checksafe)
 752 {
 753         int ret = 0;
 754         const char *filter = NULL;
 755         int required = 0;
 756         struct conv_attrs ca;
 757
 758         convert_attrs(&ca, path);
 759         if (ca.drv) {
 760                 filter = ca.drv->clean;
 761                 required = ca.drv->required;
 762         }
 763
 764         ret |= apply_filter(path, src, len, dst, filter);
 765         if (!ret && required)
 766                 die("%s: clean filter '%s' failed", path, ca.drv->name);
 767
 768         if (ret && dst) {
 769                 src = dst->buf;
 770                 len = dst->len;
 771         }
 772         ca.crlf_action = input_crlf_action(ca.crlf_action, ca.eol_attr);
 773         ret |= crlf_to_git(path, src, len, dst, ca.crlf_action, checksafe);
 774         if (ret && dst) {
 775                 src = dst->buf;
 776                 len = dst->len;
 777         }
 778         return ret | ident_to_git(path, src, len, dst, ca.ident);
 779 }
 780
 781 static int convert_to_working_tree_internal(const char *path, const char *src,
 782                                             size_t len, struct strbuf *dst,
 783                                             int normalizing)
 784 {
 785         int ret = 0, ret_filter = 0;
 786         const char *filter = NULL;
 787         int required = 0;
 788         struct conv_attrs ca;
 789
 790         convert_attrs(&ca, path);
 791         if (ca.drv) {
 792                 filter = ca.drv->smudge;
 793                 required = ca.drv->required;
 794         }
 795
 796         ret |= ident_to_worktree(path, src, len, dst, ca.ident);
 797         if (ret) {
 798                 src = dst->buf;
 799                 len = dst->len;
 800         }
 801         /*
 802          * CRLF conversion can be skipped if normalizing, unless there
 803          * is a smudge filter.  The filter might expect CRLFs.
 804          */
 805         if (filter || !normalizing) {
 806                 ca.crlf_action = input_crlf_action(ca.crlf_action, ca.eol_attr);
 807                 ret |= crlf_to_worktree(path, src, len, dst, ca.crlf_action);
 808                 if (ret) {
 809                         src = dst->buf;
 810                         len = dst->len;
 811                 }
 812         }
 813
 814         ret_filter = apply_filter(path, src, len, dst, filter);
 815         if (!ret_filter && required)
 816                 die("%s: smudge filter %s failed", path, ca.drv->name);
 817
 818         return ret | ret_filter;
 819 }
 820
 821 int convert_to_working_tree(const char *path, const char *src, size_t len, struct strbuf *dst)
 822 {
 823         return convert_to_working_tree_internal(path, src, len, dst, 0);
 824 }
 825
 826 int renormalize_buffer(const char *path, const char *src, size_t len, struct strbuf *dst)
 827 {
 828         int ret = convert_to_working_tree_internal(path, src, len, dst, 1);
 829         if (ret) {
 830                 src = dst->buf;
 831                 len = dst->len;
 832         }
 833         return ret | convert_to_git(path, src, len, dst, SAFE_CRLF_FALSE);
 834 }
 835
 836 /*****************************************************************
 837  *
 838  * Streaming conversion support
 839  *
 840  *****************************************************************/
 841
 842 typedef int (*filter_fn)(struct stream_filter *,
 843                          const char *input, size_t *isize_p,
 844                          char *output, size_t *osize_p);
 845 typedef void (*free_fn)(struct stream_filter *);
 846
 847 struct stream_filter_vtbl {
 848         filter_fn filter;
 849         free_fn free;
 850 };
 851
 852 struct stream_filter {
 853         struct stream_filter_vtbl *vtbl;
 854 };
 855
 856 static int null_filter_fn(struct stream_filter *filter,
 857                           const char *input, size_t *isize_p,
 858                           char *output, size_t *osize_p)
 859 {
 860         size_t count;
 861
 862         if (!input)
 863                 return 0; /* we do not keep any states */
 864         count = *isize_p;
 865         if (*osize_p < count)
 866                 count = *osize_p;
 867         if (count) {
 868                 memmove(output, input, count);
 869                 *isize_p -= count;
 870                 *osize_p -= count;
 871         }
 872         return 0;
 873 }
 874
 875 static void null_free_fn(struct stream_filter *filter)
 876 {
 877         ; /* nothing -- null instances are shared */
 878 }
 879
 880 static struct stream_filter_vtbl null_vtbl = {
 881         null_filter_fn,
 882         null_free_fn,
 883 };
 884
 885 static struct stream_filter null_filter_singleton = {
 886         &null_vtbl,
 887 };
 888
 889 int is_null_stream_filter(struct stream_filter *filter)
 890 {
 891         return filter == &null_filter_singleton;
 892 }
 893
 894
 895 /*
 896  * LF-to-CRLF filter
 897  */
 898
 899 struct lf_to_crlf_filter {
 900         struct stream_filter filter;
 901         unsigned has_held:1;
 902         char held;
 903 };
 904
 905 static int lf_to_crlf_filter_fn(struct stream_filter *filter,
 906                                 const char *input, size_t *isize_p,
 907                                 char *output, size_t *osize_p)
 908 {
 909         size_t count, o = 0;
 910         struct lf_to_crlf_filter *lf_to_crlf = (struct lf_to_crlf_filter *)filter;
 911
 912         /*
 913          * We may be holding onto the CR to see if it is followed by a
 914          * LF, in which case we would need to go to the main loop.
 915          * Otherwise, just emit it to the output stream.
 916          */
 917         if (lf_to_crlf->has_held && (lf_to_crlf->held != '\r' || !input)) {
 918                 output[o++] = lf_to_crlf->held;
 919                 lf_to_crlf->has_held = 0;
 920         }
 921
 922         /* We are told to drain */
 923         if (!input) {
 924                 *osize_p -= o;
 925                 return 0;
 926         }
 927
 928         count = *isize_p;
 929         if (count || lf_to_crlf->has_held) {
 930                 size_t i;
 931                 int was_cr = 0;
 932
 933                 if (lf_to_crlf->has_held) {
 934                         was_cr = 1;
 935                         lf_to_crlf->has_held = 0;
 936                 }
 937
 938                 for (i = 0; o < *osize_p && i < count; i++) {
 939                         char ch = input[i];
 940
 941                         if (ch == '\n') {
 942                                 output[o++] = '\r';
 943                         } else if (was_cr) {
 944                                 /*
 945                                  * Previous round saw CR and it is not followed
 946                                  * by a LF; emit the CR before processing the
 947                                  * current character.
 948                                  */
 949                                 output[o++] = '\r';
 950                         }
 951
 952                         /*
 953                          * We may have consumed the last output slot,
 954                          * in which case we need to break out of this
 955                          * loop; hold the current character before
 956                          * returning.
 957                          */
 958                         if (*osize_p <= o) {
 959                                 lf_to_crlf->has_held = 1;
 960                                 lf_to_crlf->held = ch;
 961                                 continue; /* break but increment i */
 962                         }
 963
 964                         if (ch == '\r') {
 965                                 was_cr = 1;
 966                                 continue;
 967                         }
 968
 969                         was_cr = 0;
 970                         output[o++] = ch;
 971                 }
 972
 973                 *osize_p -= o;
 974                 *isize_p -= i;
 975
 976                 if (!lf_to_crlf->has_held && was_cr) {
 977                         lf_to_crlf->has_held = 1;
 978                         lf_to_crlf->held = '\r';
 979                 }
 980         }
 981         return 0;
 982 }
 983
 984 static void lf_to_crlf_free_fn(struct stream_filter *filter)
 985 {
 986         free(filter);
 987 }
 988
 989 static struct stream_filter_vtbl lf_to_crlf_vtbl = {
 990         lf_to_crlf_filter_fn,
 991         lf_to_crlf_free_fn,
 992 };
 993
 994 static struct stream_filter *lf_to_crlf_filter(void)
 995 {
 996         struct lf_to_crlf_filter *lf_to_crlf = xcalloc(1, sizeof(*lf_to_crlf));
 997
 998         lf_to_crlf->filter.vtbl = &lf_to_crlf_vtbl;
 999         return (struct stream_filter *)lf_to_crlf;
1000 }
1001
1002 /*
1003  * Cascade filter
1004  */
1005 #define FILTER_BUFFER 1024
1006 struct cascade_filter {
1007         struct stream_filter filter;
1008         struct stream_filter *one;
1009         struct stream_filter *two;
1010         char buf[FILTER_BUFFER];
1011         int end, ptr;
1012 };
1013
1014 static int cascade_filter_fn(struct stream_filter *filter,
1015                              const char *input, size_t *isize_p,
1016                              char *output, size_t *osize_p)
1017 {
1018         struct cascade_filter *cas = (struct cascade_filter *) filter;
1019         size_t filled = 0;
1020         size_t sz = *osize_p;
1021         size_t to_feed, remaining;
1022
1023         /*
1024          * input -- (one) --> buf -- (two) --> output
1025          */
1026         while (filled < sz) {
1027                 remaining = sz - filled;
1028
1029                 /* do we already have something to feed two with? */
1030                 if (cas->ptr < cas->end) {
1031                         to_feed = cas->end - cas->ptr;
1032                         if (stream_filter(cas->two,
1033                                           cas->buf + cas->ptr, &to_feed,
1034                                           output + filled, &remaining))
1035                                 return -1;
1036                         cas->ptr += (cas->end - cas->ptr) - to_feed;
1037                         filled = sz - remaining;
1038                         continue;
1039                 }
1040
1041                 /* feed one from upstream and have it emit into our buffer */
1042                 to_feed = input ? *isize_p : 0;
1043                 if (input && !to_feed)
1044                         break;
1045                 remaining = sizeof(cas->buf);
1046                 if (stream_filter(cas->one,
1047                                   input, &to_feed,
1048                                   cas->buf, &remaining))
1049                         return -1;
1050                 cas->end = sizeof(cas->buf) - remaining;
1051                 cas->ptr = 0;
1052                 if (input) {
1053                         size_t fed = *isize_p - to_feed;
1054                         *isize_p -= fed;
1055                         input += fed;
1056                 }
1057
1058                 /* do we know that we drained one completely? */
1059                 if (input || cas->end)
1060                         continue;
1061
1062                 /* tell two to drain; we have nothing more to give it */
1063                 to_feed = 0;
1064                 remaining = sz - filled;
1065                 if (stream_filter(cas->two,
1066                                   NULL, &to_feed,
1067                                   output + filled, &remaining))
1068                         return -1;
1069                 if (remaining == (sz - filled))
1070                         break; /* completely drained two */
1071                 filled = sz - remaining;
1072         }
1073         *osize_p -= filled;
1074         return 0;
1075 }
1076
1077 static void cascade_free_fn(struct stream_filter *filter)
1078 {
1079         struct cascade_filter *cas = (struct cascade_filter *)filter;
1080         free_stream_filter(cas->one);
1081         free_stream_filter(cas->two);
1082         free(filter);
1083 }
1084
1085 static struct stream_filter_vtbl cascade_vtbl = {
1086         cascade_filter_fn,
1087         cascade_free_fn,
1088 };
1089
1090 static struct stream_filter *cascade_filter(struct stream_filter *one,
1091                                             struct stream_filter *two)
1092 {
1093         struct cascade_filter *cascade;
1094
1095         if (!one || is_null_stream_filter(one))
1096                 return two;
1097         if (!two || is_null_stream_filter(two))
1098                 return one;
1099
1100         cascade = xmalloc(sizeof(*cascade));
1101         cascade->one = one;
1102         cascade->two = two;
1103         cascade->end = cascade->ptr = 0;
1104         cascade->filter.vtbl = &cascade_vtbl;
1105         return (struct stream_filter *)cascade;
1106 }
1107
1108 /*
1109  * ident filter
1110  */
1111 #define IDENT_DRAINING (-1)
1112 #define IDENT_SKIPPING (-2)
1113 struct ident_filter {
1114         struct stream_filter filter;
1115         struct strbuf left;
1116         int state;
1117         char ident[45]; /* ": x40 $" */
1118 };
1119
1120 static int is_foreign_ident(const char *str)
1121 {
1122         int i;
1123
1124         if (!starts_with(str, "$Id: "))
1125                 return 0;
1126         for (i = 5; str[i]; i++) {
1127                 if (isspace(str[i]) && str[i+1] != '$')
1128                         return 1;
1129         }
1130         return 0;
1131 }
1132
1133 static void ident_drain(struct ident_filter *ident, char **output_p, size_t *osize_p)
1134 {
1135         size_t to_drain = ident->left.len;
1136
1137         if (*osize_p < to_drain)
1138                 to_drain = *osize_p;
1139         if (to_drain) {
1140                 memcpy(*output_p, ident->left.buf, to_drain);
1141                 strbuf_remove(&ident->left, 0, to_drain);
1142                 *output_p += to_drain;
1143                 *osize_p -= to_drain;
1144         }
1145         if (!ident->left.len)
1146                 ident->state = 0;
1147 }
1148
1149 static int ident_filter_fn(struct stream_filter *filter,
1150                            const char *input, size_t *isize_p,
1151                            char *output, size_t *osize_p)
1152 {
1153         struct ident_filter *ident = (struct ident_filter *)filter;
1154         static const char head[] = "$Id";
1155
1156         if (!input) {
1157                 /* drain upon eof */
1158                 switch (ident->state) {
1159                 default:
1160                         strbuf_add(&ident->left, head, ident->state);
1161                 case IDENT_SKIPPING:
1162                         /* fallthru */
1163                 case IDENT_DRAINING:
1164                         ident_drain(ident, &output, osize_p);
1165                 }
1166                 return 0;
1167         }
1168
1169         while (*isize_p || (ident->state == IDENT_DRAINING)) {
1170                 int ch;
1171
1172                 if (ident->state == IDENT_DRAINING) {
1173                         ident_drain(ident, &output, osize_p);
1174                         if (!*osize_p)
1175                                 break;
1176                         continue;
1177                 }
1178
1179                 ch = *(input++);
1180                 (*isize_p)--;
1181
1182                 if (ident->state == IDENT_SKIPPING) {
1183                         /*
1184                          * Skipping until '$' or LF, but keeping them
1185                          * in case it is a foreign ident.
1186                          */
1187                         strbuf_addch(&ident->left, ch);
1188                         if (ch != '\n' && ch != '$')
1189                                 continue;
1190                         if (ch == '$' && !is_foreign_ident(ident->left.buf)) {
1191                                 strbuf_setlen(&ident->left, sizeof(head) - 1);
1192                                 strbuf_addstr(&ident->left, ident->ident);
1193                         }
1194                         ident->state = IDENT_DRAINING;
1195                         continue;
1196                 }
1197
1198                 if (ident->state < sizeof(head) &&
1199                     head[ident->state] == ch) {
1200                         ident->state++;
1201                         continue;
1202                 }
1203
1204                 if (ident->state)
1205                         strbuf_add(&ident->left, head, ident->state);
1206                 if (ident->state == sizeof(head) - 1) {
1207                         if (ch != ':' && ch != '$') {
1208                                 strbuf_addch(&ident->left, ch);
1209                                 ident->state = 0;
1210                                 continue;
1211                         }
1212
1213                         if (ch == ':') {
1214                                 strbuf_addch(&ident->left, ch);
1215                                 ident->state = IDENT_SKIPPING;
1216                         } else {
1217                                 strbuf_addstr(&ident->left, ident->ident);
1218                                 ident->state = IDENT_DRAINING;
1219                         }
1220                         continue;
1221                 }
1222
1223                 strbuf_addch(&ident->left, ch);
1224                 ident->state = IDENT_DRAINING;
1225         }
1226         return 0;
1227 }
1228
1229 static void ident_free_fn(struct stream_filter *filter)
1230 {
1231         struct ident_filter *ident = (struct ident_filter *)filter;
1232         strbuf_release(&ident->left);
1233         free(filter);
1234 }
1235
1236 static struct stream_filter_vtbl ident_vtbl = {
1237         ident_filter_fn,
1238         ident_free_fn,
1239 };
1240
1241 static struct stream_filter *ident_filter(const unsigned char *sha1)
1242 {
1243         struct ident_filter *ident = xmalloc(sizeof(*ident));
1244
1245         sprintf(ident->ident, ": %s $", sha1_to_hex(sha1));
1246         strbuf_init(&ident->left, 0);
1247         ident->filter.vtbl = &ident_vtbl;
1248         ident->state = 0;
1249         return (struct stream_filter *)ident;
1250 }
1251
1252 /*
1253  * Return an appropriately constructed filter for the path, or NULL if
1254  * the contents cannot be filtered without reading the whole thing
1255  * in-core.
1256  *
1257  * Note that you would be crazy to set CRLF, smuge/clean or ident to a
1258  * large binary blob you would want us not to slurp into the memory!
1259  */
1260 struct stream_filter *get_stream_filter(const char *path, const unsigned char *sha1)
1261 {
1262         struct conv_attrs ca;
1263         enum crlf_action crlf_action;
1264         struct stream_filter *filter = NULL;
1265
1266         convert_attrs(&ca, path);
1267
1268         if (ca.drv && (ca.drv->smudge || ca.drv->clean))
1269                 return filter;
1270
1271         if (ca.ident)
1272                 filter = ident_filter(sha1);
1273
1274         crlf_action = input_crlf_action(ca.crlf_action, ca.eol_attr);
1275
1276         if ((crlf_action == CRLF_BINARY) || (crlf_action == CRLF_INPUT) ||
1277             (crlf_action == CRLF_GUESS && auto_crlf == AUTO_CRLF_FALSE))
1278                 filter = cascade_filter(filter, &null_filter_singleton);
1279
1280         else if (output_eol(crlf_action) == EOL_CRLF &&
1281                  !(crlf_action == CRLF_AUTO || crlf_action == CRLF_GUESS))
1282                 filter = cascade_filter(filter, lf_to_crlf_filter());
1283
1284         return filter;
1285 }
1286
1287 void free_stream_filter(struct stream_filter *filter)
1288 {
1289         filter->vtbl->free(filter);
1290 }
1291
1292 int stream_filter(struct stream_filter *filter,
1293                   const char *input, size_t *isize_p,
1294                   char *output, size_t *osize_p)
1295 {
1296         return filter->vtbl->filter(filter, input, isize_p, output, osize_p);
1297 }