On Mon, Aug 1, 2011 at 8:30 AM, Anthony Liguori <anth...@codemonkey.ws> wrote: > On 07/29/2011 07:18 PM, Peter Maydell wrote: >> >> On 29 July 2011 20:30, Stefan Weil<w...@mail.berlios.de> 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. > > As long as it's not mixed, it shouldn't be a problem. > > I think using g_file_get_contents would make sense here. I have also met this problem on fedora 15 today. Currently i disable werror option to build successfully. How to completely this problem regardless of gcc>=4.6?
> > Regards, > > Anthony Liguori > >> >> -- PMM >> >> > > > -- Regards, Zhi Yong Wu
