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 char *malloc_base(const char *base, int baselen, const char *path, int pathlen)
  10 {
  11         char *newbase = xmalloc(baselen + pathlen + 2);
  12         memcpy(newbase, base, baselen);
  13         memcpy(newbase + baselen, path, pathlen);
  14         memcpy(newbase + baselen + pathlen, "/", 2);
  15         return newbase;
  16 }
  17
  18 static char *malloc_fullname(const char *base, int baselen, const char *path, int pathlen)
  19 {
  20         char *fullname = xmalloc(baselen + pathlen + 1);
  21         memcpy(fullname, base, baselen);
  22         memcpy(fullname + baselen, path, pathlen);
  23         fullname[baselen + pathlen] = 0;
  24         return fullname;
  25 }
  26
  27 static void show_entry(struct diff_options *opt, const char *prefix, struct tree_desc *desc,
  28                        const char *base, int baselen);
  29
  30 static int compare_tree_entry(struct tree_desc *t1, struct tree_desc *t2, const char *base, int baselen, struct diff_options *opt)
  31 {
  32         unsigned mode1, mode2;
  33         const char *path1, *path2;
  34         const unsigned char *sha1, *sha2;
  35         int cmp, pathlen1, pathlen2;
  36         char *fullname;
  37
  38         sha1 = tree_entry_extract(t1, &path1, &mode1);
  39         sha2 = tree_entry_extract(t2, &path2, &mode2);
  40
  41         pathlen1 = tree_entry_len(path1, sha1);
  42         pathlen2 = tree_entry_len(path2, sha2);
  43         cmp = base_name_compare(path1, pathlen1, mode1, path2, pathlen2, mode2);
  44         if (cmp < 0) {
  45                 show_entry(opt, "-", t1, base, baselen);
  46                 return -1;
  47         }
  48         if (cmp > 0) {
  49                 show_entry(opt, "+", t2, base, baselen);
  50                 return 1;
  51         }
  52         if (!DIFF_OPT_TST(opt, FIND_COPIES_HARDER) && !hashcmp(sha1, sha2) && mode1 == mode2)
  53                 return 0;
  54
  55         /*
  56          * If the filemode has changed to/from a directory from/to a regular
  57          * file, we need to consider it a remove and an add.
  58          */
  59         if (S_ISDIR(mode1) != S_ISDIR(mode2)) {
  60                 show_entry(opt, "-", t1, base, baselen);
  61                 show_entry(opt, "+", t2, base, baselen);
  62                 return 0;
  63         }
  64
  65         if (DIFF_OPT_TST(opt, RECURSIVE) && S_ISDIR(mode1)) {
  66                 int retval;
  67                 char *newbase = malloc_base(base, baselen, path1, pathlen1);
  68                 if (DIFF_OPT_TST(opt, TREE_IN_RECURSIVE)) {
  69                         newbase[baselen + pathlen1] = 0;
  70                         opt->change(opt, mode1, mode2,
  71                                     sha1, sha2, newbase, 0, 0);
  72                         newbase[baselen + pathlen1] = '/';
  73                 }
  74                 retval = diff_tree_sha1(sha1, sha2, newbase, opt);
  75                 free(newbase);
  76                 return retval;
  77         }
  78
  79         fullname = malloc_fullname(base, baselen, path1, pathlen1);
  80         opt->change(opt, mode1, mode2, sha1, sha2, fullname, 0, 0);
  81         free(fullname);
  82         return 0;
  83 }
  84
  85 /* A whole sub-tree went away or appeared */
  86 static void show_tree(struct diff_options *opt, const char *prefix, struct tree_desc *desc, const char *base, int baselen)
  87 {
  88         int all_interesting = 0;
  89         while (desc->size) {
  90                 int show;
  91
  92                 if (all_interesting)
  93                         show = 1;
  94                 else {
  95                         show = tree_entry_interesting(&desc->entry, base, baselen, &opt->pathspec);
  96                         if (show == 2)
  97                                 all_interesting = 1;
  98                 }
  99                 if (show < 0)
 100                         break;
 101                 if (show)
 102                         show_entry(opt, prefix, desc, base, baselen);
 103                 update_tree_entry(desc);
 104         }
 105 }
 106
 107 /* A file entry went away or appeared */
 108 static void show_entry(struct diff_options *opt, const char *prefix, struct tree_desc *desc,
 109                        const char *base, int baselen)
 110 {
 111         unsigned mode;
 112         const char *path;
 113         const unsigned char *sha1 = tree_entry_extract(desc, &path, &mode);
 114         int pathlen = tree_entry_len(path, sha1);
 115
 116         if (DIFF_OPT_TST(opt, RECURSIVE) && S_ISDIR(mode)) {
 117                 enum object_type type;
 118                 char *newbase = malloc_base(base, baselen, path, pathlen);
 119                 struct tree_desc inner;
 120                 void *tree;
 121                 unsigned long size;
 122
 123                 tree = read_sha1_file(sha1, &type, &size);
 124                 if (!tree || type != OBJ_TREE)
 125                         die("corrupt tree sha %s", sha1_to_hex(sha1));
 126
 127                 if (DIFF_OPT_TST(opt, TREE_IN_RECURSIVE)) {
 128                         newbase[baselen + pathlen] = 0;
 129                         opt->add_remove(opt, *prefix, mode, sha1, newbase, 0);
 130                         newbase[baselen + pathlen] = '/';
 131                 }
 132
 133                 init_tree_desc(&inner, tree, size);
 134                 show_tree(opt, prefix, &inner, newbase, baselen + 1 + pathlen);
 135
 136                 free(tree);
 137                 free(newbase);
 138         } else {
 139                 char *fullname = malloc_fullname(base, baselen, path, pathlen);
 140                 opt->add_remove(opt, prefix[0], mode, sha1, fullname, 0);
 141                 free(fullname);
 142         }
 143 }
 144
 145 static void skip_uninteresting(struct tree_desc *t, const char *base, int baselen, struct diff_options *opt, int *all_interesting)
 146 {
 147         while (t->size) {
 148                 int show = tree_entry_interesting(&t->entry, base, baselen, &opt->pathspec);
 149                 if (show == 2)
 150                         *all_interesting = 1;
 151                 if (!show) {
 152                         update_tree_entry(t);
 153                         continue;
 154                 }
 155                 /* Skip it all? */
 156                 if (show < 0)
 157                         t->size = 0;
 158                 return;
 159         }
 160 }
 161
 162 int diff_tree(struct tree_desc *t1, struct tree_desc *t2, const char *base, struct diff_options *opt)
 163 {
 164         int baselen = strlen(base);
 165         int all_t1_interesting = 0;
 166         int all_t2_interesting = 0;
 167
 168         for (;;) {
 169                 if (DIFF_OPT_TST(opt, QUICK) &&
 170                     DIFF_OPT_TST(opt, HAS_CHANGES))
 171                         break;
 172                 if (opt->pathspec.nr) {
 173                         if (!all_t1_interesting)
 174                                 skip_uninteresting(t1, base, baselen, opt,
 175                                                    &all_t1_interesting);
 176                         if (!all_t2_interesting)
 177                                 skip_uninteresting(t2, base, baselen, opt,
 178                                                    &all_t2_interesting);
 179                 }
 180                 if (!t1->size) {
 181                         if (!t2->size)
 182                                 break;
 183                         show_entry(opt, "+", t2, base, baselen);
 184                         update_tree_entry(t2);
 185                         continue;
 186                 }
 187                 if (!t2->size) {
 188                         show_entry(opt, "-", t1, base, baselen);
 189                         update_tree_entry(t1);
 190                         continue;
 191                 }
 192                 switch (compare_tree_entry(t1, t2, base, baselen, opt)) {
 193                 case -1:
 194                         update_tree_entry(t1);
 195                         continue;
 196                 case 0:
 197                         update_tree_entry(t1);
 198                         /* Fallthrough */
 199                 case 1:
 200                         update_tree_entry(t2);
 201                         continue;
 202                 }
 203                 die("git diff-tree: internal error");
 204         }
 205         return 0;
 206 }
 207
 208 /*
 209  * Does it look like the resulting diff might be due to a rename?
 210  *  - single entry
 211  *  - not a valid previous file
 212  */
 213 static inline int diff_might_be_rename(void)
 214 {
 215         return diff_queued_diff.nr == 1 &&
 216                 !DIFF_FILE_VALID(diff_queued_diff.queue[0]->one);
 217 }
 218
 219 static void try_to_follow_renames(struct tree_desc *t1, struct tree_desc *t2, const char *base, struct diff_options *opt)
 220 {
 221         struct diff_options diff_opts;
 222         struct diff_queue_struct *q = &diff_queued_diff;
 223         struct diff_filepair *choice;
 224         const char *paths[1];
 225         int i;
 226
 227         /* Remove the file creation entry from the diff queue, and remember it */
 228         choice = q->queue[0];
 229         q->nr = 0;
 230
 231         diff_setup(&diff_opts);
 232         DIFF_OPT_SET(&diff_opts, RECURSIVE);
 233         DIFF_OPT_SET(&diff_opts, FIND_COPIES_HARDER);
 234         diff_opts.output_format = DIFF_FORMAT_NO_OUTPUT;
 235         diff_opts.single_follow = opt->pathspec.raw[0];
 236         diff_opts.break_opt = opt->break_opt;
 237         paths[0] = NULL;
 238         diff_tree_setup_paths(paths, &diff_opts);
 239         if (diff_setup_done(&diff_opts) < 0)
 240                 die("unable to set up diff options to follow renames");
 241         diff_tree(t1, t2, base, &diff_opts);
 242         diffcore_std(&diff_opts);
 243         diff_tree_release_paths(&diff_opts);
 244
 245         /* Go through the new set of filepairing, and see if we find a more interesting one */
 246         opt->found_follow = 0;
 247         for (i = 0; i < q->nr; i++) {
 248                 struct diff_filepair *p = q->queue[i];
 249
 250                 /*
 251                  * Found a source? Not only do we use that for the new
 252                  * diff_queued_diff, we will also use that as the path in
 253                  * the future!
 254                  */
 255                 if ((p->status == 'R' || p->status == 'C') &&
 256                     !strcmp(p->two->path, opt->pathspec.raw[0])) {
 257                         /* Switch the file-pairs around */
 258                         q->queue[i] = choice;
 259                         choice = p;
 260
 261                         /* Update the path we use from now on.. */
 262                         diff_tree_release_paths(opt);
 263                         opt->pathspec.raw[0] = xstrdup(p->one->path);
 264                         diff_tree_setup_paths(opt->pathspec.raw, opt);
 265
 266                         /*
 267                          * The caller expects us to return a set of vanilla
 268                          * filepairs to let a later call to diffcore_std()
 269                          * it makes to sort the renames out (among other
 270                          * things), but we already have found renames
 271                          * ourselves; signal diffcore_std() not to muck with
 272                          * rename information.
 273                          */
 274                         opt->found_follow = 1;
 275                         break;
 276                 }
 277         }
 278
 279         /*
 280          * Then, discard all the non-relevant file pairs...
 281          */
 282         for (i = 0; i < q->nr; i++) {
 283                 struct diff_filepair *p = q->queue[i];
 284                 diff_free_filepair(p);
 285         }
 286
 287         /*
 288          * .. and re-instate the one we want (which might be either the
 289          * original one, or the rename/copy we found)
 290          */
 291         q->queue[0] = choice;
 292         q->nr = 1;
 293 }
 294
 295 int diff_tree_sha1(const unsigned char *old, const unsigned char *new, const char *base, struct diff_options *opt)
 296 {
 297         void *tree1, *tree2;
 298         struct tree_desc t1, t2;
 299         unsigned long size1, size2;
 300         int retval;
 301
 302         tree1 = read_object_with_reference(old, tree_type, &size1, NULL);
 303         if (!tree1)
 304                 die("unable to read source tree (%s)", sha1_to_hex(old));
 305         tree2 = read_object_with_reference(new, tree_type, &size2, NULL);
 306         if (!tree2)
 307                 die("unable to read destination tree (%s)", sha1_to_hex(new));
 308         init_tree_desc(&t1, tree1, size1);
 309         init_tree_desc(&t2, tree2, size2);
 310         retval = diff_tree(&t1, &t2, base, opt);
 311         if (!*base && DIFF_OPT_TST(opt, FOLLOW_RENAMES) && diff_might_be_rename()) {
 312                 init_tree_desc(&t1, tree1, size1);
 313                 init_tree_desc(&t2, tree2, size2);
 314                 try_to_follow_renames(&t1, &t2, base, opt);
 315         }
 316         free(tree1);
 317         free(tree2);
 318         return retval;
 319 }
 320
 321 int diff_root_tree_sha1(const unsigned char *new, const char *base, struct diff_options *opt)
 322 {
 323         int retval;
 324         void *tree;
 325         unsigned long size;
 326         struct tree_desc empty, real;
 327
 328         tree = read_object_with_reference(new, tree_type, &size, NULL);
 329         if (!tree)
 330                 die("unable to read root tree (%s)", sha1_to_hex(new));
 331         init_tree_desc(&real, tree, size);
 332
 333         init_tree_desc(&empty, "", 0);
 334         retval = diff_tree(&empty, &real, base, opt);
 335         free(tree);
 336         return retval;
 337 }
 338
 339 void diff_tree_release_paths(struct diff_options *opt)
 340 {
 341         free_pathspec(&opt->pathspec);
 342 }
 343
 344 void diff_tree_setup_paths(const char **p, struct diff_options *opt)
 345 {
 346         init_pathspec(&opt->pathspec, p);
 347 }