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