[apparmor] [PATCH 10/11] Fix caching when used with a newer kernel with the feature directory

[John Johansen]

On 03/08/2012 11:17 AM, Steve Beattie wrote:
> On Thu, Mar 08, 2012 at 11:15:12AM -0800, Steve Beattie wrote:
>> On Wed, Mar 07, 2012 at 06:17:29AM -0800, John Johansen wrote:
>>> On newer kernels the features directory causes the creation of a
>>> cache/.feature file that contains newline characters.  This causes the
>>> feature comparison to fail, because get_flags_string() uses fgets
>>> which stop reading in the feature file after the first newline.
>>>
>>> This caches the features comparision to compare a single line of the
>>> file against the full kernel feature directory resulting in caching
>>> failure.
>>>
>>> Worse this also means the cache won't get updated as the parser doesn't
>>> change what set gets caches after the .feature file gets created.
>>>
>>> Signed-off-by: John Johansen <john.johansen at canonical.com>
>>
>> Acked-By: Steve Beattie <sbeattie at ubuntu.com>
> 
> Actually, fread() doesn't null terminate what it reads like fgets()
> does. I think you'll need to address that.
> 
How about with this additional patch on top

diff --git a/parser/parser_main.c b/parser/parser_main.c
index 67ab231..3f4789b 100644
--- a/parser/parser_main.c
+++ b/parser/parser_main.c
@@ -844,6 +844,7 @@ out:
 static void get_flags_string(char **flags, char *flags_file) {
 	char *pos;
 	FILE *f = NULL;
+	size_t size;
 
 	/* abort if missing or already set */
 	if (!flags || *flags)
@@ -857,8 +858,10 @@ static void get_flags_string(char **flags, char *flags_file) {
 	if (!*flags)
 		goto fail;
 
-	if (!fread(*flags, 1, FLAGS_STRING_SIZE, f))
+	size = fread(*flags, 1, FLAGS_STRING_SIZE - 1, f);
+	if (ferror(f))
 		goto fail;
+	*flags[size] = 0;
 
 	fclose(f);
 	pos = strstr(*flags, "change_hat=");