git wrapper: more careful argument stuffing

diff --git a/sha1_name.c b/sha1_name.c
index cc320d3d7fc38787190598034fceb787d95336d6..faac158b16ca978914696ed5d2801770a122cce2 100644 (file)
--- a/sha1_name.c
+++ b/sha1_name.c
@@ -203,6 +203,29 @@ const char *find_unique_abbrev(const unsigned char *sha1, int len)
        return NULL;
 }
 
+static int ambiguous_path(const char *path)
+{
+       int slash = 1;
+
+       for (;;) {
+               switch (*path++) {
+               case '\0':
+                       break;
+               case '/':
+                       if (slash)
+                               break;
+                       slash = 1;
+                       continue;
+               case '.':
+                       continue;
+               default:
+                       slash = 0;
+                       continue;
+               }
+               return slash;
+       }
+}
+
 static int get_sha1_basic(const char *str, int len, unsigned char *sha1)
 {
        static const char *prefix[] = {
@@ -213,16 +236,31 @@ static int get_sha1_basic(const char *str, int len, unsigned char *sha1)
                NULL
        };
        const char **p;
+       int found = 0;
 
        if (len == 40 && !get_sha1_hex(str, sha1))
                return 0;
 
+       /* Accept only unambiguous ref paths. */
+       if (ambiguous_path(str))
+               return -1;
+
        for (p = prefix; *p; p++) {
                char *pathname = git_path("%s/%.*s", *p, len, str);
-               if (!read_ref(pathname, sha1))
-                       return 0;
+               if (!read_ref(pathname, sha1)) {
+                       /* Must be unique; i.e. when heads/foo and
+                        * tags/foo are both present, reject "foo".
+                        * Note that read_ref() eventually calls
+                        * get_sha1_hex() which can smudge initial
+                        * part of the buffer even if what is read
+                        * is found to be invalid halfway.
+                        */
+                       if (1 < found++)
+                               return -1;
+               }
        }
-
+       if (found == 1)
+               return 0;
        return -1;
 }
 
@@ -322,7 +360,7 @@ static int peel_onion(const char *name, int len, unsigned char *sha1)
        if (!o)
                return -1;
        if (!type_string) {
-               o = deref_tag(o);
+               o = deref_tag(o, name, sp - name - 2);
                if (!o || (!o->parsed && !parse_object(o->sha1)))
                        return -1;
                memcpy(sha1, o->sha1, 20);