[Date Prev][Date Next]   [Thread Prev][Thread Next]   [Thread Index] [Date Index] [Author Index]

[Libvir] ignore leading zeros, too [Change MAC address to case insensitive



"Daniel P. Berrange" <berrange redhat com> wrote:
> On Tue, Feb 26, 2008 at 12:13:43PM +0100, Jim Meyering wrote:
>> "Richard W.M. Jones" <rjones redhat com> wrote:
>> > I'll apply this today (using our STRCASEEQ macros) if no one else
>> > objects.
>>
>> What do you think about using a MAC-address-specific comparison
>> function?  I.e., one that is not only case-independent, but that also
>> knows leading zeros are unnecessary?
>>
>> i.e., it would admit that these two match:
>>
>>   00:0A:FF:3A:00:09
>>   0:a:ff:3a:0:9
>
> Yes, we should add a helper function for comparing mac addresses for
> equality.

With this patch, they now match:

	Also ignore leading zeros when comparing MAC addresses.
	* src/util.c: Include <ctype.h>.
	(TOLOWER): Define.
	(__virMacAddrCompare): Rewrite to also ignore leading zeros.

Signed-off-by: Jim Meyering <meyering redhat com>
---
 src/util.c |   34 +++++++++++++++++++++++++++++-----
 1 files changed, 29 insertions(+), 5 deletions(-)

diff --git a/src/util.c b/src/util.c
index 4d61540..edaa5aa 100644
--- a/src/util.c
+++ b/src/util.c
@@ -35,6 +35,7 @@
 #include <sys/stat.h>
 #include <sys/wait.h>
 #include <string.h>
+#include <ctype.h>

 #ifdef HAVE_PATHS_H
 #include <paths.h>
@@ -50,6 +51,8 @@

 #define MAX_ERROR_LEN   1024

+#define TOLOWER(Ch) (isupper (Ch) ? tolower (Ch) : (Ch))
+
 #define virLog(msg...) fprintf(stderr, msg)

 #ifndef PROXY
@@ -654,14 +657,35 @@ virParseNumber(const char **str)
     return (ret);
 }

-/* Use this function when comparing two MAC addresses.  It deals with
- * string case compare and will eventually be extended to understand
- * that 01:02:03:04:05:06 is the same as 1:2:3:4:5:6.
+/* Compare two MAC addresses, ignoring differences in case,
+ * as well as leading zeros.
  */
 int
-__virMacAddrCompare (const char *mac1, const char *mac2)
+__virMacAddrCompare (const char *p, const char *q)
 {
-    return strcasecmp (mac1, mac2);
+    unsigned char c, d;
+    do {
+        while (*p == '0' && isxdigit (p[1]))
+            ++p;
+        while (*q == '0' && isxdigit (q[1]))
+            ++q;
+        c = TOLOWER (*p);
+        d = TOLOWER (*q);
+
+        if (c == 0 || d == 0)
+            break;
+
+        ++p;
+        ++q;
+    } while (c == d);
+
+    if (UCHAR_MAX <= INT_MAX)
+        return c - d;
+
+    /* On machines where 'char' and 'int' are types of the same size, the
+       difference of two 'unsigned char' values - including the sign bit -
+       doesn't fit in an 'int'.  */
+    return (c > d ? 1 : c < d ? -1 : 0);
 }

 /*
--
1.5.4.3.326.g7655e3


[Date Prev][Date Next]   [Thread Prev][Thread Next]   [Thread Index] [Date Index] [Author Index]