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  * NOTE empty (=invalid) descriptor(s) take part in comparison as +infty,
  17  *      so that they sort *after* valid tree entries.
  18  *
  19  *      Due to this convention, if trees are scanned in sorted order, all
  20  *      non-empty descriptors will be processed first.
  21  */
  22 static int tree_entry_pathcmp(struct tree_desc *t1, struct tree_desc *t2)
  23 {
  24         struct name_entry *e1, *e2;
  25         int cmp;
  26
  27         /* empty descriptors sort after valid tree entries */
  28         if (!t1->size)
  29                 return t2->size ? 1 : 0;
  30         else if (!t2->size)
  31                 return -1;
  32
  33         e1 = &t1->entry;
  34         e2 = &t2->entry;
  35         cmp = base_name_compare(e1->path, tree_entry_len(e1), e1->mode,
  36                                 e2->path, tree_entry_len(e2), e2->mode);
  37         return cmp;
  38 }
  39
  40
  41 /* convert path, t1/t2 -> opt->diff_*() callbacks */
  42 static void emit_diff(struct diff_options *opt, struct strbuf *path,
  43                       struct tree_desc *t1, struct tree_desc *t2)
  44 {
  45         unsigned int mode1 = t1 ? t1->entry.mode : 0;
  46         unsigned int mode2 = t2 ? t2->entry.mode : 0;
  47
  48         if (mode1 && mode2) {
  49                 opt->change(opt, mode1, mode2, t1->entry.sha1, t2->entry.sha1,
  50                         1, 1, path->buf, 0, 0);
  51         }
  52         else {
  53                 const unsigned char *sha1;
  54                 unsigned int mode;
  55                 int addremove;
  56
  57                 if (mode2) {
  58                         addremove = '+';
  59                         sha1 = t2->entry.sha1;
  60                         mode = mode2;
  61                 } else {
  62                         addremove = '-';
  63                         sha1 = t1->entry.sha1;
  64                         mode = mode1;
  65                 }
  66
  67                 opt->add_remove(opt, addremove, mode, sha1, 1, path->buf, 0);
  68         }
  69 }
  70
  71
  72 /* new path should be added to diff
  73  *
  74  * 3 cases on how/when it should be called and behaves:
  75  *
  76  *      !t1,  t2        -> path added, parent lacks it
  77  *       t1, !t2        -> path removed from parent
  78  *       t1,  t2        -> path modified
  79  */
  80 static void show_path(struct strbuf *base, struct diff_options *opt,
  81                       struct tree_desc *t1, struct tree_desc *t2)
  82 {
  83         unsigned mode;
  84         const char *path;
  85         int pathlen;
  86         int old_baselen = base->len;
  87         int isdir, recurse = 0, emitthis = 1;
  88
  89         /* at least something has to be valid */
  90         assert(t1 || t2);
  91
  92         if (t2) {
  93                 /* path present in resulting tree */
  94                 tree_entry_extract(t2, &path, &mode);
  95                 pathlen = tree_entry_len(&t2->entry);
  96                 isdir = S_ISDIR(mode);
  97         } else {
  98                 /*
  99                  * a path was removed - take path from parent. Also take
 100                  * mode from parent, to decide on recursion.
 101                  */
 102                 tree_entry_extract(t1, &path, &mode);
 103                 pathlen = tree_entry_len(&t1->entry);
 104
 105                 isdir = S_ISDIR(mode);
 106                 mode = 0;
 107         }
 108
 109         if (DIFF_OPT_TST(opt, RECURSIVE) && isdir) {
 110                 recurse = 1;
 111                 emitthis = DIFF_OPT_TST(opt, TREE_IN_RECURSIVE);
 112         }
 113
 114         strbuf_add(base, path, pathlen);
 115
 116         if (emitthis)
 117                 emit_diff(opt, base, t1, t2);
 118
 119         if (recurse) {
 120                 strbuf_addch(base, '/');
 121                 diff_tree_sha1(t1 ? t1->entry.sha1 : NULL,
 122                                t2 ? t2->entry.sha1 : NULL, base->buf, opt);
 123         }
 124
 125         strbuf_setlen(base, old_baselen);
 126 }
 127
 128 static void skip_uninteresting(struct tree_desc *t, struct strbuf *base,
 129                                struct diff_options *opt)
 130 {
 131         enum interesting match;
 132
 133         while (t->size) {
 134                 match = tree_entry_interesting(&t->entry, base, 0, &opt->pathspec);
 135                 if (match) {
 136                         if (match == all_entries_not_interesting)
 137                                 t->size = 0;
 138                         break;
 139                 }
 140                 update_tree_entry(t);
 141         }
 142 }
 143
 144 static int ll_diff_tree_sha1(const unsigned char *old, const unsigned char *new,
 145                              const char *base_str, struct diff_options *opt)
 146 {
 147         struct tree_desc t1, t2;
 148         void *t1tree, *t2tree;
 149         struct strbuf base;
 150         int baselen = strlen(base_str);
 151
 152         t1tree = fill_tree_descriptor(&t1, old);
 153         t2tree = fill_tree_descriptor(&t2, new);
 154
 155         /* Enable recursion indefinitely */
 156         opt->pathspec.recursive = DIFF_OPT_TST(opt, RECURSIVE);
 157
 158         strbuf_init(&base, PATH_MAX);
 159         strbuf_add(&base, base_str, baselen);
 160
 161         for (;;) {
 162                 int cmp;
 163
 164                 if (diff_can_quit_early(opt))
 165                         break;
 166                 if (opt->pathspec.nr) {
 167                         skip_uninteresting(&t1, &base, opt);
 168                         skip_uninteresting(&t2, &base, opt);
 169                 }
 170                 if (!t1.size && !t2.size)
 171                         break;
 172
 173                 cmp = tree_entry_pathcmp(&t1, &t2);
 174
 175                 /* t1 = t2 */
 176                 if (cmp == 0) {
 177                         if (DIFF_OPT_TST(opt, FIND_COPIES_HARDER) ||
 178                             hashcmp(t1.entry.sha1, t2.entry.sha1) ||
 179                             (t1.entry.mode != t2.entry.mode))
 180                                 show_path(&base, opt, &t1, &t2);
 181
 182                         update_tree_entry(&t1);
 183                         update_tree_entry(&t2);
 184                 }
 185
 186                 /* t1 < t2 */
 187                 else if (cmp < 0) {
 188                         show_path(&base, opt, &t1, /*t2=*/NULL);
 189                         update_tree_entry(&t1);
 190                 }
 191
 192                 /* t1 > t2 */
 193                 else {
 194                         show_path(&base, opt, /*t1=*/NULL, &t2);
 195                         update_tree_entry(&t2);
 196                 }
 197         }
 198
 199         strbuf_release(&base);
 200         free(t2tree);
 201         free(t1tree);
 202         return 0;
 203 }
 204
 205 /*
 206  * Does it look like the resulting diff might be due to a rename?
 207  *  - single entry
 208  *  - not a valid previous file
 209  */
 210 static inline int diff_might_be_rename(void)
 211 {
 212         return diff_queued_diff.nr == 1 &&
 213                 !DIFF_FILE_VALID(diff_queued_diff.queue[0]->one);
 214 }
 215
 216 static void try_to_follow_renames(const unsigned char *old, const unsigned char *new, const char *base, struct diff_options *opt)
 217 {
 218         struct diff_options diff_opts;
 219         struct diff_queue_struct *q = &diff_queued_diff;
 220         struct diff_filepair *choice;
 221         int i;
 222
 223         /*
 224          * follow-rename code is very specific, we need exactly one
 225          * path. Magic that matches more than one path is not
 226          * supported.
 227          */
 228         GUARD_PATHSPEC(&opt->pathspec, PATHSPEC_FROMTOP | PATHSPEC_LITERAL);
 229 #if 0
 230         /*
 231          * We should reject wildcards as well. Unfortunately we
 232          * haven't got a reliable way to detect that 'foo\*bar' in
 233          * fact has no wildcards. nowildcard_len is merely a hint for
 234          * optimization. Let it slip for now until wildmatch is taught
 235          * about dry-run mode and returns wildcard info.
 236          */
 237         if (opt->pathspec.has_wildcard)
 238                 die("BUG:%s:%d: wildcards are not supported",
 239                     __FILE__, __LINE__);
 240 #endif
 241
 242         /* Remove the file creation entry from the diff queue, and remember it */
 243         choice = q->queue[0];
 244         q->nr = 0;
 245
 246         diff_setup(&diff_opts);
 247         DIFF_OPT_SET(&diff_opts, RECURSIVE);
 248         DIFF_OPT_SET(&diff_opts, FIND_COPIES_HARDER);
 249         diff_opts.output_format = DIFF_FORMAT_NO_OUTPUT;
 250         diff_opts.single_follow = opt->pathspec.items[0].match;
 251         diff_opts.break_opt = opt->break_opt;
 252         diff_opts.rename_score = opt->rename_score;
 253         diff_setup_done(&diff_opts);
 254         ll_diff_tree_sha1(old, new, base, &diff_opts);
 255         diffcore_std(&diff_opts);
 256         free_pathspec(&diff_opts.pathspec);
 257
 258         /* Go through the new set of filepairing, and see if we find a more interesting one */
 259         opt->found_follow = 0;
 260         for (i = 0; i < q->nr; i++) {
 261                 struct diff_filepair *p = q->queue[i];
 262
 263                 /*
 264                  * Found a source? Not only do we use that for the new
 265                  * diff_queued_diff, we will also use that as the path in
 266                  * the future!
 267                  */
 268                 if ((p->status == 'R' || p->status == 'C') &&
 269                     !strcmp(p->two->path, opt->pathspec.items[0].match)) {
 270                         const char *path[2];
 271
 272                         /* Switch the file-pairs around */
 273                         q->queue[i] = choice;
 274                         choice = p;
 275
 276                         /* Update the path we use from now on.. */
 277                         path[0] = p->one->path;
 278                         path[1] = NULL;
 279                         free_pathspec(&opt->pathspec);
 280                         parse_pathspec(&opt->pathspec,
 281                                        PATHSPEC_ALL_MAGIC & ~PATHSPEC_LITERAL,
 282                                        PATHSPEC_LITERAL_PATH, "", path);
 283
 284                         /*
 285                          * The caller expects us to return a set of vanilla
 286                          * filepairs to let a later call to diffcore_std()
 287                          * it makes to sort the renames out (among other
 288                          * things), but we already have found renames
 289                          * ourselves; signal diffcore_std() not to muck with
 290                          * rename information.
 291                          */
 292                         opt->found_follow = 1;
 293                         break;
 294                 }
 295         }
 296
 297         /*
 298          * Then, discard all the non-relevant file pairs...
 299          */
 300         for (i = 0; i < q->nr; i++) {
 301                 struct diff_filepair *p = q->queue[i];
 302                 diff_free_filepair(p);
 303         }
 304
 305         /*
 306          * .. and re-instate the one we want (which might be either the
 307          * original one, or the rename/copy we found)
 308          */
 309         q->queue[0] = choice;
 310         q->nr = 1;
 311 }
 312
 313 int diff_tree_sha1(const unsigned char *old, const unsigned char *new, const char *base, struct diff_options *opt)
 314 {
 315         int retval;
 316
 317         retval = ll_diff_tree_sha1(old, new, base, opt);
 318         if (!*base && DIFF_OPT_TST(opt, FOLLOW_RENAMES) && diff_might_be_rename())
 319                 try_to_follow_renames(old, new, base, opt);
 320
 321         return retval;
 322 }
 323
 324 int diff_root_tree_sha1(const unsigned char *new, const char *base, struct diff_options *opt)
 325 {
 326         return diff_tree_sha1(NULL, new, base, opt);
 327 }