apply.c

   1 /*
   2  * apply.c
   3  *
   4  * Copyright (C) Linus Torvalds, 2005
   5  *
   6  * This applies patches on top of some (arbitrary) version of the SCM.
   7  *
   8  * NOTE! It does all its work in the index file, and only cares about
   9  * the files in the working directory if you tell it to "merge" the
  10  * patch apply.
  11  *
  12  * Even when merging it always takes the source from the index, and
  13  * uses the working tree as a "branch" for a 3-way merge.
  14  */
  15 #include <ctype.h>
  16
  17 #include "cache.h"
  18
  19 // We default to the merge behaviour, since that's what most people would
  20 // expect
  21 static int merge_patch = 1;
  22 static int diffstat = 0;
  23 static int check = 1;
  24 static const char apply_usage[] = "git-apply <patch>";
  25
  26 /*
  27  * For "diff-stat" like behaviour, we keep track of the biggest change
  28  * we've seen, and the longest filename. That allows us to do simple
  29  * scaling.
  30  */
  31 static int max_change, max_len;
  32
  33 /*
  34  * Various "current state", notably line numbers and what
  35  * file (and how) we're patching right now.. The "is_xxxx"
  36  * things are flags, where -1 means "don't know yet".
  37  */
  38 static int linenr = 1;
  39
  40 struct fragment {
  41         unsigned long oldpos, oldlines;
  42         unsigned long newpos, newlines;
  43         const char *patch;
  44         int size;
  45         struct fragment *next;
  46 };
  47
  48 struct patch {
  49         char *new_name, *old_name, *def_name;
  50         unsigned int old_mode, new_mode;
  51         int is_rename, is_copy, is_new, is_delete;
  52         int lines_added, lines_deleted;
  53         struct fragment *fragments;
  54         struct patch *next;
  55 };
  56
  57 #define CHUNKSIZE (8192)
  58 #define SLOP (16)
  59
  60 static void *read_patch_file(int fd, unsigned long *sizep)
  61 {
  62         unsigned long size = 0, alloc = CHUNKSIZE;
  63         void *buffer = xmalloc(alloc);
  64
  65         for (;;) {
  66                 int nr = alloc - size;
  67                 if (nr < 1024) {
  68                         alloc += CHUNKSIZE;
  69                         buffer = xrealloc(buffer, alloc);
  70                         nr = alloc - size;
  71                 }
  72                 nr = read(fd, buffer + size, nr);
  73                 if (!nr)
  74                         break;
  75                 if (nr < 0) {
  76                         if (errno == EAGAIN)
  77                                 continue;
  78                         die("git-apply: read returned %s", strerror(errno));
  79                 }
  80                 size += nr;
  81         }
  82         *sizep = size;
  83
  84         /*
  85          * Make sure that we have some slop in the buffer
  86          * so that we can do speculative "memcmp" etc, and
  87          * see to it that it is NUL-filled.
  88          */
  89         if (alloc < size + SLOP)
  90                 buffer = xrealloc(buffer, size + SLOP);
  91         memset(buffer + size, 0, SLOP);
  92         return buffer;
  93 }
  94
  95 static unsigned long linelen(char *buffer, unsigned long size)
  96 {
  97         unsigned long len = 0;
  98         while (size--) {
  99                 len++;
 100                 if (*buffer++ == '\n')
 101                         break;
 102         }
 103         return len;
 104 }
 105
 106 static int is_dev_null(const char *str)
 107 {
 108         return !memcmp("/dev/null", str, 9) && isspace(str[9]);
 109 }
 110
 111 #define TERM_EXIST      1
 112 #define TERM_SPACE      2
 113 #define TERM_TAB        4
 114
 115 static int name_terminate(const char *name, int namelen, int c, int terminate)
 116 {
 117         if (c == ' ' && !(terminate & TERM_SPACE))
 118                 return 0;
 119         if (c == '\t' && !(terminate & TERM_TAB))
 120                 return 0;
 121
 122         /*
 123          * Do we want an existing name? Return false and
 124          * continue if it's not there.
 125          */
 126         if (terminate & TERM_EXIST)
 127                 return cache_name_pos(name, namelen) >= 0;
 128
 129         return 1;
 130 }
 131
 132 static char * find_name(const char *line, char *def, int p_value, int terminate)
 133 {
 134         int len;
 135         const char *start = line;
 136         char *name;
 137
 138         for (;;) {
 139                 char c = *line;
 140
 141                 if (isspace(c)) {
 142                         if (c == '\n')
 143                                 break;
 144                         if (name_terminate(start, line-start, c, terminate))
 145                                 break;
 146                 }
 147                 line++;
 148                 if (c == '/' && !--p_value)
 149                         start = line;
 150         }
 151         if (!start)
 152                 return def;
 153         len = line - start;
 154         if (!len)
 155                 return def;
 156
 157         /*
 158          * Generally we prefer the shorter name, especially
 159          * if the other one is just a variation of that with
 160          * something else tacked on to the end (ie "file.orig"
 161          * or "file~").
 162          */
 163         if (def) {
 164                 int deflen = strlen(def);
 165                 if (deflen < len && !strncmp(start, def, deflen))
 166                         return def;
 167         }
 168
 169         name = xmalloc(len + 1);
 170         memcpy(name, start, len);
 171         name[len] = 0;
 172         free(def);
 173         return name;
 174 }
 175
 176 /*
 177  * Get the name etc info from the --/+++ lines of a traditional patch header
 178  *
 179  * NOTE! This hardcodes "-p1" behaviour in filename detection.
 180  *
 181  * FIXME! The end-of-filename heuristics are kind of screwy. For existing
 182  * files, we can happily check the index for a match, but for creating a
 183  * new file we should try to match whatever "patch" does. I have no idea.
 184  */
 185 static void parse_traditional_patch(const char *first, const char *second, struct patch *patch)
 186 {
 187         int p_value = 1;
 188         char *name;
 189
 190         first += 4;     // skip "--- "
 191         second += 4;    // skip "+++ "
 192         if (is_dev_null(first)) {
 193                 patch->is_new = 1;
 194                 patch->is_delete = 0;
 195                 name = find_name(second, NULL, p_value, TERM_SPACE | TERM_TAB);
 196                 patch->new_name = name;
 197         } else if (is_dev_null(second)) {
 198                 patch->is_new = 0;
 199                 patch->is_delete = 1;
 200                 name = find_name(first, NULL, p_value, TERM_EXIST | TERM_SPACE | TERM_TAB);
 201                 patch->old_name = name;
 202         } else {
 203                 name = find_name(first, NULL, p_value, TERM_EXIST | TERM_SPACE | TERM_TAB);
 204                 name = find_name(second, name, p_value, TERM_EXIST | TERM_SPACE | TERM_TAB);
 205                 patch->old_name = patch->new_name = name;
 206         }
 207         if (!name)
 208                 die("unable to find filename in patch at line %d", linenr);
 209 }
 210
 211 static int gitdiff_hdrend(const char *line, struct patch *patch)
 212 {
 213         return -1;
 214 }
 215
 216 /*
 217  * We're anal about diff header consistency, to make
 218  * sure that we don't end up having strange ambiguous
 219  * patches floating around.
 220  *
 221  * As a result, gitdiff_{old|new}name() will check
 222  * their names against any previous information, just
 223  * to make sure..
 224  */
 225 static char *gitdiff_verify_name(const char *line, int isnull, char *orig_name, const char *oldnew)
 226 {
 227         int len;
 228         const char *name;
 229
 230         if (!orig_name && !isnull)
 231                 return find_name(line, NULL, 1, 0);
 232
 233         name = "/dev/null";
 234         len = 9;
 235         if (orig_name) {
 236                 name = orig_name;
 237                 len = strlen(name);
 238                 if (isnull)
 239                         die("git-apply: bad git-diff - expected /dev/null, got %s on line %d", name, linenr);
 240         }
 241
 242         if (*name == '/')
 243                 goto absolute_path;
 244
 245         for (;;) {
 246                 char c = *line++;
 247                 if (c == '\n')
 248                         break;
 249                 if (c != '/')
 250                         continue;
 251 absolute_path:
 252                 if (memcmp(line, name, len) || line[len] != '\n')
 253                         break;
 254                 return orig_name;
 255         }
 256         die("git-apply: bad git-diff - inconsistent %s filename on line %d", oldnew, linenr);
 257         return NULL;
 258 }
 259
 260 static int gitdiff_oldname(const char *line, struct patch *patch)
 261 {
 262         patch->old_name = gitdiff_verify_name(line, patch->is_new, patch->old_name, "old");
 263         return 0;
 264 }
 265
 266 static int gitdiff_newname(const char *line, struct patch *patch)
 267 {
 268         patch->new_name = gitdiff_verify_name(line, patch->is_delete, patch->new_name, "new");
 269         return 0;
 270 }
 271
 272 static int gitdiff_oldmode(const char *line, struct patch *patch)
 273 {
 274         patch->old_mode = strtoul(line, NULL, 8);
 275         return 0;
 276 }
 277
 278 static int gitdiff_newmode(const char *line, struct patch *patch)
 279 {
 280         patch->new_mode = strtoul(line, NULL, 8);
 281         return 0;
 282 }
 283
 284 static int gitdiff_delete(const char *line, struct patch *patch)
 285 {
 286         patch->is_delete = 1;
 287         patch->old_name = patch->def_name;
 288         return gitdiff_oldmode(line, patch);
 289 }
 290
 291 static int gitdiff_newfile(const char *line, struct patch *patch)
 292 {
 293         patch->is_new = 1;
 294         patch->new_name = patch->def_name;
 295         return gitdiff_newmode(line, patch);
 296 }
 297
 298 static int gitdiff_copysrc(const char *line, struct patch *patch)
 299 {
 300         patch->is_copy = 1;
 301         patch->old_name = find_name(line, NULL, 0, 0);
 302         return 0;
 303 }
 304
 305 static int gitdiff_copydst(const char *line, struct patch *patch)
 306 {
 307         patch->is_copy = 1;
 308         patch->new_name = find_name(line, NULL, 0, 0);
 309         return 0;
 310 }
 311
 312 static int gitdiff_renamesrc(const char *line, struct patch *patch)
 313 {
 314         patch->is_rename = 1;
 315         patch->old_name = find_name(line, NULL, 0, 0);
 316         return 0;
 317 }
 318
 319 static int gitdiff_renamedst(const char *line, struct patch *patch)
 320 {
 321         patch->is_rename = 1;
 322         patch->new_name = find_name(line, NULL, 0, 0);
 323         return 0;
 324 }
 325
 326 static int gitdiff_similarity(const char *line, struct patch *patch)
 327 {
 328         return 0;
 329 }
 330
 331 /*
 332  * This is normal for a diff that doesn't change anything: we'll fall through
 333  * into the next diff. Tell the parser to break out.
 334  */
 335 static int gitdiff_unrecognized(const char *line, struct patch *patch)
 336 {
 337         return -1;
 338 }
 339
 340 static char *git_header_name(char *line)
 341 {
 342         int len;
 343         char *name, *second;
 344
 345         /*
 346          * Find the first '/'
 347          */
 348         name = line;
 349         for (;;) {
 350                 char c = *name++;
 351                 if (c == '\n')
 352                         return NULL;
 353                 if (c == '/')
 354                         break;
 355         }
 356
 357         /*
 358          * We don't accept absolute paths (/dev/null) as possibly valid
 359          */
 360         if (name == line+1)
 361                 return NULL;
 362
 363         /*
 364          * Accept a name only if it shows up twice, exactly the same
 365          * form.
 366          */
 367         for (len = 0 ; ; len++) {
 368                 char c = name[len];
 369
 370                 switch (c) {
 371                 default:
 372                         continue;
 373                 case '\n':
 374                         break;
 375                 case '\t': case ' ':
 376                         second = name+len;
 377                         for (;;) {
 378                                 char c = *second++;
 379                                 if (c == '\n')
 380                                         return NULL;
 381                                 if (c == '/')
 382                                         break;
 383                         }
 384                         if (second[len] == '\n' && !memcmp(name, second, len)) {
 385                                 char *ret = xmalloc(len + 1);
 386                                 memcpy(ret, name, len);
 387                                 ret[len] = 0;
 388                                 return ret;
 389                         }
 390                 }
 391         }
 392         return NULL;
 393 }
 394
 395 /* Verify that we recognize the lines following a git header */
 396 static int parse_git_header(char *line, int len, unsigned int size, struct patch *patch)
 397 {
 398         unsigned long offset;
 399
 400         /* A git diff has explicit new/delete information, so we don't guess */
 401         patch->is_new = 0;
 402         patch->is_delete = 0;
 403
 404         /*
 405          * Some things may not have the old name in the
 406          * rest of the headers anywhere (pure mode changes,
 407          * or removing or adding empty files), so we get
 408          * the default name from the header.
 409          */
 410         patch->def_name = git_header_name(line + strlen("diff --git "));
 411
 412         line += len;
 413         size -= len;
 414         linenr++;
 415         for (offset = len ; size > 0 ; offset += len, size -= len, line += len, linenr++) {
 416                 static const struct opentry {
 417                         const char *str;
 418                         int (*fn)(const char *, struct patch *);
 419                 } optable[] = {
 420                         { "@@ -", gitdiff_hdrend },
 421                         { "--- ", gitdiff_oldname },
 422                         { "+++ ", gitdiff_newname },
 423                         { "old mode ", gitdiff_oldmode },
 424                         { "new mode ", gitdiff_newmode },
 425                         { "deleted file mode ", gitdiff_delete },
 426                         { "new file mode ", gitdiff_newfile },
 427                         { "copy from ", gitdiff_copysrc },
 428                         { "copy to ", gitdiff_copydst },
 429                         { "rename from ", gitdiff_renamesrc },
 430                         { "rename to ", gitdiff_renamedst },
 431                         { "similarity index ", gitdiff_similarity },
 432                         { "", gitdiff_unrecognized },
 433                 };
 434                 int i;
 435
 436                 len = linelen(line, size);
 437                 if (!len || line[len-1] != '\n')
 438                         break;
 439                 for (i = 0; i < sizeof(optable) / sizeof(optable[0]); i++) {
 440                         const struct opentry *p = optable + i;
 441                         int oplen = strlen(p->str);
 442                         if (len < oplen || memcmp(p->str, line, oplen))
 443                                 continue;
 444                         if (p->fn(line + oplen, patch) < 0)
 445                                 return offset;
 446                         break;
 447                 }
 448         }
 449
 450         return offset;
 451 }
 452
 453 static int parse_num(const char *line, unsigned long *p)
 454 {
 455         char *ptr;
 456
 457         if (!isdigit(*line))
 458                 return 0;
 459         *p = strtoul(line, &ptr, 10);
 460         return ptr - line;
 461 }
 462
 463 static int parse_range(const char *line, int len, int offset, const char *expect,
 464                         unsigned long *p1, unsigned long *p2)
 465 {
 466         int digits, ex;
 467
 468         if (offset < 0 || offset >= len)
 469                 return -1;
 470         line += offset;
 471         len -= offset;
 472
 473         digits = parse_num(line, p1);
 474         if (!digits)
 475                 return -1;
 476
 477         offset += digits;
 478         line += digits;
 479         len -= digits;
 480
 481         *p2 = *p1;
 482         if (*line == ',') {
 483                 digits = parse_num(line+1, p2);
 484                 if (!digits)
 485                         return -1;
 486
 487                 offset += digits+1;
 488                 line += digits+1;
 489                 len -= digits+1;
 490         }
 491
 492         ex = strlen(expect);
 493         if (ex > len)
 494                 return -1;
 495         if (memcmp(line, expect, ex))
 496                 return -1;
 497
 498         return offset + ex;
 499 }
 500
 501 /*
 502  * Parse a unified diff fragment header of the
 503  * form "@@ -a,b +c,d @@"
 504  */
 505 static int parse_fragment_header(char *line, int len, struct fragment *fragment)
 506 {
 507         int offset;
 508
 509         if (!len || line[len-1] != '\n')
 510                 return -1;
 511
 512         /* Figure out the number of lines in a fragment */
 513         offset = parse_range(line, len, 4, " +", &fragment->oldpos, &fragment->oldlines);
 514         offset = parse_range(line, len, offset, " @@", &fragment->newpos, &fragment->newlines);
 515
 516         return offset;
 517 }
 518
 519 static int find_header(char *line, unsigned long size, int *hdrsize, struct patch *patch)
 520 {
 521         unsigned long offset, len;
 522
 523         patch->is_rename = patch->is_copy = 0;
 524         patch->is_new = patch->is_delete = -1;
 525         patch->old_mode = patch->new_mode = 0;
 526         patch->old_name = patch->new_name = NULL;
 527         for (offset = 0; size > 0; offset += len, size -= len, line += len, linenr++) {
 528                 unsigned long nextlen;
 529
 530                 len = linelen(line, size);
 531                 if (!len)
 532                         break;
 533
 534                 /* Testing this early allows us to take a few shortcuts.. */
 535                 if (len < 6)
 536                         continue;
 537
 538                 /*
 539                  * Make sure we don't find any unconnected patch fragmants.
 540                  * That's a sign that we didn't find a header, and that a
 541                  * patch has become corrupted/broken up.
 542                  */
 543                 if (!memcmp("@@ -", line, 4)) {
 544                         struct fragment dummy;
 545                         if (parse_fragment_header(line, len, &dummy) < 0)
 546                                 continue;
 547                         error("patch fragment without header at line %d: %.*s", linenr, len-1, line);
 548                 }
 549
 550                 if (size < len + 6)
 551                         break;
 552
 553                 /*
 554                  * Git patch? It might not have a real patch, just a rename
 555                  * or mode change, so we handle that specially
 556                  */
 557                 if (!memcmp("diff --git ", line, 11)) {
 558                         int git_hdr_len = parse_git_header(line, len, size, patch);
 559                         if (git_hdr_len < 0)
 560                                 continue;
 561                         if (!patch->old_name && !patch->new_name)
 562                                 die("git diff header lacks filename information");
 563                         *hdrsize = git_hdr_len;
 564                         return offset;
 565                 }
 566
 567                 /** --- followed by +++ ? */
 568                 if (memcmp("--- ", line,  4) || memcmp("+++ ", line + len, 4))
 569                         continue;
 570
 571                 /*
 572                  * We only accept unified patches, so we want it to
 573                  * at least have "@@ -a,b +c,d @@\n", which is 14 chars
 574                  * minimum
 575                  */
 576                 nextlen = linelen(line + len, size - len);
 577                 if (size < nextlen + 14 || memcmp("@@ -", line + len + nextlen, 4))
 578                         continue;
 579
 580                 /* Ok, we'll consider it a patch */
 581                 parse_traditional_patch(line, line+len, patch);
 582                 *hdrsize = len + nextlen;
 583                 linenr += 2;
 584                 return offset;
 585         }
 586         return -1;
 587 }
 588
 589 /*
 590  * Parse a unified diff. Note that this really needs
 591  * to parse each fragment separately, since the only
 592  * way to know the difference between a "---" that is
 593  * part of a patch, and a "---" that starts the next
 594  * patch is to look at the line counts..
 595  */
 596 static int parse_fragment(char *line, unsigned long size, struct patch *patch, struct fragment *fragment)
 597 {
 598         int added, deleted;
 599         int len = linelen(line, size), offset;
 600         unsigned long pos[4], oldlines, newlines;
 601
 602         offset = parse_fragment_header(line, len, fragment);
 603         if (offset < 0)
 604                 return -1;
 605         oldlines = fragment->oldlines;
 606         newlines = fragment->newlines;
 607
 608         if (patch->is_new < 0 && (pos[0] || oldlines))
 609                 patch->is_new = 0;
 610         if (patch->is_delete < 0 && (pos[1] || newlines))
 611                 patch->is_delete = 0;
 612
 613         /* Parse the thing.. */
 614         line += len;
 615         size -= len;
 616         linenr++;
 617         added = deleted = 0;
 618         for (offset = len; size > 0; offset += len, size -= len, line += len, linenr++) {
 619                 if (!oldlines && !newlines)
 620                         break;
 621                 len = linelen(line, size);
 622                 if (!len || line[len-1] != '\n')
 623                         return -1;
 624                 switch (*line) {
 625                 default:
 626                         return -1;
 627                 case ' ':
 628                         oldlines--;
 629                         newlines--;
 630                         break;
 631                 case '-':
 632                         deleted++;
 633                         oldlines--;
 634                         break;
 635                 case '+':
 636                         added++;
 637                         newlines--;
 638                         break;
 639                 /* We allow "\ No newline at end of file" */
 640                 case '\\':
 641                         break;
 642                 }
 643         }
 644         patch->lines_added += added;
 645         patch->lines_deleted += deleted;
 646         return offset;
 647 }
 648
 649 static int parse_single_patch(char *line, unsigned long size, struct patch *patch)
 650 {
 651         unsigned long offset = 0;
 652         struct fragment **fragp = &patch->fragments;
 653
 654         while (size > 4 && !memcmp(line, "@@ -", 4)) {
 655                 struct fragment *fragment;
 656                 int len;
 657
 658                 fragment = xmalloc(sizeof(*fragment));
 659                 memset(fragment, 0, sizeof(*fragment));
 660                 len = parse_fragment(line, size, patch, fragment);
 661                 if (len <= 0)
 662                         die("corrupt patch at line %d", linenr);
 663
 664                 fragment->patch = line;
 665                 fragment->size = len;
 666
 667                 *fragp = fragment;
 668                 fragp = &fragment->next;
 669
 670                 offset += len;
 671                 line += len;
 672                 size -= len;
 673         }
 674         return offset;
 675 }
 676
 677 static int parse_chunk(char *buffer, unsigned long size, struct patch *patch)
 678 {
 679         int hdrsize, patchsize;
 680         int offset = find_header(buffer, size, &hdrsize, patch);
 681
 682         if (offset < 0)
 683                 return offset;
 684
 685         patchsize = parse_single_patch(buffer + offset + hdrsize, size - offset - hdrsize, patch);
 686
 687         return offset + hdrsize + patchsize;
 688 }
 689
 690 const char pluses[] = "++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++";
 691 const char minuses[]= "----------------------------------------------------------------------";
 692
 693 static void show_stats(struct patch *patch)
 694 {
 695         char *name = patch->old_name;
 696         int len, max, add, del;
 697
 698         if (!name)
 699                 name = patch->new_name;
 700
 701         /*
 702          * "scale" the filename
 703          */
 704         len = strlen(name);
 705         max = max_len;
 706         if (max > 50)
 707                 max = 50;
 708         if (len > max)
 709                 name += len - max;
 710         len = max;
 711
 712         /*
 713          * scale the add/delete
 714          */
 715         max = max_change;
 716         if (max + len > 70)
 717                 max = 70 - len;
 718
 719         add = (patch->lines_added * max + max_change/2) / max_change;
 720         del = (patch->lines_deleted * max + max_change/2) / max_change;
 721         printf(" %-*s |%5d %.*s%.*s\n",
 722                 len, name, patch->lines_added + patch->lines_deleted,
 723                 add, pluses, del, minuses);
 724 }
 725
 726 static void check_patch(struct patch *patch)
 727 {
 728         const char *old_name = patch->old_name;
 729         const char *new_name = patch->new_name;
 730
 731         if (old_name) {
 732                 if (cache_name_pos(old_name, strlen(old_name)) < 0)
 733                         die("file %s does not exist", old_name);
 734                 if (patch->is_new < 0)
 735                         patch->is_new = 0;
 736         }
 737         if (new_name && (patch->is_new | patch->is_rename | patch->is_copy)) {
 738                 if (cache_name_pos(new_name, strlen(new_name)) >= 0)
 739                         die("file %s already exists", new_name);
 740         }
 741 }
 742
 743 static void apply_patch_list(struct patch *patch)
 744 {
 745         int files, adds, dels;
 746
 747         files = adds = dels = 0;
 748         if (!patch)
 749                 die("no patch found");
 750         do {
 751                 if (check)
 752                         check_patch(patch);
 753
 754                 if (diffstat) {
 755                         files++;
 756                         adds += patch->lines_added;
 757                         dels += patch->lines_deleted;
 758                         show_stats(patch);
 759                 }
 760         } while ((patch = patch->next) != NULL);
 761
 762         if (diffstat)
 763                 printf(" %d files changed, %d insertions(+), %d deletions(-)\n", files, adds, dels);
 764 }
 765
 766 static void patch_stats(struct patch *patch)
 767 {
 768         int lines = patch->lines_added + patch->lines_deleted;
 769
 770         if (lines > max_change)
 771                 max_change = lines;
 772         if (patch->old_name) {
 773                 int len = strlen(patch->old_name);
 774                 if (len > max_len)
 775                         max_len = len;
 776         }
 777         if (patch->new_name) {
 778                 int len = strlen(patch->new_name);
 779                 if (len > max_len)
 780                         max_len = len;
 781         }
 782 }
 783
 784 static int apply_patch(int fd)
 785 {
 786         unsigned long offset, size;
 787         char *buffer = read_patch_file(fd, &size);
 788         struct patch *list = NULL, **listp = &list;
 789
 790         if (!buffer)
 791                 return -1;
 792         offset = 0;
 793         while (size > 0) {
 794                 struct patch *patch;
 795                 int nr;
 796
 797                 patch = xmalloc(sizeof(*patch));
 798                 memset(patch, 0, sizeof(*patch));
 799                 nr = parse_chunk(buffer + offset, size, patch);
 800                 if (nr < 0)
 801                         break;
 802                 patch_stats(patch);
 803                 *listp = patch;
 804                 listp = &patch->next;
 805                 offset += nr;
 806                 size -= nr;
 807         }
 808
 809         apply_patch_list(list);
 810
 811         free(buffer);
 812         return 0;
 813 }
 814
 815 int main(int argc, char **argv)
 816 {
 817         int i;
 818         int read_stdin = 1;
 819
 820         if (read_cache() < 0)
 821                 die("unable to read index file");
 822
 823         for (i = 1; i < argc; i++) {
 824                 const char *arg = argv[i];
 825                 int fd;
 826
 827                 if (!strcmp(arg, "-")) {
 828                         apply_patch(0);
 829                         read_stdin = 0;
 830                         continue;
 831                 }
 832                 if (!strcmp(arg, "--no-merge")) {
 833                         merge_patch = 0;
 834                         continue;
 835                 }
 836                 if (!strcmp(arg, "--stat")) {
 837                         check = 0;
 838                         diffstat = 1;
 839                         continue;
 840                 }
 841                 fd = open(arg, O_RDONLY);
 842                 if (fd < 0)
 843                         usage(apply_usage);
 844                 read_stdin = 0;
 845                 apply_patch(fd);
 846                 close(fd);
 847         }
 848         if (read_stdin)
 849                 apply_patch(0);
 850         return 0;
 851 }