We do not like "HEAD" as a new branch name

diff --git a/sha1_name.c b/sha1_name.c
index be1755a70b2c53fc102db41a62e6099fa0adac1b..bf8f0f0e1feef55ba6be764f60815d15036efa4e 100644 (file)
--- a/sha1_name.c
+++ b/sha1_name.c
@@ -203,11 +203,12 @@ const char *find_unique_abbrev(const unsigned char *sha1, int len)
        return NULL;
 }
 
-static int ambiguous_path(const char *path)
+static int ambiguous_path(const char *path, int len)
 {
        int slash = 1;
+       int cnt;
 
-       for (;;) {
+       for (cnt = 0; cnt < len; cnt++) {
                switch (*path++) {
                case '\0':
                        break;
@@ -224,6 +225,7 @@ static int ambiguous_path(const char *path)
                }
                return slash;
        }
+       return slash;
 }
 
 static int get_sha1_basic(const char *str, int len, unsigned char *sha1)
@@ -236,21 +238,47 @@ 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))
+       if (ambiguous_path(str, len))
                return -1;
 
        for (p = prefix; *p; p++) {
                char *pathname = git_path("%s/%.*s", *p, len, str);
-               if (!read_ref(pathname, sha1))
-                       return 0;
-       }
 
-       return -1;
+               if (!read_ref(pathname, sha1)) {
+                       /* Must be unique; i.e. when heads/foo and
+                        * tags/foo are both present, reject "foo".
+                        */
+                       if (1 < found++)
+                               return -1;
+               }
+
+               /* We want to allow .git/description file and
+                * "description" branch to exist at the same time.
+                * "git-rev-parse description" should silently skip
+                * .git/description file as a candidate for
+                * get_sha1().  However, having garbage file anywhere
+                * under refs/ is not OK, and we would not have caught
+                * ambiguous heads and tags with the above test.
+                */
+               else if (**p && !access(pathname, F_OK)) {
+                       /* Garbage exists under .git/refs */
+                       return error("garbage ref found '%s'", pathname);
+               }
+       }
+       switch (found) {
+       case 0:
+               return -1;
+       case 1:
+               return 0;
+       default:
+               return error("ambiguous refname '%.*s'", len, str);
+       }
 }
 
 static int get_sha1_1(const char *name, int len, unsigned char *sha1);