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;
  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                 /*
 115                  * Does match sort strictly earlier than path with their
 116                  * common parts?
 117                  */
 118                 m = strncmp(match, path,
 119                             (matchlen < pathlen) ? matchlen : pathlen);
 120                 if (m < 0)
 121                         continue;
 122
 123                 /*
 124                  * If we come here even once, that means there is at
 125                  * least one pathspec that would sort equal to or
 126                  * later than the path we are currently looking at.
 127                  * In other words, if we have never reached this point
 128                  * after iterating all pathspecs, it means all
 129                  * pathspecs are either outside of base, or inside the
 130                  * base but sorts strictly earlier than the current
 131                  * one.  In either case, they will never match the
 132                  * subsequent entries.  In such a case, we initialized
 133                  * the variable to -1 and that is what will be
 134                  * returned, allowing the caller to terminate early.
 135                  */
 136                 never_interesting = 0;
 137
 138                 if (pathlen > matchlen)
 139                         continue;
 140
 141                 if (matchlen > pathlen) {
 142                         if (match[pathlen] != '/')
 143                                 continue;
 144                         if (!S_ISDIR(mode))
 145                                 continue;
 146                 }
 147
 148                 /*
 149                  * If common part matched earlier then it is a hit,
 150                  * because we rejected the case where path is not a
 151                  * leading directory and is shorter than match.
 152                  */
 153                 if (!m)
 154                         return 1;
 155         }
 156         return never_interesting; /* No matches */
 157 }
 158
 159 /* A whole sub-tree went away or appeared */
 160 static void show_tree(struct diff_options *opt, const char *prefix, struct tree_desc *desc, const char *base, int baselen)
 161 {
 162         while (desc->size) {
 163                 int show = tree_entry_interesting(desc, base, baselen, opt);
 164                 if (show < 0)
 165                         break;
 166                 if (show)
 167                         show_entry(opt, prefix, desc, base, baselen);
 168                 update_tree_entry(desc);
 169         }
 170 }
 171
 172 /* A file entry went away or appeared */
 173 static void show_entry(struct diff_options *opt, const char *prefix, struct tree_desc *desc,
 174                        const char *base, int baselen)
 175 {
 176         unsigned mode;
 177         const char *path;
 178         const unsigned char *sha1 = tree_entry_extract(desc, &path, &mode);
 179
 180         if (opt->recursive && S_ISDIR(mode)) {
 181                 enum object_type type;
 182                 int pathlen = tree_entry_len(path, sha1);
 183                 char *newbase = malloc_base(base, baselen, path, pathlen);
 184                 struct tree_desc inner;
 185                 void *tree;
 186                 unsigned long size;
 187
 188                 tree = read_sha1_file(sha1, &type, &size);
 189                 if (!tree || type != OBJ_TREE)
 190                         die("corrupt tree sha %s", sha1_to_hex(sha1));
 191
 192                 init_tree_desc(&inner, tree, size);
 193                 show_tree(opt, prefix, &inner, newbase, baselen + 1 + pathlen);
 194
 195                 free(tree);
 196                 free(newbase);
 197         } else {
 198                 opt->add_remove(opt, prefix[0], mode, sha1, base, path);
 199         }
 200 }
 201
 202 static void skip_uninteresting(struct tree_desc *t, const char *base, int baselen, struct diff_options *opt)
 203 {
 204         while (t->size) {
 205                 int show = tree_entry_interesting(t, base, baselen, opt);
 206                 if (!show) {
 207                         update_tree_entry(t);
 208                         continue;
 209                 }
 210                 /* Skip it all? */
 211                 if (show < 0)
 212                         t->size = 0;
 213                 return;
 214         }
 215 }
 216
 217 int diff_tree(struct tree_desc *t1, struct tree_desc *t2, const char *base, struct diff_options *opt)
 218 {
 219         int baselen = strlen(base);
 220
 221         for (;;) {
 222                 if (opt->quiet && opt->has_changes)
 223                         break;
 224                 if (opt->nr_paths) {
 225                         skip_uninteresting(t1, base, baselen, opt);
 226                         skip_uninteresting(t2, base, baselen, opt);
 227                 }
 228                 if (!t1->size) {
 229                         if (!t2->size)
 230                                 break;
 231                         show_entry(opt, "+", t2, base, baselen);
 232                         update_tree_entry(t2);
 233                         continue;
 234                 }
 235                 if (!t2->size) {
 236                         show_entry(opt, "-", t1, base, baselen);
 237                         update_tree_entry(t1);
 238                         continue;
 239                 }
 240                 switch (compare_tree_entry(t1, t2, base, baselen, opt)) {
 241                 case -1:
 242                         update_tree_entry(t1);
 243                         continue;
 244                 case 0:
 245                         update_tree_entry(t1);
 246                         /* Fallthrough */
 247                 case 1:
 248                         update_tree_entry(t2);
 249                         continue;
 250                 }
 251                 die("git-diff-tree: internal error");
 252         }
 253         return 0;
 254 }
 255
 256 int diff_tree_sha1(const unsigned char *old, const unsigned char *new, const char *base, struct diff_options *opt)
 257 {
 258         void *tree1, *tree2;
 259         struct tree_desc t1, t2;
 260         unsigned long size1, size2;
 261         int retval;
 262
 263         tree1 = read_object_with_reference(old, tree_type, &size1, NULL);
 264         if (!tree1)
 265                 die("unable to read source tree (%s)", sha1_to_hex(old));
 266         tree2 = read_object_with_reference(new, tree_type, &size2, NULL);
 267         if (!tree2)
 268                 die("unable to read destination tree (%s)", sha1_to_hex(new));
 269         init_tree_desc(&t1, tree1, size1);
 270         init_tree_desc(&t2, tree2, size2);
 271         retval = diff_tree(&t1, &t2, base, opt);
 272         free(tree1);
 273         free(tree2);
 274         return retval;
 275 }
 276
 277 int diff_root_tree_sha1(const unsigned char *new, const char *base, struct diff_options *opt)
 278 {
 279         int retval;
 280         void *tree;
 281         unsigned long size;
 282         struct tree_desc empty, real;
 283
 284         tree = read_object_with_reference(new, tree_type, &size, NULL);
 285         if (!tree)
 286                 die("unable to read root tree (%s)", sha1_to_hex(new));
 287         init_tree_desc(&real, tree, size);
 288
 289         init_tree_desc(&empty, "", 0);
 290         retval = diff_tree(&empty, &real, base, opt);
 291         free(tree);
 292         return retval;
 293 }
 294
 295 static int count_paths(const char **paths)
 296 {
 297         int i = 0;
 298         while (*paths++)
 299                 i++;
 300         return i;
 301 }
 302
 303 void diff_tree_release_paths(struct diff_options *opt)
 304 {
 305         free(opt->pathlens);
 306 }
 307
 308 void diff_tree_setup_paths(const char **p, struct diff_options *opt)
 309 {
 310         opt->nr_paths = 0;
 311         opt->pathlens = NULL;
 312         opt->paths = NULL;
 313
 314         if (p) {
 315                 int i;
 316
 317                 opt->paths = p;
 318                 opt->nr_paths = count_paths(p);
 319                 if (opt->nr_paths == 0) {
 320                         opt->pathlens = NULL;
 321                         return;
 322                 }
 323                 opt->pathlens = xmalloc(opt->nr_paths * sizeof(int));
 324                 for (i=0; i < opt->nr_paths; i++)
 325                         opt->pathlens[i] = strlen(p[i]);
 326         }
 327 }