> Subject: Re: [Qemu-devel] [PATCH 1/4] os-posix/win32: convert fprintf/perror
> to
> error_report
>
> On 09/25/2014 03:46 AM, arei.gong...@huawei.com wrote:
> > From: Gonglei <arei.gong...@huawei.com>
> >
> > Signed-off-by: Gonglei <arei.gong...@huawei.com>
> > ---
> > os-posix.c | 34 ++++++++++++++++++----------------
> > os-win32.c | 3 ++-
> > 2 files changed, 20 insertions(+), 17 deletions(-)
> >
> > diff --git a/os-posix.c b/os-posix.c
> > index cb2a7f7..9d5ae70 100644
> > --- a/os-posix.c
> > +++ b/os-posix.c
> > @@ -39,6 +39,7 @@
> > #include "sysemu/sysemu.h"
> > #include "net/slirp.h"
> > #include "qemu-options.h"
> > +#include "qemu/error-report.h"
> >
> > #ifdef CONFIG_LINUX
> > #include <sys/prctl.h>
> > @@ -120,11 +121,11 @@ void os_set_proc_name(const char *s)
> > /* Could rewrite argv[0] too, but that's a bit more complicated.
> > This simple way is enough for `top'. */
> > if (prctl(PR_SET_NAME, name)) {
> > - perror("unable to change process name");
> > + error_report("unable to change process name");
>
> This loses the value of errno that perror would have displayed. Is that
> reduction in error message quality intentional?
Of course not. :)
> If not, then this is
> not a trivial conversion; if it is, then your commit message should call
> it out.
>
I agree with you. Actually I missed the usage of perror(), thanks for
your point. Maybe I should remove the changes about perror() in
next version.
> > @@ -167,20 +168,20 @@ static void change_process_uid(void)
> > {
> > if (user_pwd) {
> > if (setgid(user_pwd->pw_gid) < 0) {
> > - fprintf(stderr, "Failed to setgid(%d)\n", user_pwd->pw_gid);
> > + error_report("Failed to setgid(%d)\n", user_pwd->pw_gid);
>
> No trailing \n for error_report, please. (You got it right in most of
> your conversions)
>
Hmm, yes.
>
> > @@ -190,11 +191,11 @@ static void change_root(void)
> > {
> > if (chroot_dir) {
> > if (chroot(chroot_dir) < 0) {
> > - fprintf(stderr, "chroot failed\n");
> > + error_report("chroot failed");
> > exit(1);
> > }
> > if (chdir("/")) {
> > - perror("not able to chdir to /");
> > + error_report("not able to chdir to /");
>
> Another loss of errno value from perror.
>
> > exit(1);
> > }
> > }
> > @@ -224,7 +225,7 @@ void os_daemonize(void)
> > if (len != 1)
> > exit(1);
> > else if (status == 1) {
> > - fprintf(stderr, "Could not acquire pidfile: %s\n",
> strerror(errno));
> > + error_report("Could not acquire pidfile: %s",
> strerror(errno));
>
> This code is broken. The earlier 'if (len != 1)' fails to print a
> message before exiting (not to mention it violates coding style by
> omitting {}). Then, if we get inside the 'else if (status == 1)'
> conditional, then we KNOW that read() succeeded, and therefore errno is
> unspecified. Printing strerror(errno) on a random value is NOT helpful.
>
Good catch! Will fix those. :) Thanks for your reviewing! Eric.
Best regards,
-Gonglei
>
> > @@ -267,7 +268,7 @@ void os_setup_post(void)
> > exit(1);
> >
> > if (chdir("/")) {
> > - perror("not able to chdir to /");
> > + error_report("not able to chdir to /");
>
> Another loss of errno reporting.
>
> > exit(1);
> > }
> > TFR(fd = qemu_open("/dev/null", O_RDWR));
> > @@ -292,10 +293,11 @@ void os_pidfile_error(void)
> > if (daemonize) {
> > uint8_t status = 1;
> > if (write(fds[1], &status, 1) != 1) {
> > - perror("daemonize. Writing to pipe\n");
> > + error_report("daemonize. Writing to pipe");
>
> and another.
>
> > @@ -338,7 +340,7 @@ int os_mlock(void)
> >
> > ret = mlockall(MCL_CURRENT | MCL_FUTURE);
> > if (ret < 0) {
> > - perror("mlockall");
> > + error_report("mlockall");
>
> and another.
>
> --
> Eric Blake eblake redhat com +1-919-301-3266
> Libvirt virtualization library http://libvirt.org
