On Tue, 15 May 2012 09:14:13 -0500
Michael Roth <mdr...@linux.vnet.ibm.com> wrote:
> On Tue, May 15, 2012 at 10:04:32AM -0300, Luiz Capitulino wrote:
> > On Mon, 14 May 2012 17:04:17 -0500
> > Michael Roth <mdr...@linux.vnet.ibm.com> wrote:
> >
> > > Currently, if we fail to open the specified log file (generally due to a
> > > permissions issue), we'll assign NULL to the logfile handle (stderr,
> > > initially) used by the logging routines, which can cause a segfault to
> > > occur when we attempt to report the error before exiting.
> > >
> > > Instead, only re-assign if the open() was successful.
> > >
> > > Signed-off-by: Michael Roth <mdr...@linux.vnet.ibm.com>
> > > ---
> > > qemu-ga.c | 6 ++++--
> > > 1 files changed, 4 insertions(+), 2 deletions(-)
> > >
> > > diff --git a/qemu-ga.c b/qemu-ga.c
> > > index 3a88333..e2725c8 100644
> > > --- a/qemu-ga.c
> > > +++ b/qemu-ga.c
> > > @@ -681,6 +681,7 @@ int main(int argc, char **argv)
> > > const char *log_filepath = NULL;
> > > const char *pid_filepath = QGA_PIDFILE_DEFAULT;
> > > const char *state_dir = QGA_STATEDIR_DEFAULT;
> > > + FILE *log_file;
> > > #ifdef _WIN32
> > > const char *service = NULL;
> > > #endif
> > > @@ -836,12 +837,13 @@ int main(int argc, char **argv)
> > > become_daemon(pid_filepath);
> > > }
> > > if (log_filepath) {
> > > - s->log_file = fopen(log_filepath, "a");
> > > - if (!s->log_file) {
> > > + log_file = fopen(log_filepath, "a");
> > > + if (!log_file) {
> > > g_critical("unable to open specified log file: %s",
> > > strerror(errno));
> > > goto out_bad;
> > > }
> > > + s->log_file = log_file;
> >
> > Is it safe to change the log file this way? Isn't it necessary
> > to go through g_log_set_default_handler() or some other function?
>
> Are you worried about a race condition?
Actually, I was worried that glib could store the old s->log_file pointer
somewhere, but I think I misread its documentation. Now I see that it's only
used by ga_log().
I think that doing the log setup before logging anything would be the best
solution, but that's a future improvement:
Acked-by: Luiz Capitulino <lcapitul...@redhat.com>
