diff-tree.c

   1 #include "cache.h"
   2
   3 struct tree_entry;
   4
   5 static struct tree_entry *update_tree_entry(void **bufp, unsigned long *sizep)
   6 {
   7         void *buf = *bufp;
   8         unsigned long size = *sizep;
   9         int len = strlen(buf) + 1 + 20;
  10
  11         if (size < len)
  12                 usage("corrupt tree file");
  13         *bufp = buf + len;
  14         *sizep = size - len;
  15         return buf;
  16 }
  17
  18 static const unsigned char *extract(void *tree, unsigned long size, const char **pathp, unsigned int *modep)
  19 {
  20         int len = strlen(tree)+1;
  21         const unsigned char *sha1 = tree + len;
  22         const char *path = strchr(tree, ' ');
  23
  24         if (!path || size < len + 20 || sscanf(tree, "%o", modep) != 1)
  25                 usage("corrupt tree file");
  26         *pathp = path+1;
  27         return sha1;
  28 }
  29
  30 static void show_file(const char *prefix, void *tree, unsigned long size)
  31 {
  32         unsigned mode;
  33         const char *path;
  34         const unsigned char *sha1 = extract(tree, size, &path, &mode);
  35         printf("%s%o %s %s%c", prefix, mode, sha1_to_hex(sha1), path, 0);
  36 }
  37
  38 static int compare_tree_entry(void *tree1, unsigned long size1, void *tree2, unsigned long size2)
  39 {
  40         unsigned mode1, mode2;
  41         const char *path1, *path2;
  42         const unsigned char *sha1, *sha2;
  43         int cmp;
  44
  45         sha1 = extract(tree1, size1, &path1, &mode1);
  46         sha2 = extract(tree2, size2, &path2, &mode2);
  47
  48         cmp = cache_name_compare(path1, strlen(path1), path2, strlen(path2));
  49         if (cmp < 0) {
  50                 show_file("-", tree1, size1);
  51                 return -1;
  52         }
  53         if (cmp > 0) {
  54                 show_file("+", tree2, size2);
  55                 return 1;
  56         }
  57         if (!memcmp(sha1, sha2, 20) && mode1 == mode2)
  58                 return 0;
  59         show_file("<", tree1, size1);
  60         show_file(">", tree2, size2);
  61         return 0;
  62 }
  63
  64 static int diff_tree(void *tree1, unsigned long size1, void *tree2, unsigned long size2)
  65 {
  66         while (size1 | size2) {
  67                 if (!size1) {
  68                         show_file("+", tree2, size2);
  69                         update_tree_entry(&tree2, &size2);
  70                         continue;
  71                 }
  72                 if (!size2) {
  73                         show_file("-", tree1, size1);
  74                         update_tree_entry(&tree1, &size1);
  75                         continue;
  76                 }
  77                 switch (compare_tree_entry(tree1, size1, tree2, size2)) {
  78                 case -1:
  79                         update_tree_entry(&tree1, &size1);
  80                         continue;
  81                 case 0:
  82                         update_tree_entry(&tree1, &size1);
  83                         /* Fallthrough */
  84                 case 1:
  85                         update_tree_entry(&tree2, &size2);
  86                         continue;
  87                 }
  88                 usage("diff-tree: internal error");
  89         }
  90         return 0;
  91 }
  92
  93 int main(int argc, char **argv)
  94 {
  95         unsigned char old[20], new[20];
  96         void *tree1, *tree2;
  97         unsigned long size1, size2;
  98         char type[20];
  99
 100         if (argc != 3 || get_sha1_hex(argv[1], old) || get_sha1_hex(argv[2], new))
 101                 usage("diff-tree <tree sha1> <tree sha1>");
 102         tree1 = read_sha1_file(old, type, &size1);
 103         if (!tree1 || strcmp(type, "tree"))
 104                 usage("unable to read source tree");
 105         tree2 = read_sha1_file(new, type, &size2);
 106         if (!tree2 || strcmp(type, "tree"))
 107                 usage("unable to read destination tree");
 108         return diff_tree(tree1, size1, tree2, size2);
 109 }