git.oblomov.eu Git - git/blob - 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 /*
  10  * Compare two tree entries, taking into account only path/S_ISDIR(mode),
  11  * but not their sha1's.
  12  *
  13  * NOTE files and directories *always* compare differently, even when having
  14  *      the same name - thanks to base_name_compare().
  15  */
  16 static int tree_entry_pathcmp(struct tree_desc *t1, struct tree_desc *t2)
  17 {
  18         struct name_entry *e1, *e2;
  19         int cmp;
  20
  21         e1 = &t1->entry;
  22         e2 = &t2->entry;
  23         cmp = base_name_compare(e1->path, tree_entry_len(e1), e1->mode,
  24                                 e2->path, tree_entry_len(e2), e2->mode);
  25         return cmp;
  26 }
  27
  28
  29 /* convert path, t1/t2 -> opt->diff_*() callbacks */
  30 static void emit_diff(struct diff_options *opt, struct strbuf *path,
  31                       struct tree_desc *t1, struct tree_desc *t2)
  32 {
  33         unsigned int mode1 = t1 ? t1->entry.mode : 0;
  34         unsigned int mode2 = t2 ? t2->entry.mode : 0;
  35
  36         if (mode1 && mode2) {
  37                 opt->change(opt, mode1, mode2, t1->entry.sha1, t2->entry.sha1,
  38                         1, 1, path->buf, 0, 0);
  39         }
  40         else {
  41                 const unsigned char *sha1;
  42                 unsigned int mode;
  43                 int addremove;
  44
  45                 if (mode2) {
  46                         addremove = '+';
  47                         sha1 = t2->entry.sha1;
  48                         mode = mode2;
  49                 } else {
  50                         addremove = '-';
  51                         sha1 = t1->entry.sha1;
  52                         mode = mode1;
  53                 }
  54
  55                 opt->add_remove(opt, addremove, mode, sha1, 1, path->buf, 0);
  56         }
  57 }
  58
  59
  60 /* new path should be added to diff
  61  *
  62  * 3 cases on how/when it should be called and behaves:
  63  *
  64  *      !t1,  t2        -> path added, parent lacks it
  65  *       t1, !t2        -> path removed from parent
  66  *       t1,  t2        -> path modified
  67  */
  68 static void show_path(struct strbuf *base, struct diff_options *opt,
  69                       struct tree_desc *t1, struct tree_desc *t2)
  70 {
  71         unsigned mode;
  72         const char *path;
  73         int pathlen;
  74         int old_baselen = base->len;
  75         int isdir, recurse = 0, emitthis = 1;
  76
  77         /* at least something has to be valid */
  78         assert(t1 || t2);
  79
  80         if (t2) {
  81                 /* path present in resulting tree */
  82                 tree_entry_extract(t2, &path, &mode);
  83                 pathlen = tree_entry_len(&t2->entry);
  84                 isdir = S_ISDIR(mode);
  85         } else {
  86                 /*
  87                  * a path was removed - take path from parent. Also take
  88                  * mode from parent, to decide on recursion.
  89                  */
  90                 tree_entry_extract(t1, &path, &mode);
  91                 pathlen = tree_entry_len(&t1->entry);
  92
  93                 isdir = S_ISDIR(mode);
  94                 mode = 0;
  95         }
  96
  97         if (DIFF_OPT_TST(opt, RECURSIVE) && isdir) {
  98                 recurse = 1;
  99                 emitthis = DIFF_OPT_TST(opt, TREE_IN_RECURSIVE);
 100         }
 101
 102         strbuf_add(base, path, pathlen);
 103
 104         if (emitthis)
 105                 emit_diff(opt, base, t1, t2);
 106
 107         if (recurse) {
 108                 strbuf_addch(base, '/');
 109                 diff_tree_sha1(t1 ? t1->entry.sha1 : NULL,
 110                                t2 ? t2->entry.sha1 : NULL, base->buf, opt);
 111         }
 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 {
 119         enum interesting match;
 120
 121         while (t->size) {
 122                 match = tree_entry_interesting(&t->entry, base, 0, &opt->pathspec);
 123                 if (match) {
 124                         if (match == all_entries_not_interesting)
 125                                 t->size = 0;
 126                         break;
 127                 }
 128                 update_tree_entry(t);
 129         }
 130 }
 131
 132 int diff_tree(struct tree_desc *t1, struct tree_desc *t2,
 133               const char *base_str, struct diff_options *opt)
 134 {
 135         struct strbuf base;
 136         int baselen = strlen(base_str);
 137
 138         /* Enable recursion indefinitely */
 139         opt->pathspec.recursive = DIFF_OPT_TST(opt, RECURSIVE);
 140
 141         strbuf_init(&base, PATH_MAX);
 142         strbuf_add(&base, base_str, baselen);
 143
 144         for (;;) {
 145                 int cmp;
 146
 147                 if (diff_can_quit_early(opt))
 148                         break;
 149                 if (opt->pathspec.nr) {
 150                         skip_uninteresting(t1, &base, opt);
 151                         skip_uninteresting(t2, &base, opt);
 152                 }
 153                 if (!t1->size) {
 154                         if (!t2->size)
 155                                 break;
 156                         show_path(&base, opt, /*t1=*/NULL, t2);
 157                         update_tree_entry(t2);
 158                         continue;
 159                 }
 160                 if (!t2->size) {
 161                         show_path(&base, opt, t1, /*t2=*/NULL);
 162                         update_tree_entry(t1);
 163                         continue;
 164                 }
 165
 166                 cmp = tree_entry_pathcmp(t1, t2);
 167
 168                 /* t1 = t2 */
 169                 if (cmp == 0) {
 170                         if (DIFF_OPT_TST(opt, FIND_COPIES_HARDER) ||
 171                             hashcmp(t1->entry.sha1, t2->entry.sha1) ||
 172                             (t1->entry.mode != t2->entry.mode))
 173                                 show_path(&base, opt, t1, t2);
 174
 175                         update_tree_entry(t1);
 176                         update_tree_entry(t2);
 177                 }
 178
 179                 /* t1 < t2 */
 180                 else if (cmp < 0) {
 181                         show_path(&base, opt, t1, /*t2=*/NULL);
 182                         update_tree_entry(t1);
 183                 }
 184
 185                 /* t1 > t2 */
 186                 else {
 187                         show_path(&base, opt, /*t1=*/NULL, t2);
 188                         update_tree_entry(t2);
 189                 }
 190         }
 191
 192         strbuf_release(&base);
 193         return 0;
 194 }
 195
 196 /*
 197  * Does it look like the resulting diff might be due to a rename?
 198  *  - single entry
 199  *  - not a valid previous file
 200  */
 201 static inline int diff_might_be_rename(void)
 202 {
 203         return diff_queued_diff.nr == 1 &&
 204                 !DIFF_FILE_VALID(diff_queued_diff.queue[0]->one);
 205 }
 206
 207 static void try_to_follow_renames(struct tree_desc *t1, struct tree_desc *t2, const char *base, struct diff_options *opt)
 208 {
 209         struct diff_options diff_opts;
 210         struct diff_queue_struct *q = &diff_queued_diff;
 211         struct diff_filepair *choice;
 212         int i;
 213
 214         /*
 215          * follow-rename code is very specific, we need exactly one
 216          * path. Magic that matches more than one path is not
 217          * supported.
 218          */
 219         GUARD_PATHSPEC(&opt->pathspec, PATHSPEC_FROMTOP | PATHSPEC_LITERAL);
 220 #if 0
 221         /*
 222          * We should reject wildcards as well. Unfortunately we
 223          * haven't got a reliable way to detect that 'foo\*bar' in
 224          * fact has no wildcards. nowildcard_len is merely a hint for
 225          * optimization. Let it slip for now until wildmatch is taught
 226          * about dry-run mode and returns wildcard info.
 227          */
 228         if (opt->pathspec.has_wildcard)
 229                 die("BUG:%s:%d: wildcards are not supported",
 230                     __FILE__, __LINE__);
 231 #endif
 232
 233         /* Remove the file creation entry from the diff queue, and remember it */
 234         choice = q->queue[0];
 235         q->nr = 0;
 236
 237         diff_setup(&diff_opts);
 238         DIFF_OPT_SET(&diff_opts, RECURSIVE);
 239         DIFF_OPT_SET(&diff_opts, FIND_COPIES_HARDER);
 240         diff_opts.output_format = DIFF_FORMAT_NO_OUTPUT;
 241         diff_opts.single_follow = opt->pathspec.items[0].match;
 242         diff_opts.break_opt = opt->break_opt;
 243         diff_opts.rename_score = opt->rename_score;
 244         diff_setup_done(&diff_opts);
 245         diff_tree(t1, t2, base, &diff_opts);
 246         diffcore_std(&diff_opts);
 247         free_pathspec(&diff_opts.pathspec);
 248
 249         /* Go through the new set of filepairing, and see if we find a more interesting one */
 250         opt->found_follow = 0;
 251         for (i = 0; i < q->nr; i++) {
 252                 struct diff_filepair *p = q->queue[i];
 253
 254                 /*
 255                  * Found a source? Not only do we use that for the new
 256                  * diff_queued_diff, we will also use that as the path in
 257                  * the future!
 258                  */
 259                 if ((p->status == 'R' || p->status == 'C') &&
 260                     !strcmp(p->two->path, opt->pathspec.items[0].match)) {
 261                         const char *path[2];
 262
 263                         /* Switch the file-pairs around */
 264                         q->queue[i] = choice;
 265                         choice = p;
 266
 267                         /* Update the path we use from now on.. */
 268                         path[0] = p->one->path;
 269                         path[1] = NULL;
 270                         free_pathspec(&opt->pathspec);
 271                         parse_pathspec(&opt->pathspec,
 272                                        PATHSPEC_ALL_MAGIC & ~PATHSPEC_LITERAL,
 273                                        PATHSPEC_LITERAL_PATH, "", path);
 274
 275                         /*
 276                          * The caller expects us to return a set of vanilla
 277                          * filepairs to let a later call to diffcore_std()
 278                          * it makes to sort the renames out (among other
 279                          * things), but we already have found renames
 280                          * ourselves; signal diffcore_std() not to muck with
 281                          * rename information.
 282                          */
 283                         opt->found_follow = 1;
 284                         break;
 285                 }
 286         }
 287
 288         /*
 289          * Then, discard all the non-relevant file pairs...
 290          */
 291         for (i = 0; i < q->nr; i++) {
 292                 struct diff_filepair *p = q->queue[i];
 293                 diff_free_filepair(p);
 294         }
 295
 296         /*
 297          * .. and re-instate the one we want (which might be either the
 298          * original one, or the rename/copy we found)
 299          */
 300         q->queue[0] = choice;
 301         q->nr = 1;
 302 }
 303
 304 int diff_tree_sha1(const unsigned char *old, const unsigned char *new, const char *base, struct diff_options *opt)
 305 {
 306         void *tree1, *tree2;
 307         struct tree_desc t1, t2;
 308         unsigned long size1, size2;
 309         int retval;
 310
 311         tree1 = fill_tree_descriptor(&t1, old);
 312         tree2 = fill_tree_descriptor(&t2, new);
 313         size1 = t1.size;
 314         size2 = t2.size;
 315         retval = diff_tree(&t1, &t2, base, opt);
 316         if (!*base && DIFF_OPT_TST(opt, FOLLOW_RENAMES) && diff_might_be_rename()) {
 317                 init_tree_desc(&t1, tree1, size1);
 318                 init_tree_desc(&t2, tree2, size2);
 319                 try_to_follow_renames(&t1, &t2, base, opt);
 320         }
 321         free(tree1);
 322         free(tree2);
 323         return retval;
 324 }
 325
 326 int diff_root_tree_sha1(const unsigned char *new, const char *base, struct diff_options *opt)
 327 {
 328         return diff_tree_sha1(NULL, new, base, opt);
 329 }