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