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Re: [Qemu-devel] [PATCH] log: Redirect stderr to logfile if deamonized
From: |
Paolo Bonzini |
Subject: |
Re: [Qemu-devel] [PATCH] log: Redirect stderr to logfile if deamonized |
Date: |
Fri, 19 Feb 2016 18:25:35 +0100 |
User-agent: |
Mozilla/5.0 (X11; Linux x86_64; rv:38.0) Gecko/20100101 Thunderbird/38.5.0 |
On 18/02/2016 18:12, Dimitris Aragiorgis wrote:
> * Paolo Bonzini <address@hidden> [2016-02-18 16:22:13 +0100]:
>
>>
>>
>> On 18/02/2016 12:38, Dimitris Aragiorgis wrote:
>>> In case of daemonize, use the logfile passed with the -D option in
>>> order to redirect stderr to it instead of /dev/null.
>>>
>>> Also remove some unused code in log.h.
>>>
>>> Signed-off-by: Dimitris Aragiorgis <address@hidden>
>>> ---
>>> include/qemu/log.h | 6 ------
>>> os-posix.c | 6 +++++-
>>> util/log.c | 11 +++++++++--
>>> 3 files changed, 14 insertions(+), 9 deletions(-)
>>>
>>> diff --git a/include/qemu/log.h b/include/qemu/log.h
>>> index 30817f7..dda65fd 100644
>>> --- a/include/qemu/log.h
>>> +++ b/include/qemu/log.h
>>> @@ -94,12 +94,6 @@ static inline void qemu_log_close(void)
>>> }
>>> }
>>>
>>> -/* Set up a new log file */
>>> -static inline void qemu_log_set_file(FILE *f)
>>> -{
>>> - qemu_logfile = f;
>>> -}
>>> -
>>> /* define log items */
>>> typedef struct QEMULogItem {
>>> int mask;
>>> diff --git a/os-posix.c b/os-posix.c
>>> index cce62ed..92fa3ba 100644
>>> --- a/os-posix.c
>>> +++ b/os-posix.c
>>> @@ -37,6 +37,7 @@
>>> #include "qemu-options.h"
>>> #include "qemu/rcu.h"
>>> #include "qemu/error-report.h"
>>> +#include "qemu/log.h"
>>>
>>> #ifdef CONFIG_LINUX
>>> #include <sys/prctl.h>
>>> @@ -275,7 +276,10 @@ void os_setup_post(void)
>>>
>>> dup2(fd, 0);
>>> dup2(fd, 1);
>>> - dup2(fd, 2);
>>> + /* In case -D is given do not redirect stderr to /dev/null */
>>> + if (!qemu_logfile) {
>>> + dup2(fd, 2);
>>> + }
>>>
>>> close(fd);
>>>
>>> diff --git a/util/log.c b/util/log.c
>>> index 2709e98..a7ddc7e 100644
>>> --- a/util/log.c
>>> +++ b/util/log.c
>>> @@ -56,13 +56,20 @@ void do_qemu_set_log(int log_flags, bool
>>> use_own_buffers)
>>> #ifdef CONFIG_TRACE_LOG
>>> qemu_loglevel |= LOG_TRACE;
>>> #endif
>>> - if (qemu_loglevel && !qemu_logfile) {
>>> + if ((qemu_loglevel || is_daemonized()) && !qemu_logfile) {
>>> if (logfilename) {
>>> qemu_logfile = fopen(logfilename, log_append ? "a" : "w");
>>> if (!qemu_logfile) {
>>> perror(logfilename);
>>> _exit(1);
>>> }
>>> + /* In case we are a daemon redirect stderr to logfile */
>>> + if (is_daemonized()) {
>>> + dup2(fileno(qemu_logfile), STDERR_FILENO);
>>> + fclose(qemu_logfile);
>>> + /* This will skip closing logfile in qemu_log_close() */
>>> + qemu_logfile = stderr;
>>> + }
>>> } else {
>>> /* Default to stderr if no log file specified */
>>> qemu_logfile = stderr;
>>> @@ -82,7 +89,7 @@ void do_qemu_set_log(int log_flags, bool use_own_buffers)
>>> log_append = 1;
>>> }
>>> }
>>> - if (!qemu_loglevel && qemu_logfile) {
>>> + if (!qemu_loglevel && !is_daemonized() && qemu_logfile) {
>>> qemu_log_close();
>>> }
>>
>> Why is this necessary? Perhaps qemu_log_close should dup(1,2) if QEMU
>> is daemonized. The rest looks great.
>>
>
> Without !is_daemonized(), if we use -daemon with -D without -d,
> qemu_log_close() will eventually set qemu_logfile to NULL. This
> will make os_setup_post() redirect stderr to /dev/null, which
> is unwanted.
Sorry, I missed the context of this hunk. The patch is okay, thanks for
putting up with me!
Paolo
- Re: [Qemu-devel] [PATCH] os-posix: Log to logfile in case of daemonize, Paolo Bonzini, 2016/02/08
- Re: [Qemu-devel] [PATCH] os-posix: Log to logfile in case of daemonize, Dimitris Aragiorgis, 2016/02/11
- Re: [Qemu-devel] [PATCH] os-posix: Log to logfile in case of daemonize, Paolo Bonzini, 2016/02/11
- Re: [Qemu-devel] [PATCH] os-posix: Log to logfile in case of daemonize, Dimitris Aragiorgis, 2016/02/11
- Re: [Qemu-devel] [PATCH] os-posix: Log to logfile in case of daemonize, Paolo Bonzini, 2016/02/11
- [Qemu-devel] [PATCH] log: Redirect stderr to logfile if deamonized, Dimitris Aragiorgis, 2016/02/18
- Re: [Qemu-devel] [PATCH] log: Redirect stderr to logfile if deamonized, Paolo Bonzini, 2016/02/18
- Re: [Qemu-devel] [PATCH] log: Redirect stderr to logfile if deamonized, Dimitris Aragiorgis, 2016/02/18
- Re: [Qemu-devel] [PATCH] log: Redirect stderr to logfile if deamonized,
Paolo Bonzini <=