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 <limits.h>
   8 #include "cache.h"
   9 #include "diff.h"
  10 #include "diffcore.h"
  11
  12 static const char *diff_opts = "-pu";
  13 static unsigned char null_sha1[20] = { 0, };
  14
  15 static int detect_rename;
  16 static int reverse_diff;
  17 static int diff_raw_output = -1;
  18 static const char **pathspec;
  19 static int speccnt;
  20 static const char *pickaxe;
  21 static int minimum_score;
  22
  23 static const char *external_diff(void)
  24 {
  25         static const char *external_diff_cmd = NULL;
  26         static int done_preparing = 0;
  27
  28         if (done_preparing)
  29                 return external_diff_cmd;
  30
  31         /*
  32          * Default values above are meant to match the
  33          * Linux kernel development style.  Examples of
  34          * alternative styles you can specify via environment
  35          * variables are:
  36          *
  37          * GIT_DIFF_OPTS="-c";
  38          */
  39         if (gitenv("GIT_EXTERNAL_DIFF"))
  40                 external_diff_cmd = gitenv("GIT_EXTERNAL_DIFF");
  41
  42         /* In case external diff fails... */
  43         diff_opts = gitenv("GIT_DIFF_OPTS") ? : diff_opts;
  44
  45         done_preparing = 1;
  46         return external_diff_cmd;
  47 }
  48
  49 /* Help to copy the thing properly quoted for the shell safety.
  50  * any single quote is replaced with '\'', and the caller is
  51  * expected to enclose the result within a single quote pair.
  52  *
  53  * E.g.
  54  *  original     sq_expand     result
  55  *  name     ==> name      ==> 'name'
  56  *  a b      ==> a b       ==> 'a b'
  57  *  a'b      ==> a'\''b    ==> 'a'\''b'
  58  */
  59 static char *sq_expand(const char *src)
  60 {
  61         static char *buf = NULL;
  62         int cnt, c;
  63         const char *cp;
  64         char *bp;
  65
  66         /* count bytes needed to store the quoted string. */
  67         for (cnt = 1, cp = src; *cp; cnt++, cp++)
  68                 if (*cp == '\'')
  69                         cnt += 3;
  70
  71         buf = xmalloc(cnt);
  72         bp = buf;
  73         while ((c = *src++)) {
  74                 if (c != '\'')
  75                         *bp++ = c;
  76                 else {
  77                         bp = strcpy(bp, "'\\''");
  78                         bp += 4;
  79                 }
  80         }
  81         *bp = 0;
  82         return buf;
  83 }
  84
  85 static struct diff_tempfile {
  86         const char *name; /* filename external diff should read from */
  87         char hex[41];
  88         char mode[10];
  89         char tmp_path[50];
  90 } diff_temp[2];
  91
  92 static void builtin_diff(const char *name_a,
  93                          const char *name_b,
  94                          struct diff_tempfile *temp,
  95                          const char *xfrm_msg)
  96 {
  97         int i, next_at, cmd_size;
  98         const char *diff_cmd = "diff -L'%s%s' -L'%s%s'";
  99         const char *diff_arg  = "'%s' '%s'||:"; /* "||:" is to return 0 */
 100         const char *input_name_sq[2];
 101         const char *path0[2];
 102         const char *path1[2];
 103         const char *name_sq[2];
 104         char *cmd;
 105
 106         name_sq[0] = sq_expand(name_a);
 107         name_sq[1] = sq_expand(name_b);
 108
 109         /* diff_cmd and diff_arg have 6 %s in total which makes
 110          * the sum of these strings 12 bytes larger than required.
 111          * we use 2 spaces around diff-opts, and we need to count
 112          * terminating NUL, so we subtract 9 here.
 113          */
 114         cmd_size = (strlen(diff_cmd) + strlen(diff_opts) +
 115                         strlen(diff_arg) - 9);
 116         for (i = 0; i < 2; i++) {
 117                 input_name_sq[i] = sq_expand(temp[i].name);
 118                 if (!strcmp(temp[i].name, "/dev/null")) {
 119                         path0[i] = "/dev/null";
 120                         path1[i] = "";
 121                 } else {
 122                         path0[i] = i ? "b/" : "a/";
 123                         path1[i] = name_sq[i];
 124                 }
 125                 cmd_size += (strlen(path0[i]) + strlen(path1[i]) +
 126                              strlen(input_name_sq[i]));
 127         }
 128
 129         cmd = xmalloc(cmd_size);
 130
 131         next_at = 0;
 132         next_at += snprintf(cmd+next_at, cmd_size-next_at,
 133                             diff_cmd,
 134                             path0[0], path1[0], path0[1], path1[1]);
 135         next_at += snprintf(cmd+next_at, cmd_size-next_at,
 136                             " %s ", diff_opts);
 137         next_at += snprintf(cmd+next_at, cmd_size-next_at,
 138                             diff_arg, input_name_sq[0], input_name_sq[1]);
 139
 140         printf("diff --git a/%s b/%s\n", name_a, name_b);
 141         if (!path1[0][0])
 142                 printf("new file mode %s\n", temp[1].mode);
 143         else if (!path1[1][0])
 144                 printf("deleted file mode %s\n", temp[0].mode);
 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                         fputs(xfrm_msg, stdout);
 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 = spec->file_valid = 0;
 170         spec->xfrm_flags = 0;
 171         spec->size = 0;
 172         spec->data = 0;
 173         return spec;
 174 }
 175
 176 void fill_filespec(struct diff_filespec *spec, const unsigned char *sha1,
 177                    unsigned short mode)
 178 {
 179         spec->mode = mode;
 180         memcpy(spec->sha1, sha1, 20);
 181         spec->sha1_valid = !!memcmp(sha1, null_sha1, 20);
 182         spec->file_valid = 1;
 183 }
 184
 185 /*
 186  * Given a name and sha1 pair, if the dircache tells us the file in
 187  * the work tree has that object contents, return true, so that
 188  * prepare_temp_file() does not have to inflate and extract.
 189  */
 190 static int work_tree_matches(const char *name, const unsigned char *sha1)
 191 {
 192         struct cache_entry *ce;
 193         struct stat st;
 194         int pos, len;
 195
 196         /* We do not read the cache ourselves here, because the
 197          * benchmark with my previous version that always reads cache
 198          * shows that it makes things worse for diff-tree comparing
 199          * two linux-2.6 kernel trees in an already checked out work
 200          * tree.  This is because most diff-tree comparisons deal with
 201          * only a small number of files, while reading the cache is
 202          * expensive for a large project, and its cost outweighs the
 203          * savings we get by not inflating the object to a temporary
 204          * file.  Practically, this code only helps when we are used
 205          * by diff-cache --cached, which does read the cache before
 206          * calling us.
 207          */
 208         if (!active_cache)
 209                 return 0;
 210
 211         len = strlen(name);
 212         pos = cache_name_pos(name, len);
 213         if (pos < 0)
 214                 return 0;
 215         ce = active_cache[pos];
 216         if ((lstat(name, &st) < 0) ||
 217             !S_ISREG(st.st_mode) || /* careful! */
 218             ce_match_stat(ce, &st) ||
 219             memcmp(sha1, ce->sha1, 20))
 220                 return 0;
 221         /* we return 1 only when we can stat, it is a regular file,
 222          * stat information matches, and sha1 recorded in the cache
 223          * matches.  I.e. we know the file in the work tree really is
 224          * the same as the <name, sha1> pair.
 225          */
 226         return 1;
 227 }
 228
 229 /*
 230  * While doing rename detection and pickaxe operation, we may need to
 231  * grab the data for the blob (or file) for our own in-core comparison.
 232  * diff_filespec has data and size fields for this purpose.
 233  */
 234 int diff_populate_filespec(struct diff_filespec *s)
 235 {
 236         int err = 0;
 237         if (!s->file_valid)
 238                 die("internal error: asking to populate invalid file.");
 239         if (S_ISDIR(s->mode))
 240                 return -1;
 241
 242         if (s->data)
 243                 return err;
 244         if (!s->sha1_valid ||
 245             work_tree_matches(s->path, s->sha1)) {
 246                 struct stat st;
 247                 int fd;
 248                 if (lstat(s->path, &st) < 0) {
 249                         if (errno == ENOENT) {
 250                         err_empty:
 251                                 err = -1;
 252                         empty:
 253                                 s->data = "";
 254                                 s->size = 0;
 255                                 return err;
 256                         }
 257                 }
 258                 s->size = st.st_size;
 259                 if (!s->size)
 260                         goto empty;
 261                 if (S_ISLNK(st.st_mode)) {
 262                         int ret;
 263                         s->data = xmalloc(s->size);
 264                         s->should_free = 1;
 265                         ret = readlink(s->path, s->data, s->size);
 266                         if (ret < 0) {
 267                                 free(s->data);
 268                                 goto err_empty;
 269                         }
 270                         return 0;
 271                 }
 272                 fd = open(s->path, O_RDONLY);
 273                 if (fd < 0)
 274                         goto err_empty;
 275                 s->data = mmap(NULL, s->size, PROT_READ, MAP_PRIVATE, fd, 0);
 276                 s->should_munmap = 1;
 277                 close(fd);
 278         }
 279         else {
 280                 char type[20];
 281                 s->data = read_sha1_file(s->sha1, type, &s->size);
 282                 s->should_free = 1;
 283         }
 284         return 0;
 285 }
 286
 287 void diff_free_filespec_data(struct diff_filespec *s)
 288 {
 289         if (s->should_free)
 290                 free(s->data);
 291         else if (s->should_munmap)
 292                 munmap(s->data, s->size);
 293         s->should_free = s->should_munmap = 0;
 294         s->data = 0;
 295 }
 296
 297 static void prep_temp_blob(struct diff_tempfile *temp,
 298                            void *blob,
 299                            unsigned long size,
 300                            unsigned char *sha1,
 301                            int mode)
 302 {
 303         int fd;
 304
 305         strcpy(temp->tmp_path, ".diff_XXXXXX");
 306         fd = mkstemp(temp->tmp_path);
 307         if (fd < 0)
 308                 die("unable to create temp-file");
 309         if (write(fd, blob, size) != size)
 310                 die("unable to write temp-file");
 311         close(fd);
 312         temp->name = temp->tmp_path;
 313         strcpy(temp->hex, sha1_to_hex(sha1));
 314         temp->hex[40] = 0;
 315         sprintf(temp->mode, "%06o", mode);
 316 }
 317
 318 static void prepare_temp_file(const char *name,
 319                               struct diff_tempfile *temp,
 320                               struct diff_filespec *one)
 321 {
 322         if (!one->file_valid) {
 323         not_a_valid_file:
 324                 /* A '-' entry produces this for file-2, and
 325                  * a '+' entry produces this for file-1.
 326                  */
 327                 temp->name = "/dev/null";
 328                 strcpy(temp->hex, ".");
 329                 strcpy(temp->mode, ".");
 330                 return;
 331         }
 332
 333         if (!one->sha1_valid ||
 334             work_tree_matches(name, one->sha1)) {
 335                 struct stat st;
 336                 if (lstat(name, &st) < 0) {
 337                         if (errno == ENOENT)
 338                                 goto not_a_valid_file;
 339                         die("stat(%s): %s", name, strerror(errno));
 340                 }
 341                 if (S_ISLNK(st.st_mode)) {
 342                         int ret;
 343                         char *buf, buf_[1024];
 344                         buf = ((sizeof(buf_) < st.st_size) ?
 345                                xmalloc(st.st_size) : buf_);
 346                         ret = readlink(name, buf, st.st_size);
 347                         if (ret < 0)
 348                                 die("readlink(%s)", name);
 349                         prep_temp_blob(temp, buf, st.st_size,
 350                                        (one->sha1_valid ?
 351                                         one->sha1 : null_sha1),
 352                                        (one->sha1_valid ?
 353                                         one->mode : S_IFLNK));
 354                 }
 355                 else {
 356                         /* we can borrow from the file in the work tree */
 357                         temp->name = name;
 358                         if (!one->sha1_valid)
 359                                 strcpy(temp->hex, sha1_to_hex(null_sha1));
 360                         else
 361                                 strcpy(temp->hex, sha1_to_hex(one->sha1));
 362                         sprintf(temp->mode, "%06o",
 363                                 S_IFREG |ce_permissions(st.st_mode));
 364                 }
 365                 return;
 366         }
 367         else {
 368                 if (diff_populate_filespec(one))
 369                         die("cannot read data blob for %s", one->path);
 370                 prep_temp_blob(temp, one->data, one->size,
 371                                one->sha1, one->mode);
 372         }
 373 }
 374
 375 static void remove_tempfile(void)
 376 {
 377         int i;
 378
 379         for (i = 0; i < 2; i++)
 380                 if (diff_temp[i].name == diff_temp[i].tmp_path) {
 381                         unlink(diff_temp[i].name);
 382                         diff_temp[i].name = NULL;
 383                 }
 384 }
 385
 386 static void remove_tempfile_on_signal(int signo)
 387 {
 388         remove_tempfile();
 389 }
 390
 391 static int matches_pathspec(const char *name)
 392 {
 393         int i;
 394         int namelen;
 395
 396         if (speccnt == 0)
 397                 return 1;
 398
 399         namelen = strlen(name);
 400         for (i = 0; i < speccnt; i++) {
 401                 int speclen = strlen(pathspec[i]);
 402                 if (! strncmp(pathspec[i], name, speclen) &&
 403                     speclen <= namelen &&
 404                     (name[speclen] == 0 || name[speclen] == '/'))
 405                         return 1;
 406         }
 407         return 0;
 408 }
 409
 410 /* An external diff command takes:
 411  *
 412  * diff-cmd name infile1 infile1-sha1 infile1-mode \
 413  *               infile2 infile2-sha1 infile2-mode [ rename-to ]
 414  *
 415  */
 416 static void run_external_diff(const char *name,
 417                               const char *other,
 418                               struct diff_filespec *one,
 419                               struct diff_filespec *two,
 420                               const char *xfrm_msg)
 421 {
 422         struct diff_tempfile *temp = diff_temp;
 423         pid_t pid;
 424         int status;
 425         static int atexit_asked = 0;
 426
 427         if (!matches_pathspec(name) && (!other || !matches_pathspec(other)))
 428                 return;
 429
 430         if (one && two) {
 431                 prepare_temp_file(name, &temp[0], one);
 432                 prepare_temp_file(other ? : name, &temp[1], two);
 433                 if (! atexit_asked &&
 434                     (temp[0].name == temp[0].tmp_path ||
 435                      temp[1].name == temp[1].tmp_path)) {
 436                         atexit_asked = 1;
 437                         atexit(remove_tempfile);
 438                 }
 439                 signal(SIGINT, remove_tempfile_on_signal);
 440         }
 441
 442         fflush(NULL);
 443         pid = fork();
 444         if (pid < 0)
 445                 die("unable to fork");
 446         if (!pid) {
 447                 const char *pgm = external_diff();
 448                 if (pgm) {
 449                         if (one && two) {
 450                                 const char *exec_arg[10];
 451                                 const char **arg = &exec_arg[0];
 452                                 *arg++ = pgm;
 453                                 *arg++ = name;
 454                                 *arg++ = temp[0].name;
 455                                 *arg++ = temp[0].hex;
 456                                 *arg++ = temp[0].mode;
 457                                 *arg++ = temp[1].name;
 458                                 *arg++ = temp[1].hex;
 459                                 *arg++ = temp[1].mode;
 460                                 if (other) {
 461                                         *arg++ = other;
 462                                         *arg++ = xfrm_msg;
 463                                 }
 464                                 *arg = 0;
 465                                 execvp(pgm, (char *const*) exec_arg);
 466                         }
 467                         else
 468                                 execlp(pgm, pgm, name, NULL);
 469                 }
 470                 /*
 471                  * otherwise we use the built-in one.
 472                  */
 473                 if (one && two)
 474                         builtin_diff(name, other ? : name, temp, xfrm_msg);
 475                 else
 476                         printf("* Unmerged path %s\n", name);
 477                 exit(0);
 478         }
 479         if (waitpid(pid, &status, 0) < 0 ||
 480             !WIFEXITED(status) || WEXITSTATUS(status)) {
 481                 /* Earlier we did not check the exit status because
 482                  * diff exits non-zero if files are different, and
 483                  * we are not interested in knowing that.  It was a
 484                  * mistake which made it harder to quit a diff-*
 485                  * session that uses the git-apply-patch-script as
 486                  * the GIT_EXTERNAL_DIFF.  A custom GIT_EXTERNAL_DIFF
 487                  * should also exit non-zero only when it wants to
 488                  * abort the entire diff-* session.
 489                  */
 490                 remove_tempfile();
 491                 fprintf(stderr, "external diff died, stopping at %s.\n", name);
 492                 exit(1);
 493         }
 494         remove_tempfile();
 495 }
 496
 497 int diff_scoreopt_parse(const char *opt)
 498 {
 499         int diglen, num, scale, i;
 500         if (opt[0] != '-' || (opt[1] != 'M' && opt[1] != 'C'))
 501                 return -1; /* that is not a -M nor -C option */
 502         diglen = strspn(opt+2, "0123456789");
 503         if (diglen == 0 || strlen(opt+2) != diglen)
 504                 return 0; /* use default */
 505         sscanf(opt+2, "%d", &num);
 506         for (i = 0, scale = 1; i < diglen; i++)
 507                 scale *= 10;
 508
 509         /* user says num divided by scale and we say internally that
 510          * is MAX_SCORE * num / scale.
 511          */
 512         return MAX_SCORE * num / scale;
 513 }
 514
 515 void diff_setup(int detect_rename_, int minimum_score_,
 516                 const char *pickaxe_,
 517                 int reverse_diff_, int diff_raw_output_,
 518                 const char **pathspec_, int speccnt_)
 519 {
 520         detect_rename = detect_rename_;
 521         reverse_diff = reverse_diff_;
 522         pathspec = pathspec_;
 523         diff_raw_output = diff_raw_output_;
 524         speccnt = speccnt_;
 525         minimum_score = minimum_score_ ? : DEFAULT_MINIMUM_SCORE;
 526         pickaxe = pickaxe_;
 527 }
 528
 529 static struct diff_queue_struct queued_diff;
 530
 531 struct diff_filepair *diff_queue(struct diff_queue_struct *queue,
 532                                   struct diff_filespec *one,
 533                                   struct diff_filespec *two)
 534 {
 535         struct diff_filepair *dp = xmalloc(sizeof(*dp));
 536         dp->one = one;
 537         dp->two = two;
 538         dp->xfrm_msg = 0;
 539         dp->orig_order = queue->nr;
 540         dp->xfrm_work = 0;
 541         if (queue->alloc <= queue->nr) {
 542                 queue->alloc = alloc_nr(queue->alloc);
 543                 queue->queue = xrealloc(queue->queue,
 544                                        sizeof(dp) * queue->alloc);
 545         }
 546         queue->queue[queue->nr++] = dp;
 547         return dp;
 548 }
 549
 550 static const char *git_object_type(unsigned mode)
 551 {
 552         return S_ISDIR(mode) ? "tree" : "blob";
 553 }
 554
 555 static void diff_flush_raw(struct diff_filepair *p)
 556 {
 557         struct diff_filespec *it;
 558         int addremove;
 559
 560         /* raw output does not have a way to express rename nor copy */
 561         if (strcmp(p->one->path, p->two->path))
 562                 return;
 563
 564         if (p->one->file_valid && p->two->file_valid) {
 565                 char hex[41];
 566                 strcpy(hex, sha1_to_hex(p->one->sha1));
 567                 printf("*%06o->%06o %s %s->%s %s%c",
 568                        p->one->mode, p->two->mode,
 569                        git_object_type(p->one->mode),
 570                        hex, sha1_to_hex(p->two->sha1),
 571                        p->one->path, diff_raw_output);
 572                 return;
 573         }
 574
 575         if (p->one->file_valid) {
 576                 it = p->one;
 577                 addremove = '-';
 578         } else {
 579                 it = p->two;
 580                 addremove = '+';
 581         }
 582
 583         printf("%c%06o %s %s %s%c",
 584                addremove,
 585                it->mode, git_object_type(it->mode),
 586                sha1_to_hex(it->sha1), it->path, diff_raw_output);
 587 }
 588
 589 static void diff_flush_patch(struct diff_filepair *p)
 590 {
 591         const char *name, *other;
 592
 593         name = p->one->path;
 594         other = (strcmp(name, p->two->path) ? p->two->path : NULL);
 595         if ((p->one->file_valid && S_ISDIR(p->one->mode)) ||
 596             (p->two->file_valid && S_ISDIR(p->two->mode)))
 597                 return; /* no tree diffs in patch format */
 598
 599         run_external_diff(name, other, p->one, p->two, p->xfrm_msg);
 600 }
 601
 602 static int identical(struct diff_filespec *one, struct diff_filespec *two)
 603 {
 604         /* This function is written stricter than necessary to support
 605          * the currently implemented transformers, but the idea is to
 606          * let transformers to produce diff_filepairs any way they want,
 607          * and filter and clean them up here before producing the output.
 608          */
 609
 610         if (!one->file_valid && !two->file_valid)
 611                 return 1; /* not interesting */
 612
 613         /* deletion, addition, mode change and renames are all interesting. */
 614         if ((one->file_valid != two->file_valid) || (one->mode != two->mode) ||
 615             strcmp(one->path, two->path))
 616                 return 0;
 617
 618         /* both are valid and point at the same path.  that is, we are
 619          * dealing with a change.
 620          */
 621         if (one->sha1_valid && two->sha1_valid &&
 622             !memcmp(one->sha1, two->sha1, sizeof(one->sha1)))
 623                 return 1; /* no change */
 624         if (!one->sha1_valid && !two->sha1_valid)
 625                 return 1; /* both look at the same file on the filesystem. */
 626         return 0;
 627 }
 628
 629 static void diff_flush_one(struct diff_filepair *p)
 630 {
 631         if (identical(p->one, p->two))
 632                 return;
 633         if (0 <= diff_raw_output)
 634                 diff_flush_raw(p);
 635         else
 636                 diff_flush_patch(p);
 637 }
 638
 639 void diff_flush(void)
 640 {
 641         struct diff_queue_struct *q = &queued_diff;
 642         int i;
 643
 644         if (detect_rename)
 645                 diff_detect_rename(q, detect_rename, minimum_score);
 646         if (pickaxe)
 647                 diff_pickaxe(q, pickaxe);
 648         for (i = 0; i < q->nr; i++)
 649                 diff_flush_one(q->queue[i]);
 650
 651         for (i = 0; i < q->nr; i++) {
 652                 struct diff_filepair *p = q->queue[i];
 653                 diff_free_filespec_data(p->one);
 654                 diff_free_filespec_data(p->two);
 655                 free(p->xfrm_msg);
 656                 free(p);
 657         }
 658         free(q->queue);
 659         q->queue = NULL;
 660         q->nr = q->alloc = 0;
 661 }
 662
 663 void diff_addremove(int addremove, unsigned mode,
 664                     const unsigned char *sha1,
 665                     const char *base, const char *path)
 666 {
 667         char concatpath[PATH_MAX];
 668         struct diff_filespec *one, *two;
 669
 670         /* This may look odd, but it is a preparation for
 671          * feeding "there are unchanged files which should
 672          * not produce diffs, but when you are doing copy
 673          * detection you would need them, so here they are"
 674          * entries to the diff-core.  They will be prefixed
 675          * with something like '=' or '*' (I haven't decided
 676          * which but should not make any difference).
 677          * Feeding the same new and old to diff_change() should
 678          * also have the same effect.  diff_flush() should
 679          * filter the identical ones out at the final output
 680          * stage.
 681          */
 682         if (reverse_diff)
 683                 addremove = (addremove == '+' ? '-' :
 684                              addremove == '-' ? '+' : addremove);
 685
 686         if (!path) path = "";
 687         sprintf(concatpath, "%s%s", base, path);
 688         one = alloc_filespec(concatpath);
 689         two = alloc_filespec(concatpath);
 690
 691         if (addremove != '+')
 692                 fill_filespec(one, sha1, mode);
 693         if (addremove != '-')
 694                 fill_filespec(two, sha1, mode);
 695
 696         diff_queue(&queued_diff, one, two);
 697 }
 698
 699 void diff_change(unsigned old_mode, unsigned new_mode,
 700                  const unsigned char *old_sha1,
 701                  const unsigned char *new_sha1,
 702                  const char *base, const char *path) {
 703         char concatpath[PATH_MAX];
 704         struct diff_filespec *one, *two;
 705
 706         if (reverse_diff) {
 707                 unsigned tmp;
 708                 const unsigned char *tmp_c;
 709                 tmp = old_mode; old_mode = new_mode; new_mode = tmp;
 710                 tmp_c = old_sha1; old_sha1 = new_sha1; new_sha1 = tmp_c;
 711         }
 712         if (!path) path = "";
 713         sprintf(concatpath, "%s%s", base, path);
 714         one = alloc_filespec(concatpath);
 715         two = alloc_filespec(concatpath);
 716         fill_filespec(one, old_sha1, old_mode);
 717         fill_filespec(two, new_sha1, new_mode);
 718
 719         diff_queue(&queued_diff, one, two);
 720 }
 721
 722 void diff_unmerge(const char *path)
 723 {
 724         if (0 <= diff_raw_output) {
 725                 printf("U %s%c", path, diff_raw_output);
 726                 return;
 727         }
 728         run_external_diff(path, NULL, NULL, NULL, NULL);
 729 }