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                 if (xfrm_msg && xfrm_msg[0])
 138                         puts(xfrm_msg);
 139         }
 140         else if (!path1[1][0]) {
 141                 printf("deleted file mode %s\n", temp[0].mode);
 142                 if (xfrm_msg && xfrm_msg[0])
 143                         puts(xfrm_msg);
 144         }
 145         else {
 146                 if (strcmp(temp[0].mode, temp[1].mode)) {
 147                         printf("old mode %s\n", temp[0].mode);
 148                         printf("new mode %s\n", temp[1].mode);
 149                 }
 150                 if (xfrm_msg && xfrm_msg[0])
 151                         puts(xfrm_msg);
 152
 153                 if (strncmp(temp[0].mode, temp[1].mode, 3))
 154                         /* we do not run diff between different kind
 155                          * of objects.
 156                          */
 157                         exit(0);
 158         }
 159         fflush(NULL);
 160         execlp("/bin/sh","sh", "-c", cmd, NULL);
 161 }
 162
 163 struct diff_filespec *alloc_filespec(const char *path)
 164 {
 165         int namelen = strlen(path);
 166         struct diff_filespec *spec = xmalloc(sizeof(*spec) + namelen + 1);
 167         spec->path = (char *)(spec + 1);
 168         strcpy(spec->path, path);
 169         spec->should_free = spec->should_munmap = 0;
 170         spec->xfrm_flags = 0;
 171         spec->size = 0;
 172         spec->data = NULL;
 173         spec->mode = 0;
 174         memset(spec->sha1, 0, 20);
 175         return spec;
 176 }
 177
 178 void fill_filespec(struct diff_filespec *spec, const unsigned char *sha1,
 179                    unsigned short mode)
 180 {
 181         if (mode) {
 182                 spec->mode = DIFF_FILE_CANON_MODE(mode);
 183                 memcpy(spec->sha1, sha1, 20);
 184                 spec->sha1_valid = !!memcmp(sha1, null_sha1, 20);
 185         }
 186 }
 187
 188 /*
 189  * Given a name and sha1 pair, if the dircache tells us the file in
 190  * the work tree has that object contents, return true, so that
 191  * prepare_temp_file() does not have to inflate and extract.
 192  */
 193 static int work_tree_matches(const char *name, const unsigned char *sha1)
 194 {
 195         struct cache_entry *ce;
 196         struct stat st;
 197         int pos, len;
 198
 199         /* We do not read the cache ourselves here, because the
 200          * benchmark with my previous version that always reads cache
 201          * shows that it makes things worse for diff-tree comparing
 202          * two linux-2.6 kernel trees in an already checked out work
 203          * tree.  This is because most diff-tree comparisons deal with
 204          * only a small number of files, while reading the cache is
 205          * expensive for a large project, and its cost outweighs the
 206          * savings we get by not inflating the object to a temporary
 207          * file.  Practically, this code only helps when we are used
 208          * by diff-cache --cached, which does read the cache before
 209          * calling us.
 210          */
 211         if (!active_cache)
 212                 return 0;
 213
 214         len = strlen(name);
 215         pos = cache_name_pos(name, len);
 216         if (pos < 0)
 217                 return 0;
 218         ce = active_cache[pos];
 219         if ((lstat(name, &st) < 0) ||
 220             !S_ISREG(st.st_mode) || /* careful! */
 221             ce_match_stat(ce, &st) ||
 222             memcmp(sha1, ce->sha1, 20))
 223                 return 0;
 224         /* we return 1 only when we can stat, it is a regular file,
 225          * stat information matches, and sha1 recorded in the cache
 226          * matches.  I.e. we know the file in the work tree really is
 227          * the same as the <name, sha1> pair.
 228          */
 229         return 1;
 230 }
 231
 232 static struct sha1_size_cache {
 233         unsigned char sha1[20];
 234         unsigned long size;
 235 } **sha1_size_cache;
 236 static int sha1_size_cache_nr, sha1_size_cache_alloc;
 237
 238 static struct sha1_size_cache *locate_size_cache(unsigned char *sha1,
 239                                                  unsigned long size)
 240 {
 241         int first, last;
 242         struct sha1_size_cache *e;
 243
 244         first = 0;
 245         last = sha1_size_cache_nr;
 246         while (last > first) {
 247                 int next = (last + first) >> 1;
 248                 e = sha1_size_cache[next];
 249                 int cmp = memcmp(e->sha1, sha1, 20);
 250                 if (!cmp)
 251                         return e;
 252                 if (cmp < 0) {
 253                         last = next;
 254                         continue;
 255                 }
 256                 first = next+1;
 257         }
 258         /* not found */
 259         if (size == UINT_MAX)
 260                 return NULL;
 261         /* insert to make it at "first" */
 262         if (sha1_size_cache_alloc <= sha1_size_cache_nr) {
 263                 sha1_size_cache_alloc = alloc_nr(sha1_size_cache_alloc);
 264                 sha1_size_cache = xrealloc(sha1_size_cache,
 265                                            sha1_size_cache_alloc *
 266                                            sizeof(*sha1_size_cache));
 267         }
 268         sha1_size_cache_nr++;
 269         if (first < sha1_size_cache_nr)
 270                 memmove(sha1_size_cache + first + 1, sha1_size_cache + first,
 271                         (sha1_size_cache_nr - first - 1) *
 272                         sizeof(*sha1_size_cache));
 273         e = xmalloc(sizeof(struct sha1_size_cache));
 274         sha1_size_cache[first] = e;
 275         memcpy(e->sha1, sha1, 20);
 276         e->size = size;
 277         return e;
 278 }
 279
 280 /*
 281  * While doing rename detection and pickaxe operation, we may need to
 282  * grab the data for the blob (or file) for our own in-core comparison.
 283  * diff_filespec has data and size fields for this purpose.
 284  */
 285 int diff_populate_filespec(struct diff_filespec *s, int size_only)
 286 {
 287         int err = 0;
 288         if (!DIFF_FILE_VALID(s))
 289                 die("internal error: asking to populate invalid file.");
 290         if (S_ISDIR(s->mode))
 291                 return -1;
 292
 293         if (!use_size_cache)
 294                 size_only = 0;
 295
 296         if (s->data)
 297                 return err;
 298         if (!s->sha1_valid ||
 299             work_tree_matches(s->path, s->sha1)) {
 300                 struct stat st;
 301                 int fd;
 302                 if (lstat(s->path, &st) < 0) {
 303                         if (errno == ENOENT) {
 304                         err_empty:
 305                                 err = -1;
 306                         empty:
 307                                 s->data = "";
 308                                 s->size = 0;
 309                                 return err;
 310                         }
 311                 }
 312                 s->size = st.st_size;
 313                 if (!s->size)
 314                         goto empty;
 315                 if (size_only)
 316                         return 0;
 317                 if (S_ISLNK(st.st_mode)) {
 318                         int ret;
 319                         s->data = xmalloc(s->size);
 320                         s->should_free = 1;
 321                         ret = readlink(s->path, s->data, s->size);
 322                         if (ret < 0) {
 323                                 free(s->data);
 324                                 goto err_empty;
 325                         }
 326                         return 0;
 327                 }
 328                 fd = open(s->path, O_RDONLY);
 329                 if (fd < 0)
 330                         goto err_empty;
 331                 s->data = mmap(NULL, s->size, PROT_READ, MAP_PRIVATE, fd, 0);
 332                 s->should_munmap = 1;
 333                 close(fd);
 334         }
 335         else {
 336                 /* We cannot do size only for SHA1 blobs */
 337                 char type[20];
 338                 struct sha1_size_cache *e;
 339
 340                 if (size_only) {
 341                         e = locate_size_cache(s->sha1, UINT_MAX);
 342                         if (e) {
 343                                 s->size = e->size;
 344                                 return 0;
 345                         }
 346                 }
 347                 s->data = read_sha1_file(s->sha1, type, &s->size);
 348                 s->should_free = 1;
 349                 if (s->data && size_only)
 350                         locate_size_cache(s->sha1, s->size);
 351         }
 352         return 0;
 353 }
 354
 355 void diff_free_filespec_data(struct diff_filespec *s)
 356 {
 357         if (s->should_free)
 358                 free(s->data);
 359         else if (s->should_munmap)
 360                 munmap(s->data, s->size);
 361         s->should_free = s->should_munmap = 0;
 362         s->data = NULL;
 363 }
 364
 365 static void prep_temp_blob(struct diff_tempfile *temp,
 366                            void *blob,
 367                            unsigned long size,
 368                            unsigned char *sha1,
 369                            int mode)
 370 {
 371         int fd;
 372
 373         strcpy(temp->tmp_path, ".diff_XXXXXX");
 374         fd = mkstemp(temp->tmp_path);
 375         if (fd < 0)
 376                 die("unable to create temp-file");
 377         if (write(fd, blob, size) != size)
 378                 die("unable to write temp-file");
 379         close(fd);
 380         temp->name = temp->tmp_path;
 381         strcpy(temp->hex, sha1_to_hex(sha1));
 382         temp->hex[40] = 0;
 383         sprintf(temp->mode, "%06o", mode);
 384 }
 385
 386 static void prepare_temp_file(const char *name,
 387                               struct diff_tempfile *temp,
 388                               struct diff_filespec *one)
 389 {
 390         if (!DIFF_FILE_VALID(one)) {
 391         not_a_valid_file:
 392                 /* A '-' entry produces this for file-2, and
 393                  * a '+' entry produces this for file-1.
 394                  */
 395                 temp->name = "/dev/null";
 396                 strcpy(temp->hex, ".");
 397                 strcpy(temp->mode, ".");
 398                 return;
 399         }
 400
 401         if (!one->sha1_valid ||
 402             work_tree_matches(name, one->sha1)) {
 403                 struct stat st;
 404                 if (lstat(name, &st) < 0) {
 405                         if (errno == ENOENT)
 406                                 goto not_a_valid_file;
 407                         die("stat(%s): %s", name, strerror(errno));
 408                 }
 409                 if (S_ISLNK(st.st_mode)) {
 410                         int ret;
 411                         char *buf, buf_[1024];
 412                         buf = ((sizeof(buf_) < st.st_size) ?
 413                                xmalloc(st.st_size) : buf_);
 414                         ret = readlink(name, buf, st.st_size);
 415                         if (ret < 0)
 416                                 die("readlink(%s)", name);
 417                         prep_temp_blob(temp, buf, st.st_size,
 418                                        (one->sha1_valid ?
 419                                         one->sha1 : null_sha1),
 420                                        (one->sha1_valid ?
 421                                         one->mode : S_IFLNK));
 422                 }
 423                 else {
 424                         /* we can borrow from the file in the work tree */
 425                         temp->name = name;
 426                         if (!one->sha1_valid)
 427                                 strcpy(temp->hex, sha1_to_hex(null_sha1));
 428                         else
 429                                 strcpy(temp->hex, sha1_to_hex(one->sha1));
 430                         /* Even though we may sometimes borrow the
 431                          * contents from the work tree, we always want
 432                          * one->mode.  mode is trustworthy even when
 433                          * !(one->sha1_valid), as long as
 434                          * DIFF_FILE_VALID(one).
 435                          */
 436                         sprintf(temp->mode, "%06o", one->mode);
 437                 }
 438                 return;
 439         }
 440         else {
 441                 if (diff_populate_filespec(one, 0))
 442                         die("cannot read data blob for %s", one->path);
 443                 prep_temp_blob(temp, one->data, one->size,
 444                                one->sha1, one->mode);
 445         }
 446 }
 447
 448 static void remove_tempfile(void)
 449 {
 450         int i;
 451
 452         for (i = 0; i < 2; i++)
 453                 if (diff_temp[i].name == diff_temp[i].tmp_path) {
 454                         unlink(diff_temp[i].name);
 455                         diff_temp[i].name = NULL;
 456                 }
 457 }
 458
 459 static void remove_tempfile_on_signal(int signo)
 460 {
 461         remove_tempfile();
 462 }
 463
 464 /* An external diff command takes:
 465  *
 466  * diff-cmd name infile1 infile1-sha1 infile1-mode \
 467  *               infile2 infile2-sha1 infile2-mode [ rename-to ]
 468  *
 469  */
 470 static void run_external_diff(const char *pgm,
 471                               const char *name,
 472                               const char *other,
 473                               struct diff_filespec *one,
 474                               struct diff_filespec *two,
 475                               const char *xfrm_msg)
 476 {
 477         struct diff_tempfile *temp = diff_temp;
 478         pid_t pid;
 479         int status;
 480         static int atexit_asked = 0;
 481
 482         if (one && two) {
 483                 prepare_temp_file(name, &temp[0], one);
 484                 prepare_temp_file(other ? : name, &temp[1], two);
 485                 if (! atexit_asked &&
 486                     (temp[0].name == temp[0].tmp_path ||
 487                      temp[1].name == temp[1].tmp_path)) {
 488                         atexit_asked = 1;
 489                         atexit(remove_tempfile);
 490                 }
 491                 signal(SIGINT, remove_tempfile_on_signal);
 492         }
 493
 494         fflush(NULL);
 495         pid = fork();
 496         if (pid < 0)
 497                 die("unable to fork");
 498         if (!pid) {
 499                 if (pgm) {
 500                         if (one && two) {
 501                                 const char *exec_arg[10];
 502                                 const char **arg = &exec_arg[0];
 503                                 *arg++ = pgm;
 504                                 *arg++ = name;
 505                                 *arg++ = temp[0].name;
 506                                 *arg++ = temp[0].hex;
 507                                 *arg++ = temp[0].mode;
 508                                 *arg++ = temp[1].name;
 509                                 *arg++ = temp[1].hex;
 510                                 *arg++ = temp[1].mode;
 511                                 if (other) {
 512                                         *arg++ = other;
 513                                         *arg++ = xfrm_msg;
 514                                 }
 515                                 *arg = NULL;
 516                                 execvp(pgm, (char *const*) exec_arg);
 517                         }
 518                         else
 519                                 execlp(pgm, pgm, name, NULL);
 520                 }
 521                 /*
 522                  * otherwise we use the built-in one.
 523                  */
 524                 if (one && two)
 525                         builtin_diff(name, other ? : name, temp, xfrm_msg);
 526                 else
 527                         printf("* Unmerged path %s\n", name);
 528                 exit(0);
 529         }
 530         if (waitpid(pid, &status, 0) < 0 ||
 531             !WIFEXITED(status) || WEXITSTATUS(status)) {
 532                 /* Earlier we did not check the exit status because
 533                  * diff exits non-zero if files are different, and
 534                  * we are not interested in knowing that.  It was a
 535                  * mistake which made it harder to quit a diff-*
 536                  * session that uses the git-apply-patch-script as
 537                  * the GIT_EXTERNAL_DIFF.  A custom GIT_EXTERNAL_DIFF
 538                  * should also exit non-zero only when it wants to
 539                  * abort the entire diff-* session.
 540                  */
 541                 remove_tempfile();
 542                 fprintf(stderr, "external diff died, stopping at %s.\n", name);
 543                 exit(1);
 544         }
 545         remove_tempfile();
 546 }
 547
 548 static void run_diff(const char *name,
 549                      const char *other,
 550                      struct diff_filespec *one,
 551                      struct diff_filespec *two,
 552                      const char *xfrm_msg)
 553 {
 554         const char *pgm = external_diff();
 555         if (!pgm &&
 556             DIFF_FILE_VALID(one) && DIFF_FILE_VALID(two) &&
 557             (S_IFMT & one->mode) != (S_IFMT & two->mode)) {
 558                 /* a filepair that changes between file and symlink
 559                  * needs to be split into deletion and creation.
 560                  */
 561                 struct diff_filespec *null = alloc_filespec(two->path);
 562                 run_external_diff(NULL, name, other, one, null, xfrm_msg);
 563                 free(null);
 564                 null = alloc_filespec(one->path);
 565                 run_external_diff(NULL, name, other, null, two, xfrm_msg);
 566                 free(null);
 567         }
 568         else
 569                 run_external_diff(pgm, name, other, one, two, xfrm_msg);
 570 }
 571
 572 void diff_setup(int flags)
 573 {
 574         if (flags & DIFF_SETUP_REVERSE)
 575                 reverse_diff = 1;
 576         if (flags & DIFF_SETUP_USE_CACHE) {
 577                 if (!active_cache)
 578                         /* read-cache does not die even when it fails
 579                          * so it is safe for us to do this here.  Also
 580                          * it does not smudge active_cache or active_nr
 581                          * when it fails, so we do not have to worry about
 582                          * cleaning it up oufselves either.
 583                          */
 584                         read_cache();
 585         }
 586         if (flags & DIFF_SETUP_USE_SIZE_CACHE)
 587                 use_size_cache = 1;
 588
 589 }
 590
 591 struct diff_queue_struct diff_queued_diff;
 592
 593 void diff_q(struct diff_queue_struct *queue, struct diff_filepair *dp)
 594 {
 595         if (queue->alloc <= queue->nr) {
 596                 queue->alloc = alloc_nr(queue->alloc);
 597                 queue->queue = xrealloc(queue->queue,
 598                                         sizeof(dp) * queue->alloc);
 599         }
 600         queue->queue[queue->nr++] = dp;
 601 }
 602
 603 struct diff_filepair *diff_queue(struct diff_queue_struct *queue,
 604                                  struct diff_filespec *one,
 605                                  struct diff_filespec *two)
 606 {
 607         struct diff_filepair *dp = xmalloc(sizeof(*dp));
 608         dp->one = one;
 609         dp->two = two;
 610         dp->score = 0;
 611         dp->source_stays = 0;
 612         dp->broken_pair = 0;
 613         diff_q(queue, dp);
 614         return dp;
 615 }
 616
 617 void diff_free_filepair(struct diff_filepair *p)
 618 {
 619         diff_free_filespec_data(p->one);
 620         diff_free_filespec_data(p->two);
 621         free(p);
 622 }
 623
 624 static void diff_flush_raw(struct diff_filepair *p,
 625                            int line_termination,
 626                            int inter_name_termination)
 627 {
 628         int two_paths;
 629         char status[10];
 630
 631         if (line_termination) {
 632                 const char *err = "path %s cannot be expressed without -z";
 633                 if (strchr(p->one->path, line_termination) ||
 634                     strchr(p->one->path, inter_name_termination))
 635                         die(err, p->one->path);
 636                 if (strchr(p->two->path, line_termination) ||
 637                     strchr(p->two->path, inter_name_termination))
 638                         die(err, p->two->path);
 639         }
 640
 641         switch (p->status) {
 642         case 'C': case 'R':
 643                 two_paths = 1;
 644                 sprintf(status, "%c%03d", p->status,
 645                         (int)(0.5 + p->score * 100.0/MAX_SCORE));
 646                 break;
 647         case 'N': case 'D':
 648                 two_paths = 0;
 649                 if (p->score)
 650                         sprintf(status, "%c%03d", p->status,
 651                                 (int)(0.5 + p->score * 100.0/MAX_SCORE));
 652                 else {
 653                         status[0] = p->status;
 654                         status[1] = 0;
 655                 }
 656                 break;
 657         default:
 658                 two_paths = 0;
 659                 status[0] = p->status;
 660                 status[1] = 0;
 661                 break;
 662         }
 663         printf(":%06o %06o %s ",
 664                p->one->mode, p->two->mode, sha1_to_hex(p->one->sha1));
 665         printf("%s %s%c%s",
 666                sha1_to_hex(p->two->sha1),
 667                status,
 668                inter_name_termination,
 669                p->one->path);
 670         if (two_paths)
 671                 printf("%c%s", inter_name_termination, p->two->path);
 672         putchar(line_termination);
 673 }
 674
 675 int diff_unmodified_pair(struct diff_filepair *p)
 676 {
 677         /* This function is written stricter than necessary to support
 678          * the currently implemented transformers, but the idea is to
 679          * let transformers to produce diff_filepairs any way they want,
 680          * and filter and clean them up here before producing the output.
 681          */
 682         struct diff_filespec *one, *two;
 683
 684         if (DIFF_PAIR_UNMERGED(p))
 685                 return 0; /* unmerged is interesting */
 686
 687         one = p->one;
 688         two = p->two;
 689
 690         /* deletion, addition, mode or type change
 691          * and rename are all interesting.
 692          */
 693         if (DIFF_FILE_VALID(one) != DIFF_FILE_VALID(two) ||
 694             DIFF_PAIR_MODE_CHANGED(p) ||
 695             strcmp(one->path, two->path))
 696                 return 0;
 697
 698         /* both are valid and point at the same path.  that is, we are
 699          * dealing with a change.
 700          */
 701         if (one->sha1_valid && two->sha1_valid &&
 702             !memcmp(one->sha1, two->sha1, sizeof(one->sha1)))
 703                 return 1; /* no change */
 704         if (!one->sha1_valid && !two->sha1_valid)
 705                 return 1; /* both look at the same file on the filesystem. */
 706         return 0;
 707 }
 708
 709 static void diff_flush_patch(struct diff_filepair *p)
 710 {
 711         const char *name, *other;
 712         char msg_[PATH_MAX*2+200], *msg;
 713
 714         if (diff_unmodified_pair(p))
 715                 return;
 716
 717         name = p->one->path;
 718         other = (strcmp(name, p->two->path) ? p->two->path : NULL);
 719         if ((DIFF_FILE_VALID(p->one) && S_ISDIR(p->one->mode)) ||
 720             (DIFF_FILE_VALID(p->two) && S_ISDIR(p->two->mode)))
 721                 return; /* no tree diffs in patch format */
 722
 723         switch (p->status) {
 724         case 'C':
 725                 sprintf(msg_,
 726                         "similarity index %d%%\n"
 727                         "copy from %s\n"
 728                         "copy to %s",
 729                         (int)(0.5 + p->score * 100.0/MAX_SCORE),
 730                         p->one->path, p->two->path);
 731                 msg = msg_;
 732                 break;
 733         case 'R':
 734                 sprintf(msg_,
 735                         "similarity index %d%%\n"
 736                         "rename old %s\n"
 737                         "rename new %s",
 738                         (int)(0.5 + p->score * 100.0/MAX_SCORE),
 739                         p->one->path, p->two->path);
 740                 msg = msg_;
 741                 break;
 742         case 'D': case 'N':
 743                 if (DIFF_PAIR_BROKEN(p)) {
 744                         sprintf(msg_,
 745                                 "dissimilarity index %d%%",
 746                                 (int)(0.5 + p->score * 100.0/MAX_SCORE));
 747                         msg = msg_;
 748                 }
 749                 else
 750                         msg = NULL;
 751                 break;
 752         default:
 753                 msg = NULL;
 754         }
 755
 756         if (DIFF_PAIR_UNMERGED(p))
 757                 run_diff(name, NULL, NULL, NULL, NULL);
 758         else
 759                 run_diff(name, other, p->one, p->two, msg);
 760 }
 761
 762 int diff_queue_is_empty(void)
 763 {
 764         struct diff_queue_struct *q = &diff_queued_diff;
 765         int i;
 766         for (i = 0; i < q->nr; i++)
 767                 if (!diff_unmodified_pair(q->queue[i]))
 768                         return 0;
 769         return 1;
 770 }
 771
 772 #if DIFF_DEBUG
 773 void diff_debug_filespec(struct diff_filespec *s, int x, const char *one)
 774 {
 775         fprintf(stderr, "queue[%d] %s (%s) %s %06o %s\n",
 776                 x, one ? : "",
 777                 s->path,
 778                 DIFF_FILE_VALID(s) ? "valid" : "invalid",
 779                 s->mode,
 780                 s->sha1_valid ? sha1_to_hex(s->sha1) : "");
 781         fprintf(stderr, "queue[%d] %s size %lu flags %d\n",
 782                 x, one ? : "",
 783                 s->size, s->xfrm_flags);
 784 }
 785
 786 void diff_debug_filepair(const struct diff_filepair *p, int i)
 787 {
 788         diff_debug_filespec(p->one, i, "one");
 789         diff_debug_filespec(p->two, i, "two");
 790         fprintf(stderr, "score %d, status %c stays %d broken %d\n",
 791                 p->score, p->status ? : '?',
 792                 p->source_stays, p->broken_pair);
 793 }
 794
 795 void diff_debug_queue(const char *msg, struct diff_queue_struct *q)
 796 {
 797         int i;
 798         if (msg)
 799                 fprintf(stderr, "%s\n", msg);
 800         fprintf(stderr, "q->nr = %d\n", q->nr);
 801         for (i = 0; i < q->nr; i++) {
 802                 struct diff_filepair *p = q->queue[i];
 803                 diff_debug_filepair(p, i);
 804         }
 805 }
 806 #endif
 807
 808 static void diff_resolve_rename_copy(void)
 809 {
 810         int i, j;
 811         struct diff_filepair *p, *pp;
 812         struct diff_queue_struct *q = &diff_queued_diff;
 813
 814         diff_debug_queue("resolve-rename-copy", q);
 815
 816         for (i = 0; i < q->nr; i++) {
 817                 p = q->queue[i];
 818                 p->status = 0; /* undecided */
 819                 if (DIFF_PAIR_UNMERGED(p))
 820                         p->status = 'U';
 821                 else if (!DIFF_FILE_VALID(p->one))
 822                         p->status = 'N';
 823                 else if (!DIFF_FILE_VALID(p->two))
 824                         p->status = 'D';
 825                 else if (DIFF_PAIR_TYPE_CHANGED(p))
 826                         p->status = 'T';
 827
 828                 /* from this point on, we are dealing with a pair
 829                  * whose both sides are valid and of the same type, i.e.
 830                  * either in-place edit or rename/copy edit.
 831                  */
 832                 else if (DIFF_PAIR_RENAME(p)) {
 833                         if (p->source_stays) {
 834                                 p->status = 'C';
 835                                 continue;
 836                         }
 837                         /* See if there is some other filepair that
 838                          * copies from the same source as us.  If so
 839                          * we are a copy.  Otherwise we are a rename.
 840                          */
 841                         for (j = i + 1; j < q->nr; j++) {
 842                                 pp = q->queue[j];
 843                                 if (strcmp(pp->one->path, p->one->path))
 844                                         continue; /* not us */
 845                                 if (!DIFF_PAIR_RENAME(pp))
 846                                         continue; /* not a rename/copy */
 847                                 /* pp is a rename/copy from the same source */
 848                                 p->status = 'C';
 849                                 break;
 850                         }
 851                         if (!p->status)
 852                                 p->status = 'R';
 853                 }
 854                 else if (memcmp(p->one->sha1, p->two->sha1, 20) ||
 855                          p->one->mode != p->two->mode)
 856                         p->status = 'M';
 857                 else
 858                         /* this is a "no-change" entry.
 859                          * should not happen anymore.
 860                          * p->status = 'X';
 861                          */
 862                         die("internal error in diffcore: unmodified entry remains");
 863         }
 864         diff_debug_queue("resolve-rename-copy done", q);
 865 }
 866
 867 void diff_flush(int diff_output_style, int resolve_rename_copy)
 868 {
 869         struct diff_queue_struct *q = &diff_queued_diff;
 870         int i;
 871         int line_termination = '\n';
 872         int inter_name_termination = '\t';
 873
 874         if (diff_output_style == DIFF_FORMAT_MACHINE)
 875                 line_termination = inter_name_termination = 0;
 876         if (resolve_rename_copy)
 877                 diff_resolve_rename_copy();
 878
 879         for (i = 0; i < q->nr; i++) {
 880                 struct diff_filepair *p = q->queue[i];
 881                 if ((diff_output_style == DIFF_FORMAT_NO_OUTPUT) ||
 882                     (p->status == 'X'))
 883                         continue;
 884                 if (p->status == 0)
 885                         die("internal error in diff-resolve-rename-copy");
 886                 switch (diff_output_style) {
 887                 case DIFF_FORMAT_PATCH:
 888                         diff_flush_patch(p);
 889                         break;
 890                 case DIFF_FORMAT_HUMAN:
 891                 case DIFF_FORMAT_MACHINE:
 892                         diff_flush_raw(p, line_termination,
 893                                        inter_name_termination);
 894                         break;
 895                 }
 896         }
 897         for (i = 0; i < q->nr; i++)
 898                 diff_free_filepair(q->queue[i]);
 899         free(q->queue);
 900         q->queue = NULL;
 901         q->nr = q->alloc = 0;
 902 }
 903
 904 void diffcore_std(const char **paths,
 905                   int detect_rename, int rename_score,
 906                   const char *pickaxe, int pickaxe_opts,
 907                   int break_opt,
 908                   const char *orderfile)
 909 {
 910         if (paths && paths[0])
 911                 diffcore_pathspec(paths);
 912         if (0 <= break_opt)
 913                 diffcore_break(break_opt);
 914         if (detect_rename)
 915                 diffcore_rename(detect_rename, rename_score);
 916         if (pickaxe)
 917                 diffcore_pickaxe(pickaxe, pickaxe_opts);
 918         if (orderfile)
 919                 diffcore_order(orderfile);
 920 }
 921
 922 void diff_addremove(int addremove, unsigned mode,
 923                     const unsigned char *sha1,
 924                     const char *base, const char *path)
 925 {
 926         char concatpath[PATH_MAX];
 927         struct diff_filespec *one, *two;
 928
 929         /* This may look odd, but it is a preparation for
 930          * feeding "there are unchanged files which should
 931          * not produce diffs, but when you are doing copy
 932          * detection you would need them, so here they are"
 933          * entries to the diff-core.  They will be prefixed
 934          * with something like '=' or '*' (I haven't decided
 935          * which but should not make any difference).
 936          * Feeding the same new and old to diff_change()
 937          * also has the same effect.
 938          * Before the final output happens, they are pruned after
 939          * merged into rename/copy pairs as appropriate.
 940          */
 941         if (reverse_diff)
 942                 addremove = (addremove == '+' ? '-' :
 943                              addremove == '-' ? '+' : addremove);
 944
 945         if (!path) path = "";
 946         sprintf(concatpath, "%s%s", base, path);
 947         one = alloc_filespec(concatpath);
 948         two = alloc_filespec(concatpath);
 949
 950         if (addremove != '+')
 951                 fill_filespec(one, sha1, mode);
 952         if (addremove != '-')
 953                 fill_filespec(two, sha1, mode);
 954
 955         diff_queue(&diff_queued_diff, one, two);
 956 }
 957
 958 void diff_helper_input(unsigned old_mode,
 959                        unsigned new_mode,
 960                        const unsigned char *old_sha1,
 961                        const unsigned char *new_sha1,
 962                        const char *old_path,
 963                        int status,
 964                        int score,
 965                        const char *new_path)
 966 {
 967         struct diff_filespec *one, *two;
 968         struct diff_filepair *dp;
 969
 970         one = alloc_filespec(old_path);
 971         two = alloc_filespec(new_path);
 972         if (old_mode)
 973                 fill_filespec(one, old_sha1, old_mode);
 974         if (new_mode)
 975                 fill_filespec(two, new_sha1, new_mode);
 976         dp = diff_queue(&diff_queued_diff, one, two);
 977         dp->score = score * MAX_SCORE / 100;
 978         dp->status = status;
 979 }
 980
 981 void diff_change(unsigned old_mode, unsigned new_mode,
 982                  const unsigned char *old_sha1,
 983                  const unsigned char *new_sha1,
 984                  const char *base, const char *path)
 985 {
 986         char concatpath[PATH_MAX];
 987         struct diff_filespec *one, *two;
 988
 989         if (reverse_diff) {
 990                 unsigned tmp;
 991                 const unsigned char *tmp_c;
 992                 tmp = old_mode; old_mode = new_mode; new_mode = tmp;
 993                 tmp_c = old_sha1; old_sha1 = new_sha1; new_sha1 = tmp_c;
 994         }
 995         if (!path) path = "";
 996         sprintf(concatpath, "%s%s", base, path);
 997         one = alloc_filespec(concatpath);
 998         two = alloc_filespec(concatpath);
 999         fill_filespec(one, old_sha1, old_mode);
1000         fill_filespec(two, new_sha1, new_mode);
1001
1002         diff_queue(&diff_queued_diff, one, two);
1003 }
1004
1005 void diff_unmerge(const char *path)
1006 {
1007         struct diff_filespec *one, *two;
1008         one = alloc_filespec(path);
1009         two = alloc_filespec(path);
1010         diff_queue(&diff_queued_diff, one, two);
1011 }