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 static void show_path(struct strbuf *base, struct diff_options *opt,
  10                       struct tree_desc *t1, struct tree_desc *t2);
  11
  12 /*
  13  * Compare two tree entries, taking into account only path/S_ISDIR(mode),
  14  * but not their sha1's.
  15  *
  16  * NOTE files and directories *always* compare differently, even when having
  17  *      the same name - thanks to base_name_compare().
  18  */
  19 static int tree_entry_pathcmp(struct tree_desc *t1, struct tree_desc *t2)
  20 {
  21         unsigned mode1, mode2;
  22         const char *path1, *path2;
  23         const unsigned char *sha1, *sha2;
  24         int cmp, pathlen1, pathlen2;
  25
  26         sha1 = tree_entry_extract(t1, &path1, &mode1);
  27         sha2 = tree_entry_extract(t2, &path2, &mode2);
  28
  29         pathlen1 = tree_entry_len(&t1->entry);
  30         pathlen2 = tree_entry_len(&t2->entry);
  31
  32         cmp = base_name_compare(path1, pathlen1, mode1, path2, pathlen2, mode2);
  33         return cmp;
  34 }
  35
  36
  37 /* convert path, t1/t2 -> opt->diff_*() callbacks */
  38 static void emit_diff(struct diff_options *opt, struct strbuf *path,
  39                       struct tree_desc *t1, struct tree_desc *t2)
  40 {
  41         unsigned int mode1 = t1 ? t1->entry.mode : 0;
  42         unsigned int mode2 = t2 ? t2->entry.mode : 0;
  43
  44         if (mode1 && mode2) {
  45                 opt->change(opt, mode1, mode2, t1->entry.sha1, t2->entry.sha1,
  46                         1, 1, path->buf, 0, 0);
  47         }
  48         else {
  49                 const unsigned char *sha1;
  50                 unsigned int mode;
  51                 int addremove;
  52
  53                 if (mode2) {
  54                         addremove = '+';
  55                         sha1 = t2->entry.sha1;
  56                         mode = mode2;
  57                 } else {
  58                         addremove = '-';
  59                         sha1 = t1->entry.sha1;
  60                         mode = mode1;
  61                 }
  62
  63                 opt->add_remove(opt, addremove, mode, sha1, 1, path->buf, 0);
  64         }
  65 }
  66
  67
  68 /* new path should be added to diff
  69  *
  70  * 3 cases on how/when it should be called and behaves:
  71  *
  72  *      !t1,  t2        -> path added, parent lacks it
  73  *       t1, !t2        -> path removed from parent
  74  *       t1,  t2        -> path modified
  75  */
  76 static void show_path(struct strbuf *base, struct diff_options *opt,
  77                       struct tree_desc *t1, struct tree_desc *t2)
  78 {
  79         unsigned mode;
  80         const char *path;
  81         int pathlen;
  82         int old_baselen = base->len;
  83         int isdir, recurse = 0, emitthis = 1;
  84
  85         /* at least something has to be valid */
  86         assert(t1 || t2);
  87
  88         if (t2) {
  89                 /* path present in resulting tree */
  90                 tree_entry_extract(t2, &path, &mode);
  91                 pathlen = tree_entry_len(&t2->entry);
  92                 isdir = S_ISDIR(mode);
  93         } else {
  94                 /*
  95                  * a path was removed - take path from parent. Also take
  96                  * mode from parent, to decide on recursion.
  97                  */
  98                 tree_entry_extract(t1, &path, &mode);
  99                 pathlen = tree_entry_len(&t1->entry);
 100
 101                 isdir = S_ISDIR(mode);
 102                 mode = 0;
 103         }
 104
 105         if (DIFF_OPT_TST(opt, RECURSIVE) && isdir) {
 106                 recurse = 1;
 107                 emitthis = DIFF_OPT_TST(opt, TREE_IN_RECURSIVE);
 108         }
 109
 110         strbuf_add(base, path, pathlen);
 111
 112         if (emitthis)
 113                 emit_diff(opt, base, t1, t2);
 114
 115         if (recurse) {
 116                 strbuf_addch(base, '/');
 117                 diff_tree_sha1(t1 ? t1->entry.sha1 : NULL,
 118                                t2 ? t2->entry.sha1 : NULL, base->buf, opt);
 119         }
 120
 121         strbuf_setlen(base, old_baselen);
 122 }
 123
 124 static void skip_uninteresting(struct tree_desc *t, struct strbuf *base,
 125                                struct diff_options *opt)
 126 {
 127         enum interesting match;
 128
 129         while (t->size) {
 130                 match = tree_entry_interesting(&t->entry, base, 0, &opt->pathspec);
 131                 if (match) {
 132                         if (match == all_entries_not_interesting)
 133                                 t->size = 0;
 134                         break;
 135                 }
 136                 update_tree_entry(t);
 137         }
 138 }
 139
 140 int diff_tree(struct tree_desc *t1, struct tree_desc *t2,
 141               const char *base_str, struct diff_options *opt)
 142 {
 143         struct strbuf base;
 144         int baselen = strlen(base_str);
 145
 146         /* Enable recursion indefinitely */
 147         opt->pathspec.recursive = DIFF_OPT_TST(opt, RECURSIVE);
 148
 149         strbuf_init(&base, PATH_MAX);
 150         strbuf_add(&base, base_str, baselen);
 151
 152         for (;;) {
 153                 int cmp;
 154
 155                 if (diff_can_quit_early(opt))
 156                         break;
 157                 if (opt->pathspec.nr) {
 158                         skip_uninteresting(t1, &base, opt);
 159                         skip_uninteresting(t2, &base, opt);
 160                 }
 161                 if (!t1->size) {
 162                         if (!t2->size)
 163                                 break;
 164                         show_path(&base, opt, /*t1=*/NULL, t2);
 165                         update_tree_entry(t2);
 166                         continue;
 167                 }
 168                 if (!t2->size) {
 169                         show_path(&base, opt, t1, /*t2=*/NULL);
 170                         update_tree_entry(t1);
 171                         continue;
 172                 }
 173
 174                 cmp = tree_entry_pathcmp(t1, t2);
 175
 176                 /* t1 = t2 */
 177                 if (cmp == 0) {
 178                         if (DIFF_OPT_TST(opt, FIND_COPIES_HARDER) ||
 179                             hashcmp(t1->entry.sha1, t2->entry.sha1) ||
 180                             (t1->entry.mode != t2->entry.mode))
 181                                 show_path(&base, opt, t1, t2);
 182
 183                         update_tree_entry(t1);
 184                         update_tree_entry(t2);
 185                 }
 186
 187                 /* t1 < t2 */
 188                 else if (cmp < 0) {
 189                         show_path(&base, opt, t1, /*t2=*/NULL);
 190                         update_tree_entry(t1);
 191                 }
 192
 193                 /* t1 > t2 */
 194                 else {
 195                         show_path(&base, opt, /*t1=*/NULL, t2);
 196                         update_tree_entry(t2);
 197                 }
 198         }
 199
 200         strbuf_release(&base);
 201         return 0;
 202 }
 203
 204 /*
 205  * Does it look like the resulting diff might be due to a rename?
 206  *  - single entry
 207  *  - not a valid previous file
 208  */
 209 static inline int diff_might_be_rename(void)
 210 {
 211         return diff_queued_diff.nr == 1 &&
 212                 !DIFF_FILE_VALID(diff_queued_diff.queue[0]->one);
 213 }
 214
 215 static void try_to_follow_renames(struct tree_desc *t1, struct tree_desc *t2, const char *base, struct diff_options *opt)
 216 {
 217         struct diff_options diff_opts;
 218         struct diff_queue_struct *q = &diff_queued_diff;
 219         struct diff_filepair *choice;
 220         int i;
 221
 222         /*
 223          * follow-rename code is very specific, we need exactly one
 224          * path. Magic that matches more than one path is not
 225          * supported.
 226          */
 227         GUARD_PATHSPEC(&opt->pathspec, PATHSPEC_FROMTOP | PATHSPEC_LITERAL);
 228 #if 0
 229         /*
 230          * We should reject wildcards as well. Unfortunately we
 231          * haven't got a reliable way to detect that 'foo\*bar' in
 232          * fact has no wildcards. nowildcard_len is merely a hint for
 233          * optimization. Let it slip for now until wildmatch is taught
 234          * about dry-run mode and returns wildcard info.
 235          */
 236         if (opt->pathspec.has_wildcard)
 237                 die("BUG:%s:%d: wildcards are not supported",
 238                     __FILE__, __LINE__);
 239 #endif
 240
 241         /* Remove the file creation entry from the diff queue, and remember it */
 242         choice = q->queue[0];
 243         q->nr = 0;
 244
 245         diff_setup(&diff_opts);
 246         DIFF_OPT_SET(&diff_opts, RECURSIVE);
 247         DIFF_OPT_SET(&diff_opts, FIND_COPIES_HARDER);
 248         diff_opts.output_format = DIFF_FORMAT_NO_OUTPUT;
 249         diff_opts.single_follow = opt->pathspec.items[0].match;
 250         diff_opts.break_opt = opt->break_opt;
 251         diff_opts.rename_score = opt->rename_score;
 252         diff_setup_done(&diff_opts);
 253         diff_tree(t1, t2, base, &diff_opts);
 254         diffcore_std(&diff_opts);
 255         free_pathspec(&diff_opts.pathspec);
 256
 257         /* Go through the new set of filepairing, and see if we find a more interesting one */
 258         opt->found_follow = 0;
 259         for (i = 0; i < q->nr; i++) {
 260                 struct diff_filepair *p = q->queue[i];
 261
 262                 /*
 263                  * Found a source? Not only do we use that for the new
 264                  * diff_queued_diff, we will also use that as the path in
 265                  * the future!
 266                  */
 267                 if ((p->status == 'R' || p->status == 'C') &&
 268                     !strcmp(p->two->path, opt->pathspec.items[0].match)) {
 269                         const char *path[2];
 270
 271                         /* Switch the file-pairs around */
 272                         q->queue[i] = choice;
 273                         choice = p;
 274
 275                         /* Update the path we use from now on.. */
 276                         path[0] = p->one->path;
 277                         path[1] = NULL;
 278                         free_pathspec(&opt->pathspec);
 279                         parse_pathspec(&opt->pathspec,
 280                                        PATHSPEC_ALL_MAGIC & ~PATHSPEC_LITERAL,
 281                                        PATHSPEC_LITERAL_PATH, "", path);
 282
 283                         /*
 284                          * The caller expects us to return a set of vanilla
 285                          * filepairs to let a later call to diffcore_std()
 286                          * it makes to sort the renames out (among other
 287                          * things), but we already have found renames
 288                          * ourselves; signal diffcore_std() not to muck with
 289                          * rename information.
 290                          */
 291                         opt->found_follow = 1;
 292                         break;
 293                 }
 294         }
 295
 296         /*
 297          * Then, discard all the non-relevant file pairs...
 298          */
 299         for (i = 0; i < q->nr; i++) {
 300                 struct diff_filepair *p = q->queue[i];
 301                 diff_free_filepair(p);
 302         }
 303
 304         /*
 305          * .. and re-instate the one we want (which might be either the
 306          * original one, or the rename/copy we found)
 307          */
 308         q->queue[0] = choice;
 309         q->nr = 1;
 310 }
 311
 312 int diff_tree_sha1(const unsigned char *old, const unsigned char *new, const char *base, struct diff_options *opt)
 313 {
 314         void *tree1, *tree2;
 315         struct tree_desc t1, t2;
 316         unsigned long size1, size2;
 317         int retval;
 318
 319         tree1 = fill_tree_descriptor(&t1, old);
 320         tree2 = fill_tree_descriptor(&t2, new);
 321         size1 = t1.size;
 322         size2 = t2.size;
 323         retval = diff_tree(&t1, &t2, base, opt);
 324         if (!*base && DIFF_OPT_TST(opt, FOLLOW_RENAMES) && diff_might_be_rename()) {
 325                 init_tree_desc(&t1, tree1, size1);
 326                 init_tree_desc(&t2, tree2, size2);
 327                 try_to_follow_renames(&t1, &t2, base, opt);
 328         }
 329         free(tree1);
 330         free(tree2);
 331         return retval;
 332 }
 333
 334 int diff_root_tree_sha1(const unsigned char *new, const char *base, struct diff_options *opt)
 335 {
 336         return diff_tree_sha1(NULL, new, base, opt);
 337 }