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[PATCH] Fix "is_refname_available(): query only possibly-conflicting references"

From
mhagger@alum.mit.edu <mhagger@alum.mit.edu>
Date
Nov 15, 2011, 05:55 UTC
Message-ID
<1321336525-19374-1-git-send-email-mhagger@alum.mit.edu>
In-Reply-To
<1319804921-17545-27-git-send-email-mhagger@alum.mit.edu>
From: Michael Haggerty <mhagger@alum.mit.edu>

The above-named commit didn't do all that its commit message claimed. The problem is that do_for_each_ref_in_dir() doesn't avoid iterating through reference subtrees outside of "prefix"; it only skips passing those references to the callback function. So the function unnecessarily caused all loose references to be loaded rather than just those in the required subtree.

So instead, explicitly select the possibly-conflicting subtree and pass it to do_for_each_ref_in_dir().

Also, simplify name_conflict_fn(). Since it will only be called for possibly-conflicting references, there is necessarily a conflict if it is called for *any* reference besides "oldrefname".

Remove function names_conflict(), which is now unused.
Signed-off-by: Michael Haggerty <mhagger@alum.mit.edu>
---

This patch can be squashed on top of "is_refname_available(): query only possibly-conflicting references", or applied at the end of mh/ref-api-take-2; it does not conflict with the two commits later in the series.

 refs.c |   40 +++++++++++++++++-----------------------
 1 files changed, 17 insertions(+), 23 deletions(-)
diff --git a/refs.c b/refs.c
index 6a7f9c3..b185c32 100644
--- a/refs.c
+++ b/refs.c
@@ -633,23 +633,7 @@ static int do_for_each_ref_in_dirs(struct ref_entry *direntry1,
 	}
 }
 
-/*
- * Return true iff refname1 and refname2 conflict with each other.
- * Two reference names conflict if one of them exactly matches the
- * leading components of the other; e.g., "foo/bar" conflicts with
- * both "foo" and with "foo/bar/baz" but not with "foo/bar" or
- * "foo/barbados".
- */
-static int names_conflict(const char *refname1, const char *refname2)
-{
-	for (; *refname1 && *refname1 == *refname2; refname1++, refname2++)
-		;
-	return (*refname1 == '\0' && *refname2 == '/')
-		|| (*refname1 == '/' && *refname2 == '\0');
-}
-
 struct name_conflict_cb {
-	const char *refname;
 	const char *oldrefname;
 	const char *conflicting_refname;
 };
@@ -660,11 +644,13 @@ static int name_conflict_fn(const char *existingrefname, const unsigned char *sh
 	struct name_conflict_cb *data = (struct name_conflict_cb *)cb_data;
 	if (!strcmp(data->oldrefname, existingrefname))
 		return 0;
-	if (names_conflict(data->refname, existingrefname)) {
-		data->conflicting_refname = existingrefname;
-		return 1;
-	}
-	return 0;
+
+	/*
+	 * Since we are only iterating over the subtree that has the
+	 * new refname as prefix, *any* reference found is a conflict.
+	 */
+	data->conflicting_refname = existingrefname;
+	return 1;
 }
 
 /*
@@ -673,6 +659,11 @@ static int name_conflict_fn(const char *existingrefname, const unsigned char *sh
  * oldrefname is non-NULL, ignore potential conflicts with oldrefname
  * (e.g., because oldrefname is scheduled for deletion in the same
  * operation).
+ *
+ * Two reference names conflict if one of them exactly matches the
+ * leading components of the other; e.g., "foo/bar" conflicts with
+ * both "foo" and with "foo/bar/baz" but not with "foo/bar" or
+ * "foo/barbados".
  */
 static int is_refname_available(const char *refname, const char *oldrefname,
 				struct ref_entry *direntry)
@@ -706,11 +697,14 @@ static int is_refname_available(const char *refname, const char *oldrefname,
 	/* Check whether refname is a proper prefix of an existing reference: */
 	prefix[prefixlen++] = '/';
 	prefix[prefixlen] = '\0';
-	data.refname = refname;
 	data.oldrefname = oldrefname;
 	data.conflicting_refname = NULL;
 
-	if (do_for_each_ref_in_dir(direntry, 0, prefix, name_conflict_fn,
+	direntry = find_containing_direntry(direntry, prefix, 0);
+	if (!direntry)
+		return 1;
+
+	if (do_for_each_ref_in_dir(direntry, 0, "", name_conflict_fn,
 				   0, DO_FOR_EACH_INCLUDE_BROKEN,
 				   &data)) {
 		error("'%s' exists; cannot create '%s'",

-- 
1.7.7.2
Previous: mhagger@alum.mit.eduNext: Junio C Hamano
Message 28 of 36 in “Store references hierarchically in cache”
  1. 00/28 Store references hierarchically in cachemhagger@alum.mit.edu, Oct 28, 2011
  2. 01/28 refs.c: reorder definitions more logicallymhagger@alum.mit.edu, Oct 28, 2011
  3. 02/28 free_ref_entry(): new functionmhagger@alum.mit.edu, Oct 28, 2011
  4. 03/28 check_refname_component(): return 0 for zero-length componentsmhagger@alum.mit.edu, Oct 28, 2011
  5. 04/28 struct ref_entry: nest the value part in a unionmhagger@alum.mit.edu, Oct 28, 2011
  6. 05/28 refs.c: rename ref_array -> ref_dirmhagger@alum.mit.edu, Oct 28, 2011
  7. 06/28 refs: store references hierarchicallymhagger@alum.mit.edu, Oct 28, 2011
  8. 07/28 sort_ref_dir(): do not sort if already sortedmhagger@alum.mit.edu, Oct 28, 2011
  9. 08/28 refs: sort ref_dirs lazilymhagger@alum.mit.edu, Oct 28, 2011
  10. 09/28 do_for_each_ref(): only iterate over the subtree that was requestedmhagger@alum.mit.edu, Oct 28, 2011
  11. 10/28 get_ref_dir(): keep track of the current ref_dirmhagger@alum.mit.edu, Oct 28, 2011
  12. 11/28 refs: wrap top-level ref_dirs in ref_entriesmhagger@alum.mit.edu, Oct 28, 2011
  13. 12/28 get_packed_refs(): return (ref_entry *) instead of (ref_dir *)mhagger@alum.mit.edu, Oct 28, 2011
  14. 13/28 get_loose_refs(): return (ref_entry *) instead of (ref_dir *)mhagger@alum.mit.edu, Oct 28, 2011
  15. 14/28 is_refname_available(): take (ref_entry *) instead of (ref_dir *)mhagger@alum.mit.edu, Oct 28, 2011
  16. 15/28 find_ref(): take (ref_entry *) instead of (ref_dir *)mhagger@alum.mit.edu, Oct 28, 2011
  17. 16/28 read_packed_refs(): take (ref_entry *) instead of (ref_dir *)mhagger@alum.mit.edu, Oct 28, 2011
  18. 17/28 add_ref(): take (ref_entry *) instead of (ref_dir *)mhagger@alum.mit.edu, Oct 28, 2011
  19. 18/28 find_containing_direntry(): use (ref_entry *) instead of (ref_dir *)mhagger@alum.mit.edu, Oct 28, 2011
  20. 19/28 search_ref_dir(): take (ref_entry *) instead of (ref_dir *)mhagger@alum.mit.edu, Oct 28, 2011
  21. 20/28 add_entry(): take (ref_entry *) instead of (ref_dir *)mhagger@alum.mit.edu, Oct 28, 2011
  22. 21/28 do_for_each_ref_in_dir*(): take (ref_entry *) instead of (ref_dir *)mhagger@alum.mit.edu, Oct 28, 2011
  23. 22/28 sort_ref_dir(): take (ref_entry *) instead of (ref_dir *)mhagger@alum.mit.edu, Oct 28, 2011
  24. 23/28 struct ref_dir: store a reference to the enclosing ref_cachemhagger@alum.mit.edu, Oct 28, 2011
  25. 24/28 read_loose_refs(): take a (ref_entry *) as argumentmhagger@alum.mit.edu, Oct 28, 2011
  26. 25/28 refs: read loose references lazilymhagger@alum.mit.edu, Oct 28, 2011
  27. 26/28 is_refname_available(): query only possibly-conflicting referencesmhagger@alum.mit.edu, Oct 28, 2011
  28. Fix "is_refname_available(): query only possibly-conflicting references"mhagger@alum.mit.edu, Nov 15, 2011
  29. Junio C HamanoNov 15, 2011
  30. Michael HaggertyNov 15, 2011
  31. Junio C HamanoNov 15, 2011
  32. 27/28 read_packed_refs(): keep track of the directory being worked inmhagger@alum.mit.edu, Oct 28, 2011
  33. 28/28 repack_without_ref(): call clear_packed_ref_cache()mhagger@alum.mit.edu, Oct 28, 2011
  34. Ramkumar RamachandraOct 28, 2011
  35. Michael HaggertyOct 28, 2011
  36. Michael HaggertyNov 16, 2011

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