diff mbox

[v5,5/9] qemu-log: support simple pid substitution in logfile

Message ID 1454597781-18115-6-git-send-email-alex.bennee@linaro.org
State Superseded
Headers show

Commit Message

Alex Bennée Feb. 4, 2016, 2:56 p.m. UTC 
When debugging stuff that occurs over several forks it would be useful
not to keep overwriting the one logfile you've set-up. This allows a
simple %d to be included once in the logfile parameter which is
substituted with getpid().

Signed-off-by: Alex Bennée <alex.bennee@linaro.org>

Reviewed-by: Leandro Dorileo <l@dorileo.org>

Reviewed-by: Aurelien Jarno <aurelien@aurel32.net>


---
v5
  - add another r-b
---
 qemu-log.c | 17 +++++++++++++++--
 1 file changed, 15 insertions(+), 2 deletions(-)

-- 
2.7.0

Comments

Alex Bennée Feb. 5, 2016, 1:34 p.m. UTC | #1 
Eric Blake <eblake@redhat.com> writes:

> On 02/04/2016 03:26 PM, Richard Henderson wrote:

>> On 02/05/2016 01:56 AM, Alex Bennée wrote:

>>> +    if (g_strrstr(filename, "%d")) {

>>> +        /* if we are going to format this we'd better validate first */

>>> +        if (g_regex_match_simple("^[^%]+%d[^%]+$", filename, 0, 0)) {

>>

>> Why g_strrstr instead of strstr?  There should be only one, so why look

>> for the last?


Yeah, my fault for using the glib functions, I guess
g_strstr_len(filename, -1, "%d") would be the glib equivalent for
strstr.

> For that matter, why use a heavyweight regex, when you can achieve the

> same validation with the faster:

>

> char *tmp = strchr(filename, '%');

> if (tmp) {

>     if (tmp[1] != 'd' || strchr(tmp + 2, '%')) {

>         ...report invalid string

>     }


For option parsing I'm not too worried about speed. At least a regex
gives the explicit format we expect (for those that read regex). I guess
I can do it manually if preferred.

--
Alex Bennée
diff mbox

Patch

diff --git a/qemu-log.c b/qemu-log.c
index 8c59063..2eebac0 100644
--- a/qemu-log.c
+++ b/qemu-log.c
@@ -70,11 +70,24 @@  void do_qemu_set_log(int log_flags, bool use_own_buffers)
         qemu_log_close();
     }
 }
-
+/*
+ * Allow the user to include %d in their logfile which will be
+ * substituted with the current PID. This is useful for debugging many
+ * nested linux-user tasks but will result in lots of logs.
+ */
 void qemu_set_log_filename(const char *filename)
 {
     g_free(logfilename);
-    logfilename = g_strdup(filename);
+    if (g_strrstr(filename, "%d")) {
+        /* if we are going to format this we'd better validate first */
+        if (g_regex_match_simple("^[^%]+%d[^%]+$", filename, 0, 0)) {
+            logfilename = g_strdup_printf(filename, getpid());
+        } else {
+            g_error("Bad logfile format: %s", filename);
+        }
+    } else {
+        logfilename = g_strdup(filename);
+    }
     qemu_log_close();
     qemu_set_log(qemu_loglevel);
 }