convert.c

   1 #include "cache.h"
   2 #include "attr.h"
   3 #include "run-command.h"
   4
   5 /*
   6  * convert.c - convert a file when checking it out and checking it in.
   7  *
   8  * This should use the pathname to decide on whether it wants to do some
   9  * more interesting conversions (automatic gzip/unzip, general format
  10  * conversions etc etc), but by default it just does automatic CRLF<->LF
  11  * translation when the "auto_crlf" option is set.
  12  */
  13
  14 #define CRLF_GUESS      (-1)
  15 #define CRLF_BINARY     0
  16 #define CRLF_TEXT       1
  17 #define CRLF_INPUT      2
  18
  19 struct text_stat {
  20         /* NUL, CR, LF and CRLF counts */
  21         unsigned nul, cr, lf, crlf;
  22
  23         /* These are just approximations! */
  24         unsigned printable, nonprintable;
  25 };
  26
  27 static void gather_stats(const char *buf, unsigned long size, struct text_stat *stats)
  28 {
  29         unsigned long i;
  30
  31         memset(stats, 0, sizeof(*stats));
  32
  33         for (i = 0; i < size; i++) {
  34                 unsigned char c = buf[i];
  35                 if (c == '\r') {
  36                         stats->cr++;
  37                         if (i+1 < size && buf[i+1] == '\n')
  38                                 stats->crlf++;
  39                         continue;
  40                 }
  41                 if (c == '\n') {
  42                         stats->lf++;
  43                         continue;
  44                 }
  45                 if (c == 127)
  46                         /* DEL */
  47                         stats->nonprintable++;
  48                 else if (c < 32) {
  49                         switch (c) {
  50                                 /* BS, HT, ESC and FF */
  51                         case '\b': case '\t': case '\033': case '\014':
  52                                 stats->printable++;
  53                                 break;
  54                         case 0:
  55                                 stats->nul++;
  56                                 /* fall through */
  57                         default:
  58                                 stats->nonprintable++;
  59                         }
  60                 }
  61                 else
  62                         stats->printable++;
  63         }
  64 }
  65
  66 /*
  67  * The same heuristics as diff.c::mmfile_is_binary()
  68  */
  69 static int is_binary(unsigned long size, struct text_stat *stats)
  70 {
  71
  72         if (stats->nul)
  73                 return 1;
  74         if ((stats->printable >> 7) < stats->nonprintable)
  75                 return 1;
  76         /*
  77          * Other heuristics? Average line length might be relevant,
  78          * as might LF vs CR vs CRLF counts..
  79          *
  80          * NOTE! It might be normal to have a low ratio of CRLF to LF
  81          * (somebody starts with a LF-only file and edits it with an editor
  82          * that adds CRLF only to lines that are added..). But do  we
  83          * want to support CR-only? Probably not.
  84          */
  85         return 0;
  86 }
  87
  88 static int crlf_to_git(const char *path, const char *src, size_t len,
  89                        struct strbuf *buf, int action)
  90 {
  91         struct text_stat stats;
  92         char *dst;
  93
  94         if ((action == CRLF_BINARY) || !auto_crlf || !len)
  95                 return 0;
  96
  97         gather_stats(src, len, &stats);
  98         /* No CR? Nothing to convert, regardless. */
  99         if (!stats.cr)
 100                 return 0;
 101
 102         if (action == CRLF_GUESS) {
 103                 /*
 104                  * We're currently not going to even try to convert stuff
 105                  * that has bare CR characters. Does anybody do that crazy
 106                  * stuff?
 107                  */
 108                 if (stats.cr != stats.crlf)
 109                         return 0;
 110
 111                 /*
 112                  * And add some heuristics for binary vs text, of course...
 113                  */
 114                 if (is_binary(len, &stats))
 115                         return 0;
 116         }
 117
 118         /* only grow if not in place */
 119         if (strbuf_avail(buf) + buf->len < len)
 120                 strbuf_grow(buf, len - buf->len);
 121         dst = buf->buf;
 122         if (action == CRLF_GUESS) {
 123                 /*
 124                  * If we guessed, we already know we rejected a file with
 125                  * lone CR, and we can strip a CR without looking at what
 126                  * follow it.
 127                  */
 128                 do {
 129                         unsigned char c = *src++;
 130                         if (c != '\r')
 131                                 *dst++ = c;
 132                 } while (--len);
 133         } else {
 134                 do {
 135                         unsigned char c = *src++;
 136                         if (! (c == '\r' && (1 < len && *src == '\n')))
 137                                 *dst++ = c;
 138                 } while (--len);
 139         }
 140         strbuf_setlen(buf, dst - buf->buf);
 141         return 1;
 142 }
 143
 144 static int crlf_to_worktree(const char *path, const char *src, size_t len,
 145                             struct strbuf *buf, int action)
 146 {
 147         char *to_free = NULL;
 148         struct text_stat stats;
 149
 150         if ((action == CRLF_BINARY) || (action == CRLF_INPUT) ||
 151             auto_crlf <= 0)
 152                 return 0;
 153
 154         if (!len)
 155                 return 0;
 156
 157         gather_stats(src, len, &stats);
 158
 159         /* No LF? Nothing to convert, regardless. */
 160         if (!stats.lf)
 161                 return 0;
 162
 163         /* Was it already in CRLF format? */
 164         if (stats.lf == stats.crlf)
 165                 return 0;
 166
 167         if (action == CRLF_GUESS) {
 168                 /* If we have any bare CR characters, we're not going to touch it */
 169                 if (stats.cr != stats.crlf)
 170                         return 0;
 171
 172                 if (is_binary(len, &stats))
 173                         return 0;
 174         }
 175
 176         /* are we "faking" in place editing ? */
 177         if (src == buf->buf)
 178                 to_free = strbuf_detach(buf, NULL);
 179
 180         strbuf_grow(buf, len + stats.lf - stats.crlf);
 181         for (;;) {
 182                 const char *nl = memchr(src, '\n', len);
 183                 if (!nl)
 184                         break;
 185                 if (nl > src && nl[-1] == '\r') {
 186                         strbuf_add(buf, src, nl + 1 - src);
 187                 } else {
 188                         strbuf_add(buf, src, nl - src);
 189                         strbuf_addstr(buf, "\r\n");
 190                 }
 191                 len -= nl + 1 - src;
 192                 src  = nl + 1;
 193         }
 194         strbuf_add(buf, src, len);
 195
 196         free(to_free);
 197         return 1;
 198 }
 199
 200 struct filter_params {
 201         const char *src;
 202         unsigned long size;
 203         const char *cmd;
 204 };
 205
 206 static int filter_buffer(int fd, void *data)
 207 {
 208         /*
 209          * Spawn cmd and feed the buffer contents through its stdin.
 210          */
 211         struct child_process child_process;
 212         struct filter_params *params = (struct filter_params *)data;
 213         int write_err, status;
 214         const char *argv[] = { "sh", "-c", params->cmd, NULL };
 215
 216         memset(&child_process, 0, sizeof(child_process));
 217         child_process.argv = argv;
 218         child_process.in = -1;
 219         child_process.out = fd;
 220
 221         if (start_command(&child_process))
 222                 return error("cannot fork to run external filter %s", params->cmd);
 223
 224         write_err = (write_in_full(child_process.in, params->src, params->size) < 0);
 225         if (close(child_process.in))
 226                 write_err = 1;
 227         if (write_err)
 228                 error("cannot feed the input to external filter %s", params->cmd);
 229
 230         status = finish_command(&child_process);
 231         if (status)
 232                 error("external filter %s failed %d", params->cmd, -status);
 233         return (write_err || status);
 234 }
 235
 236 static int apply_filter(const char *path, const char *src, size_t len,
 237                         struct strbuf *dst, const char *cmd)
 238 {
 239         /*
 240          * Create a pipeline to have the command filter the buffer's
 241          * contents.
 242          *
 243          * (child --> cmd) --> us
 244          */
 245         int ret = 1;
 246         struct strbuf nbuf;
 247         struct async async;
 248         struct filter_params params;
 249
 250         if (!cmd)
 251                 return 0;
 252
 253         memset(&async, 0, sizeof(async));
 254         async.proc = filter_buffer;
 255         async.data = &params;
 256         params.src = src;
 257         params.size = len;
 258         params.cmd = cmd;
 259
 260         fflush(NULL);
 261         if (start_async(&async))
 262                 return 0;       /* error was already reported */
 263
 264         strbuf_init(&nbuf, 0);
 265         if (strbuf_read(&nbuf, async.out, len) < 0) {
 266                 error("read from external filter %s failed", cmd);
 267                 ret = 0;
 268         }
 269         if (close(async.out)) {
 270                 error("read from external filter %s failed", cmd);
 271                 ret = 0;
 272         }
 273         if (finish_async(&async)) {
 274                 error("external filter %s failed", cmd);
 275                 ret = 0;
 276         }
 277
 278         if (ret) {
 279                 strbuf_swap(dst, &nbuf);
 280         }
 281         strbuf_release(&nbuf);
 282         return ret;
 283 }
 284
 285 static struct convert_driver {
 286         const char *name;
 287         struct convert_driver *next;
 288         char *smudge;
 289         char *clean;
 290 } *user_convert, **user_convert_tail;
 291
 292 static int read_convert_config(const char *var, const char *value)
 293 {
 294         const char *ep, *name;
 295         int namelen;
 296         struct convert_driver *drv;
 297
 298         /*
 299          * External conversion drivers are configured using
 300          * "filter.<name>.variable".
 301          */
 302         if (prefixcmp(var, "filter.") || (ep = strrchr(var, '.')) == var + 6)
 303                 return 0;
 304         name = var + 7;
 305         namelen = ep - name;
 306         for (drv = user_convert; drv; drv = drv->next)
 307                 if (!strncmp(drv->name, name, namelen) && !drv->name[namelen])
 308                         break;
 309         if (!drv) {
 310                 drv = xcalloc(1, sizeof(struct convert_driver));
 311                 drv->name = xmemdupz(name, namelen);
 312                 *user_convert_tail = drv;
 313                 user_convert_tail = &(drv->next);
 314         }
 315
 316         ep++;
 317
 318         /*
 319          * filter.<name>.smudge and filter.<name>.clean specifies
 320          * the command line:
 321          *
 322          *      command-line
 323          *
 324          * The command-line will not be interpolated in any way.
 325          */
 326
 327         if (!strcmp("smudge", ep)) {
 328                 if (!value)
 329                         return error("%s: lacks value", var);
 330                 drv->smudge = strdup(value);
 331                 return 0;
 332         }
 333
 334         if (!strcmp("clean", ep)) {
 335                 if (!value)
 336                         return error("%s: lacks value", var);
 337                 drv->clean = strdup(value);
 338                 return 0;
 339         }
 340         return 0;
 341 }
 342
 343 static void setup_convert_check(struct git_attr_check *check)
 344 {
 345         static struct git_attr *attr_crlf;
 346         static struct git_attr *attr_ident;
 347         static struct git_attr *attr_filter;
 348
 349         if (!attr_crlf) {
 350                 attr_crlf = git_attr("crlf", 4);
 351                 attr_ident = git_attr("ident", 5);
 352                 attr_filter = git_attr("filter", 6);
 353                 user_convert_tail = &user_convert;
 354                 git_config(read_convert_config);
 355         }
 356         check[0].attr = attr_crlf;
 357         check[1].attr = attr_ident;
 358         check[2].attr = attr_filter;
 359 }
 360
 361 static int count_ident(const char *cp, unsigned long size)
 362 {
 363         /*
 364          * "$Id: 0000000000000000000000000000000000000000 $" <=> "$Id$"
 365          */
 366         int cnt = 0;
 367         char ch;
 368
 369         while (size) {
 370                 ch = *cp++;
 371                 size--;
 372                 if (ch != '$')
 373                         continue;
 374                 if (size < 3)
 375                         break;
 376                 if (memcmp("Id", cp, 2))
 377                         continue;
 378                 ch = cp[2];
 379                 cp += 3;
 380                 size -= 3;
 381                 if (ch == '$')
 382                         cnt++; /* $Id$ */
 383                 if (ch != ':')
 384                         continue;
 385
 386                 /*
 387                  * "$Id: ... "; scan up to the closing dollar sign and discard.
 388                  */
 389                 while (size) {
 390                         ch = *cp++;
 391                         size--;
 392                         if (ch == '$') {
 393                                 cnt++;
 394                                 break;
 395                         }
 396                 }
 397         }
 398         return cnt;
 399 }
 400
 401 static int ident_to_git(const char *path, const char *src, size_t len,
 402                         struct strbuf *buf, int ident)
 403 {
 404         char *dst, *dollar;
 405
 406         if (!ident || !count_ident(src, len))
 407                 return 0;
 408
 409         /* only grow if not in place */
 410         if (strbuf_avail(buf) + buf->len < len)
 411                 strbuf_grow(buf, len - buf->len);
 412         dst = buf->buf;
 413         for (;;) {
 414                 dollar = memchr(src, '$', len);
 415                 if (!dollar)
 416                         break;
 417                 memcpy(dst, src, dollar + 1 - src);
 418                 dst += dollar + 1 - src;
 419                 len -= dollar + 1 - src;
 420                 src  = dollar + 1;
 421
 422                 if (len > 3 && !memcmp(src, "Id:", 3)) {
 423                         dollar = memchr(src + 3, '$', len - 3);
 424                         if (!dollar)
 425                                 break;
 426                         memcpy(dst, "Id$", 3);
 427                         dst += 3;
 428                         len -= dollar + 1 - src;
 429                         src  = dollar + 1;
 430                 }
 431         }
 432         memcpy(dst, src, len);
 433         strbuf_setlen(buf, dst + len - buf->buf);
 434         return 1;
 435 }
 436
 437 static int ident_to_worktree(const char *path, const char *src, size_t len,
 438                              struct strbuf *buf, int ident)
 439 {
 440         unsigned char sha1[20];
 441         char *to_free = NULL, *dollar;
 442         int cnt;
 443
 444         if (!ident)
 445                 return 0;
 446
 447         cnt = count_ident(src, len);
 448         if (!cnt)
 449                 return 0;
 450
 451         /* are we "faking" in place editing ? */
 452         if (src == buf->buf)
 453                 to_free = strbuf_detach(buf, NULL);
 454         hash_sha1_file(src, len, "blob", sha1);
 455
 456         strbuf_grow(buf, len + cnt * 43);
 457         for (;;) {
 458                 /* step 1: run to the next '$' */
 459                 dollar = memchr(src, '$', len);
 460                 if (!dollar)
 461                         break;
 462                 strbuf_add(buf, src, dollar + 1 - src);
 463                 len -= dollar + 1 - src;
 464                 src  = dollar + 1;
 465
 466                 /* step 2: does it looks like a bit like Id:xxx$ or Id$ ? */
 467                 if (len < 3 || memcmp("Id", src, 2))
 468                         continue;
 469
 470                 /* step 3: skip over Id$ or Id:xxxxx$ */
 471                 if (src[2] == '$') {
 472                         src += 3;
 473                         len -= 3;
 474                 } else if (src[2] == ':') {
 475                         /*
 476                          * It's possible that an expanded Id has crept its way into the
 477                          * repository, we cope with that by stripping the expansion out
 478                          */
 479                         dollar = memchr(src + 3, '$', len - 3);
 480                         if (!dollar) {
 481                                 /* incomplete keyword, no more '$', so just quit the loop */
 482                                 break;
 483                         }
 484
 485                         len -= dollar + 1 - src;
 486                         src  = dollar + 1;
 487                 } else {
 488                         /* it wasn't a "Id$" or "Id:xxxx$" */
 489                         continue;
 490                 }
 491
 492                 /* step 4: substitute */
 493                 strbuf_addstr(buf, "Id: ");
 494                 strbuf_add(buf, sha1_to_hex(sha1), 40);
 495                 strbuf_addstr(buf, " $");
 496         }
 497         strbuf_add(buf, src, len);
 498
 499         free(to_free);
 500         return 1;
 501 }
 502
 503 static int git_path_check_crlf(const char *path, struct git_attr_check *check)
 504 {
 505         const char *value = check->value;
 506
 507         if (ATTR_TRUE(value))
 508                 return CRLF_TEXT;
 509         else if (ATTR_FALSE(value))
 510                 return CRLF_BINARY;
 511         else if (ATTR_UNSET(value))
 512                 ;
 513         else if (!strcmp(value, "input"))
 514                 return CRLF_INPUT;
 515         return CRLF_GUESS;
 516 }
 517
 518 static struct convert_driver *git_path_check_convert(const char *path,
 519                                              struct git_attr_check *check)
 520 {
 521         const char *value = check->value;
 522         struct convert_driver *drv;
 523
 524         if (ATTR_TRUE(value) || ATTR_FALSE(value) || ATTR_UNSET(value))
 525                 return NULL;
 526         for (drv = user_convert; drv; drv = drv->next)
 527                 if (!strcmp(value, drv->name))
 528                         return drv;
 529         return NULL;
 530 }
 531
 532 static int git_path_check_ident(const char *path, struct git_attr_check *check)
 533 {
 534         const char *value = check->value;
 535
 536         return !!ATTR_TRUE(value);
 537 }
 538
 539 int convert_to_git(const char *path, const char *src, size_t len, struct strbuf *dst)
 540 {
 541         struct git_attr_check check[3];
 542         int crlf = CRLF_GUESS;
 543         int ident = 0, ret = 0;
 544         char *filter = NULL;
 545
 546         setup_convert_check(check);
 547         if (!git_checkattr(path, ARRAY_SIZE(check), check)) {
 548                 struct convert_driver *drv;
 549                 crlf = git_path_check_crlf(path, check + 0);
 550                 ident = git_path_check_ident(path, check + 1);
 551                 drv = git_path_check_convert(path, check + 2);
 552                 if (drv && drv->clean)
 553                         filter = drv->clean;
 554         }
 555
 556         ret |= apply_filter(path, src, len, dst, filter);
 557         if (ret) {
 558                 src = dst->buf;
 559                 len = dst->len;
 560         }
 561         ret |= crlf_to_git(path, src, len, dst, crlf);
 562         if (ret) {
 563                 src = dst->buf;
 564                 len = dst->len;
 565         }
 566         return ret | ident_to_git(path, src, len, dst, ident);
 567 }
 568
 569 int convert_to_working_tree(const char *path, const char *src, size_t len, struct strbuf *dst)
 570 {
 571         struct git_attr_check check[3];
 572         int crlf = CRLF_GUESS;
 573         int ident = 0, ret = 0;
 574         char *filter = NULL;
 575
 576         setup_convert_check(check);
 577         if (!git_checkattr(path, ARRAY_SIZE(check), check)) {
 578                 struct convert_driver *drv;
 579                 crlf = git_path_check_crlf(path, check + 0);
 580                 ident = git_path_check_ident(path, check + 1);
 581                 drv = git_path_check_convert(path, check + 2);
 582                 if (drv && drv->smudge)
 583                         filter = drv->smudge;
 584         }
 585
 586         ret |= ident_to_worktree(path, src, len, dst, ident);
 587         if (ret) {
 588                 src = dst->buf;
 589                 len = dst->len;
 590         }
 591         ret |= crlf_to_worktree(path, src, len, dst, crlf);
 592         if (ret) {
 593                 src = dst->buf;
 594                 len = dst->len;
 595         }
 596         return ret | apply_filter(path, src, len, dst, filter);
 597 }