On 29 July 2011 20:30, Stefan Weil<address@hidden> wrote:
Commit 3d3b8303c6f83b9b245bc774af530a6403cc4ce6
breaks builds with gcc-4.6:
hw/fw_cfg.c: In function ‘probe_splashfile’:
hw/fw_cfg.c:66:9: error: variable ‘fop_ret’ set but not used
[-Werror=unused-but-set-variable]
hw/fw_cfg.c: In function ‘fw_cfg_bootsplash’:
hw/fw_cfg.c:130:9: error: variable ‘fop_ret’ set but not used
[-Werror=unused-but-set-variable]
Remove fop_ret. Testing the result of fread() is normally
a good idea, but I don't think it is needed here.
@@ -86,7 +85,7 @@ static FILE *probe_splashfile(char *filename, int
*file_sizep, int *file_typep)
}
/* check magic ID */
fseek(fp, 0L, SEEK_SET);
- fop_ret = fread(buf, 1, 2, fp);
+ (void)fread(buf, 1, 2, fp);
Usually this kind of thing is added in order to stop gcc complaining about
you ignoring the return value of a function which has been marked (by libc)
as 'don't-ignore-return-value'. In such cases a "(void)" is not sufficient
to suppress the "return value ignored" warning.
At least some of these cases really should be checking fread return values;
I see we also don't check fseek() return values either in all places. So
the easiest fix is just to check all the fread() calls.
Alternative suggestion: it would be easier to just slurp the whole file
into memory (which is what we do once we've figured out it's an image)
and then check the magic numbers in the memory buffer, which removes
a lot of these unchecked function calls altogether. Since we're linking
against glib anyway it looks like g_file_get_contents() would do 95%
of the work for us. [disclaimer: I haven't used that API myself but it
looks the right shape...g_malloc vs qemu_malloc issues, maybe?] Failing
that, fopen/fstat/fread/fclose/check magic numbers.