* Paolo Bonzini <pbonz...@redhat.com> [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 <dim...@arrikto.com>
> > ---
> > 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. To be honest, I don't understand your suggestion. How would calling dup2(1, 2) help in our case? Isn't fd 1 the standard output? Thanks, dimara > Paolo
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