tree-diff.c

   1 /*
   2  * Helper functions for tree diff generation
   3  */
   4 #include "cache.h"
   5 #include "diff.h"
   6 #include "tree.h"
   7
   8 static char *malloc_base(const char *base, int baselen, const char *path, int pathlen)
   9 {
  10         char *newbase = xmalloc(baselen + pathlen + 2);
  11         memcpy(newbase, base, baselen);
  12         memcpy(newbase + baselen, path, pathlen);
  13         memcpy(newbase + baselen + pathlen, "/", 2);
  14         return newbase;
  15 }
  16
  17 static void show_entry(struct diff_options *opt, const char *prefix, struct tree_desc *desc,
  18                        const char *base, int baselen);
  19
  20 static int compare_tree_entry(struct tree_desc *t1, struct tree_desc *t2, const char *base, int baselen, struct diff_options *opt)
  21 {
  22         unsigned mode1, mode2;
  23         const char *path1, *path2;
  24         const unsigned char *sha1, *sha2;
  25         int cmp, pathlen1, pathlen2;
  26
  27         sha1 = tree_entry_extract(t1, &path1, &mode1);
  28         sha2 = tree_entry_extract(t2, &path2, &mode2);
  29
  30         pathlen1 = tree_entry_len(path1, sha1);
  31         pathlen2 = tree_entry_len(path2, sha2);
  32         cmp = base_name_compare(path1, pathlen1, mode1, path2, pathlen2, mode2);
  33         if (cmp < 0) {
  34                 show_entry(opt, "-", t1, base, baselen);
  35                 return -1;
  36         }
  37         if (cmp > 0) {
  38                 show_entry(opt, "+", t2, base, baselen);
  39                 return 1;
  40         }
  41         if (!opt->find_copies_harder && !hashcmp(sha1, sha2) && mode1 == mode2)
  42                 return 0;
  43
  44         /*
  45          * If the filemode has changed to/from a directory from/to a regular
  46          * file, we need to consider it a remove and an add.
  47          */
  48         if (S_ISDIR(mode1) != S_ISDIR(mode2)) {
  49                 show_entry(opt, "-", t1, base, baselen);
  50                 show_entry(opt, "+", t2, base, baselen);
  51                 return 0;
  52         }
  53
  54         if (opt->recursive && S_ISDIR(mode1)) {
  55                 int retval;
  56                 char *newbase = malloc_base(base, baselen, path1, pathlen1);
  57                 if (opt->tree_in_recursive)
  58                         opt->change(opt, mode1, mode2,
  59                                     sha1, sha2, base, path1);
  60                 retval = diff_tree_sha1(sha1, sha2, newbase, opt);
  61                 free(newbase);
  62                 return retval;
  63         }
  64
  65         opt->change(opt, mode1, mode2, sha1, sha2, base, path1);
  66         return 0;
  67 }
  68
  69 /*
  70  * Is a tree entry interesting given the pathspec we have?
  71  *
  72  * Return:
  73  *  - 2 for "yes, and all subsequent entries will be"
  74  *  - 1 for yes
  75  *  - zero for no
  76  *  - negative for "no, and no subsequent entries will be either"
  77  */
  78 static int tree_entry_interesting(struct tree_desc *desc, const char *base, int baselen, struct diff_options *opt)
  79 {
  80         const char *path;
  81         const unsigned char *sha1;
  82         unsigned mode;
  83         int i;
  84         int pathlen;
  85         int never_interesting = -1;
  86
  87         if (!opt->nr_paths)
  88                 return 1;
  89
  90         sha1 = tree_entry_extract(desc, &path, &mode);
  91
  92         pathlen = tree_entry_len(path, sha1);
  93
  94         for (i = 0; i < opt->nr_paths; i++) {
  95                 const char *match = opt->paths[i];
  96                 int matchlen = opt->pathlens[i];
  97                 int m = -1; /* signals that we haven't called strncmp() */
  98
  99                 if (baselen >= matchlen) {
 100                         /* If it doesn't match, move along... */
 101                         if (strncmp(base, match, matchlen))
 102                                 continue;
 103
 104                         /*
 105                          * The base is a subdirectory of a path which
 106                          * was specified, so all of them are interesting.
 107                          */
 108                         return 2;
 109                 }
 110
 111                 /* Does the base match? */
 112                 if (strncmp(base, match, baselen))
 113                         continue;
 114
 115                 match += baselen;
 116                 matchlen -= baselen;
 117
 118                 if (never_interesting) {
 119                         /*
 120                          * We have not seen any match that sorts later
 121                          * than the current path.
 122                          */
 123
 124                         /*
 125                          * Does match sort strictly earlier than path
 126                          * with their common parts?
 127                          */
 128                         m = strncmp(match, path,
 129                                     (matchlen < pathlen) ? matchlen : pathlen);
 130                         if (m < 0)
 131                                 continue;
 132
 133                         /*
 134                          * If we come here even once, that means there is at
 135                          * least one pathspec that would sort equal to or
 136                          * later than the path we are currently looking at.
 137                          * In other words, if we have never reached this point
 138                          * after iterating all pathspecs, it means all
 139                          * pathspecs are either outside of base, or inside the
 140                          * base but sorts strictly earlier than the current
 141                          * one.  In either case, they will never match the
 142                          * subsequent entries.  In such a case, we initialized
 143                          * the variable to -1 and that is what will be
 144                          * returned, allowing the caller to terminate early.
 145                          */
 146                         never_interesting = 0;
 147                 }
 148
 149                 if (pathlen > matchlen)
 150                         continue;
 151
 152                 if (matchlen > pathlen) {
 153                         if (match[pathlen] != '/')
 154                                 continue;
 155                         if (!S_ISDIR(mode))
 156                                 continue;
 157                 }
 158
 159                 if (m == -1)
 160                         /*
 161                          * we cheated and did not do strncmp(), so we do
 162                          * that here.
 163                          */
 164                         m = strncmp(match, path, pathlen);
 165
 166                 /*
 167                  * If common part matched earlier then it is a hit,
 168                  * because we rejected the case where path is not a
 169                  * leading directory and is shorter than match.
 170                  */
 171                 if (!m)
 172                         return 1;
 173         }
 174         return never_interesting; /* No matches */
 175 }
 176
 177 /* A whole sub-tree went away or appeared */
 178 static void show_tree(struct diff_options *opt, const char *prefix, struct tree_desc *desc, const char *base, int baselen)
 179 {
 180         int all_interesting = 0;
 181         while (desc->size) {
 182                 int show;
 183
 184                 if (all_interesting)
 185                         show = 1;
 186                 else {
 187                         show = tree_entry_interesting(desc, base, baselen,
 188                                                       opt);
 189                         if (show == 2)
 190                                 all_interesting = 1;
 191                 }
 192                 if (show < 0)
 193                         break;
 194                 if (show)
 195                         show_entry(opt, prefix, desc, base, baselen);
 196                 update_tree_entry(desc);
 197         }
 198 }
 199
 200 /* A file entry went away or appeared */
 201 static void show_entry(struct diff_options *opt, const char *prefix, struct tree_desc *desc,
 202                        const char *base, int baselen)
 203 {
 204         unsigned mode;
 205         const char *path;
 206         const unsigned char *sha1 = tree_entry_extract(desc, &path, &mode);
 207
 208         if (opt->recursive && S_ISDIR(mode)) {
 209                 enum object_type type;
 210                 int pathlen = tree_entry_len(path, sha1);
 211                 char *newbase = malloc_base(base, baselen, path, pathlen);
 212                 struct tree_desc inner;
 213                 void *tree;
 214                 unsigned long size;
 215
 216                 tree = read_sha1_file(sha1, &type, &size);
 217                 if (!tree || type != OBJ_TREE)
 218                         die("corrupt tree sha %s", sha1_to_hex(sha1));
 219
 220                 init_tree_desc(&inner, tree, size);
 221                 show_tree(opt, prefix, &inner, newbase, baselen + 1 + pathlen);
 222
 223                 free(tree);
 224                 free(newbase);
 225         } else {
 226                 opt->add_remove(opt, prefix[0], mode, sha1, base, path);
 227         }
 228 }
 229
 230 static void skip_uninteresting(struct tree_desc *t, const char *base, int baselen, struct diff_options *opt)
 231 {
 232         int all_interesting = 0;
 233         while (t->size) {
 234                 int show;
 235
 236                 if (all_interesting)
 237                         show = 1;
 238                 else {
 239                         show = tree_entry_interesting(t, base, baselen, opt);
 240                         if (show == 2)
 241                                 all_interesting = 1;
 242                 }
 243                 if (!show) {
 244                         update_tree_entry(t);
 245                         continue;
 246                 }
 247                 /* Skip it all? */
 248                 if (show < 0)
 249                         t->size = 0;
 250                 return;
 251         }
 252 }
 253
 254 int diff_tree(struct tree_desc *t1, struct tree_desc *t2, const char *base, struct diff_options *opt)
 255 {
 256         int baselen = strlen(base);
 257
 258         for (;;) {
 259                 if (opt->quiet && opt->has_changes)
 260                         break;
 261                 if (opt->nr_paths) {
 262                         skip_uninteresting(t1, base, baselen, opt);
 263                         skip_uninteresting(t2, base, baselen, opt);
 264                 }
 265                 if (!t1->size) {
 266                         if (!t2->size)
 267                                 break;
 268                         show_entry(opt, "+", t2, base, baselen);
 269                         update_tree_entry(t2);
 270                         continue;
 271                 }
 272                 if (!t2->size) {
 273                         show_entry(opt, "-", t1, base, baselen);
 274                         update_tree_entry(t1);
 275                         continue;
 276                 }
 277                 switch (compare_tree_entry(t1, t2, base, baselen, opt)) {
 278                 case -1:
 279                         update_tree_entry(t1);
 280                         continue;
 281                 case 0:
 282                         update_tree_entry(t1);
 283                         /* Fallthrough */
 284                 case 1:
 285                         update_tree_entry(t2);
 286                         continue;
 287                 }
 288                 die("git-diff-tree: internal error");
 289         }
 290         return 0;
 291 }
 292
 293 int diff_tree_sha1(const unsigned char *old, const unsigned char *new, const char *base, struct diff_options *opt)
 294 {
 295         void *tree1, *tree2;
 296         struct tree_desc t1, t2;
 297         unsigned long size1, size2;
 298         int retval;
 299
 300         tree1 = read_object_with_reference(old, tree_type, &size1, NULL);
 301         if (!tree1)
 302                 die("unable to read source tree (%s)", sha1_to_hex(old));
 303         tree2 = read_object_with_reference(new, tree_type, &size2, NULL);
 304         if (!tree2)
 305                 die("unable to read destination tree (%s)", sha1_to_hex(new));
 306         init_tree_desc(&t1, tree1, size1);
 307         init_tree_desc(&t2, tree2, size2);
 308         retval = diff_tree(&t1, &t2, base, opt);
 309         free(tree1);
 310         free(tree2);
 311         return retval;
 312 }
 313
 314 int diff_root_tree_sha1(const unsigned char *new, const char *base, struct diff_options *opt)
 315 {
 316         int retval;
 317         void *tree;
 318         unsigned long size;
 319         struct tree_desc empty, real;
 320
 321         tree = read_object_with_reference(new, tree_type, &size, NULL);
 322         if (!tree)
 323                 die("unable to read root tree (%s)", sha1_to_hex(new));
 324         init_tree_desc(&real, tree, size);
 325
 326         init_tree_desc(&empty, "", 0);
 327         retval = diff_tree(&empty, &real, base, opt);
 328         free(tree);
 329         return retval;
 330 }
 331
 332 static int count_paths(const char **paths)
 333 {
 334         int i = 0;
 335         while (*paths++)
 336                 i++;
 337         return i;
 338 }
 339
 340 void diff_tree_release_paths(struct diff_options *opt)
 341 {
 342         free(opt->pathlens);
 343 }
 344
 345 void diff_tree_setup_paths(const char **p, struct diff_options *opt)
 346 {
 347         opt->nr_paths = 0;
 348         opt->pathlens = NULL;
 349         opt->paths = NULL;
 350
 351         if (p) {
 352                 int i;
 353
 354                 opt->paths = p;
 355                 opt->nr_paths = count_paths(p);
 356                 if (opt->nr_paths == 0) {
 357                         opt->pathlens = NULL;
 358                         return;
 359                 }
 360                 opt->pathlens = xmalloc(opt->nr_paths * sizeof(int));
 361                 for (i=0; i < opt->nr_paths; i++)
 362                         opt->pathlens[i] = strlen(p[i]);
 363         }
 364 }