Re: [PATCH v9 04/15] hw/i386/pc: replace use of strtol with qemu_strtol in x86_load_linux()

[Markus Armbruster]

Philippe Mathieu-Daudé <address@hidden> writes:

> Hi Sergio,
>
> On 10/15/19 1:23 PM, Sergio Lopez wrote:
>> Follow checkpatch.pl recommendation and replace the use of strtol with
>> qemu_strtol in x86_load_linux().
>
> "with qemu_strtoui"
>
>>
>> Signed-off-by: Sergio Lopez <address@hidden>
>> ---
>>   hw/i386/pc.c | 9 ++++++++-
>>   1 file changed, 8 insertions(+), 1 deletion(-)
>>
>> diff --git a/hw/i386/pc.c b/hw/i386/pc.c
>> index 77e86bfc3d..c8608b8007 100644
>> --- a/hw/i386/pc.c
>> +++ b/hw/i386/pc.c
>> @@ -68,6 +68,7 @@
>>   #include "qemu/config-file.h"
>>   #include "qemu/error-report.h"
>>   #include "qemu/option.h"
>> +#include "qemu/cutils.h"
>>   #include "hw/acpi/acpi.h"
>>   #include "hw/acpi/cpu_hotplug.h"
>>   #include "hw/boards.h"
>> @@ -1202,6 +1203,7 @@ static void x86_load_linux(PCMachineState *pcms,
>>       vmode = strstr(kernel_cmdline, "vga=");
>>       if (vmode) {
>>           unsigned int video_mode;
>> +        int ret;
>>           /* skip "vga=" */
>>           vmode += 4;
>>           if (!strncmp(vmode, "normal", 6)) {
>> @@ -1211,7 +1213,12 @@ static void x86_load_linux(PCMachineState *pcms,
>>           } else if (!strncmp(vmode, "ask", 3)) {
>>               video_mode = 0xfffd;
>>           } else {
>> -            video_mode = strtol(vmode, NULL, 0);
>> +            ret = qemu_strtoui(vmode, NULL, 0, &video_mode);
>> +            if (ret != 0) {
>> +                fprintf(stderr, "qemu: can't parse 'vga' parameter: %s\n",
>> +                        strerror(-ret));
>
> (Cc'ing Markus/Daniel just in case)
>
> I'm wondering if using fprintf() is appropriate, thinking about
> instantiating a machine via libvirt, is this error reported to the
> user?
>
> I first thought about using error_report() instead:
>
>     error_report("qemu: can't parse 'vga' parameter: %s",
>                  strerror(-ret));

Make that

     error_report("can't parse 'vga' parameter: %s", strerror(-ret));

> But this API is meaningful when used in console/monitor. We can't get
> here from the monitor,

True, but error_report() should be used anyway, because (1) it makes
intent more obvious, and (2) it uses a uniform, featureful error format.

With the proposed fprintf(), we get

    qemu: can't parse 'vga' parameter: Numerical result out of range

With error_report():

* we report the *actual* argv[0] instead of "qemu"

* we obey -msg timestamp=on

* if "[PATCHv2 1/2] util/qemu-error: add guest name helper with -msg
  options" gets accepted, we obey -msg guest-name=on, too

* we have a common way to point to the offending command line argument
  or configuration file line (not worth doing here)

Please use error_report().

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