[ostree] refs: Don't try searching for input strings that can't be objects

[Colin Walters <walters src gnome org>]

commit d5e813c52c324157c51ac96b1c162d167a5d48fb
Author: Colin Walters <walters verbum org>
Date:   Wed Jul 23 15:09:24 2014 -0400

    refs: Don't try searching for input strings that can't be objects
    
    I noticed OSTree was a bit slower, did some investigation
    and saw we were enumerating all objects for things like
    
    $ ostree rev-parse blah
    
    Since "blah" can never be an object (because of the 'l' and 'h'), just
    return no matches.

 src/libostree/ostree-repo-refs.c |    8 ++++++++
 1 files changed, 8 insertions(+), 0 deletions(-)
---
diff --git a/src/libostree/ostree-repo-refs.c b/src/libostree/ostree-repo-refs.c
index 978c5e0..ca584b6 100644
--- a/src/libostree/ostree-repo-refs.c
+++ b/src/libostree/ostree-repo-refs.c
@@ -364,6 +364,8 @@ ostree_repo_resolve_partial_checksum (OstreeRepo   *self,
                                       GError      **error)
 {
   gboolean ret = FALSE;
+  static const char hexchars[] = "0123456789abcdef";
+  gsize off;
   gs_unref_hashtable GHashTable *ref_list = NULL;
   gs_free char *ret_rev = NULL;
   guint length;
@@ -375,6 +377,12 @@ ostree_repo_resolve_partial_checksum (OstreeRepo   *self,
 
   g_return_val_if_fail (error == NULL || *error == NULL, FALSE);
 
+  /* If the input is longer than 64 chars or contains non-hex chars,
+     don't bother looking for it as an object */
+  off = strspn (refspec, hexchars);
+  if (off > 64 || refspec[off] != '\0')
+    return TRUE;
+
   /* this looks through all objects and adds them to the ref_list if:
      a) they are a commit object AND
      b) the obj checksum starts with the partual checksum defined by "refspec" */