git.oblomov.eu Git - git/blob - 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 "quote.h"
   9 #include "diff.h"
  10 #include "diffcore.h"
  11
  12 static const char *diff_opts = "-pu";
  13
  14 static int use_size_cache;
  15
  16 int diff_rename_limit_default = -1;
  17
  18 int git_diff_config(const char *var, const char *value)
  19 {
  20         if (!strcmp(var, "diff.renamelimit")) {
  21                 diff_rename_limit_default = git_config_int(var, value);
  22                 return 0;
  23         }
  24
  25         return git_default_config(var, value);
  26 }
  27
  28 static char *quote_one(const char *str)
  29 {
  30         int needlen;
  31         char *xp;
  32
  33         if (!str)
  34                 return NULL;
  35         needlen = quote_c_style(str, NULL, NULL, 0);
  36         if (!needlen)
  37                 return strdup(str);
  38         xp = xmalloc(needlen + 1);
  39         quote_c_style(str, xp, NULL, 0);
  40         return xp;
  41 }
  42
  43 static char *quote_two(const char *one, const char *two)
  44 {
  45         int need_one = quote_c_style(one, NULL, NULL, 1);
  46         int need_two = quote_c_style(two, NULL, NULL, 1);
  47         char *xp;
  48
  49         if (need_one + need_two) {
  50                 if (!need_one) need_one = strlen(one);
  51                 if (!need_two) need_one = strlen(two);
  52
  53                 xp = xmalloc(need_one + need_two + 3);
  54                 xp[0] = '"';
  55                 quote_c_style(one, xp + 1, NULL, 1);
  56                 quote_c_style(two, xp + need_one + 1, NULL, 1);
  57                 strcpy(xp + need_one + need_two + 1, "\"");
  58                 return xp;
  59         }
  60         need_one = strlen(one);
  61         need_two = strlen(two);
  62         xp = xmalloc(need_one + need_two + 1);
  63         strcpy(xp, one);
  64         strcpy(xp + need_one, two);
  65         return xp;
  66 }
  67
  68 static const char *external_diff(void)
  69 {
  70         static const char *external_diff_cmd = NULL;
  71         static int done_preparing = 0;
  72         const char *env_diff_opts;
  73
  74         if (done_preparing)
  75                 return external_diff_cmd;
  76
  77         /*
  78          * Default values above are meant to match the
  79          * Linux kernel development style.  Examples of
  80          * alternative styles you can specify via environment
  81          * variables are:
  82          *
  83          * GIT_DIFF_OPTS="-c";
  84          */
  85         external_diff_cmd = getenv("GIT_EXTERNAL_DIFF");
  86
  87         /* In case external diff fails... */
  88         env_diff_opts = getenv("GIT_DIFF_OPTS");
  89         if (env_diff_opts) diff_opts = env_diff_opts;
  90
  91         done_preparing = 1;
  92         return external_diff_cmd;
  93 }
  94
  95 #define TEMPFILE_PATH_LEN               50
  96
  97 static struct diff_tempfile {
  98         const char *name; /* filename external diff should read from */
  99         char hex[41];
 100         char mode[10];
 101         char tmp_path[TEMPFILE_PATH_LEN];
 102 } diff_temp[2];
 103
 104 static int count_lines(const char *filename)
 105 {
 106         FILE *in;
 107         int count, ch, completely_empty = 1, nl_just_seen = 0;
 108         in = fopen(filename, "r");
 109         count = 0;
 110         while ((ch = fgetc(in)) != EOF)
 111                 if (ch == '\n') {
 112                         count++;
 113                         nl_just_seen = 1;
 114                         completely_empty = 0;
 115                 }
 116                 else {
 117                         nl_just_seen = 0;
 118                         completely_empty = 0;
 119                 }
 120         fclose(in);
 121         if (completely_empty)
 122                 return 0;
 123         if (!nl_just_seen)
 124                 count++; /* no trailing newline */
 125         return count;
 126 }
 127
 128 static void print_line_count(int count)
 129 {
 130         switch (count) {
 131         case 0:
 132                 printf("0,0");
 133                 break;
 134         case 1:
 135                 printf("1");
 136                 break;
 137         default:
 138                 printf("1,%d", count);
 139                 break;
 140         }
 141 }
 142
 143 static void copy_file(int prefix, const char *filename)
 144 {
 145         FILE *in;
 146         int ch, nl_just_seen = 1;
 147         in = fopen(filename, "r");
 148         while ((ch = fgetc(in)) != EOF) {
 149                 if (nl_just_seen)
 150                         putchar(prefix);
 151                 putchar(ch);
 152                 if (ch == '\n')
 153                         nl_just_seen = 1;
 154                 else
 155                         nl_just_seen = 0;
 156         }
 157         fclose(in);
 158         if (!nl_just_seen)
 159                 printf("\n\\ No newline at end of file\n");
 160 }
 161
 162 static void emit_rewrite_diff(const char *name_a,
 163                               const char *name_b,
 164                               struct diff_tempfile *temp)
 165 {
 166         /* Use temp[i].name as input, name_a and name_b as labels */
 167         int lc_a, lc_b;
 168         lc_a = count_lines(temp[0].name);
 169         lc_b = count_lines(temp[1].name);
 170         printf("--- %s\n+++ %s\n@@ -", name_a, name_b);
 171         print_line_count(lc_a);
 172         printf(" +");
 173         print_line_count(lc_b);
 174         printf(" @@\n");
 175         if (lc_a)
 176                 copy_file('-', temp[0].name);
 177         if (lc_b)
 178                 copy_file('+', temp[1].name);
 179 }
 180
 181 static void builtin_diff(const char *name_a,
 182                          const char *name_b,
 183                          struct diff_tempfile *temp,
 184                          const char *xfrm_msg,
 185                          int complete_rewrite)
 186 {
 187         int i, next_at, cmd_size;
 188         const char *const diff_cmd = "diff -L%s -L%s";
 189         const char *const diff_arg  = "-- %s %s||:"; /* "||:" is to return 0 */
 190         const char *input_name_sq[2];
 191         const char *label_path[2];
 192         char *cmd;
 193
 194         /* diff_cmd and diff_arg have 4 %s in total which makes
 195          * the sum of these strings 8 bytes larger than required.
 196          * we use 2 spaces around diff-opts, and we need to count
 197          * terminating NUL; we used to subtract 5 here, but we do not
 198          * care about small leaks in this subprocess that is about
 199          * to exec "diff" anymore.
 200          */
 201         cmd_size = (strlen(diff_cmd) + strlen(diff_opts) + strlen(diff_arg)
 202                     + 128);
 203
 204         for (i = 0; i < 2; i++) {
 205                 input_name_sq[i] = sq_quote(temp[i].name);
 206                 if (!strcmp(temp[i].name, "/dev/null"))
 207                         label_path[i] = "/dev/null";
 208                 else if (!i)
 209                         label_path[i] = sq_quote(quote_two("a/", name_a));
 210                 else
 211                         label_path[i] = sq_quote(quote_two("b/", name_b));
 212                 cmd_size += (strlen(label_path[i]) + strlen(input_name_sq[i]));
 213         }
 214
 215         cmd = xmalloc(cmd_size);
 216
 217         next_at = 0;
 218         next_at += snprintf(cmd+next_at, cmd_size-next_at,
 219                             diff_cmd, label_path[0], label_path[1]);
 220         next_at += snprintf(cmd+next_at, cmd_size-next_at,
 221                             " %s ", diff_opts);
 222         next_at += snprintf(cmd+next_at, cmd_size-next_at,
 223                             diff_arg, input_name_sq[0], input_name_sq[1]);
 224
 225         printf("diff --git %s %s\n",
 226                quote_two("a/", name_a), quote_two("b/", name_b));
 227         if (label_path[0][0] == '/') {
 228                 /* dev/null */
 229                 printf("new file mode %s\n", temp[1].mode);
 230                 if (xfrm_msg && xfrm_msg[0])
 231                         puts(xfrm_msg);
 232         }
 233         else if (label_path[1][0] == '/') {
 234                 printf("deleted file mode %s\n", temp[0].mode);
 235                 if (xfrm_msg && xfrm_msg[0])
 236                         puts(xfrm_msg);
 237         }
 238         else {
 239                 if (strcmp(temp[0].mode, temp[1].mode)) {
 240                         printf("old mode %s\n", temp[0].mode);
 241                         printf("new mode %s\n", temp[1].mode);
 242                 }
 243                 if (xfrm_msg && xfrm_msg[0])
 244                         puts(xfrm_msg);
 245                 if (strncmp(temp[0].mode, temp[1].mode, 3))
 246                         /* we do not run diff between different kind
 247                          * of objects.
 248                          */
 249                         exit(0);
 250                 if (complete_rewrite) {
 251                         fflush(NULL);
 252                         emit_rewrite_diff(name_a, name_b, temp);
 253                         exit(0);
 254                 }
 255         }
 256         fflush(NULL);
 257         execlp("/bin/sh","sh", "-c", cmd, NULL);
 258 }
 259
 260 struct diff_filespec *alloc_filespec(const char *path)
 261 {
 262         int namelen = strlen(path);
 263         struct diff_filespec *spec = xmalloc(sizeof(*spec) + namelen + 1);
 264
 265         memset(spec, 0, sizeof(*spec));
 266         spec->path = (char *)(spec + 1);
 267         memcpy(spec->path, path, namelen+1);
 268         return spec;
 269 }
 270
 271 void fill_filespec(struct diff_filespec *spec, const unsigned char *sha1,
 272                    unsigned short mode)
 273 {
 274         if (mode) {
 275                 spec->mode = DIFF_FILE_CANON_MODE(mode);
 276                 memcpy(spec->sha1, sha1, 20);
 277                 spec->sha1_valid = !!memcmp(sha1, null_sha1, 20);
 278         }
 279 }
 280
 281 /*
 282  * Given a name and sha1 pair, if the dircache tells us the file in
 283  * the work tree has that object contents, return true, so that
 284  * prepare_temp_file() does not have to inflate and extract.
 285  */
 286 static int work_tree_matches(const char *name, const unsigned char *sha1)
 287 {
 288         struct cache_entry *ce;
 289         struct stat st;
 290         int pos, len;
 291
 292         /* We do not read the cache ourselves here, because the
 293          * benchmark with my previous version that always reads cache
 294          * shows that it makes things worse for diff-tree comparing
 295          * two linux-2.6 kernel trees in an already checked out work
 296          * tree.  This is because most diff-tree comparisons deal with
 297          * only a small number of files, while reading the cache is
 298          * expensive for a large project, and its cost outweighs the
 299          * savings we get by not inflating the object to a temporary
 300          * file.  Practically, this code only helps when we are used
 301          * by diff-cache --cached, which does read the cache before
 302          * calling us.
 303          */
 304         if (!active_cache)
 305                 return 0;
 306
 307         len = strlen(name);
 308         pos = cache_name_pos(name, len);
 309         if (pos < 0)
 310                 return 0;
 311         ce = active_cache[pos];
 312         if ((lstat(name, &st) < 0) ||
 313             !S_ISREG(st.st_mode) || /* careful! */
 314             ce_match_stat(ce, &st) ||
 315             memcmp(sha1, ce->sha1, 20))
 316                 return 0;
 317         /* we return 1 only when we can stat, it is a regular file,
 318          * stat information matches, and sha1 recorded in the cache
 319          * matches.  I.e. we know the file in the work tree really is
 320          * the same as the <name, sha1> pair.
 321          */
 322         return 1;
 323 }
 324
 325 static struct sha1_size_cache {
 326         unsigned char sha1[20];
 327         unsigned long size;
 328 } **sha1_size_cache;
 329 static int sha1_size_cache_nr, sha1_size_cache_alloc;
 330
 331 static struct sha1_size_cache *locate_size_cache(unsigned char *sha1,
 332                                                  int find_only,
 333                                                  unsigned long size)
 334 {
 335         int first, last;
 336         struct sha1_size_cache *e;
 337
 338         first = 0;
 339         last = sha1_size_cache_nr;
 340         while (last > first) {
 341                 int cmp, next = (last + first) >> 1;
 342                 e = sha1_size_cache[next];
 343                 cmp = memcmp(e->sha1, sha1, 20);
 344                 if (!cmp)
 345                         return e;
 346                 if (cmp < 0) {
 347                         last = next;
 348                         continue;
 349                 }
 350                 first = next+1;
 351         }
 352         /* not found */
 353         if (find_only)
 354                 return NULL;
 355         /* insert to make it at "first" */
 356         if (sha1_size_cache_alloc <= sha1_size_cache_nr) {
 357                 sha1_size_cache_alloc = alloc_nr(sha1_size_cache_alloc);
 358                 sha1_size_cache = xrealloc(sha1_size_cache,
 359                                            sha1_size_cache_alloc *
 360                                            sizeof(*sha1_size_cache));
 361         }
 362         sha1_size_cache_nr++;
 363         if (first < sha1_size_cache_nr)
 364                 memmove(sha1_size_cache + first + 1, sha1_size_cache + first,
 365                         (sha1_size_cache_nr - first - 1) *
 366                         sizeof(*sha1_size_cache));
 367         e = xmalloc(sizeof(struct sha1_size_cache));
 368         sha1_size_cache[first] = e;
 369         memcpy(e->sha1, sha1, 20);
 370         e->size = size;
 371         return e;
 372 }
 373
 374 /*
 375  * While doing rename detection and pickaxe operation, we may need to
 376  * grab the data for the blob (or file) for our own in-core comparison.
 377  * diff_filespec has data and size fields for this purpose.
 378  */
 379 int diff_populate_filespec(struct diff_filespec *s, int size_only)
 380 {
 381         int err = 0;
 382         if (!DIFF_FILE_VALID(s))
 383                 die("internal error: asking to populate invalid file.");
 384         if (S_ISDIR(s->mode))
 385                 return -1;
 386
 387         if (!use_size_cache)
 388                 size_only = 0;
 389
 390         if (s->data)
 391                 return err;
 392         if (!s->sha1_valid ||
 393             work_tree_matches(s->path, s->sha1)) {
 394                 struct stat st;
 395                 int fd;
 396                 if (lstat(s->path, &st) < 0) {
 397                         if (errno == ENOENT) {
 398                         err_empty:
 399                                 err = -1;
 400                         empty:
 401                                 s->data = "";
 402                                 s->size = 0;
 403                                 return err;
 404                         }
 405                 }
 406                 s->size = st.st_size;
 407                 if (!s->size)
 408                         goto empty;
 409                 if (size_only)
 410                         return 0;
 411                 if (S_ISLNK(st.st_mode)) {
 412                         int ret;
 413                         s->data = xmalloc(s->size);
 414                         s->should_free = 1;
 415                         ret = readlink(s->path, s->data, s->size);
 416                         if (ret < 0) {
 417                                 free(s->data);
 418                                 goto err_empty;
 419                         }
 420                         return 0;
 421                 }
 422                 fd = open(s->path, O_RDONLY);
 423                 if (fd < 0)
 424                         goto err_empty;
 425                 s->data = mmap(NULL, s->size, PROT_READ, MAP_PRIVATE, fd, 0);
 426                 close(fd);
 427                 if (s->data == MAP_FAILED)
 428                         goto err_empty;
 429                 s->should_munmap = 1;
 430         }
 431         else {
 432                 char type[20];
 433                 struct sha1_size_cache *e;
 434
 435                 if (size_only) {
 436                         e = locate_size_cache(s->sha1, 1, 0);
 437                         if (e) {
 438                                 s->size = e->size;
 439                                 return 0;
 440                         }
 441                         if (!sha1_object_info(s->sha1, type, &s->size))
 442                                 locate_size_cache(s->sha1, 0, s->size);
 443                 }
 444                 else {
 445                         s->data = read_sha1_file(s->sha1, type, &s->size);
 446                         s->should_free = 1;
 447                 }
 448         }
 449         return 0;
 450 }
 451
 452 void diff_free_filespec_data(struct diff_filespec *s)
 453 {
 454         if (s->should_free)
 455                 free(s->data);
 456         else if (s->should_munmap)
 457                 munmap(s->data, s->size);
 458         s->should_free = s->should_munmap = 0;
 459         s->data = NULL;
 460 }
 461
 462 static void prep_temp_blob(struct diff_tempfile *temp,
 463                            void *blob,
 464                            unsigned long size,
 465                            const unsigned char *sha1,
 466                            int mode)
 467 {
 468         int fd;
 469
 470         fd = git_mkstemp(temp->tmp_path, TEMPFILE_PATH_LEN, ".diff_XXXXXX");
 471         if (fd < 0)
 472                 die("unable to create temp-file");
 473         if (write(fd, blob, size) != size)
 474                 die("unable to write temp-file");
 475         close(fd);
 476         temp->name = temp->tmp_path;
 477         strcpy(temp->hex, sha1_to_hex(sha1));
 478         temp->hex[40] = 0;
 479         sprintf(temp->mode, "%06o", mode);
 480 }
 481
 482 static void prepare_temp_file(const char *name,
 483                               struct diff_tempfile *temp,
 484                               struct diff_filespec *one)
 485 {
 486         if (!DIFF_FILE_VALID(one)) {
 487         not_a_valid_file:
 488                 /* A '-' entry produces this for file-2, and
 489                  * a '+' entry produces this for file-1.
 490                  */
 491                 temp->name = "/dev/null";
 492                 strcpy(temp->hex, ".");
 493                 strcpy(temp->mode, ".");
 494                 return;
 495         }
 496
 497         if (!one->sha1_valid ||
 498             work_tree_matches(name, one->sha1)) {
 499                 struct stat st;
 500                 if (lstat(name, &st) < 0) {
 501                         if (errno == ENOENT)
 502                                 goto not_a_valid_file;
 503                         die("stat(%s): %s", name, strerror(errno));
 504                 }
 505                 if (S_ISLNK(st.st_mode)) {
 506                         int ret;
 507                         char *buf, buf_[1024];
 508                         buf = ((sizeof(buf_) < st.st_size) ?
 509                                xmalloc(st.st_size) : buf_);
 510                         ret = readlink(name, buf, st.st_size);
 511                         if (ret < 0)
 512                                 die("readlink(%s)", name);
 513                         prep_temp_blob(temp, buf, st.st_size,
 514                                        (one->sha1_valid ?
 515                                         one->sha1 : null_sha1),
 516                                        (one->sha1_valid ?
 517                                         one->mode : S_IFLNK));
 518                 }
 519                 else {
 520                         /* we can borrow from the file in the work tree */
 521                         temp->name = name;
 522                         if (!one->sha1_valid)
 523                                 strcpy(temp->hex, sha1_to_hex(null_sha1));
 524                         else
 525                                 strcpy(temp->hex, sha1_to_hex(one->sha1));
 526                         /* Even though we may sometimes borrow the
 527                          * contents from the work tree, we always want
 528                          * one->mode.  mode is trustworthy even when
 529                          * !(one->sha1_valid), as long as
 530                          * DIFF_FILE_VALID(one).
 531                          */
 532                         sprintf(temp->mode, "%06o", one->mode);
 533                 }
 534                 return;
 535         }
 536         else {
 537                 if (diff_populate_filespec(one, 0))
 538                         die("cannot read data blob for %s", one->path);
 539                 prep_temp_blob(temp, one->data, one->size,
 540                                one->sha1, one->mode);
 541         }
 542 }
 543
 544 static void remove_tempfile(void)
 545 {
 546         int i;
 547
 548         for (i = 0; i < 2; i++)
 549                 if (diff_temp[i].name == diff_temp[i].tmp_path) {
 550                         unlink(diff_temp[i].name);
 551                         diff_temp[i].name = NULL;
 552                 }
 553 }
 554
 555 static void remove_tempfile_on_signal(int signo)
 556 {
 557         remove_tempfile();
 558 }
 559
 560 /* An external diff command takes:
 561  *
 562  * diff-cmd name infile1 infile1-sha1 infile1-mode \
 563  *               infile2 infile2-sha1 infile2-mode [ rename-to ]
 564  *
 565  */
 566 static void run_external_diff(const char *pgm,
 567                               const char *name,
 568                               const char *other,
 569                               struct diff_filespec *one,
 570                               struct diff_filespec *two,
 571                               const char *xfrm_msg,
 572                               int complete_rewrite)
 573 {
 574         struct diff_tempfile *temp = diff_temp;
 575         pid_t pid;
 576         int status;
 577         static int atexit_asked = 0;
 578         const char *othername;
 579
 580         othername = (other? other : name);
 581         if (one && two) {
 582                 prepare_temp_file(name, &temp[0], one);
 583                 prepare_temp_file(othername, &temp[1], two);
 584                 if (! atexit_asked &&
 585                     (temp[0].name == temp[0].tmp_path ||
 586                      temp[1].name == temp[1].tmp_path)) {
 587                         atexit_asked = 1;
 588                         atexit(remove_tempfile);
 589                 }
 590                 signal(SIGINT, remove_tempfile_on_signal);
 591         }
 592
 593         fflush(NULL);
 594         pid = fork();
 595         if (pid < 0)
 596                 die("unable to fork");
 597         if (!pid) {
 598                 if (pgm) {
 599                         if (one && two) {
 600                                 const char *exec_arg[10];
 601                                 const char **arg = &exec_arg[0];
 602                                 *arg++ = pgm;
 603                                 *arg++ = name;
 604                                 *arg++ = temp[0].name;
 605                                 *arg++ = temp[0].hex;
 606                                 *arg++ = temp[0].mode;
 607                                 *arg++ = temp[1].name;
 608                                 *arg++ = temp[1].hex;
 609                                 *arg++ = temp[1].mode;
 610                                 if (other) {
 611                                         *arg++ = other;
 612                                         *arg++ = xfrm_msg;
 613                                 }
 614                                 *arg = NULL;
 615                                 execvp(pgm, (char *const*) exec_arg);
 616                         }
 617                         else
 618                                 execlp(pgm, pgm, name, NULL);
 619                 }
 620                 /*
 621                  * otherwise we use the built-in one.
 622                  */
 623                 if (one && two)
 624                         builtin_diff(name, othername, temp, xfrm_msg,
 625                                      complete_rewrite);
 626                 else
 627                         printf("* Unmerged path %s\n", name);
 628                 exit(0);
 629         }
 630         if (waitpid(pid, &status, 0) < 0 ||
 631             !WIFEXITED(status) || WEXITSTATUS(status)) {
 632                 /* Earlier we did not check the exit status because
 633                  * diff exits non-zero if files are different, and
 634                  * we are not interested in knowing that.  It was a
 635                  * mistake which made it harder to quit a diff-*
 636                  * session that uses the git-apply-patch-script as
 637                  * the GIT_EXTERNAL_DIFF.  A custom GIT_EXTERNAL_DIFF
 638                  * should also exit non-zero only when it wants to
 639                  * abort the entire diff-* session.
 640                  */
 641                 remove_tempfile();
 642                 fprintf(stderr, "external diff died, stopping at %s.\n", name);
 643                 exit(1);
 644         }
 645         remove_tempfile();
 646 }
 647
 648 static void diff_fill_sha1_info(struct diff_filespec *one)
 649 {
 650         if (DIFF_FILE_VALID(one)) {
 651                 if (!one->sha1_valid) {
 652                         struct stat st;
 653                         if (stat(one->path, &st) < 0)
 654                                 die("stat %s", one->path);
 655                         if (index_path(one->sha1, one->path, &st, 0))
 656                                 die("cannot hash %s\n", one->path);
 657                 }
 658         }
 659         else
 660                 memset(one->sha1, 0, 20);
 661 }
 662
 663 static void run_diff(struct diff_filepair *p, struct diff_options *o)
 664 {
 665         const char *pgm = external_diff();
 666         char msg[PATH_MAX*2+300], *xfrm_msg;
 667         struct diff_filespec *one;
 668         struct diff_filespec *two;
 669         const char *name;
 670         const char *other;
 671         char *name_munged, *other_munged;
 672         int complete_rewrite = 0;
 673         int len;
 674
 675         if (DIFF_PAIR_UNMERGED(p)) {
 676                 /* unmerged */
 677                 run_external_diff(pgm, p->one->path, NULL, NULL, NULL, NULL,
 678                                   0);
 679                 return;
 680         }
 681
 682         name = p->one->path;
 683         other = (strcmp(name, p->two->path) ? p->two->path : NULL);
 684         name_munged = quote_one(name);
 685         other_munged = quote_one(other);
 686         one = p->one; two = p->two;
 687
 688         diff_fill_sha1_info(one);
 689         diff_fill_sha1_info(two);
 690
 691         len = 0;
 692         switch (p->status) {
 693         case DIFF_STATUS_COPIED:
 694                 len += snprintf(msg + len, sizeof(msg) - len,
 695                                 "similarity index %d%%\n"
 696                                 "copy from %s\n"
 697                                 "copy to %s\n",
 698                                 (int)(0.5 + p->score * 100.0/MAX_SCORE),
 699                                 name_munged, other_munged);
 700                 break;
 701         case DIFF_STATUS_RENAMED:
 702                 len += snprintf(msg + len, sizeof(msg) - len,
 703                                 "similarity index %d%%\n"
 704                                 "rename from %s\n"
 705                                 "rename to %s\n",
 706                                 (int)(0.5 + p->score * 100.0/MAX_SCORE),
 707                                 name_munged, other_munged);
 708                 break;
 709         case DIFF_STATUS_MODIFIED:
 710                 if (p->score) {
 711                         len += snprintf(msg + len, sizeof(msg) - len,
 712                                         "dissimilarity index %d%%\n",
 713                                         (int)(0.5 + p->score *
 714                                               100.0/MAX_SCORE));
 715                         complete_rewrite = 1;
 716                         break;
 717                 }
 718                 /* fallthru */
 719         default:
 720                 /* nothing */
 721                 ;
 722         }
 723
 724         if (memcmp(one->sha1, two->sha1, 20)) {
 725                 char one_sha1[41];
 726                 int abbrev = o->full_index ? 40 : DIFF_DEFAULT_INDEX_ABBREV;
 727                 memcpy(one_sha1, sha1_to_hex(one->sha1), 41);
 728
 729                 len += snprintf(msg + len, sizeof(msg) - len,
 730                                 "index %.*s..%.*s",
 731                                 abbrev, one_sha1, abbrev,
 732                                 sha1_to_hex(two->sha1));
 733                 if (one->mode == two->mode)
 734                         len += snprintf(msg + len, sizeof(msg) - len,
 735                                         " %06o", one->mode);
 736                 len += snprintf(msg + len, sizeof(msg) - len, "\n");
 737         }
 738
 739         if (len)
 740                 msg[--len] = 0;
 741         xfrm_msg = len ? msg : NULL;
 742
 743         if (!pgm &&
 744             DIFF_FILE_VALID(one) && DIFF_FILE_VALID(two) &&
 745             (S_IFMT & one->mode) != (S_IFMT & two->mode)) {
 746                 /* a filepair that changes between file and symlink
 747                  * needs to be split into deletion and creation.
 748                  */
 749                 struct diff_filespec *null = alloc_filespec(two->path);
 750                 run_external_diff(NULL, name, other, one, null, xfrm_msg, 0);
 751                 free(null);
 752                 null = alloc_filespec(one->path);
 753                 run_external_diff(NULL, name, other, null, two, xfrm_msg, 0);
 754                 free(null);
 755         }
 756         else
 757                 run_external_diff(pgm, name, other, one, two, xfrm_msg,
 758                                   complete_rewrite);
 759
 760         free(name_munged);
 761         free(other_munged);
 762 }
 763
 764 void diff_setup(struct diff_options *options)
 765 {
 766         memset(options, 0, sizeof(*options));
 767         options->output_format = DIFF_FORMAT_RAW;
 768         options->line_termination = '\n';
 769         options->break_opt = -1;
 770         options->rename_limit = -1;
 771
 772         options->change = diff_change;
 773         options->add_remove = diff_addremove;
 774 }
 775
 776 int diff_setup_done(struct diff_options *options)
 777 {
 778         if ((options->find_copies_harder &&
 779              options->detect_rename != DIFF_DETECT_COPY) ||
 780             (0 <= options->rename_limit && !options->detect_rename))
 781                 return -1;
 782         if (options->detect_rename && options->rename_limit < 0)
 783                 options->rename_limit = diff_rename_limit_default;
 784         if (options->setup & DIFF_SETUP_USE_CACHE) {
 785                 if (!active_cache)
 786                         /* read-cache does not die even when it fails
 787                          * so it is safe for us to do this here.  Also
 788                          * it does not smudge active_cache or active_nr
 789                          * when it fails, so we do not have to worry about
 790                          * cleaning it up oufselves either.
 791                          */
 792                         read_cache();
 793         }
 794         if (options->setup & DIFF_SETUP_USE_SIZE_CACHE)
 795                 use_size_cache = 1;
 796         if (options->abbrev <= 0 || 40 < options->abbrev)
 797                 options->abbrev = 40; /* full */
 798
 799         return 0;
 800 }
 801
 802 int diff_opt_parse(struct diff_options *options, const char **av, int ac)
 803 {
 804         const char *arg = av[0];
 805         if (!strcmp(arg, "-p") || !strcmp(arg, "-u"))
 806                 options->output_format = DIFF_FORMAT_PATCH;
 807         else if (!strcmp(arg, "-z"))
 808                 options->line_termination = 0;
 809         else if (!strncmp(arg, "-l", 2))
 810                 options->rename_limit = strtoul(arg+2, NULL, 10);
 811         else if (!strcmp(arg, "--full-index"))
 812                 options->full_index = 1;
 813         else if (!strcmp(arg, "--name-only"))
 814                 options->output_format = DIFF_FORMAT_NAME;
 815         else if (!strcmp(arg, "--name-status"))
 816                 options->output_format = DIFF_FORMAT_NAME_STATUS;
 817         else if (!strcmp(arg, "-R"))
 818                 options->reverse_diff = 1;
 819         else if (!strncmp(arg, "-S", 2))
 820                 options->pickaxe = arg + 2;
 821         else if (!strcmp(arg, "-s"))
 822                 options->output_format = DIFF_FORMAT_NO_OUTPUT;
 823         else if (!strncmp(arg, "-O", 2))
 824                 options->orderfile = arg + 2;
 825         else if (!strncmp(arg, "--diff-filter=", 14))
 826                 options->filter = arg + 14;
 827         else if (!strcmp(arg, "--pickaxe-all"))
 828                 options->pickaxe_opts = DIFF_PICKAXE_ALL;
 829         else if (!strncmp(arg, "-B", 2)) {
 830                 if ((options->break_opt =
 831                      diff_scoreopt_parse(arg)) == -1)
 832                         return -1;
 833         }
 834         else if (!strncmp(arg, "-M", 2)) {
 835                 if ((options->rename_score =
 836                      diff_scoreopt_parse(arg)) == -1)
 837                         return -1;
 838                 options->detect_rename = DIFF_DETECT_RENAME;
 839         }
 840         else if (!strncmp(arg, "-C", 2)) {
 841                 if ((options->rename_score =
 842                      diff_scoreopt_parse(arg)) == -1)
 843                         return -1;
 844                 options->detect_rename = DIFF_DETECT_COPY;
 845         }
 846         else if (!strcmp(arg, "--find-copies-harder"))
 847                 options->find_copies_harder = 1;
 848         else if (!strcmp(arg, "--abbrev"))
 849                 options->abbrev = DIFF_DEFAULT_ABBREV;
 850         else if (!strncmp(arg, "--abbrev=", 9))
 851                 options->abbrev = strtoul(arg + 9, NULL, 10);
 852         else
 853                 return 0;
 854         return 1;
 855 }
 856
 857 static int parse_num(const char **cp_p)
 858 {
 859         unsigned long num, scale;
 860         int ch, dot;
 861         const char *cp = *cp_p;
 862
 863         num = 0;
 864         scale = 1;
 865         dot = 0;
 866         for(;;) {
 867                 ch = *cp;
 868                 if ( !dot && ch == '.' ) {
 869                         scale = 1;
 870                         dot = 1;
 871                 } else if ( ch == '%' ) {
 872                         scale = dot ? scale*100 : 100;
 873                         cp++;   /* % is always at the end */
 874                         break;
 875                 } else if ( ch >= '0' && ch <= '9' ) {
 876                         if ( scale < 100000 ) {
 877                                 scale *= 10;
 878                                 num = (num*10) + (ch-'0');
 879                         }
 880                 } else {
 881                         break;
 882                 }
 883                 cp++;
 884         }
 885         *cp_p = cp;
 886
 887         /* user says num divided by scale and we say internally that
 888          * is MAX_SCORE * num / scale.
 889          */
 890         return (num >= scale) ? MAX_SCORE : (MAX_SCORE * num / scale);
 891 }
 892
 893 int diff_scoreopt_parse(const char *opt)
 894 {
 895         int opt1, opt2, cmd;
 896
 897         if (*opt++ != '-')
 898                 return -1;
 899         cmd = *opt++;
 900         if (cmd != 'M' && cmd != 'C' && cmd != 'B')
 901                 return -1; /* that is not a -M, -C nor -B option */
 902
 903         opt1 = parse_num(&opt);
 904         if (cmd != 'B')
 905                 opt2 = 0;
 906         else {
 907                 if (*opt == 0)
 908                         opt2 = 0;
 909                 else if (*opt != '/')
 910                         return -1; /* we expect -B80/99 or -B80 */
 911                 else {
 912                         opt++;
 913                         opt2 = parse_num(&opt);
 914                 }
 915         }
 916         if (*opt != 0)
 917                 return -1;
 918         return opt1 | (opt2 << 16);
 919 }
 920
 921 struct diff_queue_struct diff_queued_diff;
 922
 923 void diff_q(struct diff_queue_struct *queue, struct diff_filepair *dp)
 924 {
 925         if (queue->alloc <= queue->nr) {
 926                 queue->alloc = alloc_nr(queue->alloc);
 927                 queue->queue = xrealloc(queue->queue,
 928                                         sizeof(dp) * queue->alloc);
 929         }
 930         queue->queue[queue->nr++] = dp;
 931 }
 932
 933 struct diff_filepair *diff_queue(struct diff_queue_struct *queue,
 934                                  struct diff_filespec *one,
 935                                  struct diff_filespec *two)
 936 {
 937         struct diff_filepair *dp = xmalloc(sizeof(*dp));
 938         dp->one = one;
 939         dp->two = two;
 940         dp->score = 0;
 941         dp->status = 0;
 942         dp->source_stays = 0;
 943         dp->broken_pair = 0;
 944         if (queue)
 945                 diff_q(queue, dp);
 946         return dp;
 947 }
 948
 949 void diff_free_filepair(struct diff_filepair *p)
 950 {
 951         diff_free_filespec_data(p->one);
 952         diff_free_filespec_data(p->two);
 953         free(p->one);
 954         free(p->two);
 955         free(p);
 956 }
 957
 958 /* This is different from find_unique_abbrev() in that
 959  * it needs to deal with 0{40} SHA1.
 960  */
 961 const char *diff_unique_abbrev(const unsigned char *sha1, int len)
 962 {
 963         int abblen;
 964         const char *abbrev;
 965         if (len == 40)
 966                 return sha1_to_hex(sha1);
 967
 968         abbrev = find_unique_abbrev(sha1, len);
 969         if (!abbrev) {
 970                 if (!memcmp(sha1, null_sha1, 20)) {
 971                         char *buf = sha1_to_hex(null_sha1);
 972                         if (len < 37)
 973                                 strcpy(buf + len, "...");
 974                         return buf;
 975                 }
 976                 else
 977                         return sha1_to_hex(sha1);
 978         }
 979         abblen = strlen(abbrev);
 980         if (abblen < 37) {
 981                 static char hex[41];
 982                 if (len < abblen && abblen <= len + 2)
 983                         sprintf(hex, "%s%.*s", abbrev, len+3-abblen, "..");
 984                 else
 985                         sprintf(hex, "%s...", abbrev);
 986                 return hex;
 987         }
 988         return sha1_to_hex(sha1);
 989 }
 990
 991 static void diff_flush_raw(struct diff_filepair *p,
 992                            int line_termination,
 993                            int inter_name_termination,
 994                            struct diff_options *options)
 995 {
 996         int two_paths;
 997         char status[10];
 998         int abbrev = options->abbrev;
 999         const char *path_one, *path_two;
1000         int output_format = options->output_format;
1001
1002         path_one = p->one->path;
1003         path_two = p->two->path;
1004         if (line_termination) {
1005                 path_one = quote_one(path_one);
1006                 path_two = quote_one(path_two);
1007         }
1008
1009         if (p->score)
1010                 sprintf(status, "%c%03d", p->status,
1011                         (int)(0.5 + p->score * 100.0/MAX_SCORE));
1012         else {
1013                 status[0] = p->status;
1014                 status[1] = 0;
1015         }
1016         switch (p->status) {
1017         case DIFF_STATUS_COPIED:
1018         case DIFF_STATUS_RENAMED:
1019                 two_paths = 1;
1020                 break;
1021         case DIFF_STATUS_ADDED:
1022         case DIFF_STATUS_DELETED:
1023                 two_paths = 0;
1024                 break;
1025         default:
1026                 two_paths = 0;
1027                 break;
1028         }
1029         if (output_format != DIFF_FORMAT_NAME_STATUS) {
1030                 printf(":%06o %06o %s ",
1031                        p->one->mode, p->two->mode,
1032                        diff_unique_abbrev(p->one->sha1, abbrev));
1033                 printf("%s ",
1034                        diff_unique_abbrev(p->two->sha1, abbrev));
1035         }
1036         printf("%s%c%s", status, inter_name_termination, path_one);
1037         if (two_paths)
1038                 printf("%c%s", inter_name_termination, path_two);
1039         putchar(line_termination);
1040         if (path_one != p->one->path)
1041                 free((void*)path_one);
1042         if (path_two != p->two->path)
1043                 free((void*)path_two);
1044 }
1045
1046 static void diff_flush_name(struct diff_filepair *p,
1047                             int inter_name_termination,
1048                             int line_termination)
1049 {
1050         char *path = p->two->path;
1051
1052         if (line_termination)
1053                 path = quote_one(p->two->path);
1054         else
1055                 path = p->two->path;
1056         printf("%s%c", path, line_termination);
1057         if (p->two->path != path)
1058                 free(path);
1059 }
1060
1061 int diff_unmodified_pair(struct diff_filepair *p)
1062 {
1063         /* This function is written stricter than necessary to support
1064          * the currently implemented transformers, but the idea is to
1065          * let transformers to produce diff_filepairs any way they want,
1066          * and filter and clean them up here before producing the output.
1067          */
1068         struct diff_filespec *one, *two;
1069
1070         if (DIFF_PAIR_UNMERGED(p))
1071                 return 0; /* unmerged is interesting */
1072
1073         one = p->one;
1074         two = p->two;
1075
1076         /* deletion, addition, mode or type change
1077          * and rename are all interesting.
1078          */
1079         if (DIFF_FILE_VALID(one) != DIFF_FILE_VALID(two) ||
1080             DIFF_PAIR_MODE_CHANGED(p) ||
1081             strcmp(one->path, two->path))
1082                 return 0;
1083
1084         /* both are valid and point at the same path.  that is, we are
1085          * dealing with a change.
1086          */
1087         if (one->sha1_valid && two->sha1_valid &&
1088             !memcmp(one->sha1, two->sha1, sizeof(one->sha1)))
1089                 return 1; /* no change */
1090         if (!one->sha1_valid && !two->sha1_valid)
1091                 return 1; /* both look at the same file on the filesystem. */
1092         return 0;
1093 }
1094
1095 static void diff_flush_patch(struct diff_filepair *p, struct diff_options *o)
1096 {
1097         if (diff_unmodified_pair(p))
1098                 return;
1099
1100         if ((DIFF_FILE_VALID(p->one) && S_ISDIR(p->one->mode)) ||
1101             (DIFF_FILE_VALID(p->two) && S_ISDIR(p->two->mode)))
1102                 return; /* no tree diffs in patch format */
1103
1104         run_diff(p, o);
1105 }
1106
1107 int diff_queue_is_empty(void)
1108 {
1109         struct diff_queue_struct *q = &diff_queued_diff;
1110         int i;
1111         for (i = 0; i < q->nr; i++)
1112                 if (!diff_unmodified_pair(q->queue[i]))
1113                         return 0;
1114         return 1;
1115 }
1116
1117 #if DIFF_DEBUG
1118 void diff_debug_filespec(struct diff_filespec *s, int x, const char *one)
1119 {
1120         fprintf(stderr, "queue[%d] %s (%s) %s %06o %s\n",
1121                 x, one ? one : "",
1122                 s->path,
1123                 DIFF_FILE_VALID(s) ? "valid" : "invalid",
1124                 s->mode,
1125                 s->sha1_valid ? sha1_to_hex(s->sha1) : "");
1126         fprintf(stderr, "queue[%d] %s size %lu flags %d\n",
1127                 x, one ? one : "",
1128                 s->size, s->xfrm_flags);
1129 }
1130
1131 void diff_debug_filepair(const struct diff_filepair *p, int i)
1132 {
1133         diff_debug_filespec(p->one, i, "one");
1134         diff_debug_filespec(p->two, i, "two");
1135         fprintf(stderr, "score %d, status %c stays %d broken %d\n",
1136                 p->score, p->status ? p->status : '?',
1137                 p->source_stays, p->broken_pair);
1138 }
1139
1140 void diff_debug_queue(const char *msg, struct diff_queue_struct *q)
1141 {
1142         int i;
1143         if (msg)
1144                 fprintf(stderr, "%s\n", msg);
1145         fprintf(stderr, "q->nr = %d\n", q->nr);
1146         for (i = 0; i < q->nr; i++) {
1147                 struct diff_filepair *p = q->queue[i];
1148                 diff_debug_filepair(p, i);
1149         }
1150 }
1151 #endif
1152
1153 static void diff_resolve_rename_copy(void)
1154 {
1155         int i, j;
1156         struct diff_filepair *p, *pp;
1157         struct diff_queue_struct *q = &diff_queued_diff;
1158
1159         diff_debug_queue("resolve-rename-copy", q);
1160
1161         for (i = 0; i < q->nr; i++) {
1162                 p = q->queue[i];
1163                 p->status = 0; /* undecided */
1164                 if (DIFF_PAIR_UNMERGED(p))
1165                         p->status = DIFF_STATUS_UNMERGED;
1166                 else if (!DIFF_FILE_VALID(p->one))
1167                         p->status = DIFF_STATUS_ADDED;
1168                 else if (!DIFF_FILE_VALID(p->two))
1169                         p->status = DIFF_STATUS_DELETED;
1170                 else if (DIFF_PAIR_TYPE_CHANGED(p))
1171                         p->status = DIFF_STATUS_TYPE_CHANGED;
1172
1173                 /* from this point on, we are dealing with a pair
1174                  * whose both sides are valid and of the same type, i.e.
1175                  * either in-place edit or rename/copy edit.
1176                  */
1177                 else if (DIFF_PAIR_RENAME(p)) {
1178                         if (p->source_stays) {
1179                                 p->status = DIFF_STATUS_COPIED;
1180                                 continue;
1181                         }
1182                         /* See if there is some other filepair that
1183                          * copies from the same source as us.  If so
1184                          * we are a copy.  Otherwise we are either a
1185                          * copy if the path stays, or a rename if it
1186                          * does not, but we already handled "stays" case.
1187                          */
1188                         for (j = i + 1; j < q->nr; j++) {
1189                                 pp = q->queue[j];
1190                                 if (strcmp(pp->one->path, p->one->path))
1191                                         continue; /* not us */
1192                                 if (!DIFF_PAIR_RENAME(pp))
1193                                         continue; /* not a rename/copy */
1194                                 /* pp is a rename/copy from the same source */
1195                                 p->status = DIFF_STATUS_COPIED;
1196                                 break;
1197                         }
1198                         if (!p->status)
1199                                 p->status = DIFF_STATUS_RENAMED;
1200                 }
1201                 else if (memcmp(p->one->sha1, p->two->sha1, 20) ||
1202                          p->one->mode != p->two->mode)
1203                         p->status = DIFF_STATUS_MODIFIED;
1204                 else {
1205                         /* This is a "no-change" entry and should not
1206                          * happen anymore, but prepare for broken callers.
1207                          */
1208                         error("feeding unmodified %s to diffcore",
1209                               p->one->path);
1210                         p->status = DIFF_STATUS_UNKNOWN;
1211                 }
1212         }
1213         diff_debug_queue("resolve-rename-copy done", q);
1214 }
1215
1216 void diff_flush(struct diff_options *options)
1217 {
1218         struct diff_queue_struct *q = &diff_queued_diff;
1219         int i;
1220         int inter_name_termination = '\t';
1221         int diff_output_format = options->output_format;
1222         int line_termination = options->line_termination;
1223
1224         if (!line_termination)
1225                 inter_name_termination = 0;
1226
1227         for (i = 0; i < q->nr; i++) {
1228                 struct diff_filepair *p = q->queue[i];
1229                 if ((diff_output_format == DIFF_FORMAT_NO_OUTPUT) ||
1230                     (p->status == DIFF_STATUS_UNKNOWN))
1231                         continue;
1232                 if (p->status == 0)
1233                         die("internal error in diff-resolve-rename-copy");
1234                 switch (diff_output_format) {
1235                 case DIFF_FORMAT_PATCH:
1236                         diff_flush_patch(p, options);
1237                         break;
1238                 case DIFF_FORMAT_RAW:
1239                 case DIFF_FORMAT_NAME_STATUS:
1240                         diff_flush_raw(p, line_termination,
1241                                        inter_name_termination,
1242                                        options);
1243                         break;
1244                 case DIFF_FORMAT_NAME:
1245                         diff_flush_name(p,
1246                                         inter_name_termination,
1247                                         line_termination);
1248                         break;
1249                 }
1250                 diff_free_filepair(q->queue[i]);
1251         }
1252         free(q->queue);
1253         q->queue = NULL;
1254         q->nr = q->alloc = 0;
1255 }
1256
1257 static void diffcore_apply_filter(const char *filter)
1258 {
1259         int i;
1260         struct diff_queue_struct *q = &diff_queued_diff;
1261         struct diff_queue_struct outq;
1262         outq.queue = NULL;
1263         outq.nr = outq.alloc = 0;
1264
1265         if (!filter)
1266                 return;
1267
1268         if (strchr(filter, DIFF_STATUS_FILTER_AON)) {
1269                 int found;
1270                 for (i = found = 0; !found && i < q->nr; i++) {
1271                         struct diff_filepair *p = q->queue[i];
1272                         if (((p->status == DIFF_STATUS_MODIFIED) &&
1273                              ((p->score &&
1274                                strchr(filter, DIFF_STATUS_FILTER_BROKEN)) ||
1275                               (!p->score &&
1276                                strchr(filter, DIFF_STATUS_MODIFIED)))) ||
1277                             ((p->status != DIFF_STATUS_MODIFIED) &&
1278                              strchr(filter, p->status)))
1279                                 found++;
1280                 }
1281                 if (found)
1282                         return;
1283
1284                 /* otherwise we will clear the whole queue
1285                  * by copying the empty outq at the end of this
1286                  * function, but first clear the current entries
1287                  * in the queue.
1288                  */
1289                 for (i = 0; i < q->nr; i++)
1290                         diff_free_filepair(q->queue[i]);
1291         }
1292         else {
1293                 /* Only the matching ones */
1294                 for (i = 0; i < q->nr; i++) {
1295                         struct diff_filepair *p = q->queue[i];
1296
1297                         if (((p->status == DIFF_STATUS_MODIFIED) &&
1298                              ((p->score &&
1299                                strchr(filter, DIFF_STATUS_FILTER_BROKEN)) ||
1300                               (!p->score &&
1301                                strchr(filter, DIFF_STATUS_MODIFIED)))) ||
1302                             ((p->status != DIFF_STATUS_MODIFIED) &&
1303                              strchr(filter, p->status)))
1304                                 diff_q(&outq, p);
1305                         else
1306                                 diff_free_filepair(p);
1307                 }
1308         }
1309         free(q->queue);
1310         *q = outq;
1311 }
1312
1313 void diffcore_std(struct diff_options *options)
1314 {
1315         if (options->paths && options->paths[0])
1316                 diffcore_pathspec(options->paths);
1317         if (options->break_opt != -1)
1318                 diffcore_break(options->break_opt);
1319         if (options->detect_rename)
1320                 diffcore_rename(options);
1321         if (options->break_opt != -1)
1322                 diffcore_merge_broken();
1323         if (options->pickaxe)
1324                 diffcore_pickaxe(options->pickaxe, options->pickaxe_opts);
1325         if (options->orderfile)
1326                 diffcore_order(options->orderfile);
1327         diff_resolve_rename_copy();
1328         diffcore_apply_filter(options->filter);
1329 }
1330
1331
1332 void diffcore_std_no_resolve(struct diff_options *options)
1333 {
1334         if (options->pickaxe)
1335                 diffcore_pickaxe(options->pickaxe, options->pickaxe_opts);
1336         if (options->orderfile)
1337                 diffcore_order(options->orderfile);
1338         diffcore_apply_filter(options->filter);
1339 }
1340
1341 void diff_addremove(struct diff_options *options,
1342                     int addremove, unsigned mode,
1343                     const unsigned char *sha1,
1344                     const char *base, const char *path)
1345 {
1346         char concatpath[PATH_MAX];
1347         struct diff_filespec *one, *two;
1348
1349         /* This may look odd, but it is a preparation for
1350          * feeding "there are unchanged files which should
1351          * not produce diffs, but when you are doing copy
1352          * detection you would need them, so here they are"
1353          * entries to the diff-core.  They will be prefixed
1354          * with something like '=' or '*' (I haven't decided
1355          * which but should not make any difference).
1356          * Feeding the same new and old to diff_change()
1357          * also has the same effect.
1358          * Before the final output happens, they are pruned after
1359          * merged into rename/copy pairs as appropriate.
1360          */
1361         if (options->reverse_diff)
1362                 addremove = (addremove == '+' ? '-' :
1363                              addremove == '-' ? '+' : addremove);
1364
1365         if (!path) path = "";
1366         sprintf(concatpath, "%s%s", base, path);
1367         one = alloc_filespec(concatpath);
1368         two = alloc_filespec(concatpath);
1369
1370         if (addremove != '+')
1371                 fill_filespec(one, sha1, mode);
1372         if (addremove != '-')
1373                 fill_filespec(two, sha1, mode);
1374
1375         diff_queue(&diff_queued_diff, one, two);
1376 }
1377
1378 void diff_change(struct diff_options *options,
1379                  unsigned old_mode, unsigned new_mode,
1380                  const unsigned char *old_sha1,
1381                  const unsigned char *new_sha1,
1382                  const char *base, const char *path)
1383 {
1384         char concatpath[PATH_MAX];
1385         struct diff_filespec *one, *two;
1386
1387         if (options->reverse_diff) {
1388                 unsigned tmp;
1389                 const unsigned char *tmp_c;
1390                 tmp = old_mode; old_mode = new_mode; new_mode = tmp;
1391                 tmp_c = old_sha1; old_sha1 = new_sha1; new_sha1 = tmp_c;
1392         }
1393         if (!path) path = "";
1394         sprintf(concatpath, "%s%s", base, path);
1395         one = alloc_filespec(concatpath);
1396         two = alloc_filespec(concatpath);
1397         fill_filespec(one, old_sha1, old_mode);
1398         fill_filespec(two, new_sha1, new_mode);
1399
1400         diff_queue(&diff_queued_diff, one, two);
1401 }
1402
1403 void diff_unmerge(struct diff_options *options,
1404                   const char *path)
1405 {
1406         struct diff_filespec *one, *two;
1407         one = alloc_filespec(path);
1408         two = alloc_filespec(path);
1409         diff_queue(&diff_queued_diff, one, two);
1410 }