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Re: [libvirt] [PATCH] eliminate strerror from qemu_driver.c: use virReportSystemError instead



On Thu, Jan 29, 2009 at 09:54:59PM +0100, Jim Meyering wrote:
> diff --git a/src/qemu_driver.c b/src/qemu_driver.c
> index 36e12b2..8fd789d 100644
> --- a/src/qemu_driver.c
> +++ b/src/qemu_driver.c
> @@ -89,31 +89,19 @@ static void qemuDriverUnlock(struct qemud_driver *driver)
> 
>  static int qemudSetCloseExec(int fd) {
>      int flags;
> -    if ((flags = fcntl(fd, F_GETFD)) < 0)
> -        goto error;
> -    flags |= FD_CLOEXEC;
> -    if ((fcntl(fd, F_SETFD, flags)) < 0)
> -        goto error;
> -    return 0;
> - error:
> -    qemudLog(QEMUD_ERR,
> -             "%s", _("Failed to set close-on-exec file descriptor flag\n"));
> -    return -1;
> +    return ((flags = fcntl(fd, F_GETFD)) < 0
> +             || fcntl(fd, F_SETFD, flags | FD_CLOEXEC) < 0
> +            ? -1
> +            : 0);
>  }
> 
> 
>  static int qemudSetNonBlock(int fd) {
>      int flags;
> -    if ((flags = fcntl(fd, F_GETFL)) < 0)
> -        goto error;
> -    flags |= O_NONBLOCK;
> -    if ((fcntl(fd, F_SETFL, flags)) < 0)
> -        goto error;
> -    return 0;
> - error:
> -    qemudLog(QEMUD_ERR,
> -             "%s", _("Failed to set non-blocking file descriptor flag\n"));
> -    return -1;
> +    return ((flags = fcntl(fd, F_GETFL)) < 0
> +             || fcntl(fd, F_SETFL, flags | O_NONBLOCK) < 0
> +            ? -1
> +            : 0);
>  }

You can actually just kill off the SetNonBlock method, since we
added one to util.h. We should probably do same for SetCloseExec
since I believe we have several copies of that with the sme
problem too.

> @@ -854,8 +842,7 @@ static int qemudWaitForMonitor(virConnectPtr conn,
>                                   qemudFindCharDevicePTYs,
>                                   "console", 3000);
>      if (close(logfd) < 0)
> -        qemudLog(QEMUD_WARN, _("Unable to close logfile: %s\n"),
> -                 strerror(errno));
> +        virReportSystemError(NULL, errno, "%s", _("Unable to close logfile"));
>      return ret;
>  }

If you report an error in this scenario then you must also ensure
a failure code is returned. This particular scenario is non-fatal
though, so I don't think we should be raising an error here at all.
I'd be inclined to just keep qemudLog, but with the raw errno value
as an int.

> @@ -1134,30 +1121,30 @@ static int qemudStartVMDaemon(virConnectPtr conn,
>      tmp = progenv;
>      while (*tmp) {
>          if (safewrite(vm->logfile, *tmp, strlen(*tmp)) < 0)
> -            qemudLog(QEMUD_WARN, _("Unable to write envv to logfile %d: %s\n"),
> -                     errno, strerror(errno));
> +            virReportSystemError(NULL, errno,
> +                                 "%s", _("Unable to write envv to logfile"));
>          if (safewrite(vm->logfile, " ", 1) < 0)
> -            qemudLog(QEMUD_WARN, _("Unable to write envv to logfile %d: %s\n"),
> -                     errno, strerror(errno));
> +            virReportSystemError(NULL, errno,
> +                                 "%s", _("Unable to write envv to logfile"));
>          tmp++;
>      }
>      tmp = argv;
>      while (*tmp) {
>          if (safewrite(vm->logfile, *tmp, strlen(*tmp)) < 0)
> -            qemudLog(QEMUD_WARN, _("Unable to write argv to logfile %d: %s\n"),
> -                     errno, strerror(errno));
> +            virReportSystemError(NULL, errno,
> +                                 "%s", _("Unable to write argv to logfile"));
>          if (safewrite(vm->logfile, " ", 1) < 0)
> -            qemudLog(QEMUD_WARN, _("Unable to write argv to logfile %d: %s\n"),
> -                     errno, strerror(errno));
> +            virReportSystemError(NULL, errno,
> +                                 "%s", _("Unable to write argv to logfile"));
>          tmp++;
>      }
>      if (safewrite(vm->logfile, "\n", 1) < 0)
> -        qemudLog(QEMUD_WARN, _("Unable to write argv to logfile %d: %s\n"),
> -                 errno, strerror(errno));
> +        virReportSystemError(NULL, errno,
> +                             "%s", _("Unable to write argv to logfile"));
> 
>      if ((pos = lseek(vm->logfile, 0, SEEK_END)) < 0)
> -        qemudLog(QEMUD_WARN, _("Unable to seek to end of logfile %d: %s\n"),
> -                 errno, strerror(errno));
> +        virReportSystemError(NULL, errno,
> +                             "%s", _("Unable to seek to end of logfile"));



Likewise with all these - we're just printing ARGV to a logfile - this should
not result in errors propagated to the caller - unless we intend to tear down
the VM we just started, but I think that's overkill.

> @@ -1222,14 +1210,14 @@ static void qemudShutdownVMDaemon(virConnectPtr conn ATTRIBUTE_UNUSED,
> 
>      if (virKillProcess(vm->pid, 0) == 0 &&
>          virKillProcess(vm->pid, SIGTERM) < 0)
> -        qemudLog(QEMUD_ERROR, _("Failed to send SIGTERM to %s (%d): %s\n"),
> -                 vm->def->name, vm->pid, strerror(errno));
> +        virReportSystemError(conn, errno,
> +                             _("Failed to send SIGTERM to %s (%d)"),
> +                             vm->def->name, vm->pid);
> 
>      virEventRemoveHandle(vm->monitor_watch);
> 
>      if (close(vm->logfile) < 0)
> -        qemudLog(QEMUD_WARN, _("Unable to close logfile %d: %s\n"),
> -                 errno, strerror(errno));
> +        virReportSystemError(conn, errno, "%s", _("Unable to close logfile"));
>      if (vm->monitor != -1)
>          close(vm->monitor);
>      vm->logfile = -1;
> @@ -1384,8 +1372,8 @@ qemudMonitorCommand (const virDomainObjPtr vm,
> 
>      /* Log, but ignore failures to write logfile for VM */
>      if (safewrite(vm->logfile, buf, strlen(buf)) < 0)
> -        qemudLog(QEMUD_WARN, _("Unable to log VM console data: %s\n"),
> -                 strerror(errno));
> +        virReportSystemError(NULL, errno,
> +                             "%s", _("Unable to log VM console data"));
> 
>      *reply = buf;
>      return 0;
> @@ -1394,8 +1382,8 @@ qemudMonitorCommand (const virDomainObjPtr vm,
>      if (buf) {
>          /* Log, but ignore failures to write logfile for VM */
>          if (safewrite(vm->logfile, buf, strlen(buf)) < 0)
> -            qemudLog(QEMUD_WARN, _("Unable to log VM console data: %s\n"),
> -                     strerror(errno));
> +            virReportSystemError(NULL, errno,
> +                                 "%s", _("Unable to log VM console data"));
>          VIR_FREE(buf);
>      }
>      return -1;


Hmm, these Log -> Error conversions all are same non-fatal scneario
I mention earlier.

> @@ -1492,7 +1480,7 @@ static int kvmGetMaxVCPUs(void) {
> 
>      fd = open(KVM_DEVICE, O_RDONLY);
>      if (fd < 0) {
> -        qemudLog(QEMUD_WARN, _("Unable to open %s: %s\n"), KVM_DEVICE, strerror(errno));
> +        virReportSystemError(NULL, errno, _("Unable to open %s"), KVM_DEVICE);
>          return maxvcpus;
>      }
> 

This conversion looks good - we SHOULD be raising a real error
here. The original code was wrong to return 'maxvcpus' here,
it should be -1 upon error.

Daniel
-- 
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