afs: Ensure afs_calc_inum yields nonzero ino

[openafs.git] / src / afs / afs_util.c

diff --git a/src/afs/afs_util.c b/src/afs/afs_util.c
index 7dfc5c7..783ebc1 100644 (file)
--- a/src/afs/afs_util.c
+++ b/src/afs/afs_util.c
@@ -372,18 +372,32 @@ afs_data_pointer_to_int32(const void *p)
 afs_int32
 afs_calc_inum(afs_int32 volume, afs_int32 vnode)
 {
-    afs_int32 ino, vno = vnode;
+    afs_int32 ino = 0, vno = vnode;
     char digest[16];
     struct md5 ct;
 
     if (afs_new_inum) {
+       int offset;
        MD5_Init(&ct);
        MD5_Update(&ct, &volume, 4);
        MD5_Update(&ct, &vnode, 4);
        MD5_Final(digest, &ct);
-       memcpy(&ino, digest, sizeof(afs_int32));
-       ino ^= (ino ^ vno) & 1;
-    } else {
+
+       /* Userspace may react oddly to an inode number of 0 or 1, so keep
+        * reading more of the md5 digest if we get back one of those.
+        * Make sure not to read beyond the end of the digest; if we somehow
+        * still have a 0, we will fall through to the non-md5 calculation. */
+       for (offset = 0;
+            (ino == 0 || ino == 1) &&
+             offset + sizeof(ino) <= sizeof(digest);
+            offset++) {
+
+           memcpy(&ino, &digest[offset], sizeof(ino));
+           ino ^= (ino ^ vno) & 1;
+           ino &= 0x7fffffff;      /* Assumes 32 bit ino_t ..... */
+       }
+    }
+    if (ino == 0 || ino == 1) {
        ino = (volume << 16) + vnode;
     }
     ino &= 0x7fffffff;      /* Assumes 32 bit ino_t ..... */