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                                enum interesting *match)
 114 {
 115         while (t->size) {
 116                 *match = tree_entry_interesting(&t->entry, base, 0, &opt->pathspec);
 117                 if (*match) {
 118                         if (*match == all_entries_not_interesting)
 119                                 t->size = 0;
 120                         break;
 121                 }
 122                 update_tree_entry(t);
 123         }
 124 }
 125
 126 int diff_tree(struct tree_desc *t1, struct tree_desc *t2,
 127               const char *base_str, struct diff_options *opt)
 128 {
 129         struct strbuf base;
 130         int baselen = strlen(base_str);
 131         enum interesting t1_match = entry_not_interesting;
 132         enum interesting t2_match = entry_not_interesting;
 133
 134         /* Enable recursion indefinitely */
 135         opt->pathspec.recursive = DIFF_OPT_TST(opt, RECURSIVE);
 136
 137         strbuf_init(&base, PATH_MAX);
 138         strbuf_add(&base, base_str, baselen);
 139
 140         for (;;) {
 141                 if (diff_can_quit_early(opt))
 142                         break;
 143                 if (opt->pathspec.nr) {
 144                         skip_uninteresting(t1, &base, opt, &t1_match);
 145                         skip_uninteresting(t2, &base, opt, &t2_match);
 146                 }
 147                 if (!t1->size) {
 148                         if (!t2->size)
 149                                 break;
 150                         show_entry(opt, "+", t2, &base);
 151                         update_tree_entry(t2);
 152                         continue;
 153                 }
 154                 if (!t2->size) {
 155                         show_entry(opt, "-", t1, &base);
 156                         update_tree_entry(t1);
 157                         continue;
 158                 }
 159                 switch (compare_tree_entry(t1, t2, &base, opt)) {
 160                 case -1:
 161                         update_tree_entry(t1);
 162                         continue;
 163                 case 0:
 164                         update_tree_entry(t1);
 165                         /* Fallthrough */
 166                 case 1:
 167                         update_tree_entry(t2);
 168                         continue;
 169                 }
 170                 die("git diff-tree: internal error");
 171         }
 172
 173         strbuf_release(&base);
 174         return 0;
 175 }
 176
 177 /*
 178  * Does it look like the resulting diff might be due to a rename?
 179  *  - single entry
 180  *  - not a valid previous file
 181  */
 182 static inline int diff_might_be_rename(void)
 183 {
 184         return diff_queued_diff.nr == 1 &&
 185                 !DIFF_FILE_VALID(diff_queued_diff.queue[0]->one);
 186 }
 187
 188 static void try_to_follow_renames(struct tree_desc *t1, struct tree_desc *t2, const char *base, struct diff_options *opt)
 189 {
 190         struct diff_options diff_opts;
 191         struct diff_queue_struct *q = &diff_queued_diff;
 192         struct diff_filepair *choice;
 193         int i;
 194
 195         /*
 196          * follow-rename code is very specific, we need exactly one
 197          * path. Magic that matches more than one path is not
 198          * supported.
 199          */
 200         GUARD_PATHSPEC(&opt->pathspec, PATHSPEC_FROMTOP | PATHSPEC_LITERAL);
 201 #if 0
 202         /*
 203          * We should reject wildcards as well. Unfortunately we
 204          * haven't got a reliable way to detect that 'foo\*bar' in
 205          * fact has no wildcards. nowildcard_len is merely a hint for
 206          * optimization. Let it slip for now until wildmatch is taught
 207          * about dry-run mode and returns wildcard info.
 208          */
 209         if (opt->pathspec.has_wildcard)
 210                 die("BUG:%s:%d: wildcards are not supported",
 211                     __FILE__, __LINE__);
 212 #endif
 213
 214         /* Remove the file creation entry from the diff queue, and remember it */
 215         choice = q->queue[0];
 216         q->nr = 0;
 217
 218         diff_setup(&diff_opts);
 219         DIFF_OPT_SET(&diff_opts, RECURSIVE);
 220         DIFF_OPT_SET(&diff_opts, FIND_COPIES_HARDER);
 221         diff_opts.output_format = DIFF_FORMAT_NO_OUTPUT;
 222         diff_opts.single_follow = opt->pathspec.items[0].match;
 223         diff_opts.break_opt = opt->break_opt;
 224         diff_opts.rename_score = opt->rename_score;
 225         diff_setup_done(&diff_opts);
 226         diff_tree(t1, t2, base, &diff_opts);
 227         diffcore_std(&diff_opts);
 228         free_pathspec(&diff_opts.pathspec);
 229
 230         /* Go through the new set of filepairing, and see if we find a more interesting one */
 231         opt->found_follow = 0;
 232         for (i = 0; i < q->nr; i++) {
 233                 struct diff_filepair *p = q->queue[i];
 234
 235                 /*
 236                  * Found a source? Not only do we use that for the new
 237                  * diff_queued_diff, we will also use that as the path in
 238                  * the future!
 239                  */
 240                 if ((p->status == 'R' || p->status == 'C') &&
 241                     !strcmp(p->two->path, opt->pathspec.items[0].match)) {
 242                         const char *path[2];
 243
 244                         /* Switch the file-pairs around */
 245                         q->queue[i] = choice;
 246                         choice = p;
 247
 248                         /* Update the path we use from now on.. */
 249                         path[0] = p->one->path;
 250                         path[1] = NULL;
 251                         free_pathspec(&opt->pathspec);
 252                         parse_pathspec(&opt->pathspec,
 253                                        PATHSPEC_ALL_MAGIC & ~PATHSPEC_LITERAL,
 254                                        PATHSPEC_LITERAL_PATH, "", path);
 255
 256                         /*
 257                          * The caller expects us to return a set of vanilla
 258                          * filepairs to let a later call to diffcore_std()
 259                          * it makes to sort the renames out (among other
 260                          * things), but we already have found renames
 261                          * ourselves; signal diffcore_std() not to muck with
 262                          * rename information.
 263                          */
 264                         opt->found_follow = 1;
 265                         break;
 266                 }
 267         }
 268
 269         /*
 270          * Then, discard all the non-relevant file pairs...
 271          */
 272         for (i = 0; i < q->nr; i++) {
 273                 struct diff_filepair *p = q->queue[i];
 274                 diff_free_filepair(p);
 275         }
 276
 277         /*
 278          * .. and re-instate the one we want (which might be either the
 279          * original one, or the rename/copy we found)
 280          */
 281         q->queue[0] = choice;
 282         q->nr = 1;
 283 }
 284
 285 int diff_tree_sha1(const unsigned char *old, const unsigned char *new, const char *base, struct diff_options *opt)
 286 {
 287         void *tree1, *tree2;
 288         struct tree_desc t1, t2;
 289         unsigned long size1, size2;
 290         int retval;
 291
 292         tree1 = fill_tree_descriptor(&t1, old);
 293         tree2 = fill_tree_descriptor(&t2, new);
 294         size1 = t1.size;
 295         size2 = t2.size;
 296         retval = diff_tree(&t1, &t2, base, opt);
 297         if (!*base && DIFF_OPT_TST(opt, FOLLOW_RENAMES) && diff_might_be_rename()) {
 298                 init_tree_desc(&t1, tree1, size1);
 299                 init_tree_desc(&t2, tree2, size2);
 300                 try_to_follow_renames(&t1, &t2, base, opt);
 301         }
 302         free(tree1);
 303         free(tree2);
 304         return retval;
 305 }
 306
 307 int diff_root_tree_sha1(const unsigned char *new, const char *base, struct diff_options *opt)
 308 {
 309         return diff_tree_sha1(NULL, new, base, opt);
 310 }