tree-diff.c

   1 /*
   2  * Helper functions for tree diff generation
   3  */
   4 #include "cache.h"
   5 #include "diff.h"
   6 #include "diffcore.h"
   7 #include "tree.h"
   8
   9 static char *malloc_base(const char *base, int baselen, const char *path, int pathlen)
  10 {
  11         char *newbase = xmalloc(baselen + pathlen + 2);
  12         memcpy(newbase, base, baselen);
  13         memcpy(newbase + baselen, path, pathlen);
  14         memcpy(newbase + baselen + pathlen, "/", 2);
  15         return newbase;
  16 }
  17
  18 static char *malloc_fullname(const char *base, int baselen, const char *path, int pathlen)
  19 {
  20         char *fullname = xmalloc(baselen + pathlen + 1);
  21         memcpy(fullname, base, baselen);
  22         memcpy(fullname + baselen, path, pathlen);
  23         fullname[baselen + pathlen] = 0;
  24         return fullname;
  25 }
  26
  27 static void show_entry(struct diff_options *opt, const char *prefix, struct tree_desc *desc,
  28                        const char *base, int baselen);
  29
  30 static int compare_tree_entry(struct tree_desc *t1, struct tree_desc *t2, const char *base, int baselen, struct diff_options *opt)
  31 {
  32         unsigned mode1, mode2;
  33         const char *path1, *path2;
  34         const unsigned char *sha1, *sha2;
  35         int cmp, pathlen1, pathlen2;
  36         char *fullname;
  37
  38         sha1 = tree_entry_extract(t1, &path1, &mode1);
  39         sha2 = tree_entry_extract(t2, &path2, &mode2);
  40
  41         pathlen1 = tree_entry_len(path1, sha1);
  42         pathlen2 = tree_entry_len(path2, sha2);
  43         cmp = base_name_compare(path1, pathlen1, mode1, path2, pathlen2, mode2);
  44         if (cmp < 0) {
  45                 show_entry(opt, "-", t1, base, baselen);
  46                 return -1;
  47         }
  48         if (cmp > 0) {
  49                 show_entry(opt, "+", t2, base, baselen);
  50                 return 1;
  51         }
  52         if (!DIFF_OPT_TST(opt, FIND_COPIES_HARDER) && !hashcmp(sha1, sha2) && mode1 == mode2)
  53                 return 0;
  54
  55         /*
  56          * If the filemode has changed to/from a directory from/to a regular
  57          * file, we need to consider it a remove and an add.
  58          */
  59         if (S_ISDIR(mode1) != S_ISDIR(mode2)) {
  60                 show_entry(opt, "-", t1, base, baselen);
  61                 show_entry(opt, "+", t2, base, baselen);
  62                 return 0;
  63         }
  64
  65         if (DIFF_OPT_TST(opt, RECURSIVE) && S_ISDIR(mode1)) {
  66                 int retval;
  67                 char *newbase = malloc_base(base, baselen, path1, pathlen1);
  68                 if (DIFF_OPT_TST(opt, TREE_IN_RECURSIVE)) {
  69                         newbase[baselen + pathlen1] = 0;
  70                         opt->change(opt, mode1, mode2,
  71                                     sha1, sha2, newbase);
  72                         newbase[baselen + pathlen1] = '/';
  73                 }
  74                 retval = diff_tree_sha1(sha1, sha2, newbase, opt);
  75                 free(newbase);
  76                 return retval;
  77         }
  78
  79         fullname = malloc_fullname(base, baselen, path1, pathlen1);
  80         opt->change(opt, mode1, mode2, sha1, sha2, fullname);
  81         free(fullname);
  82         return 0;
  83 }
  84
  85 /*
  86  * Is a tree entry interesting given the pathspec we have?
  87  *
  88  * Return:
  89  *  - 2 for "yes, and all subsequent entries will be"
  90  *  - 1 for yes
  91  *  - zero for no
  92  *  - negative for "no, and no subsequent entries will be either"
  93  */
  94 static int tree_entry_interesting(struct tree_desc *desc, const char *base, int baselen, struct diff_options *opt)
  95 {
  96         const char *path;
  97         const unsigned char *sha1;
  98         unsigned mode;
  99         int i;
 100         int pathlen;
 101         int never_interesting = -1;
 102
 103         if (!opt->nr_paths)
 104                 return 1;
 105
 106         sha1 = tree_entry_extract(desc, &path, &mode);
 107
 108         pathlen = tree_entry_len(path, sha1);
 109
 110         for (i = 0; i < opt->nr_paths; i++) {
 111                 const char *match = opt->paths[i];
 112                 int matchlen = opt->pathlens[i];
 113                 int m = -1; /* signals that we haven't called strncmp() */
 114
 115                 if (baselen >= matchlen) {
 116                         /* If it doesn't match, move along... */
 117                         if (strncmp(base, match, matchlen))
 118                                 continue;
 119
 120                         /*
 121                          * The base is a subdirectory of a path which
 122                          * was specified, so all of them are interesting.
 123                          */
 124                         return 2;
 125                 }
 126
 127                 /* Does the base match? */
 128                 if (strncmp(base, match, baselen))
 129                         continue;
 130
 131                 match += baselen;
 132                 matchlen -= baselen;
 133
 134                 if (never_interesting) {
 135                         /*
 136                          * We have not seen any match that sorts later
 137                          * than the current path.
 138                          */
 139
 140                         /*
 141                          * Does match sort strictly earlier than path
 142                          * with their common parts?
 143                          */
 144                         m = strncmp(match, path,
 145                                     (matchlen < pathlen) ? matchlen : pathlen);
 146                         if (m < 0)
 147                                 continue;
 148
 149                         /*
 150                          * If we come here even once, that means there is at
 151                          * least one pathspec that would sort equal to or
 152                          * later than the path we are currently looking at.
 153                          * In other words, if we have never reached this point
 154                          * after iterating all pathspecs, it means all
 155                          * pathspecs are either outside of base, or inside the
 156                          * base but sorts strictly earlier than the current
 157                          * one.  In either case, they will never match the
 158                          * subsequent entries.  In such a case, we initialized
 159                          * the variable to -1 and that is what will be
 160                          * returned, allowing the caller to terminate early.
 161                          */
 162                         never_interesting = 0;
 163                 }
 164
 165                 if (pathlen > matchlen)
 166                         continue;
 167
 168                 if (matchlen > pathlen) {
 169                         if (match[pathlen] != '/')
 170                                 continue;
 171                         if (!S_ISDIR(mode))
 172                                 continue;
 173                 }
 174
 175                 if (m == -1)
 176                         /*
 177                          * we cheated and did not do strncmp(), so we do
 178                          * that here.
 179                          */
 180                         m = strncmp(match, path, pathlen);
 181
 182                 /*
 183                  * If common part matched earlier then it is a hit,
 184                  * because we rejected the case where path is not a
 185                  * leading directory and is shorter than match.
 186                  */
 187                 if (!m)
 188                         return 1;
 189         }
 190         return never_interesting; /* No matches */
 191 }
 192
 193 /* A whole sub-tree went away or appeared */
 194 static void show_tree(struct diff_options *opt, const char *prefix, struct tree_desc *desc, const char *base, int baselen)
 195 {
 196         int all_interesting = 0;
 197         while (desc->size) {
 198                 int show;
 199
 200                 if (all_interesting)
 201                         show = 1;
 202                 else {
 203                         show = tree_entry_interesting(desc, base, baselen,
 204                                                       opt);
 205                         if (show == 2)
 206                                 all_interesting = 1;
 207                 }
 208                 if (show < 0)
 209                         break;
 210                 if (show)
 211                         show_entry(opt, prefix, desc, base, baselen);
 212                 update_tree_entry(desc);
 213         }
 214 }
 215
 216 /* A file entry went away or appeared */
 217 static void show_entry(struct diff_options *opt, const char *prefix, struct tree_desc *desc,
 218                        const char *base, int baselen)
 219 {
 220         unsigned mode;
 221         const char *path;
 222         const unsigned char *sha1 = tree_entry_extract(desc, &path, &mode);
 223         int pathlen = tree_entry_len(path, sha1);
 224
 225         if (DIFF_OPT_TST(opt, RECURSIVE) && S_ISDIR(mode)) {
 226                 enum object_type type;
 227                 char *newbase = malloc_base(base, baselen, path, pathlen);
 228                 struct tree_desc inner;
 229                 void *tree;
 230                 unsigned long size;
 231
 232                 tree = read_sha1_file(sha1, &type, &size);
 233                 if (!tree || type != OBJ_TREE)
 234                         die("corrupt tree sha %s", sha1_to_hex(sha1));
 235
 236                 init_tree_desc(&inner, tree, size);
 237                 show_tree(opt, prefix, &inner, newbase, baselen + 1 + pathlen);
 238
 239                 free(tree);
 240                 free(newbase);
 241         } else {
 242                 char *fullname = malloc_fullname(base, baselen, path, pathlen);
 243                 opt->add_remove(opt, prefix[0], mode, sha1, fullname);
 244                 free(fullname);
 245         }
 246 }
 247
 248 static void skip_uninteresting(struct tree_desc *t, const char *base, int baselen, struct diff_options *opt)
 249 {
 250         int all_interesting = 0;
 251         while (t->size) {
 252                 int show;
 253
 254                 if (all_interesting)
 255                         show = 1;
 256                 else {
 257                         show = tree_entry_interesting(t, base, baselen, opt);
 258                         if (show == 2)
 259                                 all_interesting = 1;
 260                 }
 261                 if (!show) {
 262                         update_tree_entry(t);
 263                         continue;
 264                 }
 265                 /* Skip it all? */
 266                 if (show < 0)
 267                         t->size = 0;
 268                 return;
 269         }
 270 }
 271
 272 int diff_tree(struct tree_desc *t1, struct tree_desc *t2, const char *base, struct diff_options *opt)
 273 {
 274         int baselen = strlen(base);
 275
 276         for (;;) {
 277                 if (DIFF_OPT_TST(opt, QUIET) && DIFF_OPT_TST(opt, HAS_CHANGES))
 278                         break;
 279                 if (opt->nr_paths) {
 280                         skip_uninteresting(t1, base, baselen, opt);
 281                         skip_uninteresting(t2, base, baselen, opt);
 282                 }
 283                 if (!t1->size) {
 284                         if (!t2->size)
 285                                 break;
 286                         show_entry(opt, "+", t2, base, baselen);
 287                         update_tree_entry(t2);
 288                         continue;
 289                 }
 290                 if (!t2->size) {
 291                         show_entry(opt, "-", t1, base, baselen);
 292                         update_tree_entry(t1);
 293                         continue;
 294                 }
 295                 switch (compare_tree_entry(t1, t2, base, baselen, opt)) {
 296                 case -1:
 297                         update_tree_entry(t1);
 298                         continue;
 299                 case 0:
 300                         update_tree_entry(t1);
 301                         /* Fallthrough */
 302                 case 1:
 303                         update_tree_entry(t2);
 304                         continue;
 305                 }
 306                 die("git diff-tree: internal error");
 307         }
 308         return 0;
 309 }
 310
 311 /*
 312  * Does it look like the resulting diff might be due to a rename?
 313  *  - single entry
 314  *  - not a valid previous file
 315  */
 316 static inline int diff_might_be_rename(void)
 317 {
 318         return diff_queued_diff.nr == 1 &&
 319                 !DIFF_FILE_VALID(diff_queued_diff.queue[0]->one);
 320 }
 321
 322 static void try_to_follow_renames(struct tree_desc *t1, struct tree_desc *t2, const char *base, struct diff_options *opt)
 323 {
 324         struct diff_options diff_opts;
 325         struct diff_queue_struct *q = &diff_queued_diff;
 326         struct diff_filepair *choice;
 327         const char *paths[1];
 328         int i;
 329
 330         /* Remove the file creation entry from the diff queue, and remember it */
 331         choice = q->queue[0];
 332         q->nr = 0;
 333
 334         diff_setup(&diff_opts);
 335         DIFF_OPT_SET(&diff_opts, RECURSIVE);
 336         diff_opts.detect_rename = DIFF_DETECT_RENAME;
 337         diff_opts.output_format = DIFF_FORMAT_NO_OUTPUT;
 338         diff_opts.single_follow = opt->paths[0];
 339         diff_opts.break_opt = opt->break_opt;
 340         paths[0] = NULL;
 341         diff_tree_setup_paths(paths, &diff_opts);
 342         if (diff_setup_done(&diff_opts) < 0)
 343                 die("unable to set up diff options to follow renames");
 344         diff_tree(t1, t2, base, &diff_opts);
 345         diffcore_std(&diff_opts);
 346         diff_tree_release_paths(&diff_opts);
 347
 348         /* Go through the new set of filepairing, and see if we find a more interesting one */
 349         for (i = 0; i < q->nr; i++) {
 350                 struct diff_filepair *p = q->queue[i];
 351
 352                 /*
 353                  * Found a source? Not only do we use that for the new
 354                  * diff_queued_diff, we will also use that as the path in
 355                  * the future!
 356                  */
 357                 if ((p->status == 'R' || p->status == 'C') && !strcmp(p->two->path, opt->paths[0])) {
 358                         /* Switch the file-pairs around */
 359                         q->queue[i] = choice;
 360                         choice = p;
 361
 362                         /* Update the path we use from now on.. */
 363                         diff_tree_release_paths(opt);
 364                         opt->paths[0] = xstrdup(p->one->path);
 365                         diff_tree_setup_paths(opt->paths, opt);
 366                         break;
 367                 }
 368         }
 369
 370         /*
 371          * Then, discard all the non-relevane file pairs...
 372          */
 373         for (i = 0; i < q->nr; i++) {
 374                 struct diff_filepair *p = q->queue[i];
 375                 diff_free_filepair(p);
 376         }
 377
 378         /*
 379          * .. and re-instate the one we want (which might be either the
 380          * original one, or the rename/copy we found)
 381          */
 382         q->queue[0] = choice;
 383         q->nr = 1;
 384 }
 385
 386 int diff_tree_sha1(const unsigned char *old, const unsigned char *new, const char *base, struct diff_options *opt)
 387 {
 388         void *tree1, *tree2;
 389         struct tree_desc t1, t2;
 390         unsigned long size1, size2;
 391         int retval;
 392
 393         tree1 = read_object_with_reference(old, tree_type, &size1, NULL);
 394         if (!tree1)
 395                 die("unable to read source tree (%s)", sha1_to_hex(old));
 396         tree2 = read_object_with_reference(new, tree_type, &size2, NULL);
 397         if (!tree2)
 398                 die("unable to read destination tree (%s)", sha1_to_hex(new));
 399         init_tree_desc(&t1, tree1, size1);
 400         init_tree_desc(&t2, tree2, size2);
 401         retval = diff_tree(&t1, &t2, base, opt);
 402         if (DIFF_OPT_TST(opt, FOLLOW_RENAMES) && diff_might_be_rename()) {
 403                 init_tree_desc(&t1, tree1, size1);
 404                 init_tree_desc(&t2, tree2, size2);
 405                 try_to_follow_renames(&t1, &t2, base, opt);
 406         }
 407         free(tree1);
 408         free(tree2);
 409         return retval;
 410 }
 411
 412 int diff_root_tree_sha1(const unsigned char *new, const char *base, struct diff_options *opt)
 413 {
 414         int retval;
 415         void *tree;
 416         unsigned long size;
 417         struct tree_desc empty, real;
 418
 419         tree = read_object_with_reference(new, tree_type, &size, NULL);
 420         if (!tree)
 421                 die("unable to read root tree (%s)", sha1_to_hex(new));
 422         init_tree_desc(&real, tree, size);
 423
 424         init_tree_desc(&empty, "", 0);
 425         retval = diff_tree(&empty, &real, base, opt);
 426         free(tree);
 427         return retval;
 428 }
 429
 430 static int count_paths(const char **paths)
 431 {
 432         int i = 0;
 433         while (*paths++)
 434                 i++;
 435         return i;
 436 }
 437
 438 void diff_tree_release_paths(struct diff_options *opt)
 439 {
 440         free(opt->pathlens);
 441 }
 442
 443 void diff_tree_setup_paths(const char **p, struct diff_options *opt)
 444 {
 445         opt->nr_paths = 0;
 446         opt->pathlens = NULL;
 447         opt->paths = NULL;
 448
 449         if (p) {
 450                 int i;
 451
 452                 opt->paths = p;
 453                 opt->nr_paths = count_paths(p);
 454                 if (opt->nr_paths == 0) {
 455                         opt->pathlens = NULL;
 456                         return;
 457                 }
 458                 opt->pathlens = xmalloc(opt->nr_paths * sizeof(int));
 459                 for (i=0; i < opt->nr_paths; i++)
 460                         opt->pathlens[i] = strlen(p[i]);
 461         }
 462 }