diff.c

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