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