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         int retval = 0;
  21
  22         sha1 = tree_entry_extract(t1, &path1, &mode1);
  23         sha2 = tree_entry_extract(t2, &path2, &mode2);
  24
  25         pathlen1 = tree_entry_len(path1, sha1);
  26         pathlen2 = tree_entry_len(path2, sha2);
  27         cmp = base_name_compare(path1, pathlen1, mode1, path2, pathlen2, mode2);
  28         if (cmp < 0) {
  29                 show_entry(opt, "-", t1, base);
  30                 return -1;
  31         }
  32         if (cmp > 0) {
  33                 show_entry(opt, "+", t2, base);
  34                 return 1;
  35         }
  36         if (!DIFF_OPT_TST(opt, FIND_COPIES_HARDER) && !hashcmp(sha1, sha2) && mode1 == mode2)
  37                 return 0;
  38
  39         /*
  40          * If the filemode has changed to/from a directory from/to a regular
  41          * file, we need to consider it a remove and an add.
  42          */
  43         if (S_ISDIR(mode1) != S_ISDIR(mode2)) {
  44                 show_entry(opt, "-", t1, base);
  45                 show_entry(opt, "+", t2, base);
  46                 return 0;
  47         }
  48
  49         strbuf_add(base, path1, pathlen1);
  50         if (DIFF_OPT_TST(opt, RECURSIVE) && S_ISDIR(mode1)) {
  51                 if (DIFF_OPT_TST(opt, TREE_IN_RECURSIVE)) {
  52                         opt->change(opt, mode1, mode2,
  53                                     sha1, sha2, base->buf, 0, 0);
  54                 }
  55                 strbuf_addch(base, '/');
  56                 retval = diff_tree_sha1(sha1, sha2, base->buf, opt);
  57         } else {
  58                 opt->change(opt, mode1, mode2, sha1, sha2, base->buf, 0, 0);
  59         }
  60         strbuf_setlen(base, old_baselen);
  61         return 0;
  62 }
  63
  64 /* A whole sub-tree went away or appeared */
  65 static void show_tree(struct diff_options *opt, const char *prefix,
  66                       struct tree_desc *desc, struct strbuf *base)
  67 {
  68         int match = 0;
  69         for (; desc->size; update_tree_entry(desc)) {
  70                 if (match != 2) {
  71                         match = tree_entry_interesting(&desc->entry, base, 0,
  72                                                        &opt->pathspec);
  73                         if (match < 0)
  74                                 break;
  75                         if (match == 0)
  76                                 continue;
  77                 }
  78                 show_entry(opt, prefix, desc, base);
  79         }
  80 }
  81
  82 /* A file entry went away or appeared */
  83 static void show_entry(struct diff_options *opt, const char *prefix,
  84                        struct tree_desc *desc, struct strbuf *base)
  85 {
  86         unsigned mode;
  87         const char *path;
  88         const unsigned char *sha1 = tree_entry_extract(desc, &path, &mode);
  89         int pathlen = tree_entry_len(path, sha1);
  90         int old_baselen = base->len;
  91
  92         strbuf_add(base, path, pathlen);
  93         if (DIFF_OPT_TST(opt, RECURSIVE) && S_ISDIR(mode)) {
  94                 enum object_type type;
  95                 struct tree_desc inner;
  96                 void *tree;
  97                 unsigned long size;
  98
  99                 tree = read_sha1_file(sha1, &type, &size);
 100                 if (!tree || type != OBJ_TREE)
 101                         die("corrupt tree sha %s", sha1_to_hex(sha1));
 102
 103                 if (DIFF_OPT_TST(opt, TREE_IN_RECURSIVE))
 104                         opt->add_remove(opt, *prefix, mode, sha1, base->buf, 0);
 105
 106                 strbuf_addch(base, '/');
 107
 108                 init_tree_desc(&inner, tree, size);
 109                 show_tree(opt, prefix, &inner, base);
 110                 free(tree);
 111         } else
 112                 opt->add_remove(opt, prefix[0], mode, sha1, base->buf, 0);
 113
 114         strbuf_setlen(base, old_baselen);
 115 }
 116
 117 static void skip_uninteresting(struct tree_desc *t, struct strbuf *base,
 118                                struct diff_options *opt, int *match)
 119 {
 120         while (t->size) {
 121                 *match = tree_entry_interesting(&t->entry, base, 0, &opt->pathspec);
 122                 if (*match) {
 123                         if (*match < 0)
 124                                 t->size = 0;
 125                         break;
 126                 }
 127                 update_tree_entry(t);
 128         }
 129 }
 130
 131 int diff_tree(struct tree_desc *t1, struct tree_desc *t2,
 132               const char *base_str, struct diff_options *opt)
 133 {
 134         struct strbuf base;
 135         int baselen = strlen(base_str);
 136         int t1_match = 0, t2_match = 0;
 137
 138         /* Enable recursion indefinitely */
 139         opt->pathspec.recursive = DIFF_OPT_TST(opt, RECURSIVE);
 140         opt->pathspec.max_depth = -1;
 141
 142         strbuf_init(&base, PATH_MAX);
 143         strbuf_add(&base, base_str, baselen);
 144
 145         for (;;) {
 146                 if (DIFF_OPT_TST(opt, QUICK) &&
 147                     DIFF_OPT_TST(opt, HAS_CHANGES))
 148                         break;
 149                 if (opt->pathspec.nr) {
 150                         skip_uninteresting(t1, &base, opt, &t1_match);
 151                         skip_uninteresting(t2, &base, opt, &t2_match);
 152                 }
 153                 if (!t1->size) {
 154                         if (!t2->size)
 155                                 break;
 156                         show_entry(opt, "+", t2, &base);
 157                         update_tree_entry(t2);
 158                         continue;
 159                 }
 160                 if (!t2->size) {
 161                         show_entry(opt, "-", t1, &base);
 162                         update_tree_entry(t1);
 163                         continue;
 164                 }
 165                 switch (compare_tree_entry(t1, t2, &base, opt)) {
 166                 case -1:
 167                         update_tree_entry(t1);
 168                         continue;
 169                 case 0:
 170                         update_tree_entry(t1);
 171                         /* Fallthrough */
 172                 case 1:
 173                         update_tree_entry(t2);
 174                         continue;
 175                 }
 176                 die("git diff-tree: internal error");
 177         }
 178
 179         strbuf_release(&base);
 180         return 0;
 181 }
 182
 183 /*
 184  * Does it look like the resulting diff might be due to a rename?
 185  *  - single entry
 186  *  - not a valid previous file
 187  */
 188 static inline int diff_might_be_rename(void)
 189 {
 190         return diff_queued_diff.nr == 1 &&
 191                 !DIFF_FILE_VALID(diff_queued_diff.queue[0]->one);
 192 }
 193
 194 static void try_to_follow_renames(struct tree_desc *t1, struct tree_desc *t2, const char *base, struct diff_options *opt)
 195 {
 196         struct diff_options diff_opts;
 197         struct diff_queue_struct *q = &diff_queued_diff;
 198         struct diff_filepair *choice;
 199         const char *paths[1];
 200         int i;
 201
 202         /* Remove the file creation entry from the diff queue, and remember it */
 203         choice = q->queue[0];
 204         q->nr = 0;
 205
 206         diff_setup(&diff_opts);
 207         DIFF_OPT_SET(&diff_opts, RECURSIVE);
 208         DIFF_OPT_SET(&diff_opts, FIND_COPIES_HARDER);
 209         diff_opts.output_format = DIFF_FORMAT_NO_OUTPUT;
 210         diff_opts.single_follow = opt->pathspec.raw[0];
 211         diff_opts.break_opt = opt->break_opt;
 212         paths[0] = NULL;
 213         diff_tree_setup_paths(paths, &diff_opts);
 214         if (diff_setup_done(&diff_opts) < 0)
 215                 die("unable to set up diff options to follow renames");
 216         diff_tree(t1, t2, base, &diff_opts);
 217         diffcore_std(&diff_opts);
 218         diff_tree_release_paths(&diff_opts);
 219
 220         /* Go through the new set of filepairing, and see if we find a more interesting one */
 221         opt->found_follow = 0;
 222         for (i = 0; i < q->nr; i++) {
 223                 struct diff_filepair *p = q->queue[i];
 224
 225                 /*
 226                  * Found a source? Not only do we use that for the new
 227                  * diff_queued_diff, we will also use that as the path in
 228                  * the future!
 229                  */
 230                 if ((p->status == 'R' || p->status == 'C') &&
 231                     !strcmp(p->two->path, opt->pathspec.raw[0])) {
 232                         /* Switch the file-pairs around */
 233                         q->queue[i] = choice;
 234                         choice = p;
 235
 236                         /* Update the path we use from now on.. */
 237                         diff_tree_release_paths(opt);
 238                         opt->pathspec.raw[0] = xstrdup(p->one->path);
 239                         diff_tree_setup_paths(opt->pathspec.raw, opt);
 240
 241                         /*
 242                          * The caller expects us to return a set of vanilla
 243                          * filepairs to let a later call to diffcore_std()
 244                          * it makes to sort the renames out (among other
 245                          * things), but we already have found renames
 246                          * ourselves; signal diffcore_std() not to muck with
 247                          * rename information.
 248                          */
 249                         opt->found_follow = 1;
 250                         break;
 251                 }
 252         }
 253
 254         /*
 255          * Then, discard all the non-relevant file pairs...
 256          */
 257         for (i = 0; i < q->nr; i++) {
 258                 struct diff_filepair *p = q->queue[i];
 259                 diff_free_filepair(p);
 260         }
 261
 262         /*
 263          * .. and re-instate the one we want (which might be either the
 264          * original one, or the rename/copy we found)
 265          */
 266         q->queue[0] = choice;
 267         q->nr = 1;
 268 }
 269
 270 int diff_tree_sha1(const unsigned char *old, const unsigned char *new, const char *base, struct diff_options *opt)
 271 {
 272         void *tree1, *tree2;
 273         struct tree_desc t1, t2;
 274         unsigned long size1, size2;
 275         int retval;
 276
 277         tree1 = read_object_with_reference(old, tree_type, &size1, NULL);
 278         if (!tree1)
 279                 die("unable to read source tree (%s)", sha1_to_hex(old));
 280         tree2 = read_object_with_reference(new, tree_type, &size2, NULL);
 281         if (!tree2)
 282                 die("unable to read destination tree (%s)", sha1_to_hex(new));
 283         init_tree_desc(&t1, tree1, size1);
 284         init_tree_desc(&t2, tree2, size2);
 285         retval = diff_tree(&t1, &t2, base, opt);
 286         if (!*base && DIFF_OPT_TST(opt, FOLLOW_RENAMES) && diff_might_be_rename()) {
 287                 init_tree_desc(&t1, tree1, size1);
 288                 init_tree_desc(&t2, tree2, size2);
 289                 try_to_follow_renames(&t1, &t2, base, opt);
 290         }
 291         free(tree1);
 292         free(tree2);
 293         return retval;
 294 }
 295
 296 int diff_root_tree_sha1(const unsigned char *new, const char *base, struct diff_options *opt)
 297 {
 298         int retval;
 299         void *tree;
 300         unsigned long size;
 301         struct tree_desc empty, real;
 302
 303         tree = read_object_with_reference(new, tree_type, &size, NULL);
 304         if (!tree)
 305                 die("unable to read root tree (%s)", sha1_to_hex(new));
 306         init_tree_desc(&real, tree, size);
 307
 308         init_tree_desc(&empty, "", 0);
 309         retval = diff_tree(&empty, &real, base, opt);
 310         free(tree);
 311         return retval;
 312 }
 313
 314 void diff_tree_release_paths(struct diff_options *opt)
 315 {
 316         free_pathspec(&opt->pathspec);
 317 }
 318
 319 void diff_tree_setup_paths(const char **p, struct diff_options *opt)
 320 {
 321         init_pathspec(&opt->pathspec, p);
 322 }