Andrew's git / gitweb.git / apply.c
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apply.con commit [PATCH] Update git-diff-cache documentation. (b1c006d)
   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
  21static int merge_patch = 1;
  22static const char apply_usage[] = "git-apply <patch>";
  23
  24/*
  25 * Various "current state", notably line numbers and what
  26 * file (and how) we're patching right now.. The "is_xxxx"
  27 * things are flags, where -1 means "don't know yet".
  28 */
  29static int linenr = 1;
  30static int old_mode, new_mode;
  31static char *old_name, *new_name, *def_name;
  32static int is_rename, is_copy, is_new, is_delete;
  33
  34#define CHUNKSIZE (8192)
  35#define SLOP (16)
  36
  37static void *read_patch_file(int fd, unsigned long *sizep)
  38{
  39        unsigned long size = 0, alloc = CHUNKSIZE;
  40        void *buffer = xmalloc(alloc);
  41
  42        for (;;) {
  43                int nr = alloc - size;
  44                if (nr < 1024) {
  45                        alloc += CHUNKSIZE;
  46                        buffer = xrealloc(buffer, alloc);
  47                        nr = alloc - size;
  48                }
  49                nr = read(fd, buffer + size, nr);
  50                if (!nr)
  51                        break;
  52                if (nr < 0) {
  53                        if (errno == EAGAIN)
  54                                continue;
  55                        die("git-apply: read returned %s", strerror(errno));
  56                }
  57                size += nr;
  58        }
  59        *sizep = size;
  60
  61        /*
  62         * Make sure that we have some slop in the buffer
  63         * so that we can do speculative "memcmp" etc, and
  64         * see to it that it is NUL-filled.
  65         */
  66        if (alloc < size + SLOP)
  67                buffer = xrealloc(buffer, size + SLOP);
  68        memset(buffer + size, 0, SLOP);
  69        return buffer;
  70}
  71
  72static unsigned long linelen(char *buffer, unsigned long size)
  73{
  74        unsigned long len = 0;
  75        while (size--) {
  76                len++;
  77                if (*buffer++ == '\n')
  78                        break;
  79        }
  80        return len;
  81}
  82
  83static int is_dev_null(const char *str)
  84{
  85        return !memcmp("/dev/null", str, 9) && isspace(str[9]);
  86}
  87
  88#define TERM_EXIST      1
  89#define TERM_SPACE      2
  90#define TERM_TAB        4
  91
  92static int name_terminate(const char *name, int namelen, int c, int terminate)
  93{
  94        if (c == ' ' && !(terminate & TERM_SPACE))
  95                return 0;
  96        if (c == '\t' && !(terminate & TERM_TAB))
  97                return 0;
  98
  99        /*
 100         * Do we want an existing name? Return false and
 101         * continue if it's not there.
 102         */
 103        if (terminate & TERM_EXIST)
 104                return cache_name_pos(name, namelen) >= 0;
 105
 106        return 1;
 107}
 108
 109static char * find_name(const char *line, char *def, int p_value, int terminate)
 110{
 111        int len;
 112        const char *start = line;
 113        char *name;
 114
 115        for (;;) {
 116                char c = *line;
 117
 118                if (isspace(c)) {
 119                        if (c == '\n')
 120                                break;
 121                        if (name_terminate(start, line-start, c, terminate))
 122                                break;
 123                }
 124                line++;
 125                if (c == '/' && !--p_value)
 126                        start = line;
 127        }
 128        if (!start)
 129                return def;
 130        len = line - start;
 131        if (!len)
 132                return def;
 133
 134        /*
 135         * Generally we prefer the shorter name, especially
 136         * if the other one is just a variation of that with
 137         * something else tacked on to the end (ie "file.orig"
 138         * or "file~").
 139         */
 140        if (def) {
 141                int deflen = strlen(def);
 142                if (deflen < len && !strncmp(start, def, deflen))
 143                        return def;
 144        }
 145
 146        name = xmalloc(len + 1);
 147        memcpy(name, start, len);
 148        name[len] = 0;
 149        free(def);
 150        return name;
 151}
 152
 153/*
 154 * Get the name etc info from the --/+++ lines of a traditional patch header
 155 *
 156 * NOTE! This hardcodes "-p1" behaviour in filename detection.
 157 *
 158 * FIXME! The end-of-filename heuristics are kind of screwy. For existing
 159 * files, we can happily check the index for a match, but for creating a
 160 * new file we should try to match whatever "patch" does. I have no idea.
 161 */
 162static int parse_traditional_patch(const char *first, const char *second)
 163{
 164        int p_value = 1;
 165        char *name;
 166
 167        first += 4;     // skip "--- "
 168        second += 4;    // skip "+++ "
 169        if (is_dev_null(first)) {
 170                is_new = 1;
 171                name = find_name(second, def_name, p_value, TERM_SPACE | TERM_TAB);
 172                new_name = name;
 173        } else if (is_dev_null(second)) {
 174                is_delete = 1;
 175                name = find_name(first, def_name, p_value, TERM_EXIST | TERM_SPACE | TERM_TAB);
 176                old_name = name;
 177        } else {
 178                name = find_name(first, def_name, p_value, TERM_EXIST | TERM_SPACE | TERM_TAB);
 179                name = find_name(second, name, p_value, TERM_EXIST | TERM_SPACE | TERM_TAB);
 180                old_name = new_name = name;
 181        }
 182        if (!name)
 183                die("unable to find filename in patch at line %d", linenr);
 184}
 185
 186static int gitdiff_hdrend(const char *line)
 187{
 188        return -1;
 189}
 190
 191static int gitdiff_oldname(const char *line)
 192{
 193        if (!old_name && !is_new)
 194                old_name = find_name(line, NULL, 1, 0);
 195        return 0;
 196}
 197
 198static int gitdiff_newname(const char *line)
 199{
 200        if (!new_name && !is_delete)
 201                new_name = find_name(line, NULL, 1, 0);
 202        return 0;
 203}
 204
 205static int gitdiff_oldmode(const char *line)
 206{
 207        old_mode = strtoul(line, NULL, 8);
 208        return 0;
 209}
 210
 211static int gitdiff_newmode(const char *line)
 212{
 213        new_mode = strtoul(line, NULL, 8);
 214        return 0;
 215}
 216
 217static int gitdiff_delete(const char *line)
 218{
 219        is_delete = 1;
 220        return gitdiff_oldmode(line);
 221}
 222
 223static int gitdiff_newfile(const char *line)
 224{
 225        is_new = 1;
 226        return gitdiff_newmode(line);
 227}
 228
 229static int gitdiff_copysrc(const char *line)
 230{
 231        is_copy = 1;
 232        old_name = find_name(line, NULL, 0, 0);
 233        return 0;
 234}
 235
 236static int gitdiff_copydst(const char *line)
 237{
 238        is_copy = 1;
 239        new_name = find_name(line, NULL, 0, 0);
 240        return 0;
 241}
 242
 243static int gitdiff_renamesrc(const char *line)
 244{
 245        is_rename = 1;
 246        old_name = find_name(line, NULL, 0, 0);
 247        return 0;
 248}
 249
 250static int gitdiff_renamedst(const char *line)
 251{
 252        is_rename = 1;
 253        new_name = find_name(line, NULL, 0, 0);
 254        return 0;
 255}
 256
 257static int gitdiff_similarity(const char *line)
 258{
 259        return 0;
 260}
 261
 262/*
 263 * This is normal for a diff that doesn't change anything: we'll fall through
 264 * into the next diff. Tell the parser to break out.
 265 */
 266static int gitdiff_unrecognized(const char *line)
 267{
 268        return -1;
 269}
 270
 271/* Verify that we recognize the lines following a git header */
 272static int parse_git_header(char *line, int len, unsigned int size)
 273{
 274        unsigned long offset;
 275
 276        /* A git diff has explicit new/delete information, so we don't guess */
 277        is_new = 0;
 278        is_delete = 0;
 279
 280        line += len;
 281        size -= len;
 282        linenr++;
 283        for (offset = len ; size > 0 ; offset += len, size -= len, line += len, linenr++) {
 284                static const struct opentry {
 285                        const char *str;
 286                        int (*fn)(const char *);
 287                } optable[] = {
 288                        { "@@ -", gitdiff_hdrend },
 289                        { "--- ", gitdiff_oldname },
 290                        { "+++ ", gitdiff_newname },
 291                        { "old mode ", gitdiff_oldmode },
 292                        { "new mode ", gitdiff_newmode },
 293                        { "deleted file mode ", gitdiff_delete },
 294                        { "new file mode ", gitdiff_newfile },
 295                        { "copy from ", gitdiff_copysrc },
 296                        { "copy to ", gitdiff_copydst },
 297                        { "rename from ", gitdiff_renamesrc },
 298                        { "rename to ", gitdiff_renamedst },
 299                        { "similarity index ", gitdiff_similarity },
 300                        { "", gitdiff_unrecognized },
 301                };
 302                int i;
 303
 304                len = linelen(line, size);
 305                if (!len || line[len-1] != '\n')
 306                        break;
 307                for (i = 0; i < sizeof(optable) / sizeof(optable[0]); i++) {
 308                        const struct opentry *p = optable + i;
 309                        int oplen = strlen(p->str);
 310                        if (len < oplen || memcmp(p->str, line, oplen))
 311                                continue;
 312                        if (p->fn(line + oplen) < 0)
 313                                return offset;
 314                        break;
 315                }
 316        }
 317
 318        return offset;
 319}
 320
 321static int parse_num(const char *line, int len, int offset, const char *expect, unsigned long *p)
 322{
 323        char *ptr;
 324        int digits, ex;
 325
 326        if (offset < 0 || offset >= len)
 327                return -1;
 328        line += offset;
 329        len -= offset;
 330
 331        if (!isdigit(*line))
 332                return -1;
 333        *p = strtoul(line, &ptr, 10);
 334
 335        digits = ptr - line;
 336
 337        offset += digits;
 338        line += digits;
 339        len -= digits;
 340
 341        ex = strlen(expect);
 342        if (ex > len)
 343                return -1;
 344        if (memcmp(line, expect, ex))
 345                return -1;
 346
 347        return offset + ex;
 348}
 349
 350/*
 351 * Parse a unified diff fragment header of the
 352 * form "@@ -a,b +c,d @@"
 353 */
 354static int parse_fragment_header(char *line, int len, unsigned long *pos)
 355{
 356        int offset;
 357
 358        if (!len || line[len-1] != '\n')
 359                return -1;
 360
 361        /* Figure out the number of lines in a fragment */
 362        offset = parse_num(line, len, 4, ",", pos);
 363        offset = parse_num(line, len, offset, " +", pos+1);
 364        offset = parse_num(line, len, offset, ",", pos+2);
 365        offset = parse_num(line, len, offset, " @@", pos+3);
 366
 367        return offset;
 368}
 369
 370static int find_header(char *line, unsigned long size, int *hdrsize)
 371{
 372        unsigned long offset, len;
 373
 374        is_rename = is_copy = 0;
 375        is_new = is_delete = -1;
 376        old_mode = new_mode = 0;
 377        def_name = old_name = new_name = NULL;
 378        for (offset = 0; size > 0; offset += len, size -= len, line += len, linenr++) {
 379                unsigned long nextlen;
 380
 381                len = linelen(line, size);
 382                if (!len)
 383                        break;
 384
 385                /* Testing this early allows us to take a few shortcuts.. */
 386                if (len < 6)
 387                        continue;
 388
 389                /*
 390                 * Make sure we don't find any unconnected patch fragmants.
 391                 * That's a sign that we didn't find a header, and that a
 392                 * patch has become corrupted/broken up.
 393                 */
 394                if (!memcmp("@@ -", line, 4)) {
 395                        unsigned long pos[4];
 396                        if (parse_fragment_header(line, len, pos) < 0)
 397                                continue;
 398                        error("patch fragment without header at line %d: %.*s", linenr, len-1, line);
 399                }
 400
 401                if (size < len + 6)
 402                        break;
 403
 404                /*
 405                 * Git patch? It might not have a real patch, just a rename
 406                 * or mode change, so we handle that specially
 407                 */
 408                if (!memcmp("diff --git ", line, 11)) {
 409                        int git_hdr_len = parse_git_header(line, len, size);
 410                        if (git_hdr_len < 0)
 411                                continue;
 412
 413                        *hdrsize = git_hdr_len;
 414                        return offset;
 415                }
 416
 417                /** --- followed by +++ ? */
 418                if (memcmp("--- ", line,  4) || memcmp("+++ ", line + len, 4))
 419                        continue;
 420
 421                /*
 422                 * We only accept unified patches, so we want it to
 423                 * at least have "@@ -a,b +c,d @@\n", which is 14 chars
 424                 * minimum
 425                 */
 426                nextlen = linelen(line + len, size - len);
 427                if (size < nextlen + 14 || memcmp("@@ -", line + len + nextlen, 4))
 428                        continue;
 429
 430                /* Ok, we'll consider it a patch */
 431                parse_traditional_patch(line, line+len);
 432                *hdrsize = len + nextlen;
 433                linenr += 2;
 434                return offset;
 435        }
 436        return -1;
 437}
 438
 439/*
 440 * Parse a unified diff. Note that this really needs
 441 * to parse each fragment separately, since the only
 442 * way to know the difference between a "---" that is
 443 * part of a patch, and a "---" that starts the next
 444 * patch is to look at the line counts..
 445 */
 446static int apply_fragment(char *line, unsigned long size)
 447{
 448        int len = linelen(line, size), offset;
 449        unsigned long pos[4], oldlines, newlines;
 450
 451        offset = parse_fragment_header(line, len, pos);
 452        if (offset < 0)
 453                return -1;
 454        oldlines = pos[1];
 455        newlines = pos[3];
 456
 457        if (is_new < 0 && (pos[0] || oldlines))
 458                is_new = 0;
 459        if (is_delete < 0 && (pos[1] || newlines))
 460                is_delete = 0;
 461
 462        /* Parse the thing.. */
 463        line += len;
 464        size -= len;
 465        linenr++;
 466        for (offset = len; size > 0; offset += len, size -= len, line += len, linenr++) {
 467                if (!oldlines && !newlines)
 468                        break;
 469                len = linelen(line, size);
 470                if (!len || line[len-1] != '\n')
 471                        return -1;
 472                switch (*line) {
 473                default:
 474                        return -1;
 475                case ' ':
 476                        oldlines--;
 477                        newlines--;
 478                        break;
 479                case '-':
 480                        oldlines--;
 481                        break;
 482                case '+':
 483                        newlines--;
 484                        break;
 485                }
 486        }
 487        return offset;
 488}
 489
 490static int apply_single_patch(char *line, unsigned long size)
 491{
 492        unsigned long offset = 0;
 493
 494        while (size > 4 && !memcmp(line, "@@ -", 4)) {
 495                int len = apply_fragment(line, size);
 496                if (len <= 0)
 497                        die("corrupt patch at line %d", linenr);
 498
 499printf("applying fragment:\n%.*s\n\n", len, line);
 500
 501                offset += len;
 502                line += len;
 503                size -= len;
 504        }
 505        return offset;
 506}
 507
 508static int apply_chunk(char *buffer, unsigned long size)
 509{
 510        int hdrsize, patchsize;
 511        int offset = find_header(buffer, size, &hdrsize);
 512        char *header, *patch;
 513
 514        if (offset < 0)
 515                return offset;
 516        header = buffer + offset;
 517
 518printf("Found header:\n%.*s\n\n", hdrsize, header);
 519printf("Rename: %d\n", is_rename);
 520printf("Copy:   %d\n", is_copy);
 521printf("New:    %d\n", is_new);
 522printf("Delete: %d\n", is_delete);
 523printf("Mode:   %o:%o\n", old_mode, new_mode);
 524printf("Name:   '%s':'%s'\n", old_name, new_name);
 525
 526        if (old_name && cache_name_pos(old_name, strlen(old_name)) < 0)
 527                die("file %s does not exist", old_name);
 528        if (new_name && (is_new | is_rename | is_copy)) {
 529                if (cache_name_pos(new_name, strlen(new_name)) >= 0)
 530                        die("file %s already exists", new_name);
 531        }
 532
 533        patch = header + hdrsize;
 534        patchsize = apply_single_patch(patch, size - offset - hdrsize);
 535
 536        return offset + hdrsize + patchsize;
 537}
 538
 539static int apply_patch(int fd)
 540{
 541        unsigned long offset, size;
 542        char *buffer = read_patch_file(fd, &size);
 543
 544        if (!buffer)
 545                return -1;
 546        offset = 0;
 547        while (size > 0) {
 548                int nr = apply_chunk(buffer + offset, size);
 549                if (nr < 0)
 550                        break;
 551                offset += nr;
 552                size -= nr;
 553        }
 554        free(buffer);
 555        return 0;
 556}
 557
 558int main(int argc, char **argv)
 559{
 560        int i;
 561        int read_stdin = 1;
 562
 563        if (read_cache() < 0)
 564                die("unable to read index file");
 565
 566        for (i = 1; i < argc; i++) {
 567                const char *arg = argv[i];
 568                int fd;
 569
 570                if (!strcmp(arg, "-")) {
 571                        apply_patch(0);
 572                        read_stdin = 0;
 573                        continue;
 574                }
 575                if (!strcmp(arg, "--no-merge")) {
 576                        merge_patch = 0;
 577                        continue;
 578                }
 579                fd = open(arg, O_RDONLY);
 580                if (fd < 0)
 581                        usage(apply_usage);
 582                read_stdin = 0;
 583                apply_patch(fd);
 584                close(fd);
 585        }
 586        if (read_stdin)
 587                apply_patch(0);
 588        return 0;
 589}