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 static char *quote_one(const char *str)
  17 {
  18         int needlen;
  19         char *xp;
  20
  21         if (!str)
  22                 return NULL;
  23         needlen = quote_c_style(str, NULL, NULL, 0);
  24         if (!needlen)
  25                 return strdup(str);
  26         xp = xmalloc(needlen + 1);
  27         quote_c_style(str, xp, NULL, 0);
  28         return xp;
  29 }
  30
  31 static char *quote_two(const char *one, const char *two)
  32 {
  33         int need_one = quote_c_style(one, NULL, NULL, 1);
  34         int need_two = quote_c_style(two, NULL, NULL, 1);
  35         char *xp;
  36
  37         if (need_one + need_two) {
  38                 if (!need_one) need_one = strlen(one);
  39                 if (!need_two) need_one = strlen(two);
  40
  41                 xp = xmalloc(need_one + need_two + 3);
  42                 xp[0] = '"';
  43                 quote_c_style(one, xp + 1, NULL, 1);
  44                 quote_c_style(two, xp + need_one + 1, NULL, 1);
  45                 strcpy(xp + need_one + need_two + 1, "\"");
  46                 return xp;
  47         }
  48         need_one = strlen(one);
  49         need_two = strlen(two);
  50         xp = xmalloc(need_one + need_two + 1);
  51         strcpy(xp, one);
  52         strcpy(xp + need_one, two);
  53         return xp;
  54 }
  55
  56 static const char *external_diff(void)
  57 {
  58         static const char *external_diff_cmd = NULL;
  59         static int done_preparing = 0;
  60         const char *env_diff_opts;
  61
  62         if (done_preparing)
  63                 return external_diff_cmd;
  64
  65         /*
  66          * Default values above are meant to match the
  67          * Linux kernel development style.  Examples of
  68          * alternative styles you can specify via environment
  69          * variables are:
  70          *
  71          * GIT_DIFF_OPTS="-c";
  72          */
  73         external_diff_cmd = getenv("GIT_EXTERNAL_DIFF");
  74
  75         /* In case external diff fails... */
  76         env_diff_opts = getenv("GIT_DIFF_OPTS");
  77         if (env_diff_opts) diff_opts = env_diff_opts;
  78
  79         done_preparing = 1;
  80         return external_diff_cmd;
  81 }
  82
  83 #define TEMPFILE_PATH_LEN               50
  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[TEMPFILE_PATH_LEN];
  90 } diff_temp[2];
  91
  92 static int count_lines(const char *filename)
  93 {
  94         FILE *in;
  95         int count, ch, completely_empty = 1, nl_just_seen = 0;
  96         in = fopen(filename, "r");
  97         count = 0;
  98         while ((ch = fgetc(in)) != EOF)
  99                 if (ch == '\n') {
 100                         count++;
 101                         nl_just_seen = 1;
 102                         completely_empty = 0;
 103                 }
 104                 else {
 105                         nl_just_seen = 0;
 106                         completely_empty = 0;
 107                 }
 108         fclose(in);
 109         if (completely_empty)
 110                 return 0;
 111         if (!nl_just_seen)
 112                 count++; /* no trailing newline */
 113         return count;
 114 }
 115
 116 static void print_line_count(int count)
 117 {
 118         switch (count) {
 119         case 0:
 120                 printf("0,0");
 121                 break;
 122         case 1:
 123                 printf("1");
 124                 break;
 125         default:
 126                 printf("1,%d", count);
 127                 break;
 128         }
 129 }
 130
 131 static void copy_file(int prefix, const char *filename)
 132 {
 133         FILE *in;
 134         int ch, nl_just_seen = 1;
 135         in = fopen(filename, "r");
 136         while ((ch = fgetc(in)) != EOF) {
 137                 if (nl_just_seen)
 138                         putchar(prefix);
 139                 putchar(ch);
 140                 if (ch == '\n')
 141                         nl_just_seen = 1;
 142                 else
 143                         nl_just_seen = 0;
 144         }
 145         fclose(in);
 146         if (!nl_just_seen)
 147                 printf("\n\\ No newline at end of file\n");
 148 }
 149
 150 static void emit_rewrite_diff(const char *name_a,
 151                               const char *name_b,
 152                               struct diff_tempfile *temp)
 153 {
 154         /* Use temp[i].name as input, name_a and name_b as labels */
 155         int lc_a, lc_b;
 156         lc_a = count_lines(temp[0].name);
 157         lc_b = count_lines(temp[1].name);
 158         printf("--- %s\n+++ %s\n@@ -", name_a, name_b);
 159         print_line_count(lc_a);
 160         printf(" +");
 161         print_line_count(lc_b);
 162         printf(" @@\n");
 163         if (lc_a)
 164                 copy_file('-', temp[0].name);
 165         if (lc_b)
 166                 copy_file('+', temp[1].name);
 167 }
 168
 169 static void builtin_diff(const char *name_a,
 170                          const char *name_b,
 171                          struct diff_tempfile *temp,
 172                          const char *xfrm_msg,
 173                          int complete_rewrite)
 174 {
 175         int i, next_at, cmd_size;
 176         const char *const diff_cmd = "diff -L%s -L%s";
 177         const char *const diff_arg  = "-- %s %s||:"; /* "||:" is to return 0 */
 178         const char *input_name_sq[2];
 179         const char *label_path[2];
 180         char *cmd;
 181
 182         /* diff_cmd and diff_arg have 4 %s in total which makes
 183          * the sum of these strings 8 bytes larger than required.
 184          * we use 2 spaces around diff-opts, and we need to count
 185          * terminating NUL; we used to subtract 5 here, but we do not
 186          * care about small leaks in this subprocess that is about
 187          * to exec "diff" anymore.
 188          */
 189         cmd_size = (strlen(diff_cmd) + strlen(diff_opts) + strlen(diff_arg)
 190                     + 128);
 191
 192         for (i = 0; i < 2; i++) {
 193                 input_name_sq[i] = sq_quote(temp[i].name);
 194                 if (!strcmp(temp[i].name, "/dev/null"))
 195                         label_path[i] = "/dev/null";
 196                 else if (!i)
 197                         label_path[i] = sq_quote(quote_two("a/", name_a));
 198                 else
 199                         label_path[i] = sq_quote(quote_two("b/", name_b));
 200                 cmd_size += (strlen(label_path[i]) + strlen(input_name_sq[i]));
 201         }
 202
 203         cmd = xmalloc(cmd_size);
 204
 205         next_at = 0;
 206         next_at += snprintf(cmd+next_at, cmd_size-next_at,
 207                             diff_cmd, label_path[0], label_path[1]);
 208         next_at += snprintf(cmd+next_at, cmd_size-next_at,
 209                             " %s ", diff_opts);
 210         next_at += snprintf(cmd+next_at, cmd_size-next_at,
 211                             diff_arg, input_name_sq[0], input_name_sq[1]);
 212
 213         printf("diff --git %s %s\n",
 214                quote_two("a/", name_a), quote_two("b/", name_b));
 215         if (label_path[0][0] == '/') {
 216                 /* dev/null */
 217                 printf("new file mode %s\n", temp[1].mode);
 218                 if (xfrm_msg && xfrm_msg[0])
 219                         puts(xfrm_msg);
 220         }
 221         else if (label_path[1][0] == '/') {
 222                 printf("deleted file mode %s\n", temp[0].mode);
 223                 if (xfrm_msg && xfrm_msg[0])
 224                         puts(xfrm_msg);
 225         }
 226         else {
 227                 if (strcmp(temp[0].mode, temp[1].mode)) {
 228                         printf("old mode %s\n", temp[0].mode);
 229                         printf("new mode %s\n", temp[1].mode);
 230                 }
 231                 if (xfrm_msg && xfrm_msg[0])
 232                         puts(xfrm_msg);
 233                 if (strncmp(temp[0].mode, temp[1].mode, 3))
 234                         /* we do not run diff between different kind
 235                          * of objects.
 236                          */
 237                         exit(0);
 238                 if (complete_rewrite) {
 239                         fflush(NULL);
 240                         emit_rewrite_diff(name_a, name_b, temp);
 241                         exit(0);
 242                 }
 243         }
 244         fflush(NULL);
 245         execlp("/bin/sh","sh", "-c", cmd, NULL);
 246 }
 247
 248 struct diff_filespec *alloc_filespec(const char *path)
 249 {
 250         int namelen = strlen(path);
 251         struct diff_filespec *spec = xmalloc(sizeof(*spec) + namelen + 1);
 252
 253         memset(spec, 0, sizeof(*spec));
 254         spec->path = (char *)(spec + 1);
 255         memcpy(spec->path, path, namelen+1);
 256         return spec;
 257 }
 258
 259 void fill_filespec(struct diff_filespec *spec, const unsigned char *sha1,
 260                    unsigned short mode)
 261 {
 262         if (mode) {
 263                 spec->mode = DIFF_FILE_CANON_MODE(mode);
 264                 memcpy(spec->sha1, sha1, 20);
 265                 spec->sha1_valid = !!memcmp(sha1, null_sha1, 20);
 266         }
 267 }
 268
 269 /*
 270  * Given a name and sha1 pair, if the dircache tells us the file in
 271  * the work tree has that object contents, return true, so that
 272  * prepare_temp_file() does not have to inflate and extract.
 273  */
 274 static int work_tree_matches(const char *name, const unsigned char *sha1)
 275 {
 276         struct cache_entry *ce;
 277         struct stat st;
 278         int pos, len;
 279
 280         /* We do not read the cache ourselves here, because the
 281          * benchmark with my previous version that always reads cache
 282          * shows that it makes things worse for diff-tree comparing
 283          * two linux-2.6 kernel trees in an already checked out work
 284          * tree.  This is because most diff-tree comparisons deal with
 285          * only a small number of files, while reading the cache is
 286          * expensive for a large project, and its cost outweighs the
 287          * savings we get by not inflating the object to a temporary
 288          * file.  Practically, this code only helps when we are used
 289          * by diff-cache --cached, which does read the cache before
 290          * calling us.
 291          */
 292         if (!active_cache)
 293                 return 0;
 294
 295         len = strlen(name);
 296         pos = cache_name_pos(name, len);
 297         if (pos < 0)
 298                 return 0;
 299         ce = active_cache[pos];
 300         if ((lstat(name, &st) < 0) ||
 301             !S_ISREG(st.st_mode) || /* careful! */
 302             ce_match_stat(ce, &st) ||
 303             memcmp(sha1, ce->sha1, 20))
 304                 return 0;
 305         /* we return 1 only when we can stat, it is a regular file,
 306          * stat information matches, and sha1 recorded in the cache
 307          * matches.  I.e. we know the file in the work tree really is
 308          * the same as the <name, sha1> pair.
 309          */
 310         return 1;
 311 }
 312
 313 static struct sha1_size_cache {
 314         unsigned char sha1[20];
 315         unsigned long size;
 316 } **sha1_size_cache;
 317 static int sha1_size_cache_nr, sha1_size_cache_alloc;
 318
 319 static struct sha1_size_cache *locate_size_cache(unsigned char *sha1,
 320                                                  int find_only,
 321                                                  unsigned long size)
 322 {
 323         int first, last;
 324         struct sha1_size_cache *e;
 325
 326         first = 0;
 327         last = sha1_size_cache_nr;
 328         while (last > first) {
 329                 int cmp, next = (last + first) >> 1;
 330                 e = sha1_size_cache[next];
 331                 cmp = memcmp(e->sha1, sha1, 20);
 332                 if (!cmp)
 333                         return e;
 334                 if (cmp < 0) {
 335                         last = next;
 336                         continue;
 337                 }
 338                 first = next+1;
 339         }
 340         /* not found */
 341         if (find_only)
 342                 return NULL;
 343         /* insert to make it at "first" */
 344         if (sha1_size_cache_alloc <= sha1_size_cache_nr) {
 345                 sha1_size_cache_alloc = alloc_nr(sha1_size_cache_alloc);
 346                 sha1_size_cache = xrealloc(sha1_size_cache,
 347                                            sha1_size_cache_alloc *
 348                                            sizeof(*sha1_size_cache));
 349         }
 350         sha1_size_cache_nr++;
 351         if (first < sha1_size_cache_nr)
 352                 memmove(sha1_size_cache + first + 1, sha1_size_cache + first,
 353                         (sha1_size_cache_nr - first - 1) *
 354                         sizeof(*sha1_size_cache));
 355         e = xmalloc(sizeof(struct sha1_size_cache));
 356         sha1_size_cache[first] = e;
 357         memcpy(e->sha1, sha1, 20);
 358         e->size = size;
 359         return e;
 360 }
 361
 362 /*
 363  * While doing rename detection and pickaxe operation, we may need to
 364  * grab the data for the blob (or file) for our own in-core comparison.
 365  * diff_filespec has data and size fields for this purpose.
 366  */
 367 int diff_populate_filespec(struct diff_filespec *s, int size_only)
 368 {
 369         int err = 0;
 370         if (!DIFF_FILE_VALID(s))
 371                 die("internal error: asking to populate invalid file.");
 372         if (S_ISDIR(s->mode))
 373                 return -1;
 374
 375         if (!use_size_cache)
 376                 size_only = 0;
 377
 378         if (s->data)
 379                 return err;
 380         if (!s->sha1_valid ||
 381             work_tree_matches(s->path, s->sha1)) {
 382                 struct stat st;
 383                 int fd;
 384                 if (lstat(s->path, &st) < 0) {
 385                         if (errno == ENOENT) {
 386                         err_empty:
 387                                 err = -1;
 388                         empty:
 389                                 s->data = "";
 390                                 s->size = 0;
 391                                 return err;
 392                         }
 393                 }
 394                 s->size = st.st_size;
 395                 if (!s->size)
 396                         goto empty;
 397                 if (size_only)
 398                         return 0;
 399                 if (S_ISLNK(st.st_mode)) {
 400                         int ret;
 401                         s->data = xmalloc(s->size);
 402                         s->should_free = 1;
 403                         ret = readlink(s->path, s->data, s->size);
 404                         if (ret < 0) {
 405                                 free(s->data);
 406                                 goto err_empty;
 407                         }
 408                         return 0;
 409                 }
 410                 fd = open(s->path, O_RDONLY);
 411                 if (fd < 0)
 412                         goto err_empty;
 413                 s->data = mmap(NULL, s->size, PROT_READ, MAP_PRIVATE, fd, 0);
 414                 close(fd);
 415                 if (s->data == MAP_FAILED)
 416                         goto err_empty;
 417                 s->should_munmap = 1;
 418         }
 419         else {
 420                 char type[20];
 421                 struct sha1_size_cache *e;
 422
 423                 if (size_only) {
 424                         e = locate_size_cache(s->sha1, 1, 0);
 425                         if (e) {
 426                                 s->size = e->size;
 427                                 return 0;
 428                         }
 429                         if (!sha1_object_info(s->sha1, type, &s->size))
 430                                 locate_size_cache(s->sha1, 0, s->size);
 431                 }
 432                 else {
 433                         s->data = read_sha1_file(s->sha1, type, &s->size);
 434                         s->should_free = 1;
 435                 }
 436         }
 437         return 0;
 438 }
 439
 440 void diff_free_filespec_data(struct diff_filespec *s)
 441 {
 442         if (s->should_free)
 443                 free(s->data);
 444         else if (s->should_munmap)
 445                 munmap(s->data, s->size);
 446         s->should_free = s->should_munmap = 0;
 447         s->data = NULL;
 448 }
 449
 450 static void prep_temp_blob(struct diff_tempfile *temp,
 451                            void *blob,
 452                            unsigned long size,
 453                            const unsigned char *sha1,
 454                            int mode)
 455 {
 456         int fd;
 457
 458         fd = git_mkstemp(temp->tmp_path, TEMPFILE_PATH_LEN, ".diff_XXXXXX");
 459         if (fd < 0)
 460                 die("unable to create temp-file");
 461         if (write(fd, blob, size) != size)
 462                 die("unable to write temp-file");
 463         close(fd);
 464         temp->name = temp->tmp_path;
 465         strcpy(temp->hex, sha1_to_hex(sha1));
 466         temp->hex[40] = 0;
 467         sprintf(temp->mode, "%06o", mode);
 468 }
 469
 470 static void prepare_temp_file(const char *name,
 471                               struct diff_tempfile *temp,
 472                               struct diff_filespec *one)
 473 {
 474         if (!DIFF_FILE_VALID(one)) {
 475         not_a_valid_file:
 476                 /* A '-' entry produces this for file-2, and
 477                  * a '+' entry produces this for file-1.
 478                  */
 479                 temp->name = "/dev/null";
 480                 strcpy(temp->hex, ".");
 481                 strcpy(temp->mode, ".");
 482                 return;
 483         }
 484
 485         if (!one->sha1_valid ||
 486             work_tree_matches(name, one->sha1)) {
 487                 struct stat st;
 488                 if (lstat(name, &st) < 0) {
 489                         if (errno == ENOENT)
 490                                 goto not_a_valid_file;
 491                         die("stat(%s): %s", name, strerror(errno));
 492                 }
 493                 if (S_ISLNK(st.st_mode)) {
 494                         int ret;
 495                         char *buf, buf_[1024];
 496                         buf = ((sizeof(buf_) < st.st_size) ?
 497                                xmalloc(st.st_size) : buf_);
 498                         ret = readlink(name, buf, st.st_size);
 499                         if (ret < 0)
 500                                 die("readlink(%s)", name);
 501                         prep_temp_blob(temp, buf, st.st_size,
 502                                        (one->sha1_valid ?
 503                                         one->sha1 : null_sha1),
 504                                        (one->sha1_valid ?
 505                                         one->mode : S_IFLNK));
 506                 }
 507                 else {
 508                         /* we can borrow from the file in the work tree */
 509                         temp->name = name;
 510                         if (!one->sha1_valid)
 511                                 strcpy(temp->hex, sha1_to_hex(null_sha1));
 512                         else
 513                                 strcpy(temp->hex, sha1_to_hex(one->sha1));
 514                         /* Even though we may sometimes borrow the
 515                          * contents from the work tree, we always want
 516                          * one->mode.  mode is trustworthy even when
 517                          * !(one->sha1_valid), as long as
 518                          * DIFF_FILE_VALID(one).
 519                          */
 520                         sprintf(temp->mode, "%06o", one->mode);
 521                 }
 522                 return;
 523         }
 524         else {
 525                 if (diff_populate_filespec(one, 0))
 526                         die("cannot read data blob for %s", one->path);
 527                 prep_temp_blob(temp, one->data, one->size,
 528                                one->sha1, one->mode);
 529         }
 530 }
 531
 532 static void remove_tempfile(void)
 533 {
 534         int i;
 535
 536         for (i = 0; i < 2; i++)
 537                 if (diff_temp[i].name == diff_temp[i].tmp_path) {
 538                         unlink(diff_temp[i].name);
 539                         diff_temp[i].name = NULL;
 540                 }
 541 }
 542
 543 static void remove_tempfile_on_signal(int signo)
 544 {
 545         remove_tempfile();
 546 }
 547
 548 /* An external diff command takes:
 549  *
 550  * diff-cmd name infile1 infile1-sha1 infile1-mode \
 551  *               infile2 infile2-sha1 infile2-mode [ rename-to ]
 552  *
 553  */
 554 static void run_external_diff(const char *pgm,
 555                               const char *name,
 556                               const char *other,
 557                               struct diff_filespec *one,
 558                               struct diff_filespec *two,
 559                               const char *xfrm_msg,
 560                               int complete_rewrite)
 561 {
 562         struct diff_tempfile *temp = diff_temp;
 563         pid_t pid;
 564         int status;
 565         static int atexit_asked = 0;
 566         const char *othername;
 567
 568         othername = (other? other : name);
 569         if (one && two) {
 570                 prepare_temp_file(name, &temp[0], one);
 571                 prepare_temp_file(othername, &temp[1], two);
 572                 if (! atexit_asked &&
 573                     (temp[0].name == temp[0].tmp_path ||
 574                      temp[1].name == temp[1].tmp_path)) {
 575                         atexit_asked = 1;
 576                         atexit(remove_tempfile);
 577                 }
 578                 signal(SIGINT, remove_tempfile_on_signal);
 579         }
 580
 581         fflush(NULL);
 582         pid = fork();
 583         if (pid < 0)
 584                 die("unable to fork");
 585         if (!pid) {
 586                 if (pgm) {
 587                         if (one && two) {
 588                                 const char *exec_arg[10];
 589                                 const char **arg = &exec_arg[0];
 590                                 *arg++ = pgm;
 591                                 *arg++ = name;
 592                                 *arg++ = temp[0].name;
 593                                 *arg++ = temp[0].hex;
 594                                 *arg++ = temp[0].mode;
 595                                 *arg++ = temp[1].name;
 596                                 *arg++ = temp[1].hex;
 597                                 *arg++ = temp[1].mode;
 598                                 if (other) {
 599                                         *arg++ = other;
 600                                         *arg++ = xfrm_msg;
 601                                 }
 602                                 *arg = NULL;
 603                                 execvp(pgm, (char *const*) exec_arg);
 604                         }
 605                         else
 606                                 execlp(pgm, pgm, name, NULL);
 607                 }
 608                 /*
 609                  * otherwise we use the built-in one.
 610                  */
 611                 if (one && two)
 612                         builtin_diff(name, othername, temp, xfrm_msg,
 613                                      complete_rewrite);
 614                 else
 615                         printf("* Unmerged path %s\n", name);
 616                 exit(0);
 617         }
 618         if (waitpid(pid, &status, 0) < 0 ||
 619             !WIFEXITED(status) || WEXITSTATUS(status)) {
 620                 /* Earlier we did not check the exit status because
 621                  * diff exits non-zero if files are different, and
 622                  * we are not interested in knowing that.  It was a
 623                  * mistake which made it harder to quit a diff-*
 624                  * session that uses the git-apply-patch-script as
 625                  * the GIT_EXTERNAL_DIFF.  A custom GIT_EXTERNAL_DIFF
 626                  * should also exit non-zero only when it wants to
 627                  * abort the entire diff-* session.
 628                  */
 629                 remove_tempfile();
 630                 fprintf(stderr, "external diff died, stopping at %s.\n", name);
 631                 exit(1);
 632         }
 633         remove_tempfile();
 634 }
 635
 636 static void diff_fill_sha1_info(struct diff_filespec *one)
 637 {
 638         if (DIFF_FILE_VALID(one)) {
 639                 if (!one->sha1_valid) {
 640                         struct stat st;
 641                         if (stat(one->path, &st) < 0)
 642                                 die("stat %s", one->path);
 643                         if (index_path(one->sha1, one->path, &st, 0))
 644                                 die("cannot hash %s\n", one->path);
 645                 }
 646         }
 647         else
 648                 memset(one->sha1, 0, 20);
 649 }
 650
 651 static void run_diff(struct diff_filepair *p)
 652 {
 653         const char *pgm = external_diff();
 654         char msg[PATH_MAX*2+300], *xfrm_msg;
 655         struct diff_filespec *one;
 656         struct diff_filespec *two;
 657         const char *name;
 658         const char *other;
 659         char *name_munged, *other_munged;
 660         int complete_rewrite = 0;
 661         int len;
 662
 663         if (DIFF_PAIR_UNMERGED(p)) {
 664                 /* unmerged */
 665                 run_external_diff(pgm, p->one->path, NULL, NULL, NULL, NULL,
 666                                   0);
 667                 return;
 668         }
 669
 670         name = p->one->path;
 671         other = (strcmp(name, p->two->path) ? p->two->path : NULL);
 672         name_munged = quote_one(name);
 673         other_munged = quote_one(other);
 674         one = p->one; two = p->two;
 675
 676         diff_fill_sha1_info(one);
 677         diff_fill_sha1_info(two);
 678
 679         len = 0;
 680         switch (p->status) {
 681         case DIFF_STATUS_COPIED:
 682                 len += snprintf(msg + len, sizeof(msg) - len,
 683                                 "similarity index %d%%\n"
 684                                 "copy from %s\n"
 685                                 "copy to %s\n",
 686                                 (int)(0.5 + p->score * 100.0/MAX_SCORE),
 687                                 name_munged, other_munged);
 688                 break;
 689         case DIFF_STATUS_RENAMED:
 690                 len += snprintf(msg + len, sizeof(msg) - len,
 691                                 "similarity index %d%%\n"
 692                                 "rename from %s\n"
 693                                 "rename to %s\n",
 694                                 (int)(0.5 + p->score * 100.0/MAX_SCORE),
 695                                 name_munged, other_munged);
 696                 break;
 697         case DIFF_STATUS_MODIFIED:
 698                 if (p->score) {
 699                         len += snprintf(msg + len, sizeof(msg) - len,
 700                                         "dissimilarity index %d%%\n",
 701                                         (int)(0.5 + p->score *
 702                                               100.0/MAX_SCORE));
 703                         complete_rewrite = 1;
 704                         break;
 705                 }
 706                 /* fallthru */
 707         default:
 708                 /* nothing */
 709                 ;
 710         }
 711
 712         if (memcmp(one->sha1, two->sha1, 20)) {
 713                 char one_sha1[41];
 714                 memcpy(one_sha1, sha1_to_hex(one->sha1), 41);
 715
 716                 len += snprintf(msg + len, sizeof(msg) - len,
 717                                 "index %.7s..%.7s", one_sha1,
 718                                 sha1_to_hex(two->sha1));
 719                 if (one->mode == two->mode)
 720                         len += snprintf(msg + len, sizeof(msg) - len,
 721                                         " %06o", one->mode);
 722                 len += snprintf(msg + len, sizeof(msg) - len, "\n");
 723         }
 724
 725         if (len)
 726                 msg[--len] = 0;
 727         xfrm_msg = len ? msg : NULL;
 728
 729         if (!pgm &&
 730             DIFF_FILE_VALID(one) && DIFF_FILE_VALID(two) &&
 731             (S_IFMT & one->mode) != (S_IFMT & two->mode)) {
 732                 /* a filepair that changes between file and symlink
 733                  * needs to be split into deletion and creation.
 734                  */
 735                 struct diff_filespec *null = alloc_filespec(two->path);
 736                 run_external_diff(NULL, name, other, one, null, xfrm_msg, 0);
 737                 free(null);
 738                 null = alloc_filespec(one->path);
 739                 run_external_diff(NULL, name, other, null, two, xfrm_msg, 0);
 740                 free(null);
 741         }
 742         else
 743                 run_external_diff(pgm, name, other, one, two, xfrm_msg,
 744                                   complete_rewrite);
 745
 746         free(name_munged);
 747         free(other_munged);
 748 }
 749
 750 void diff_setup(struct diff_options *options)
 751 {
 752         memset(options, 0, sizeof(*options));
 753         options->output_format = DIFF_FORMAT_RAW;
 754         options->line_termination = '\n';
 755         options->break_opt = -1;
 756         options->rename_limit = -1;
 757
 758         options->change = diff_change;
 759         options->add_remove = diff_addremove;
 760 }
 761
 762 int diff_setup_done(struct diff_options *options)
 763 {
 764         if ((options->find_copies_harder || 0 <= options->rename_limit) &&
 765             options->detect_rename != DIFF_DETECT_COPY)
 766                 return -1;
 767         if (options->setup & DIFF_SETUP_USE_CACHE) {
 768                 if (!active_cache)
 769                         /* read-cache does not die even when it fails
 770                          * so it is safe for us to do this here.  Also
 771                          * it does not smudge active_cache or active_nr
 772                          * when it fails, so we do not have to worry about
 773                          * cleaning it up oufselves either.
 774                          */
 775                         read_cache();
 776         }
 777         if (options->setup & DIFF_SETUP_USE_SIZE_CACHE)
 778                 use_size_cache = 1;
 779
 780         return 0;
 781 }
 782
 783 int diff_opt_parse(struct diff_options *options, const char **av, int ac)
 784 {
 785         const char *arg = av[0];
 786         if (!strcmp(arg, "-p") || !strcmp(arg, "-u"))
 787                 options->output_format = DIFF_FORMAT_PATCH;
 788         else if (!strcmp(arg, "-z"))
 789                 options->line_termination = 0;
 790         else if (!strncmp(arg, "-l", 2))
 791                 options->rename_limit = strtoul(arg+2, NULL, 10);
 792         else if (!strcmp(arg, "--name-only"))
 793                 options->output_format = DIFF_FORMAT_NAME;
 794         else if (!strcmp(arg, "--name-status"))
 795                 options->output_format = DIFF_FORMAT_NAME_STATUS;
 796         else if (!strcmp(arg, "-R"))
 797                 options->reverse_diff = 1;
 798         else if (!strncmp(arg, "-S", 2))
 799                 options->pickaxe = arg + 2;
 800         else if (!strcmp(arg, "-s"))
 801                 options->output_format = DIFF_FORMAT_NO_OUTPUT;
 802         else if (!strncmp(arg, "-O", 2))
 803                 options->orderfile = arg + 2;
 804         else if (!strncmp(arg, "--diff-filter=", 14))
 805                 options->filter = arg + 14;
 806         else if (!strcmp(arg, "--pickaxe-all"))
 807                 options->pickaxe_opts = DIFF_PICKAXE_ALL;
 808         else if (!strncmp(arg, "-B", 2)) {
 809                 if ((options->break_opt =
 810                      diff_scoreopt_parse(arg)) == -1)
 811                         return -1;
 812         }
 813         else if (!strncmp(arg, "-M", 2)) {
 814                 if ((options->rename_score =
 815                      diff_scoreopt_parse(arg)) == -1)
 816                         return -1;
 817                 options->detect_rename = DIFF_DETECT_RENAME;
 818         }
 819         else if (!strncmp(arg, "-C", 2)) {
 820                 if ((options->rename_score =
 821                      diff_scoreopt_parse(arg)) == -1)
 822                         return -1;
 823                 options->detect_rename = DIFF_DETECT_COPY;
 824         }
 825         else if (!strcmp(arg, "--find-copies-harder"))
 826                 options->find_copies_harder = 1;
 827         else
 828                 return 0;
 829         return 1;
 830 }
 831
 832 static int parse_num(const char **cp_p)
 833 {
 834         int num, scale, ch, cnt;
 835         const char *cp = *cp_p;
 836
 837         cnt = num = 0;
 838         scale = 1;
 839         while ('0' <= (ch = *cp) && ch <= '9') {
 840                 if (cnt++ < 5) {
 841                         /* We simply ignore more than 5 digits precision. */
 842                         scale *= 10;
 843                         num = num * 10 + ch - '0';
 844                 }
 845                 cp++;
 846         }
 847         *cp_p = cp;
 848
 849         /* user says num divided by scale and we say internally that
 850          * is MAX_SCORE * num / scale.
 851          */
 852         return (MAX_SCORE * num / scale);
 853 }
 854
 855 int diff_scoreopt_parse(const char *opt)
 856 {
 857         int opt1, opt2, cmd;
 858
 859         if (*opt++ != '-')
 860                 return -1;
 861         cmd = *opt++;
 862         if (cmd != 'M' && cmd != 'C' && cmd != 'B')
 863                 return -1; /* that is not a -M, -C nor -B option */
 864
 865         opt1 = parse_num(&opt);
 866         if (cmd != 'B')
 867                 opt2 = 0;
 868         else {
 869                 if (*opt == 0)
 870                         opt2 = 0;
 871                 else if (*opt != '/')
 872                         return -1; /* we expect -B80/99 or -B80 */
 873                 else {
 874                         opt++;
 875                         opt2 = parse_num(&opt);
 876                 }
 877         }
 878         if (*opt != 0)
 879                 return -1;
 880         return opt1 | (opt2 << 16);
 881 }
 882
 883 struct diff_queue_struct diff_queued_diff;
 884
 885 void diff_q(struct diff_queue_struct *queue, struct diff_filepair *dp)
 886 {
 887         if (queue->alloc <= queue->nr) {
 888                 queue->alloc = alloc_nr(queue->alloc);
 889                 queue->queue = xrealloc(queue->queue,
 890                                         sizeof(dp) * queue->alloc);
 891         }
 892         queue->queue[queue->nr++] = dp;
 893 }
 894
 895 struct diff_filepair *diff_queue(struct diff_queue_struct *queue,
 896                                  struct diff_filespec *one,
 897                                  struct diff_filespec *two)
 898 {
 899         struct diff_filepair *dp = xmalloc(sizeof(*dp));
 900         dp->one = one;
 901         dp->two = two;
 902         dp->score = 0;
 903         dp->status = 0;
 904         dp->source_stays = 0;
 905         dp->broken_pair = 0;
 906         if (queue)
 907                 diff_q(queue, dp);
 908         return dp;
 909 }
 910
 911 void diff_free_filepair(struct diff_filepair *p)
 912 {
 913         diff_free_filespec_data(p->one);
 914         diff_free_filespec_data(p->two);
 915         free(p->one);
 916         free(p->two);
 917         free(p);
 918 }
 919
 920 static void diff_flush_raw(struct diff_filepair *p,
 921                            int line_termination,
 922                            int inter_name_termination,
 923                            int output_format)
 924 {
 925         int two_paths;
 926         char status[10];
 927         const char *path_one, *path_two;
 928
 929         path_one = p->one->path;
 930         path_two = p->two->path;
 931         if (line_termination) {
 932                 path_one = quote_one(path_one);
 933                 path_two = quote_one(path_two);
 934         }
 935
 936         if (p->score)
 937                 sprintf(status, "%c%03d", p->status,
 938                         (int)(0.5 + p->score * 100.0/MAX_SCORE));
 939         else {
 940                 status[0] = p->status;
 941                 status[1] = 0;
 942         }
 943         switch (p->status) {
 944         case DIFF_STATUS_COPIED:
 945         case DIFF_STATUS_RENAMED:
 946                 two_paths = 1;
 947                 break;
 948         case DIFF_STATUS_ADDED:
 949         case DIFF_STATUS_DELETED:
 950                 two_paths = 0;
 951                 break;
 952         default:
 953                 two_paths = 0;
 954                 break;
 955         }
 956         if (output_format != DIFF_FORMAT_NAME_STATUS) {
 957                 printf(":%06o %06o %s ",
 958                        p->one->mode, p->two->mode, sha1_to_hex(p->one->sha1));
 959                 printf("%s ", sha1_to_hex(p->two->sha1));
 960         }
 961         printf("%s%c%s", status, inter_name_termination, path_one);
 962         if (two_paths)
 963                 printf("%c%s", inter_name_termination, path_two);
 964         putchar(line_termination);
 965         if (path_one != p->one->path)
 966                 free((void*)path_one);
 967         if (path_two != p->two->path)
 968                 free((void*)path_two);
 969 }
 970
 971 static void diff_flush_name(struct diff_filepair *p,
 972                             int inter_name_termination,
 973                             int line_termination)
 974 {
 975         char *path = p->two->path;
 976
 977         if (line_termination)
 978                 path = quote_one(p->two->path);
 979         else
 980                 path = p->two->path;
 981         printf("%s%c", path, line_termination);
 982         if (p->two->path != path)
 983                 free(path);
 984 }
 985
 986 int diff_unmodified_pair(struct diff_filepair *p)
 987 {
 988         /* This function is written stricter than necessary to support
 989          * the currently implemented transformers, but the idea is to
 990          * let transformers to produce diff_filepairs any way they want,
 991          * and filter and clean them up here before producing the output.
 992          */
 993         struct diff_filespec *one, *two;
 994
 995         if (DIFF_PAIR_UNMERGED(p))
 996                 return 0; /* unmerged is interesting */
 997
 998         one = p->one;
 999         two = p->two;
1000
1001         /* deletion, addition, mode or type change
1002          * and rename are all interesting.
1003          */
1004         if (DIFF_FILE_VALID(one) != DIFF_FILE_VALID(two) ||
1005             DIFF_PAIR_MODE_CHANGED(p) ||
1006             strcmp(one->path, two->path))
1007                 return 0;
1008
1009         /* both are valid and point at the same path.  that is, we are
1010          * dealing with a change.
1011          */
1012         if (one->sha1_valid && two->sha1_valid &&
1013             !memcmp(one->sha1, two->sha1, sizeof(one->sha1)))
1014                 return 1; /* no change */
1015         if (!one->sha1_valid && !two->sha1_valid)
1016                 return 1; /* both look at the same file on the filesystem. */
1017         return 0;
1018 }
1019
1020 static void diff_flush_patch(struct diff_filepair *p)
1021 {
1022         if (diff_unmodified_pair(p))
1023                 return;
1024
1025         if ((DIFF_FILE_VALID(p->one) && S_ISDIR(p->one->mode)) ||
1026             (DIFF_FILE_VALID(p->two) && S_ISDIR(p->two->mode)))
1027                 return; /* no tree diffs in patch format */
1028
1029         run_diff(p);
1030 }
1031
1032 int diff_queue_is_empty(void)
1033 {
1034         struct diff_queue_struct *q = &diff_queued_diff;
1035         int i;
1036         for (i = 0; i < q->nr; i++)
1037                 if (!diff_unmodified_pair(q->queue[i]))
1038                         return 0;
1039         return 1;
1040 }
1041
1042 #if DIFF_DEBUG
1043 void diff_debug_filespec(struct diff_filespec *s, int x, const char *one)
1044 {
1045         fprintf(stderr, "queue[%d] %s (%s) %s %06o %s\n",
1046                 x, one ? one : "",
1047                 s->path,
1048                 DIFF_FILE_VALID(s) ? "valid" : "invalid",
1049                 s->mode,
1050                 s->sha1_valid ? sha1_to_hex(s->sha1) : "");
1051         fprintf(stderr, "queue[%d] %s size %lu flags %d\n",
1052                 x, one ? one : "",
1053                 s->size, s->xfrm_flags);
1054 }
1055
1056 void diff_debug_filepair(const struct diff_filepair *p, int i)
1057 {
1058         diff_debug_filespec(p->one, i, "one");
1059         diff_debug_filespec(p->two, i, "two");
1060         fprintf(stderr, "score %d, status %c stays %d broken %d\n",
1061                 p->score, p->status ? p->status : '?',
1062                 p->source_stays, p->broken_pair);
1063 }
1064
1065 void diff_debug_queue(const char *msg, struct diff_queue_struct *q)
1066 {
1067         int i;
1068         if (msg)
1069                 fprintf(stderr, "%s\n", msg);
1070         fprintf(stderr, "q->nr = %d\n", q->nr);
1071         for (i = 0; i < q->nr; i++) {
1072                 struct diff_filepair *p = q->queue[i];
1073                 diff_debug_filepair(p, i);
1074         }
1075 }
1076 #endif
1077
1078 static void diff_resolve_rename_copy(void)
1079 {
1080         int i, j;
1081         struct diff_filepair *p, *pp;
1082         struct diff_queue_struct *q = &diff_queued_diff;
1083
1084         diff_debug_queue("resolve-rename-copy", q);
1085
1086         for (i = 0; i < q->nr; i++) {
1087                 p = q->queue[i];
1088                 p->status = 0; /* undecided */
1089                 if (DIFF_PAIR_UNMERGED(p))
1090                         p->status = DIFF_STATUS_UNMERGED;
1091                 else if (!DIFF_FILE_VALID(p->one))
1092                         p->status = DIFF_STATUS_ADDED;
1093                 else if (!DIFF_FILE_VALID(p->two))
1094                         p->status = DIFF_STATUS_DELETED;
1095                 else if (DIFF_PAIR_TYPE_CHANGED(p))
1096                         p->status = DIFF_STATUS_TYPE_CHANGED;
1097
1098                 /* from this point on, we are dealing with a pair
1099                  * whose both sides are valid and of the same type, i.e.
1100                  * either in-place edit or rename/copy edit.
1101                  */
1102                 else if (DIFF_PAIR_RENAME(p)) {
1103                         if (p->source_stays) {
1104                                 p->status = DIFF_STATUS_COPIED;
1105                                 continue;
1106                         }
1107                         /* See if there is some other filepair that
1108                          * copies from the same source as us.  If so
1109                          * we are a copy.  Otherwise we are either a
1110                          * copy if the path stays, or a rename if it
1111                          * does not, but we already handled "stays" case.
1112                          */
1113                         for (j = i + 1; j < q->nr; j++) {
1114                                 pp = q->queue[j];
1115                                 if (strcmp(pp->one->path, p->one->path))
1116                                         continue; /* not us */
1117                                 if (!DIFF_PAIR_RENAME(pp))
1118                                         continue; /* not a rename/copy */
1119                                 /* pp is a rename/copy from the same source */
1120                                 p->status = DIFF_STATUS_COPIED;
1121                                 break;
1122                         }
1123                         if (!p->status)
1124                                 p->status = DIFF_STATUS_RENAMED;
1125                 }
1126                 else if (memcmp(p->one->sha1, p->two->sha1, 20) ||
1127                          p->one->mode != p->two->mode)
1128                         p->status = DIFF_STATUS_MODIFIED;
1129                 else {
1130                         /* This is a "no-change" entry and should not
1131                          * happen anymore, but prepare for broken callers.
1132                          */
1133                         error("feeding unmodified %s to diffcore",
1134                               p->one->path);
1135                         p->status = DIFF_STATUS_UNKNOWN;
1136                 }
1137         }
1138         diff_debug_queue("resolve-rename-copy done", q);
1139 }
1140
1141 void diff_flush(struct diff_options *options)
1142 {
1143         struct diff_queue_struct *q = &diff_queued_diff;
1144         int i;
1145         int inter_name_termination = '\t';
1146         int diff_output_format = options->output_format;
1147         int line_termination = options->line_termination;
1148
1149         if (!line_termination)
1150                 inter_name_termination = 0;
1151
1152         for (i = 0; i < q->nr; i++) {
1153                 struct diff_filepair *p = q->queue[i];
1154                 if ((diff_output_format == DIFF_FORMAT_NO_OUTPUT) ||
1155                     (p->status == DIFF_STATUS_UNKNOWN))
1156                         continue;
1157                 if (p->status == 0)
1158                         die("internal error in diff-resolve-rename-copy");
1159                 switch (diff_output_format) {
1160                 case DIFF_FORMAT_PATCH:
1161                         diff_flush_patch(p);
1162                         break;
1163                 case DIFF_FORMAT_RAW:
1164                 case DIFF_FORMAT_NAME_STATUS:
1165                         diff_flush_raw(p, line_termination,
1166                                        inter_name_termination,
1167                                        diff_output_format);
1168                         break;
1169                 case DIFF_FORMAT_NAME:
1170                         diff_flush_name(p,
1171                                         inter_name_termination,
1172                                         line_termination);
1173                         break;
1174                 }
1175                 diff_free_filepair(q->queue[i]);
1176         }
1177         free(q->queue);
1178         q->queue = NULL;
1179         q->nr = q->alloc = 0;
1180 }
1181
1182 static void diffcore_apply_filter(const char *filter)
1183 {
1184         int i;
1185         struct diff_queue_struct *q = &diff_queued_diff;
1186         struct diff_queue_struct outq;
1187         outq.queue = NULL;
1188         outq.nr = outq.alloc = 0;
1189
1190         if (!filter)
1191                 return;
1192
1193         if (strchr(filter, DIFF_STATUS_FILTER_AON)) {
1194                 int found;
1195                 for (i = found = 0; !found && i < q->nr; i++) {
1196                         struct diff_filepair *p = q->queue[i];
1197                         if (((p->status == DIFF_STATUS_MODIFIED) &&
1198                              ((p->score &&
1199                                strchr(filter, DIFF_STATUS_FILTER_BROKEN)) ||
1200                               (!p->score &&
1201                                strchr(filter, DIFF_STATUS_MODIFIED)))) ||
1202                             ((p->status != DIFF_STATUS_MODIFIED) &&
1203                              strchr(filter, p->status)))
1204                                 found++;
1205                 }
1206                 if (found)
1207                         return;
1208
1209                 /* otherwise we will clear the whole queue
1210                  * by copying the empty outq at the end of this
1211                  * function, but first clear the current entries
1212                  * in the queue.
1213                  */
1214                 for (i = 0; i < q->nr; i++)
1215                         diff_free_filepair(q->queue[i]);
1216         }
1217         else {
1218                 /* Only the matching ones */
1219                 for (i = 0; i < q->nr; i++) {
1220                         struct diff_filepair *p = q->queue[i];
1221
1222                         if (((p->status == DIFF_STATUS_MODIFIED) &&
1223                              ((p->score &&
1224                                strchr(filter, DIFF_STATUS_FILTER_BROKEN)) ||
1225                               (!p->score &&
1226                                strchr(filter, DIFF_STATUS_MODIFIED)))) ||
1227                             ((p->status != DIFF_STATUS_MODIFIED) &&
1228                              strchr(filter, p->status)))
1229                                 diff_q(&outq, p);
1230                         else
1231                                 diff_free_filepair(p);
1232                 }
1233         }
1234         free(q->queue);
1235         *q = outq;
1236 }
1237
1238 void diffcore_std(struct diff_options *options)
1239 {
1240         if (options->paths && options->paths[0])
1241                 diffcore_pathspec(options->paths);
1242         if (options->break_opt != -1)
1243                 diffcore_break(options->break_opt);
1244         if (options->detect_rename)
1245                 diffcore_rename(options);
1246         if (options->break_opt != -1)
1247                 diffcore_merge_broken();
1248         if (options->pickaxe)
1249                 diffcore_pickaxe(options->pickaxe, options->pickaxe_opts);
1250         if (options->orderfile)
1251                 diffcore_order(options->orderfile);
1252         diff_resolve_rename_copy();
1253         diffcore_apply_filter(options->filter);
1254 }
1255
1256
1257 void diffcore_std_no_resolve(struct diff_options *options)
1258 {
1259         if (options->pickaxe)
1260                 diffcore_pickaxe(options->pickaxe, options->pickaxe_opts);
1261         if (options->orderfile)
1262                 diffcore_order(options->orderfile);
1263         diffcore_apply_filter(options->filter);
1264 }
1265
1266 void diff_addremove(struct diff_options *options,
1267                     int addremove, unsigned mode,
1268                     const unsigned char *sha1,
1269                     const char *base, const char *path)
1270 {
1271         char concatpath[PATH_MAX];
1272         struct diff_filespec *one, *two;
1273
1274         /* This may look odd, but it is a preparation for
1275          * feeding "there are unchanged files which should
1276          * not produce diffs, but when you are doing copy
1277          * detection you would need them, so here they are"
1278          * entries to the diff-core.  They will be prefixed
1279          * with something like '=' or '*' (I haven't decided
1280          * which but should not make any difference).
1281          * Feeding the same new and old to diff_change()
1282          * also has the same effect.
1283          * Before the final output happens, they are pruned after
1284          * merged into rename/copy pairs as appropriate.
1285          */
1286         if (options->reverse_diff)
1287                 addremove = (addremove == '+' ? '-' :
1288                              addremove == '-' ? '+' : addremove);
1289
1290         if (!path) path = "";
1291         sprintf(concatpath, "%s%s", base, path);
1292         one = alloc_filespec(concatpath);
1293         two = alloc_filespec(concatpath);
1294
1295         if (addremove != '+')
1296                 fill_filespec(one, sha1, mode);
1297         if (addremove != '-')
1298                 fill_filespec(two, sha1, mode);
1299
1300         diff_queue(&diff_queued_diff, one, two);
1301 }
1302
1303 void diff_change(struct diff_options *options,
1304                  unsigned old_mode, unsigned new_mode,
1305                  const unsigned char *old_sha1,
1306                  const unsigned char *new_sha1,
1307                  const char *base, const char *path)
1308 {
1309         char concatpath[PATH_MAX];
1310         struct diff_filespec *one, *two;
1311
1312         if (options->reverse_diff) {
1313                 unsigned tmp;
1314                 const unsigned char *tmp_c;
1315                 tmp = old_mode; old_mode = new_mode; new_mode = tmp;
1316                 tmp_c = old_sha1; old_sha1 = new_sha1; new_sha1 = tmp_c;
1317         }
1318         if (!path) path = "";
1319         sprintf(concatpath, "%s%s", base, path);
1320         one = alloc_filespec(concatpath);
1321         two = alloc_filespec(concatpath);
1322         fill_filespec(one, old_sha1, old_mode);
1323         fill_filespec(two, new_sha1, new_mode);
1324
1325         diff_queue(&diff_queued_diff, one, two);
1326 }
1327
1328 void diff_unmerge(struct diff_options *options,
1329                   const char *path)
1330 {
1331         struct diff_filespec *one, *two;
1332         one = alloc_filespec(path);
1333         two = alloc_filespec(path);
1334         diff_queue(&diff_queued_diff, one, two);
1335 }