[libvirt] [PATCH v2] log: actually do substring matches with fnmatch

[Daniel P. Berrangé]

Historically we matched log filters with strstr(), and when switching to
fnmatch in cbb0fd3cfdc287f6f4653ef1f04a7cfb2ea51b27, it was stated that
we would continue to match substrings, with "foo" being equivalent to
"*foo*". Unfortuntely I forget to provide the code to actually make that
happen. This fixes it to prepend and append "*". We don't bother to
check if the pattern already has a leading/trailing '*', because
"**foo**" will match the same as "*foo*".

Signed-off-by: Daniel P. Berrangé <berrange at redhat.com>
---

Changed in v2:

 - Simplify to always append/prepend '*'
 - Other fixes from Erik

 src/util/virlog.c | 10 +++++++++-
 1 file changed, 9 insertions(+), 1 deletion(-)

diff --git a/src/util/virlog.c b/src/util/virlog.c
index be9fc0cf78..9b63b8e7cd 100644
--- a/src/util/virlog.c
+++ b/src/util/virlog.c
@@ -1409,6 +1409,7 @@ virLogFilterNew(const char *match,
 {
     virLogFilterPtr ret = NULL;
     char *mdup = NULL;
+    size_t mlen = strlen(match);
 
     virCheckFlags(VIR_LOG_STACK_TRACE, NULL);
 
@@ -1418,9 +1419,16 @@ virLogFilterNew(const char *match,
         return NULL;
     }
 
-    if (VIR_STRDUP_QUIET(mdup, match) < 0)
+    /* We must treat 'foo' as equiv to '*foo*' for fnmatch
+     * todo substring matches, so add 2 extra bytes */
+     */
+    if (VIR_ALLOC_N_QUIET(mdup, mlen + 3) < 0)
         return NULL;
 
+    mdup[0] = '*';
+    memcpy(mdup + 1, match, mlen);
+    mdup[mlen + 1] = '*';
+
     if (VIR_ALLOC_QUIET(ret) < 0) {
         VIR_FREE(mdup);
         return NULL;
-- 
2.17.0