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  *  - positive for yes
  74  *  - zero for no
  75  *  - negative for "no, and no subsequent entries will be either"
  76  */
  77 static int tree_entry_interesting(struct tree_desc *desc, const char *base, int baselen, struct diff_options *opt)
  78 {
  79         const char *path;
  80         const unsigned char *sha1;
  81         unsigned mode;
  82         int i;
  83         int pathlen;
  84         int never_interesting = -1;
  85
  86         if (!opt->nr_paths)
  87                 return 1;
  88
  89         sha1 = tree_entry_extract(desc, &path, &mode);
  90
  91         pathlen = tree_entry_len(path, sha1);
  92
  93         for (i = 0; i < opt->nr_paths; i++) {
  94                 const char *match = opt->paths[i];
  95                 int matchlen = opt->pathlens[i];
  96                 int m = -1; /* signals that we haven't called strncmp() */
  97
  98                 if (baselen >= matchlen) {
  99                         /* If it doesn't match, move along... */
 100                         if (strncmp(base, match, matchlen))
 101                                 continue;
 102
 103                         /* The base is a subdirectory of a path which was specified. */
 104                         return 1;
 105                 }
 106
 107                 /* Does the base match? */
 108                 if (strncmp(base, match, baselen))
 109                         continue;
 110
 111                 match += baselen;
 112                 matchlen -= baselen;
 113
 114                 if (never_interesting) {
 115                         /*
 116                          * We have not seen any match that sorts later
 117                          * than the current path.
 118                          */
 119
 120                         /*
 121                          * Does match sort strictly earlier than path
 122                          * with their common parts?
 123                          */
 124                         m = strncmp(match, path,
 125                                     (matchlen < pathlen) ? matchlen : pathlen);
 126                         if (m < 0)
 127                                 continue;
 128
 129                         /*
 130                          * If we come here even once, that means there is at
 131                          * least one pathspec that would sort equal to or
 132                          * later than the path we are currently looking at.
 133                          * In other words, if we have never reached this point
 134                          * after iterating all pathspecs, it means all
 135                          * pathspecs are either outside of base, or inside the
 136                          * base but sorts strictly earlier than the current
 137                          * one.  In either case, they will never match the
 138                          * subsequent entries.  In such a case, we initialized
 139                          * the variable to -1 and that is what will be
 140                          * returned, allowing the caller to terminate early.
 141                          */
 142                         never_interesting = 0;
 143                 }
 144
 145                 if (pathlen > matchlen)
 146                         continue;
 147
 148                 if (matchlen > pathlen) {
 149                         if (match[pathlen] != '/')
 150                                 continue;
 151                         if (!S_ISDIR(mode))
 152                                 continue;
 153                 }
 154
 155                 if (m == -1)
 156                         /*
 157                          * we cheated and did not do strncmp(), so we do
 158                          * that here.
 159                          */
 160                         m = strncmp(match, path, pathlen);
 161
 162                 /*
 163                  * If common part matched earlier then it is a hit,
 164                  * because we rejected the case where path is not a
 165                  * leading directory and is shorter than match.
 166                  */
 167                 if (!m)
 168                         return 1;
 169         }
 170         return never_interesting; /* No matches */
 171 }
 172
 173 /* A whole sub-tree went away or appeared */
 174 static void show_tree(struct diff_options *opt, const char *prefix, struct tree_desc *desc, const char *base, int baselen)
 175 {
 176         while (desc->size) {
 177                 int show = tree_entry_interesting(desc, base, baselen, opt);
 178                 if (show < 0)
 179                         break;
 180                 if (show)
 181                         show_entry(opt, prefix, desc, base, baselen);
 182                 update_tree_entry(desc);
 183         }
 184 }
 185
 186 /* A file entry went away or appeared */
 187 static void show_entry(struct diff_options *opt, const char *prefix, struct tree_desc *desc,
 188                        const char *base, int baselen)
 189 {
 190         unsigned mode;
 191         const char *path;
 192         const unsigned char *sha1 = tree_entry_extract(desc, &path, &mode);
 193
 194         if (opt->recursive && S_ISDIR(mode)) {
 195                 enum object_type type;
 196                 int pathlen = tree_entry_len(path, sha1);
 197                 char *newbase = malloc_base(base, baselen, path, pathlen);
 198                 struct tree_desc inner;
 199                 void *tree;
 200                 unsigned long size;
 201
 202                 tree = read_sha1_file(sha1, &type, &size);
 203                 if (!tree || type != OBJ_TREE)
 204                         die("corrupt tree sha %s", sha1_to_hex(sha1));
 205
 206                 init_tree_desc(&inner, tree, size);
 207                 show_tree(opt, prefix, &inner, newbase, baselen + 1 + pathlen);
 208
 209                 free(tree);
 210                 free(newbase);
 211         } else {
 212                 opt->add_remove(opt, prefix[0], mode, sha1, base, path);
 213         }
 214 }
 215
 216 static void skip_uninteresting(struct tree_desc *t, const char *base, int baselen, struct diff_options *opt)
 217 {
 218         while (t->size) {
 219                 int show = tree_entry_interesting(t, base, baselen, opt);
 220                 if (!show) {
 221                         update_tree_entry(t);
 222                         continue;
 223                 }
 224                 /* Skip it all? */
 225                 if (show < 0)
 226                         t->size = 0;
 227                 return;
 228         }
 229 }
 230
 231 int diff_tree(struct tree_desc *t1, struct tree_desc *t2, const char *base, struct diff_options *opt)
 232 {
 233         int baselen = strlen(base);
 234
 235         for (;;) {
 236                 if (opt->quiet && opt->has_changes)
 237                         break;
 238                 if (opt->nr_paths) {
 239                         skip_uninteresting(t1, base, baselen, opt);
 240                         skip_uninteresting(t2, base, baselen, opt);
 241                 }
 242                 if (!t1->size) {
 243                         if (!t2->size)
 244                                 break;
 245                         show_entry(opt, "+", t2, base, baselen);
 246                         update_tree_entry(t2);
 247                         continue;
 248                 }
 249                 if (!t2->size) {
 250                         show_entry(opt, "-", t1, base, baselen);
 251                         update_tree_entry(t1);
 252                         continue;
 253                 }
 254                 switch (compare_tree_entry(t1, t2, base, baselen, opt)) {
 255                 case -1:
 256                         update_tree_entry(t1);
 257                         continue;
 258                 case 0:
 259                         update_tree_entry(t1);
 260                         /* Fallthrough */
 261                 case 1:
 262                         update_tree_entry(t2);
 263                         continue;
 264                 }
 265                 die("git-diff-tree: internal error");
 266         }
 267         return 0;
 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         free(tree1);
 287         free(tree2);
 288         return retval;
 289 }
 290
 291 int diff_root_tree_sha1(const unsigned char *new, const char *base, struct diff_options *opt)
 292 {
 293         int retval;
 294         void *tree;
 295         unsigned long size;
 296         struct tree_desc empty, real;
 297
 298         tree = read_object_with_reference(new, tree_type, &size, NULL);
 299         if (!tree)
 300                 die("unable to read root tree (%s)", sha1_to_hex(new));
 301         init_tree_desc(&real, tree, size);
 302
 303         init_tree_desc(&empty, "", 0);
 304         retval = diff_tree(&empty, &real, base, opt);
 305         free(tree);
 306         return retval;
 307 }
 308
 309 static int count_paths(const char **paths)
 310 {
 311         int i = 0;
 312         while (*paths++)
 313                 i++;
 314         return i;
 315 }
 316
 317 void diff_tree_release_paths(struct diff_options *opt)
 318 {
 319         free(opt->pathlens);
 320 }
 321
 322 void diff_tree_setup_paths(const char **p, struct diff_options *opt)
 323 {
 324         opt->nr_paths = 0;
 325         opt->pathlens = NULL;
 326         opt->paths = NULL;
 327
 328         if (p) {
 329                 int i;
 330
 331                 opt->paths = p;
 332                 opt->nr_paths = count_paths(p);
 333                 if (opt->nr_paths == 0) {
 334                         opt->pathlens = NULL;
 335                         return;
 336                 }
 337                 opt->pathlens = xmalloc(opt->nr_paths * sizeof(int));
 338                 for (i=0; i < opt->nr_paths; i++)
 339                         opt->pathlens[i] = strlen(p[i]);
 340         }
 341 }