[PATCH] SHA1 naive collision checking

[git.git] / diff-tree.c

diff --git a/diff-tree.c b/diff-tree.c
index 207617c..1960c23 100644 (file)
--- a/diff-tree.c
+++ b/diff-tree.c
@@ -2,7 +2,7 @@
 
 static int recursive = 0;
 
-static int diff_tree_sha1(const unsigned char *old, const unsigned char *new, const char *src, const char *dst);
+static int diff_tree_sha1(const unsigned char *old, const unsigned char *new, const char *base);
 
 static void update_tree_entry(void **bufp, unsigned long *sizep)
 {
@@ -28,20 +28,61 @@ static const unsigned char *extract(void *tree, unsigned long size, const char *
        return sha1;
 }
 
+static char *malloc_base(const char *base, const char *path, int pathlen)
+{
+       int baselen = strlen(base);
+       char *newbase = malloc(baselen + pathlen + 2);
+       memcpy(newbase, base, baselen);
+       memcpy(newbase + baselen, path, pathlen);
+       memcpy(newbase + baselen + pathlen, "/", 2);
+       return newbase;
+}
+
+static void show_file(const char *prefix, void *tree, unsigned long size, const char *base);
+
+/* A whole sub-tree went away or appeared */
+static void show_tree(const char *prefix, void *tree, unsigned long size, const char *base)
+{
+       while (size) {
+               show_file(prefix, tree, size, base);
+               update_tree_entry(&tree, &size);
+       }
+}
+
+/* A file entry went away or appeared */
 static void show_file(const char *prefix, void *tree, unsigned long size, const char *base)
 {
        unsigned mode;
        const char *path;
        const unsigned char *sha1 = extract(tree, size, &path, &mode);
+
+       if (recursive && S_ISDIR(mode)) {
+               char type[20];
+               unsigned long size;
+               char *newbase = malloc_base(base, path, strlen(path));
+               void *tree;
+
+               tree = read_sha1_file(sha1, type, &size);
+               if (!tree || strcmp(type, "tree"))
+                       usage("corrupt tree sha %s", sha1_to_hex(sha1));
+
+               show_tree(prefix, tree, size, newbase);
+               
+               free(tree);
+               free(newbase);
+               return;
+       }
+
        printf("%s%o %s %s%s%c", prefix, mode, sha1_to_hex(sha1), base, path, 0);
 }
 
-static int compare_tree_entry(void *tree1, unsigned long size1, void *tree2, unsigned long size2, const char *src, const char *dst)
+static int compare_tree_entry(void *tree1, unsigned long size1, void *tree2, unsigned long size2, const char *base)
 {
        unsigned mode1, mode2;
        const char *path1, *path2;
        const unsigned char *sha1, *sha2;
        int cmp, pathlen1, pathlen2;
+       char old_sha1_hex[50];
 
        sha1 = extract(tree1, size1, &path1, &mode1);
        sha2 = extract(tree2, size2, &path2, &mode2);
@@ -50,48 +91,53 @@ static int compare_tree_entry(void *tree1, unsigned long size1, void *tree2, uns
        pathlen2 = strlen(path2);
        cmp = cache_name_compare(path1, pathlen1, path2, pathlen2);
        if (cmp < 0) {
-               show_file("-", tree1, size1, src);
+               show_file("-", tree1, size1, base);
                return -1;
        }
        if (cmp > 0) {
-               show_file("+", tree2, size2, dst);
+               show_file("+", tree2, size2, base);
                return 1;
        }
        if (!memcmp(sha1, sha2, 20) && mode1 == mode2)
                return 0;
-       if (recursive && S_ISDIR(mode1) && S_ISDIR(mode2)) {
-               int srclen = strlen(src);
-               int dstlen = strlen(dst);
-               char *srcbase = malloc(srclen + pathlen1 + 2);
-               char *dstbase = malloc(srclen + pathlen1 + 2);
-               memcpy(srcbase, src, srclen);
-               memcpy(srcbase + srclen, path1, pathlen1);
-               memcpy(srcbase + srclen + pathlen1, "/", 2);
-               memcpy(dstbase, dst, dstlen);
-               memcpy(dstbase + dstlen, path2, pathlen2);
-               memcpy(dstbase + dstlen + pathlen2, "/", 2);
-               return diff_tree_sha1(sha1, sha2, srcbase, dstbase);
+
+       /*
+        * If the filemode has changed to/from a directory from/to a regular
+        * file, we need to consider it a remove and an add. 
+        */
+       if (S_ISDIR(mode1) != S_ISDIR(mode2)) {
+               show_file("-", tree1, size1, base);
+               show_file("+", tree2, size2, base);
+               return 0;
+       }
+
+       if (recursive && S_ISDIR(mode1)) {
+               int retval;
+               char *newbase = malloc_base(base, path1, pathlen1);
+               retval = diff_tree_sha1(sha1, sha2, newbase);
+               free(newbase);
+               return retval;
        }
 
-       show_file("<", tree1, size1, src);
-       show_file(">", tree2, size2, dst);
+       strcpy(old_sha1_hex, sha1_to_hex(sha1));
+       printf("*%o->%o %s->%s %s%s%c", mode1, mode2, old_sha1_hex, sha1_to_hex(sha2), base, path1, 0);
        return 0;
 }
 
-static int diff_tree(void *tree1, unsigned long size1, void *tree2, unsigned long size2, const char *src, const char *dst)
+static int diff_tree(void *tree1, unsigned long size1, void *tree2, unsigned long size2, const char *base)
 {
        while (size1 | size2) {
                if (!size1) {
-                       show_file("+", tree2, size2, dst);
+                       show_file("+", tree2, size2, base);
                        update_tree_entry(&tree2, &size2);
                        continue;
                }
                if (!size2) {
-                       show_file("-", tree1, size1, src);
+                       show_file("-", tree1, size1, base);
                        update_tree_entry(&tree1, &size1);
                        continue;
                }
-               switch (compare_tree_entry(tree1, size1, tree2, size2, src, dst)) {
+               switch (compare_tree_entry(tree1, size1, tree2, size2, base)) {
                case -1:
                        update_tree_entry(&tree1, &size1);
                        continue;
@@ -107,7 +153,7 @@ static int diff_tree(void *tree1, unsigned long size1, void *tree2, unsigned lon
        return 0;
 }
 
-static int diff_tree_sha1(const unsigned char *old, const unsigned char *new, const char *src, const char *dst)
+static int diff_tree_sha1(const unsigned char *old, const unsigned char *new, const char *base)
 {
        void *tree1, *tree2;
        unsigned long size1, size2;
@@ -120,7 +166,7 @@ static int diff_tree_sha1(const unsigned char *old, const unsigned char *new, co
        tree2 = read_sha1_file(new, type, &size2);
        if (!tree2 || strcmp(type, "tree"))
                usage("unable to read destination tree");
-       retval = diff_tree(tree1, size1, tree2, size2, src, dst);
+       retval = diff_tree(tree1, size1, tree2, size2, base);
        free(tree1);
        free(tree2);
        return retval;
@@ -134,7 +180,7 @@ int main(int argc, char **argv)
                char *arg = argv[1];
                argv++;
                argc--;
-               if (!strcmp(arg, "-R")) {
+               if (!strcmp(arg, "-r")) {
                        recursive = 1;
                        continue;
                }
@@ -143,5 +189,5 @@ int main(int argc, char **argv)
 
        if (argc != 3 || get_sha1_hex(argv[1], old) || get_sha1_hex(argv[2], new))
                usage("diff-tree <tree sha1> <tree sha1>");
-       return diff_tree_sha1(old, new, "", "");
+       return diff_tree_sha1(old, new, "");
 }