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(path1, sha1);
  25         pathlen2 = tree_entry_len(path2, sha2);
  26         cmp = base_name_compare(path1, pathlen1, mode1, path2, pathlen2, mode2);
  27         if (cmp < 0) {
  28                 show_entry(opt, "-", t1, base);
  29                 return -1;
  30         }
  31         if (cmp > 0) {
  32                 show_entry(opt, "+", t2, base);
  33                 return 1;
  34         }
  35         if (!DIFF_OPT_TST(opt, FIND_COPIES_HARDER) && !hashcmp(sha1, sha2) && mode1 == mode2)
  36                 return 0;
  37
  38         /*
  39          * If the filemode has changed to/from a directory from/to a regular
  40          * file, we need to consider it a remove and an add.
  41          */
  42         if (S_ISDIR(mode1) != S_ISDIR(mode2)) {
  43                 show_entry(opt, "-", t1, base);
  44                 show_entry(opt, "+", t2, base);
  45                 return 0;
  46         }
  47
  48         strbuf_add(base, path1, pathlen1);
  49         if (DIFF_OPT_TST(opt, RECURSIVE) && S_ISDIR(mode1)) {
  50                 if (DIFF_OPT_TST(opt, TREE_IN_RECURSIVE)) {
  51                         opt->change(opt, mode1, mode2,
  52                                     sha1, sha2, base->buf, 0, 0);
  53                 }
  54                 strbuf_addch(base, '/');
  55                 diff_tree_sha1(sha1, sha2, base->buf, opt);
  56         } else {
  57                 opt->change(opt, mode1, mode2, sha1, sha2, base->buf, 0, 0);
  58         }
  59         strbuf_setlen(base, old_baselen);
  60         return 0;
  61 }
  62
  63 /* A whole sub-tree went away or appeared */
  64 static void show_tree(struct diff_options *opt, const char *prefix,
  65                       struct tree_desc *desc, struct strbuf *base)
  66 {
  67         int all_interesting = 0;
  68         while (desc->size) {
  69                 int show;
  70
  71                 if (all_interesting)
  72                         show = 1;
  73                 else {
  74                         show = tree_entry_interesting(&desc->entry, base, 0,
  75                                                       &opt->pathspec);
  76                         if (show == 2)
  77                                 all_interesting = 1;
  78                 }
  79                 if (show < 0)
  80                         break;
  81                 if (show)
  82                         show_entry(opt, prefix, desc, base);
  83                 update_tree_entry(desc);
  84         }
  85 }
  86
  87 /* A file entry went away or appeared */
  88 static void show_entry(struct diff_options *opt, const char *prefix,
  89                        struct tree_desc *desc, struct strbuf *base)
  90 {
  91         unsigned mode;
  92         const char *path;
  93         const unsigned char *sha1 = tree_entry_extract(desc, &path, &mode);
  94         int pathlen = tree_entry_len(path, sha1);
  95         int old_baselen = base->len;
  96
  97         strbuf_add(base, path, pathlen);
  98         if (DIFF_OPT_TST(opt, RECURSIVE) && S_ISDIR(mode)) {
  99                 enum object_type type;
 100                 struct tree_desc inner;
 101                 void *tree;
 102                 unsigned long size;
 103
 104                 tree = read_sha1_file(sha1, &type, &size);
 105                 if (!tree || type != OBJ_TREE)
 106                         die("corrupt tree sha %s", sha1_to_hex(sha1));
 107
 108                 if (DIFF_OPT_TST(opt, TREE_IN_RECURSIVE))
 109                         opt->add_remove(opt, *prefix, mode, sha1, base->buf, 0);
 110
 111                 strbuf_addch(base, '/');
 112
 113                 init_tree_desc(&inner, tree, size);
 114                 show_tree(opt, prefix, &inner, base);
 115                 free(tree);
 116         } else
 117                 opt->add_remove(opt, prefix[0], mode, sha1, base->buf, 0);
 118
 119         strbuf_setlen(base, old_baselen);
 120 }
 121
 122 static void skip_uninteresting(struct tree_desc *t, struct strbuf *base,
 123                                struct diff_options *opt, int *all_interesting)
 124 {
 125         while (t->size) {
 126                 int show = tree_entry_interesting(&t->entry, base, 0, &opt->pathspec);
 127                 if (show == 2)
 128                         *all_interesting = 1;
 129                 if (!show) {
 130                         update_tree_entry(t);
 131                         continue;
 132                 }
 133                 /* Skip it all? */
 134                 if (show < 0)
 135                         t->size = 0;
 136                 return;
 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         int all_t1_interesting = 0;
 146         int all_t2_interesting = 0;
 147
 148         /* Enable recursion indefinitely */
 149         opt->pathspec.recursive = DIFF_OPT_TST(opt, RECURSIVE);
 150         opt->pathspec.max_depth = -1;
 151
 152         strbuf_init(&base, PATH_MAX);
 153         strbuf_add(&base, base_str, baselen);
 154
 155         for (;;) {
 156                 if (DIFF_OPT_TST(opt, QUICK) &&
 157                     DIFF_OPT_TST(opt, HAS_CHANGES))
 158                         break;
 159                 if (opt->pathspec.nr) {
 160                         if (!all_t1_interesting)
 161                                 skip_uninteresting(t1, &base, opt, &all_t1_interesting);
 162                         if (!all_t2_interesting)
 163                                 skip_uninteresting(t2, &base, opt, &all_t2_interesting);
 164                 }
 165                 if (!t1->size) {
 166                         if (!t2->size)
 167                                 break;
 168                         show_entry(opt, "+", t2, &base);
 169                         update_tree_entry(t2);
 170                         continue;
 171                 }
 172                 if (!t2->size) {
 173                         show_entry(opt, "-", t1, &base);
 174                         update_tree_entry(t1);
 175                         continue;
 176                 }
 177                 switch (compare_tree_entry(t1, t2, &base, opt)) {
 178                 case -1:
 179                         update_tree_entry(t1);
 180                         continue;
 181                 case 0:
 182                         update_tree_entry(t1);
 183                         /* Fallthrough */
 184                 case 1:
 185                         update_tree_entry(t2);
 186                         continue;
 187                 }
 188                 die("git diff-tree: internal error");
 189         }
 190
 191         strbuf_release(&base);
 192         return 0;
 193 }
 194
 195 /*
 196  * Does it look like the resulting diff might be due to a rename?
 197  *  - single entry
 198  *  - not a valid previous file
 199  */
 200 static inline int diff_might_be_rename(void)
 201 {
 202         return diff_queued_diff.nr == 1 &&
 203                 !DIFF_FILE_VALID(diff_queued_diff.queue[0]->one);
 204 }
 205
 206 static void try_to_follow_renames(struct tree_desc *t1, struct tree_desc *t2, const char *base, struct diff_options *opt)
 207 {
 208         struct diff_options diff_opts;
 209         struct diff_queue_struct *q = &diff_queued_diff;
 210         struct diff_filepair *choice;
 211         const char *paths[1];
 212         int i;
 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.raw[0];
 223         diff_opts.break_opt = opt->break_opt;
 224         paths[0] = NULL;
 225         diff_tree_setup_paths(paths, &diff_opts);
 226         if (diff_setup_done(&diff_opts) < 0)
 227                 die("unable to set up diff options to follow renames");
 228         diff_tree(t1, t2, base, &diff_opts);
 229         diffcore_std(&diff_opts);
 230         diff_tree_release_paths(&diff_opts);
 231
 232         /* Go through the new set of filepairing, and see if we find a more interesting one */
 233         opt->found_follow = 0;
 234         for (i = 0; i < q->nr; i++) {
 235                 struct diff_filepair *p = q->queue[i];
 236
 237                 /*
 238                  * Found a source? Not only do we use that for the new
 239                  * diff_queued_diff, we will also use that as the path in
 240                  * the future!
 241                  */
 242                 if ((p->status == 'R' || p->status == 'C') &&
 243                     !strcmp(p->two->path, opt->pathspec.raw[0])) {
 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                         diff_tree_release_paths(opt);
 250                         opt->pathspec.raw[0] = xstrdup(p->one->path);
 251                         diff_tree_setup_paths(opt->pathspec.raw, opt);
 252
 253                         /*
 254                          * The caller expects us to return a set of vanilla
 255                          * filepairs to let a later call to diffcore_std()
 256                          * it makes to sort the renames out (among other
 257                          * things), but we already have found renames
 258                          * ourselves; signal diffcore_std() not to muck with
 259                          * rename information.
 260                          */
 261                         opt->found_follow = 1;
 262                         break;
 263                 }
 264         }
 265
 266         /*
 267          * Then, discard all the non-relevant file pairs...
 268          */
 269         for (i = 0; i < q->nr; i++) {
 270                 struct diff_filepair *p = q->queue[i];
 271                 diff_free_filepair(p);
 272         }
 273
 274         /*
 275          * .. and re-instate the one we want (which might be either the
 276          * original one, or the rename/copy we found)
 277          */
 278         q->queue[0] = choice;
 279         q->nr = 1;
 280 }
 281
 282 int diff_tree_sha1(const unsigned char *old, const unsigned char *new, const char *base, struct diff_options *opt)
 283 {
 284         void *tree1, *tree2;
 285         struct tree_desc t1, t2;
 286         unsigned long size1, size2;
 287         int retval;
 288
 289         tree1 = read_object_with_reference(old, tree_type, &size1, NULL);
 290         if (!tree1)
 291                 die("unable to read source tree (%s)", sha1_to_hex(old));
 292         tree2 = read_object_with_reference(new, tree_type, &size2, NULL);
 293         if (!tree2)
 294                 die("unable to read destination tree (%s)", sha1_to_hex(new));
 295         init_tree_desc(&t1, tree1, size1);
 296         init_tree_desc(&t2, tree2, size2);
 297         retval = diff_tree(&t1, &t2, base, opt);
 298         if (!*base && DIFF_OPT_TST(opt, FOLLOW_RENAMES) && diff_might_be_rename()) {
 299                 init_tree_desc(&t1, tree1, size1);
 300                 init_tree_desc(&t2, tree2, size2);
 301                 try_to_follow_renames(&t1, &t2, base, opt);
 302         }
 303         free(tree1);
 304         free(tree2);
 305         return retval;
 306 }
 307
 308 int diff_root_tree_sha1(const unsigned char *new, const char *base, struct diff_options *opt)
 309 {
 310         int retval;
 311         void *tree;
 312         unsigned long size;
 313         struct tree_desc empty, real;
 314
 315         tree = read_object_with_reference(new, tree_type, &size, NULL);
 316         if (!tree)
 317                 die("unable to read root tree (%s)", sha1_to_hex(new));
 318         init_tree_desc(&real, tree, size);
 319
 320         init_tree_desc(&empty, "", 0);
 321         retval = diff_tree(&empty, &real, base, opt);
 322         free(tree);
 323         return retval;
 324 }
 325
 326 void diff_tree_release_paths(struct diff_options *opt)
 327 {
 328         free_pathspec(&opt->pathspec);
 329 }
 330
 331 void diff_tree_setup_paths(const char **p, struct diff_options *opt)
 332 {
 333         init_pathspec(&opt->pathspec, p);
 334 }