Re: [PATCH v2 09/13] util/hexdump: Replace sprintf() by g_string_append_printf()

[Richard Henderson <richard.henderson@linaro.org>]

On 4/11/24 13:43, Philippe Mathieu-Daudé wrote:
> On 11/4/24 12:15, Philippe Mathieu-Daudé wrote:
>> sprintf() is deprecated on Darwin since macOS 13.0 / XCode 14.1,
>> resulting in painful developper experience.
>>
>> Replace sprintf() by GString API in order to avoid:
>>
>>    [426/1310] Compiling C object libqemuutil.a.p/util_hexdump.c.o
>>    util/hexdump.c:35:21: warning: 'sprintf' is deprecated:
>>      This function is provided for compatibility reasons only.
>>      Due to security concerns inherent in the design of sprintf(3),
>>      it is highly recommended that you use snprintf(3) instead.
>>      [-Wdeprecated-declarations]
>>              line += sprintf(line, " %02x", (unsigned char)buf[b + i]);
>>                      ^
>>    util/hexdump.c:37:21: warning: 'sprintf' is deprecated:
>>              line += sprintf(line, "   ");
>>                      ^
>>    2 warnings generated.
>>
>> Signed-off-by: Philippe Mathieu-Daudé <philmd@linaro.org>
>> ---
>>   util/hexdump.c | 17 ++++++++---------
>>   1 file changed, 8 insertions(+), 9 deletions(-)
>>
>> diff --git a/util/hexdump.c b/util/hexdump.c
>> index b6f70e93bb..2ec1171de3 100644
>> --- a/util/hexdump.c
>> +++ b/util/hexdump.c
>> @@ -19,7 +19,7 @@
>>   char *qemu_hexdump_line(const void *bufptr, unsigned offset,
>>                           unsigned int len, bool ascii)
>>   {
>> -    char linebuf[QEMU_HEXDUMP_LINE_BYTES], *line = linebuf;
>> +    g_autoptr(GString) gs = g_string_sized_new(QEMU_HEXDUMP_LINE_BYTES);
>>       const char *buf = bufptr;
>>       int i, c;
>> @@ -27,30 +27,29 @@ char *qemu_hexdump_line(const void *bufptr, unsigned offset,
>>           len = QEMU_HEXDUMP_LINE_BYTES;
>>       }
>> -    line += snprintf(line, 6, "%04x:", offset);
>> +    g_string_append_printf(gs, "%04x:", offset);
>>       for (i = 0; i < QEMU_HEXDUMP_LINE_BYTES; i++) {
>>           if ((i % 4) == 0) {
>> -            *line++ = ' ';
>> +            g_string_append_c(gs, ' ');
>>           }
>>           if (i < len) {
>> -            line += sprintf(line, " %02x", (unsigned char)buf[offset + i]);
>> +            g_string_append_printf(gs, " %02x", (unsigned char)buf[offset + i]);
> 
> I find using g_string_append_printf() simpler than checking snprintf()
> return value, and don't expect this function to be in hot path, but if
> preferred I can try to not use the GString API.

GString api is pretty good.

Reviewed-by: Richard Henderson <richard.henderson@linaro.org>


r~