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 void show_entry(struct diff_options *opt, const char *prefix,
  10                        struct tree_desc *desc, struct strbuf *base);
  11
  12 static int compare_tree_entry(struct tree_desc *t1, struct tree_desc *t2,
  13                               struct strbuf *base, struct diff_options *opt)
  14 {
  15         unsigned mode1, mode2;
  16         const char *path1, *path2;
  17         const unsigned char *sha1, *sha2;
  18         int cmp, pathlen1, pathlen2;
  19         int old_baselen = base->len;
  20
  21         sha1 = tree_entry_extract(t1, &path1, &mode1);
  22         sha2 = tree_entry_extract(t2, &path2, &mode2);
  23
  24         pathlen1 = tree_entry_len(&t1->entry);
  25         pathlen2 = tree_entry_len(&t2->entry);
  26         cmp = base_name_compare(path1, pathlen1, mode1, path2, pathlen2, mode2);
  27         if (cmp < 0) {
  28                 show_entry(opt, "-", t1, base);
  29                 return -1;
  30         }
  31         if (cmp > 0) {
  32                 show_entry(opt, "+", t2, base);
  33                 return 1;
  34         }
  35         if (!DIFF_OPT_TST(opt, FIND_COPIES_HARDER) && !hashcmp(sha1, sha2) && mode1 == mode2)
  36                 return 0;
  37
  38         /*
  39          * If the filemode has changed to/from a directory from/to a regular
  40          * file, we need to consider it a remove and an add.
  41          */
  42         if (S_ISDIR(mode1) != S_ISDIR(mode2)) {
  43                 show_entry(opt, "-", t1, base);
  44                 show_entry(opt, "+", t2, base);
  45                 return 0;
  46         }
  47
  48         strbuf_add(base, path1, pathlen1);
  49         if (DIFF_OPT_TST(opt, RECURSIVE) && S_ISDIR(mode1)) {
  50                 if (DIFF_OPT_TST(opt, TREE_IN_RECURSIVE)) {
  51                         opt->change(opt, mode1, mode2,
  52                                     sha1, sha2, 1, 1, base->buf, 0, 0);
  53                 }
  54                 strbuf_addch(base, '/');
  55                 diff_tree_sha1(sha1, sha2, base->buf, opt);
  56         } else {
  57                 opt->change(opt, mode1, mode2, sha1, sha2, 1, 1, base->buf, 0, 0);
  58         }
  59         strbuf_setlen(base, old_baselen);
  60         return 0;
  61 }
  62
  63 /* A whole sub-tree went away or appeared */
  64 static void show_tree(struct diff_options *opt, const char *prefix,
  65                       struct tree_desc *desc, struct strbuf *base)
  66 {
  67         enum interesting match = entry_not_interesting;
  68         for (; desc->size; update_tree_entry(desc)) {
  69                 if (match != all_entries_interesting) {
  70                         match = tree_entry_interesting(&desc->entry, base, 0,
  71                                                        &opt->pathspec);
  72                         if (match == all_entries_not_interesting)
  73                                 break;
  74                         if (match == entry_not_interesting)
  75                                 continue;
  76                 }
  77                 show_entry(opt, prefix, desc, base);
  78         }
  79 }
  80
  81 /* A file entry went away or appeared */
  82 static void show_entry(struct diff_options *opt, const char *prefix,
  83                        struct tree_desc *desc, struct strbuf *base)
  84 {
  85         unsigned mode;
  86         const char *path;
  87         const unsigned char *sha1 = tree_entry_extract(desc, &path, &mode);
  88         int pathlen = tree_entry_len(&desc->entry);
  89         int old_baselen = base->len;
  90
  91         strbuf_add(base, path, pathlen);
  92         if (DIFF_OPT_TST(opt, RECURSIVE) && S_ISDIR(mode)) {
  93                 enum object_type type;
  94                 struct tree_desc inner;
  95                 void *tree;
  96                 unsigned long size;
  97
  98                 tree = read_sha1_file(sha1, &type, &size);
  99                 if (!tree || type != OBJ_TREE)
 100                         die("corrupt tree sha %s", sha1_to_hex(sha1));
 101
 102                 if (DIFF_OPT_TST(opt, TREE_IN_RECURSIVE))
 103                         opt->add_remove(opt, *prefix, mode, sha1, 1, base->buf, 0);
 104
 105                 strbuf_addch(base, '/');
 106
 107                 init_tree_desc(&inner, tree, size);
 108                 show_tree(opt, prefix, &inner, base);
 109                 free(tree);
 110         } else
 111                 opt->add_remove(opt, prefix[0], mode, sha1, 1, base->buf, 0);
 112
 113         strbuf_setlen(base, old_baselen);
 114 }
 115
 116 static void skip_uninteresting(struct tree_desc *t, struct strbuf *base,
 117                                struct diff_options *opt,
 118                                enum interesting *match)
 119 {
 120         while (t->size) {
 121                 *match = tree_entry_interesting(&t->entry, base, 0, &opt->pathspec);
 122                 if (*match) {
 123                         if (*match == all_entries_not_interesting)
 124                                 t->size = 0;
 125                         break;
 126                 }
 127                 update_tree_entry(t);
 128         }
 129 }
 130
 131 int diff_tree(struct tree_desc *t1, struct tree_desc *t2,
 132               const char *base_str, struct diff_options *opt)
 133 {
 134         struct strbuf base;
 135         int baselen = strlen(base_str);
 136         enum interesting t1_match = entry_not_interesting;
 137         enum interesting t2_match = entry_not_interesting;
 138
 139         /* Enable recursion indefinitely */
 140         opt->pathspec.recursive = DIFF_OPT_TST(opt, RECURSIVE);
 141
 142         strbuf_init(&base, PATH_MAX);
 143         strbuf_add(&base, base_str, baselen);
 144
 145         for (;;) {
 146                 if (diff_can_quit_early(opt))
 147                         break;
 148                 if (opt->pathspec.nr) {
 149                         skip_uninteresting(t1, &base, opt, &t1_match);
 150                         skip_uninteresting(t2, &base, opt, &t2_match);
 151                 }
 152                 if (!t1->size) {
 153                         if (!t2->size)
 154                                 break;
 155                         show_entry(opt, "+", t2, &base);
 156                         update_tree_entry(t2);
 157                         continue;
 158                 }
 159                 if (!t2->size) {
 160                         show_entry(opt, "-", t1, &base);
 161                         update_tree_entry(t1);
 162                         continue;
 163                 }
 164                 switch (compare_tree_entry(t1, t2, &base, opt)) {
 165                 case -1:
 166                         update_tree_entry(t1);
 167                         continue;
 168                 case 0:
 169                         update_tree_entry(t1);
 170                         /* Fallthrough */
 171                 case 1:
 172                         update_tree_entry(t2);
 173                         continue;
 174                 }
 175                 die("git diff-tree: internal error");
 176         }
 177
 178         strbuf_release(&base);
 179         return 0;
 180 }
 181
 182 /*
 183  * Does it look like the resulting diff might be due to a rename?
 184  *  - single entry
 185  *  - not a valid previous file
 186  */
 187 static inline int diff_might_be_rename(void)
 188 {
 189         return diff_queued_diff.nr == 1 &&
 190                 !DIFF_FILE_VALID(diff_queued_diff.queue[0]->one);
 191 }
 192
 193 static void try_to_follow_renames(struct tree_desc *t1, struct tree_desc *t2, const char *base, struct diff_options *opt)
 194 {
 195         struct diff_options diff_opts;
 196         struct diff_queue_struct *q = &diff_queued_diff;
 197         struct diff_filepair *choice;
 198         int i;
 199
 200         /*
 201          * follow-rename code is very specific, we need exactly one
 202          * path. Magic that matches more than one path is not
 203          * supported.
 204          */
 205         GUARD_PATHSPEC(&opt->pathspec, PATHSPEC_FROMTOP | PATHSPEC_LITERAL);
 206 #if 0
 207         /*
 208          * We should reject wildcards as well. Unfortunately we
 209          * haven't got a reliable way to detect that 'foo\*bar' in
 210          * fact has no wildcards. nowildcard_len is merely a hint for
 211          * optimization. Let it slip for now until wildmatch is taught
 212          * about dry-run mode and returns wildcard info.
 213          */
 214         if (opt->pathspec.has_wildcard)
 215                 die("BUG:%s:%d: wildcards are not supported",
 216                     __FILE__, __LINE__);
 217 #endif
 218
 219         /* Remove the file creation entry from the diff queue, and remember it */
 220         choice = q->queue[0];
 221         q->nr = 0;
 222
 223         diff_setup(&diff_opts);
 224         DIFF_OPT_SET(&diff_opts, RECURSIVE);
 225         DIFF_OPT_SET(&diff_opts, FIND_COPIES_HARDER);
 226         diff_opts.output_format = DIFF_FORMAT_NO_OUTPUT;
 227         diff_opts.single_follow = opt->pathspec.items[0].match;
 228         diff_opts.break_opt = opt->break_opt;
 229         diff_opts.rename_score = opt->rename_score;
 230         diff_setup_done(&diff_opts);
 231         diff_tree(t1, t2, base, &diff_opts);
 232         diffcore_std(&diff_opts);
 233         free_pathspec(&diff_opts.pathspec);
 234
 235         /* Go through the new set of filepairing, and see if we find a more interesting one */
 236         opt->found_follow = 0;
 237         for (i = 0; i < q->nr; i++) {
 238                 struct diff_filepair *p = q->queue[i];
 239
 240                 /*
 241                  * Found a source? Not only do we use that for the new
 242                  * diff_queued_diff, we will also use that as the path in
 243                  * the future!
 244                  */
 245                 if ((p->status == 'R' || p->status == 'C') &&
 246                     !strcmp(p->two->path, opt->pathspec.items[0].match)) {
 247                         const char *path[2];
 248
 249                         /* Switch the file-pairs around */
 250                         q->queue[i] = choice;
 251                         choice = p;
 252
 253                         /* Update the path we use from now on.. */
 254                         path[0] = p->one->path;
 255                         path[1] = NULL;
 256                         free_pathspec(&opt->pathspec);
 257                         parse_pathspec(&opt->pathspec,
 258                                        PATHSPEC_ALL_MAGIC & ~PATHSPEC_LITERAL,
 259                                        PATHSPEC_LITERAL_PATH, "", path);
 260
 261                         /*
 262                          * The caller expects us to return a set of vanilla
 263                          * filepairs to let a later call to diffcore_std()
 264                          * it makes to sort the renames out (among other
 265                          * things), but we already have found renames
 266                          * ourselves; signal diffcore_std() not to muck with
 267                          * rename information.
 268                          */
 269                         opt->found_follow = 1;
 270                         break;
 271                 }
 272         }
 273
 274         /*
 275          * Then, discard all the non-relevant file pairs...
 276          */
 277         for (i = 0; i < q->nr; i++) {
 278                 struct diff_filepair *p = q->queue[i];
 279                 diff_free_filepair(p);
 280         }
 281
 282         /*
 283          * .. and re-instate the one we want (which might be either the
 284          * original one, or the rename/copy we found)
 285          */
 286         q->queue[0] = choice;
 287         q->nr = 1;
 288 }
 289
 290 int diff_tree_sha1(const unsigned char *old, const unsigned char *new, const char *base, struct diff_options *opt)
 291 {
 292         void *tree1, *tree2;
 293         struct tree_desc t1, t2;
 294         unsigned long size1, size2;
 295         int retval;
 296
 297         tree1 = read_object_with_reference(old, tree_type, &size1, NULL);
 298         if (!tree1)
 299                 die("unable to read source tree (%s)", sha1_to_hex(old));
 300         tree2 = read_object_with_reference(new, tree_type, &size2, NULL);
 301         if (!tree2)
 302                 die("unable to read destination tree (%s)", sha1_to_hex(new));
 303         init_tree_desc(&t1, tree1, size1);
 304         init_tree_desc(&t2, tree2, size2);
 305         retval = diff_tree(&t1, &t2, base, opt);
 306         if (!*base && DIFF_OPT_TST(opt, FOLLOW_RENAMES) && diff_might_be_rename()) {
 307                 init_tree_desc(&t1, tree1, size1);
 308                 init_tree_desc(&t2, tree2, size2);
 309                 try_to_follow_renames(&t1, &t2, base, opt);
 310         }
 311         free(tree1);
 312         free(tree2);
 313         return retval;
 314 }
 315
 316 int diff_root_tree_sha1(const unsigned char *new, const char *base, struct diff_options *opt)
 317 {
 318         int retval;
 319         void *tree;
 320         unsigned long size;
 321         struct tree_desc empty, real;
 322
 323         tree = read_object_with_reference(new, tree_type, &size, NULL);
 324         if (!tree)
 325                 die("unable to read root tree (%s)", sha1_to_hex(new));
 326         init_tree_desc(&real, tree, size);
 327
 328         init_tree_desc(&empty, "", 0);
 329         retval = diff_tree(&empty, &real, base, opt);
 330         free(tree);
 331         return retval;
 332 }