diff.c

   1 /*
   2  * Copyright (C) 2005 Junio C Hamano
   3  */
   4 #include <sys/types.h>
   5 #include <sys/wait.h>
   6 #include <signal.h>
   7 #include "cache.h"
   8 #include "diff.h"
   9 #include "diffcore.h"
  10
  11 static const char *diff_opts = "-pu";
  12 static unsigned char null_sha1[20] = { 0, };
  13
  14 static int reverse_diff;
  15 static int use_size_cache;
  16
  17 static const char *external_diff(void)
  18 {
  19         static const char *external_diff_cmd = NULL;
  20         static int done_preparing = 0;
  21
  22         if (done_preparing)
  23                 return external_diff_cmd;
  24
  25         /*
  26          * Default values above are meant to match the
  27          * Linux kernel development style.  Examples of
  28          * alternative styles you can specify via environment
  29          * variables are:
  30          *
  31          * GIT_DIFF_OPTS="-c";
  32          */
  33         if (gitenv("GIT_EXTERNAL_DIFF"))
  34                 external_diff_cmd = gitenv("GIT_EXTERNAL_DIFF");
  35
  36         /* In case external diff fails... */
  37         diff_opts = gitenv("GIT_DIFF_OPTS") ? : diff_opts;
  38
  39         done_preparing = 1;
  40         return external_diff_cmd;
  41 }
  42
  43 /* Help to copy the thing properly quoted for the shell safety.
  44  * any single quote is replaced with '\'', and the caller is
  45  * expected to enclose the result within a single quote pair.
  46  *
  47  * E.g.
  48  *  original     sq_expand     result
  49  *  name     ==> name      ==> 'name'
  50  *  a b      ==> a b       ==> 'a b'
  51  *  a'b      ==> a'\''b    ==> 'a'\''b'
  52  */
  53 static char *sq_expand(const char *src)
  54 {
  55         static char *buf = NULL;
  56         int cnt, c;
  57         const char *cp;
  58         char *bp;
  59
  60         /* count bytes needed to store the quoted string. */
  61         for (cnt = 1, cp = src; *cp; cnt++, cp++)
  62                 if (*cp == '\'')
  63                         cnt += 3;
  64
  65         buf = xmalloc(cnt);
  66         bp = buf;
  67         while ((c = *src++)) {
  68                 if (c != '\'')
  69                         *bp++ = c;
  70                 else {
  71                         bp = strcpy(bp, "'\\''");
  72                         bp += 4;
  73                 }
  74         }
  75         *bp = 0;
  76         return buf;
  77 }
  78
  79 static struct diff_tempfile {
  80         const char *name; /* filename external diff should read from */
  81         char hex[41];
  82         char mode[10];
  83         char tmp_path[50];
  84 } diff_temp[2];
  85
  86 static void builtin_diff(const char *name_a,
  87                          const char *name_b,
  88                          struct diff_tempfile *temp,
  89                          const char *xfrm_msg)
  90 {
  91         int i, next_at, cmd_size;
  92         const char *diff_cmd = "diff -L'%s%s' -L'%s%s'";
  93         const char *diff_arg  = "'%s' '%s'||:"; /* "||:" is to return 0 */
  94         const char *input_name_sq[2];
  95         const char *path0[2];
  96         const char *path1[2];
  97         const char *name_sq[2];
  98         char *cmd;
  99
 100         name_sq[0] = sq_expand(name_a);
 101         name_sq[1] = sq_expand(name_b);
 102
 103         /* diff_cmd and diff_arg have 6 %s in total which makes
 104          * the sum of these strings 12 bytes larger than required.
 105          * we use 2 spaces around diff-opts, and we need to count
 106          * terminating NUL, so we subtract 9 here.
 107          */
 108         cmd_size = (strlen(diff_cmd) + strlen(diff_opts) +
 109                         strlen(diff_arg) - 9);
 110         for (i = 0; i < 2; i++) {
 111                 input_name_sq[i] = sq_expand(temp[i].name);
 112                 if (!strcmp(temp[i].name, "/dev/null")) {
 113                         path0[i] = "/dev/null";
 114                         path1[i] = "";
 115                 } else {
 116                         path0[i] = i ? "b/" : "a/";
 117                         path1[i] = name_sq[i];
 118                 }
 119                 cmd_size += (strlen(path0[i]) + strlen(path1[i]) +
 120                              strlen(input_name_sq[i]));
 121         }
 122
 123         cmd = xmalloc(cmd_size);
 124
 125         next_at = 0;
 126         next_at += snprintf(cmd+next_at, cmd_size-next_at,
 127                             diff_cmd,
 128                             path0[0], path1[0], path0[1], path1[1]);
 129         next_at += snprintf(cmd+next_at, cmd_size-next_at,
 130                             " %s ", diff_opts);
 131         next_at += snprintf(cmd+next_at, cmd_size-next_at,
 132                             diff_arg, input_name_sq[0], input_name_sq[1]);
 133
 134         printf("diff --git a/%s b/%s\n", name_a, name_b);
 135         if (!path1[0][0])
 136                 printf("new file mode %s\n", temp[1].mode);
 137         else if (!path1[1][0])
 138                 printf("deleted file mode %s\n", temp[0].mode);
 139         else {
 140                 if (strcmp(temp[0].mode, temp[1].mode)) {
 141                         printf("old mode %s\n", temp[0].mode);
 142                         printf("new mode %s\n", temp[1].mode);
 143                 }
 144                 if (xfrm_msg && xfrm_msg[0])
 145                         puts(xfrm_msg);
 146
 147                 if (strncmp(temp[0].mode, temp[1].mode, 3))
 148                         /* we do not run diff between different kind
 149                          * of objects.
 150                          */
 151                         exit(0);
 152         }
 153         fflush(NULL);
 154         execlp("/bin/sh","sh", "-c", cmd, NULL);
 155 }
 156
 157 struct diff_filespec *alloc_filespec(const char *path)
 158 {
 159         int namelen = strlen(path);
 160         struct diff_filespec *spec = xmalloc(sizeof(*spec) + namelen + 1);
 161         spec->path = (char *)(spec + 1);
 162         strcpy(spec->path, path);
 163         spec->should_free = spec->should_munmap = 0;
 164         spec->xfrm_flags = 0;
 165         spec->size = 0;
 166         spec->data = NULL;
 167         spec->mode = 0;
 168         memset(spec->sha1, 0, 20);
 169         return spec;
 170 }
 171
 172 void fill_filespec(struct diff_filespec *spec, const unsigned char *sha1,
 173                    unsigned short mode)
 174 {
 175         if (mode) {
 176                 spec->mode = DIFF_FILE_CANON_MODE(mode);
 177                 memcpy(spec->sha1, sha1, 20);
 178                 spec->sha1_valid = !!memcmp(sha1, null_sha1, 20);
 179         }
 180 }
 181
 182 /*
 183  * Given a name and sha1 pair, if the dircache tells us the file in
 184  * the work tree has that object contents, return true, so that
 185  * prepare_temp_file() does not have to inflate and extract.
 186  */
 187 static int work_tree_matches(const char *name, const unsigned char *sha1)
 188 {
 189         struct cache_entry *ce;
 190         struct stat st;
 191         int pos, len;
 192
 193         /* We do not read the cache ourselves here, because the
 194          * benchmark with my previous version that always reads cache
 195          * shows that it makes things worse for diff-tree comparing
 196          * two linux-2.6 kernel trees in an already checked out work
 197          * tree.  This is because most diff-tree comparisons deal with
 198          * only a small number of files, while reading the cache is
 199          * expensive for a large project, and its cost outweighs the
 200          * savings we get by not inflating the object to a temporary
 201          * file.  Practically, this code only helps when we are used
 202          * by diff-cache --cached, which does read the cache before
 203          * calling us.
 204          */
 205         if (!active_cache)
 206                 return 0;
 207
 208         len = strlen(name);
 209         pos = cache_name_pos(name, len);
 210         if (pos < 0)
 211                 return 0;
 212         ce = active_cache[pos];
 213         if ((lstat(name, &st) < 0) ||
 214             !S_ISREG(st.st_mode) || /* careful! */
 215             ce_match_stat(ce, &st) ||
 216             memcmp(sha1, ce->sha1, 20))
 217                 return 0;
 218         /* we return 1 only when we can stat, it is a regular file,
 219          * stat information matches, and sha1 recorded in the cache
 220          * matches.  I.e. we know the file in the work tree really is
 221          * the same as the <name, sha1> pair.
 222          */
 223         return 1;
 224 }
 225
 226 static struct sha1_size_cache {
 227         unsigned char sha1[20];
 228         unsigned long size;
 229 } **sha1_size_cache;
 230 static int sha1_size_cache_nr, sha1_size_cache_alloc;
 231
 232 static struct sha1_size_cache *locate_size_cache(unsigned char *sha1,
 233                                                  unsigned long size)
 234 {
 235         int first, last;
 236         struct sha1_size_cache *e;
 237
 238         first = 0;
 239         last = sha1_size_cache_nr;
 240         while (last > first) {
 241                 int next = (last + first) >> 1;
 242                 e = sha1_size_cache[next];
 243                 int cmp = memcmp(e->sha1, sha1, 20);
 244                 if (!cmp)
 245                         return e;
 246                 if (cmp < 0) {
 247                         last = next;
 248                         continue;
 249                 }
 250                 first = next+1;
 251         }
 252         /* not found */
 253         if (size == UINT_MAX)
 254                 return NULL;
 255         /* insert to make it at "first" */
 256         if (sha1_size_cache_alloc <= sha1_size_cache_nr) {
 257                 sha1_size_cache_alloc = alloc_nr(sha1_size_cache_alloc);
 258                 sha1_size_cache = xrealloc(sha1_size_cache,
 259                                            sha1_size_cache_alloc *
 260                                            sizeof(*sha1_size_cache));
 261         }
 262         sha1_size_cache_nr++;
 263         if (first < sha1_size_cache_nr)
 264                 memmove(sha1_size_cache + first + 1, sha1_size_cache + first,
 265                         (sha1_size_cache_nr - first - 1) *
 266                         sizeof(*sha1_size_cache));
 267         e = xmalloc(sizeof(struct sha1_size_cache));
 268         sha1_size_cache[first] = e;
 269         memcpy(e->sha1, sha1, 20);
 270         e->size = size;
 271         return e;
 272 }
 273
 274 /*
 275  * While doing rename detection and pickaxe operation, we may need to
 276  * grab the data for the blob (or file) for our own in-core comparison.
 277  * diff_filespec has data and size fields for this purpose.
 278  */
 279 int diff_populate_filespec(struct diff_filespec *s, int size_only)
 280 {
 281         int err = 0;
 282         if (!DIFF_FILE_VALID(s))
 283                 die("internal error: asking to populate invalid file.");
 284         if (S_ISDIR(s->mode))
 285                 return -1;
 286
 287         if (!use_size_cache)
 288                 size_only = 0;
 289
 290         if (s->data)
 291                 return err;
 292         if (!s->sha1_valid ||
 293             work_tree_matches(s->path, s->sha1)) {
 294                 struct stat st;
 295                 int fd;
 296                 if (lstat(s->path, &st) < 0) {
 297                         if (errno == ENOENT) {
 298                         err_empty:
 299                                 err = -1;
 300                         empty:
 301                                 s->data = "";
 302                                 s->size = 0;
 303                                 return err;
 304                         }
 305                 }
 306                 s->size = st.st_size;
 307                 if (!s->size)
 308                         goto empty;
 309                 if (size_only)
 310                         return 0;
 311                 if (S_ISLNK(st.st_mode)) {
 312                         int ret;
 313                         s->data = xmalloc(s->size);
 314                         s->should_free = 1;
 315                         ret = readlink(s->path, s->data, s->size);
 316                         if (ret < 0) {
 317                                 free(s->data);
 318                                 goto err_empty;
 319                         }
 320                         return 0;
 321                 }
 322                 fd = open(s->path, O_RDONLY);
 323                 if (fd < 0)
 324                         goto err_empty;
 325                 s->data = mmap(NULL, s->size, PROT_READ, MAP_PRIVATE, fd, 0);
 326                 s->should_munmap = 1;
 327                 close(fd);
 328         }
 329         else {
 330                 /* We cannot do size only for SHA1 blobs */
 331                 char type[20];
 332                 struct sha1_size_cache *e;
 333
 334                 if (size_only) {
 335                         e = locate_size_cache(s->sha1, UINT_MAX);
 336                         if (e) {
 337                                 s->size = e->size;
 338                                 return 0;
 339                         }
 340                 }
 341                 s->data = read_sha1_file(s->sha1, type, &s->size);
 342                 s->should_free = 1;
 343                 if (s->data && size_only)
 344                         locate_size_cache(s->sha1, s->size);
 345         }
 346         return 0;
 347 }
 348
 349 void diff_free_filespec_data(struct diff_filespec *s)
 350 {
 351         if (s->should_free)
 352                 free(s->data);
 353         else if (s->should_munmap)
 354                 munmap(s->data, s->size);
 355         s->should_free = s->should_munmap = 0;
 356         s->data = NULL;
 357 }
 358
 359 static void prep_temp_blob(struct diff_tempfile *temp,
 360                            void *blob,
 361                            unsigned long size,
 362                            unsigned char *sha1,
 363                            int mode)
 364 {
 365         int fd;
 366
 367         strcpy(temp->tmp_path, ".diff_XXXXXX");
 368         fd = mkstemp(temp->tmp_path);
 369         if (fd < 0)
 370                 die("unable to create temp-file");
 371         if (write(fd, blob, size) != size)
 372                 die("unable to write temp-file");
 373         close(fd);
 374         temp->name = temp->tmp_path;
 375         strcpy(temp->hex, sha1_to_hex(sha1));
 376         temp->hex[40] = 0;
 377         sprintf(temp->mode, "%06o", mode);
 378 }
 379
 380 static void prepare_temp_file(const char *name,
 381                               struct diff_tempfile *temp,
 382                               struct diff_filespec *one)
 383 {
 384         if (!DIFF_FILE_VALID(one)) {
 385         not_a_valid_file:
 386                 /* A '-' entry produces this for file-2, and
 387                  * a '+' entry produces this for file-1.
 388                  */
 389                 temp->name = "/dev/null";
 390                 strcpy(temp->hex, ".");
 391                 strcpy(temp->mode, ".");
 392                 return;
 393         }
 394
 395         if (!one->sha1_valid ||
 396             work_tree_matches(name, one->sha1)) {
 397                 struct stat st;
 398                 if (lstat(name, &st) < 0) {
 399                         if (errno == ENOENT)
 400                                 goto not_a_valid_file;
 401                         die("stat(%s): %s", name, strerror(errno));
 402                 }
 403                 if (S_ISLNK(st.st_mode)) {
 404                         int ret;
 405                         char *buf, buf_[1024];
 406                         buf = ((sizeof(buf_) < st.st_size) ?
 407                                xmalloc(st.st_size) : buf_);
 408                         ret = readlink(name, buf, st.st_size);
 409                         if (ret < 0)
 410                                 die("readlink(%s)", name);
 411                         prep_temp_blob(temp, buf, st.st_size,
 412                                        (one->sha1_valid ?
 413                                         one->sha1 : null_sha1),
 414                                        (one->sha1_valid ?
 415                                         one->mode : S_IFLNK));
 416                 }
 417                 else {
 418                         /* we can borrow from the file in the work tree */
 419                         temp->name = name;
 420                         if (!one->sha1_valid)
 421                                 strcpy(temp->hex, sha1_to_hex(null_sha1));
 422                         else
 423                                 strcpy(temp->hex, sha1_to_hex(one->sha1));
 424                         sprintf(temp->mode, "%06o",
 425                                 S_IFREG |ce_permissions(st.st_mode));
 426                 }
 427                 return;
 428         }
 429         else {
 430                 if (diff_populate_filespec(one, 0))
 431                         die("cannot read data blob for %s", one->path);
 432                 prep_temp_blob(temp, one->data, one->size,
 433                                one->sha1, one->mode);
 434         }
 435 }
 436
 437 static void remove_tempfile(void)
 438 {
 439         int i;
 440
 441         for (i = 0; i < 2; i++)
 442                 if (diff_temp[i].name == diff_temp[i].tmp_path) {
 443                         unlink(diff_temp[i].name);
 444                         diff_temp[i].name = NULL;
 445                 }
 446 }
 447
 448 static void remove_tempfile_on_signal(int signo)
 449 {
 450         remove_tempfile();
 451 }
 452
 453 /* An external diff command takes:
 454  *
 455  * diff-cmd name infile1 infile1-sha1 infile1-mode \
 456  *               infile2 infile2-sha1 infile2-mode [ rename-to ]
 457  *
 458  */
 459 static void run_external_diff(const char *pgm,
 460                               const char *name,
 461                               const char *other,
 462                               struct diff_filespec *one,
 463                               struct diff_filespec *two,
 464                               const char *xfrm_msg)
 465 {
 466         struct diff_tempfile *temp = diff_temp;
 467         pid_t pid;
 468         int status;
 469         static int atexit_asked = 0;
 470
 471         if (one && two) {
 472                 prepare_temp_file(name, &temp[0], one);
 473                 prepare_temp_file(other ? : name, &temp[1], two);
 474                 if (! atexit_asked &&
 475                     (temp[0].name == temp[0].tmp_path ||
 476                      temp[1].name == temp[1].tmp_path)) {
 477                         atexit_asked = 1;
 478                         atexit(remove_tempfile);
 479                 }
 480                 signal(SIGINT, remove_tempfile_on_signal);
 481         }
 482
 483         fflush(NULL);
 484         pid = fork();
 485         if (pid < 0)
 486                 die("unable to fork");
 487         if (!pid) {
 488                 if (pgm) {
 489                         if (one && two) {
 490                                 const char *exec_arg[10];
 491                                 const char **arg = &exec_arg[0];
 492                                 *arg++ = pgm;
 493                                 *arg++ = name;
 494                                 *arg++ = temp[0].name;
 495                                 *arg++ = temp[0].hex;
 496                                 *arg++ = temp[0].mode;
 497                                 *arg++ = temp[1].name;
 498                                 *arg++ = temp[1].hex;
 499                                 *arg++ = temp[1].mode;
 500                                 if (other) {
 501                                         *arg++ = other;
 502                                         *arg++ = xfrm_msg;
 503                                 }
 504                                 *arg = NULL;
 505                                 execvp(pgm, (char *const*) exec_arg);
 506                         }
 507                         else
 508                                 execlp(pgm, pgm, name, NULL);
 509                 }
 510                 /*
 511                  * otherwise we use the built-in one.
 512                  */
 513                 if (one && two)
 514                         builtin_diff(name, other ? : name, temp, xfrm_msg);
 515                 else
 516                         printf("* Unmerged path %s\n", name);
 517                 exit(0);
 518         }
 519         if (waitpid(pid, &status, 0) < 0 ||
 520             !WIFEXITED(status) || WEXITSTATUS(status)) {
 521                 /* Earlier we did not check the exit status because
 522                  * diff exits non-zero if files are different, and
 523                  * we are not interested in knowing that.  It was a
 524                  * mistake which made it harder to quit a diff-*
 525                  * session that uses the git-apply-patch-script as
 526                  * the GIT_EXTERNAL_DIFF.  A custom GIT_EXTERNAL_DIFF
 527                  * should also exit non-zero only when it wants to
 528                  * abort the entire diff-* session.
 529                  */
 530                 remove_tempfile();
 531                 fprintf(stderr, "external diff died, stopping at %s.\n", name);
 532                 exit(1);
 533         }
 534         remove_tempfile();
 535 }
 536
 537 static void run_diff(const char *name,
 538                      const char *other,
 539                      struct diff_filespec *one,
 540                      struct diff_filespec *two,
 541                      const char *xfrm_msg)
 542 {
 543         const char *pgm = external_diff();
 544         if (!pgm &&
 545             DIFF_FILE_VALID(one) && DIFF_FILE_VALID(two) &&
 546             (S_IFMT & one->mode) != (S_IFMT & two->mode)) {
 547                 /* a filepair that changes between file and symlink
 548                  * needs to be split into deletion and creation.
 549                  */
 550                 struct diff_filespec *null = alloc_filespec(two->path);
 551                 run_external_diff(NULL, name, other, one, null, xfrm_msg);
 552                 free(null);
 553                 null = alloc_filespec(one->path);
 554                 run_external_diff(NULL, name, other, null, two, xfrm_msg);
 555                 free(null);
 556         }
 557         else
 558                 run_external_diff(pgm, name, other, one, two, xfrm_msg);
 559 }
 560
 561 void diff_setup(int flags)
 562 {
 563         if (flags & DIFF_SETUP_REVERSE)
 564                 reverse_diff = 1;
 565         if (flags & DIFF_SETUP_USE_CACHE) {
 566                 if (!active_cache)
 567                         /* read-cache does not die even when it fails
 568                          * so it is safe for us to do this here.  Also
 569                          * it does not smudge active_cache or active_nr
 570                          * when it fails, so we do not have to worry about
 571                          * cleaning it up oufselves either.
 572                          */
 573                         read_cache();
 574         }
 575         if (flags & DIFF_SETUP_USE_SIZE_CACHE)
 576                 use_size_cache = 1;
 577
 578 }
 579
 580 struct diff_queue_struct diff_queued_diff;
 581
 582 void diff_q(struct diff_queue_struct *queue, struct diff_filepair *dp)
 583 {
 584         if (queue->alloc <= queue->nr) {
 585                 queue->alloc = alloc_nr(queue->alloc);
 586                 queue->queue = xrealloc(queue->queue,
 587                                         sizeof(dp) * queue->alloc);
 588         }
 589         queue->queue[queue->nr++] = dp;
 590 }
 591
 592 struct diff_filepair *diff_queue(struct diff_queue_struct *queue,
 593                                  struct diff_filespec *one,
 594                                  struct diff_filespec *two)
 595 {
 596         struct diff_filepair *dp = xmalloc(sizeof(*dp));
 597         dp->one = one;
 598         dp->two = two;
 599         dp->score = 0;
 600         dp->source_stays = 0;
 601         diff_q(queue, dp);
 602         return dp;
 603 }
 604
 605 void diff_free_filepair(struct diff_filepair *p)
 606 {
 607         diff_free_filespec_data(p->one);
 608         diff_free_filespec_data(p->two);
 609         free(p);
 610 }
 611
 612 static void diff_flush_raw(struct diff_filepair *p,
 613                            int line_termination,
 614                            int inter_name_termination)
 615 {
 616         int two_paths;
 617         char status[10];
 618
 619         if (line_termination) {
 620                 const char *err = "path %s cannot be expressed without -z";
 621                 if (strchr(p->one->path, line_termination) ||
 622                     strchr(p->one->path, inter_name_termination))
 623                         die(err, p->one->path);
 624                 if (strchr(p->two->path, line_termination) ||
 625                     strchr(p->two->path, inter_name_termination))
 626                         die(err, p->two->path);
 627         }
 628
 629         switch (p->status) {
 630         case 'C': case 'R':
 631                 two_paths = 1;
 632                 sprintf(status, "%c%03d", p->status,
 633                         (int)(0.5 + p->score * 100.0/MAX_SCORE));
 634                 break;
 635         default:
 636                 two_paths = 0;
 637                 status[0] = p->status;
 638                 status[1] = 0;
 639                 break;
 640         }
 641         printf(":%06o %06o %s ",
 642                p->one->mode, p->two->mode, sha1_to_hex(p->one->sha1));
 643         printf("%s %s%c%s",
 644                sha1_to_hex(p->two->sha1),
 645                status,
 646                inter_name_termination,
 647                p->one->path);
 648         if (two_paths)
 649                 printf("%c%s", inter_name_termination, p->two->path);
 650         putchar(line_termination);
 651 }
 652
 653 int diff_unmodified_pair(struct diff_filepair *p)
 654 {
 655         /* This function is written stricter than necessary to support
 656          * the currently implemented transformers, but the idea is to
 657          * let transformers to produce diff_filepairs any way they want,
 658          * and filter and clean them up here before producing the output.
 659          */
 660         struct diff_filespec *one, *two;
 661
 662         if (DIFF_PAIR_UNMERGED(p))
 663                 return 0; /* unmerged is interesting */
 664
 665         one = p->one;
 666         two = p->two;
 667
 668         /* deletion, addition, mode or type change
 669          * and rename are all interesting.
 670          */
 671         if (DIFF_FILE_VALID(one) != DIFF_FILE_VALID(two) ||
 672             DIFF_PAIR_MODE_CHANGED(p) ||
 673             strcmp(one->path, two->path))
 674                 return 0;
 675
 676         /* both are valid and point at the same path.  that is, we are
 677          * dealing with a change.
 678          */
 679         if (one->sha1_valid && two->sha1_valid &&
 680             !memcmp(one->sha1, two->sha1, sizeof(one->sha1)))
 681                 return 1; /* no change */
 682         if (!one->sha1_valid && !two->sha1_valid)
 683                 return 1; /* both look at the same file on the filesystem. */
 684         return 0;
 685 }
 686
 687 static void diff_flush_patch(struct diff_filepair *p)
 688 {
 689         const char *name, *other;
 690         char msg_[PATH_MAX*2+200], *msg;
 691
 692         if (diff_unmodified_pair(p))
 693                 return;
 694
 695         name = p->one->path;
 696         other = (strcmp(name, p->two->path) ? p->two->path : NULL);
 697         if ((DIFF_FILE_VALID(p->one) && S_ISDIR(p->one->mode)) ||
 698             (DIFF_FILE_VALID(p->two) && S_ISDIR(p->two->mode)))
 699                 return; /* no tree diffs in patch format */
 700
 701         switch (p->status) {
 702         case 'C':
 703                 sprintf(msg_,
 704                         "similarity index %d%%\n"
 705                         "copy from %s\n"
 706                         "copy to %s",
 707                         (int)(0.5 + p->score * 100.0/MAX_SCORE),
 708                         p->one->path, p->two->path);
 709                 msg = msg_;
 710                 break;
 711         case 'R':
 712                 sprintf(msg_,
 713                         "similarity index %d%%\n"
 714                         "rename old %s\n"
 715                         "rename new %s",
 716                         (int)(0.5 + p->score * 100.0/MAX_SCORE),
 717                         p->one->path, p->two->path);
 718                 msg = msg_;
 719                 break;
 720         default:
 721                 msg = NULL;
 722         }
 723
 724         if (DIFF_PAIR_UNMERGED(p))
 725                 run_diff(name, NULL, NULL, NULL, NULL);
 726         else
 727                 run_diff(name, other, p->one, p->two, msg);
 728 }
 729
 730 int diff_queue_is_empty(void)
 731 {
 732         struct diff_queue_struct *q = &diff_queued_diff;
 733         int i;
 734         for (i = 0; i < q->nr; i++)
 735                 if (!diff_unmodified_pair(q->queue[i]))
 736                         return 0;
 737         return 1;
 738 }
 739
 740 #if DIFF_DEBUG
 741 void diff_debug_filespec(struct diff_filespec *s, int x, const char *one)
 742 {
 743         fprintf(stderr, "queue[%d] %s (%s) %s %06o %s\n",
 744                 x, one ? : "",
 745                 s->path,
 746                 DIFF_FILE_VALID(s) ? "valid" : "invalid",
 747                 s->mode,
 748                 s->sha1_valid ? sha1_to_hex(s->sha1) : "");
 749         fprintf(stderr, "queue[%d] %s size %lu flags %d\n",
 750                 x, one ? : "",
 751                 s->size, s->xfrm_flags);
 752 }
 753
 754 void diff_debug_filepair(const struct diff_filepair *p, int i)
 755 {
 756         diff_debug_filespec(p->one, i, "one");
 757         diff_debug_filespec(p->two, i, "two");
 758         fprintf(stderr, "score %d, status %c source_stays %d\n",
 759                 p->score, p->status ? : '?', p->source_stays);
 760 }
 761
 762 void diff_debug_queue(const char *msg, struct diff_queue_struct *q)
 763 {
 764         int i;
 765         if (msg)
 766                 fprintf(stderr, "%s\n", msg);
 767         fprintf(stderr, "q->nr = %d\n", q->nr);
 768         for (i = 0; i < q->nr; i++) {
 769                 struct diff_filepair *p = q->queue[i];
 770                 diff_debug_filepair(p, i);
 771         }
 772 }
 773 #endif
 774
 775 static void diff_resolve_rename_copy(void)
 776 {
 777         int i, j;
 778         struct diff_filepair *p, *pp;
 779         struct diff_queue_struct *q = &diff_queued_diff;
 780
 781         diff_debug_queue("resolve-rename-copy", q);
 782
 783         for (i = 0; i < q->nr; i++) {
 784                 p = q->queue[i];
 785                 p->status = 0; /* undecided */
 786                 if (DIFF_PAIR_UNMERGED(p))
 787                         p->status = 'U';
 788                 else if (!DIFF_FILE_VALID(p->one))
 789                         p->status = 'N';
 790                 else if (!DIFF_FILE_VALID(p->two)) {
 791                         /* Deleted entry may have been picked up by
 792                          * another rename-copy entry.  So we scan the
 793                          * queue and if we find one that uses us as the
 794                          * source we do not say delete for this entry.
 795                          */
 796                         for (j = 0; j < q->nr; j++) {
 797                                 pp = q->queue[j];
 798                                 if (!strcmp(p->one->path, pp->one->path) &&
 799                                     pp->score) {
 800                                         /* rename/copy are always valid
 801                                          * so we do not say DIFF_FILE_VALID()
 802                                          * on pp->one and pp->two.
 803                                          */
 804                                         p->status = 'X';
 805                                         break;
 806                                 }
 807                         }
 808                         if (!p->status)
 809                                 p->status = 'D';
 810                 }
 811                 else if (DIFF_PAIR_TYPE_CHANGED(p))
 812                         p->status = 'T';
 813
 814                 /* from this point on, we are dealing with a pair
 815                  * whose both sides are valid and of the same type, i.e.
 816                  * either in-place edit or rename/copy edit.
 817                  */
 818                 else if (p->score) {
 819                         if (p->source_stays) {
 820                                 p->status = 'C';
 821                                 continue;
 822                         }
 823                         /* See if there is some other filepair that
 824                          * copies from the same source as us.  If so
 825                          * we are a copy.  Otherwise we are a rename.
 826                          */
 827                         for (j = i + 1; j < q->nr; j++) {
 828                                 pp = q->queue[j];
 829                                 if (strcmp(pp->one->path, p->one->path))
 830                                         continue; /* not us */
 831                                 if (!pp->score)
 832                                         continue; /* not a rename/copy */
 833                                 /* pp is a rename/copy from the same source */
 834                                 p->status = 'C';
 835                                 break;
 836                         }
 837                         if (!p->status)
 838                                 p->status = 'R';
 839                 }
 840                 else if (memcmp(p->one->sha1, p->two->sha1, 20) ||
 841                          p->one->mode != p->two->mode)
 842                         p->status = 'M';
 843                 else
 844                         /* this is a "no-change" entry.
 845                          * should not happen anymore.
 846                          * p->status = 'X';
 847                          */
 848                         die("internal error in diffcore: unmodified entry remains");
 849         }
 850         diff_debug_queue("resolve-rename-copy done", q);
 851 }
 852
 853 void diff_flush(int diff_output_style, int resolve_rename_copy)
 854 {
 855         struct diff_queue_struct *q = &diff_queued_diff;
 856         int i;
 857         int line_termination = '\n';
 858         int inter_name_termination = '\t';
 859
 860         if (diff_output_style == DIFF_FORMAT_MACHINE)
 861                 line_termination = inter_name_termination = 0;
 862         if (resolve_rename_copy)
 863                 diff_resolve_rename_copy();
 864
 865         for (i = 0; i < q->nr; i++) {
 866                 struct diff_filepair *p = q->queue[i];
 867                 if ((diff_output_style == DIFF_FORMAT_NO_OUTPUT) ||
 868                     (p->status == 'X'))
 869                         continue;
 870                 if (p->status == 0)
 871                         die("internal error in diff-resolve-rename-copy");
 872                 switch (diff_output_style) {
 873                 case DIFF_FORMAT_PATCH:
 874                         diff_flush_patch(p);
 875                         break;
 876                 case DIFF_FORMAT_HUMAN:
 877                 case DIFF_FORMAT_MACHINE:
 878                         diff_flush_raw(p, line_termination,
 879                                        inter_name_termination);
 880                         break;
 881                 }
 882         }
 883         for (i = 0; i < q->nr; i++)
 884                 diff_free_filepair(q->queue[i]);
 885         free(q->queue);
 886         q->queue = NULL;
 887         q->nr = q->alloc = 0;
 888 }
 889
 890 void diff_addremove(int addremove, unsigned mode,
 891                     const unsigned char *sha1,
 892                     const char *base, const char *path)
 893 {
 894         char concatpath[PATH_MAX];
 895         struct diff_filespec *one, *two;
 896
 897         /* This may look odd, but it is a preparation for
 898          * feeding "there are unchanged files which should
 899          * not produce diffs, but when you are doing copy
 900          * detection you would need them, so here they are"
 901          * entries to the diff-core.  They will be prefixed
 902          * with something like '=' or '*' (I haven't decided
 903          * which but should not make any difference).
 904          * Feeding the same new and old to diff_change()
 905          * also has the same effect.
 906          * Before the final output happens, they are pruned after
 907          * merged into rename/copy pairs as appropriate.
 908          */
 909         if (reverse_diff)
 910                 addremove = (addremove == '+' ? '-' :
 911                              addremove == '-' ? '+' : addremove);
 912
 913         if (!path) path = "";
 914         sprintf(concatpath, "%s%s", base, path);
 915         one = alloc_filespec(concatpath);
 916         two = alloc_filespec(concatpath);
 917
 918         if (addremove != '+')
 919                 fill_filespec(one, sha1, mode);
 920         if (addremove != '-')
 921                 fill_filespec(two, sha1, mode);
 922
 923         diff_queue(&diff_queued_diff, one, two);
 924 }
 925
 926 void diff_helper_input(unsigned old_mode,
 927                        unsigned new_mode,
 928                        const unsigned char *old_sha1,
 929                        const unsigned char *new_sha1,
 930                        const char *old_path,
 931                        int status,
 932                        int score,
 933                        const char *new_path)
 934 {
 935         struct diff_filespec *one, *two;
 936         struct diff_filepair *dp;
 937
 938         one = alloc_filespec(old_path);
 939         two = alloc_filespec(new_path);
 940         if (old_mode)
 941                 fill_filespec(one, old_sha1, old_mode);
 942         if (new_mode)
 943                 fill_filespec(two, new_sha1, new_mode);
 944         dp = diff_queue(&diff_queued_diff, one, two);
 945         dp->score = score * MAX_SCORE / 100;
 946         dp->status = status;
 947 }
 948
 949 void diff_change(unsigned old_mode, unsigned new_mode,
 950                  const unsigned char *old_sha1,
 951                  const unsigned char *new_sha1,
 952                  const char *base, const char *path)
 953 {
 954         char concatpath[PATH_MAX];
 955         struct diff_filespec *one, *two;
 956
 957         if (reverse_diff) {
 958                 unsigned tmp;
 959                 const unsigned char *tmp_c;
 960                 tmp = old_mode; old_mode = new_mode; new_mode = tmp;
 961                 tmp_c = old_sha1; old_sha1 = new_sha1; new_sha1 = tmp_c;
 962         }
 963         if (!path) path = "";
 964         sprintf(concatpath, "%s%s", base, path);
 965         one = alloc_filespec(concatpath);
 966         two = alloc_filespec(concatpath);
 967         fill_filespec(one, old_sha1, old_mode);
 968         fill_filespec(two, new_sha1, new_mode);
 969
 970         diff_queue(&diff_queued_diff, one, two);
 971 }
 972
 973 void diff_unmerge(const char *path)
 974 {
 975         struct diff_filespec *one, *two;
 976         one = alloc_filespec(path);
 977         two = alloc_filespec(path);
 978         diff_queue(&diff_queued_diff, one, two);
 979 }