Em 13-01-2011 01:05, Pawel Osciak escreveu: > Hi Mauro, > > On Wed, Jan 12, 2011 at 10:49, Mauro Carvalho Chehab <mchehab@xxxxxxxxxx> wrote: >> Em 12-01-2011 08:25, Marek Szyprowski escreveu: >>> Hello Mauro, >>> >>> I've rebased our fimc and saa patches onto http://linuxtv.org/git/mchehab/experimental.git >>> vb2_test branch. >> >> Thanks! >> >> As before, I'll be commenting the patches as I'll be seeing any issues. >> >>> Pawel Osciak (2): >>> Fix mmap() example in the V4L2 API DocBook >> >> In fact, the check for retval < 0 instead of retval == -1 is not a fix. According with >> mmap man pages: >> RETURN VALUE >> On success, mmap() returns a pointer to the mapped area. On error, the value MAP_FAILED (that is, (void *) -1) is returned, and errno >> is set appropriately. On success, munmap() returns 0, on failure -1, and errno is set (probably to EINVAL). >> >> The change is not wrong, as -1 is lower than 0, but using -1 is more compliant with >> libc. So, I'll be applying just the CodingStyle fixes on it. > > Sorry, but I think you got it wrong. The example is called "mmap() > example". But I did not change return value checking of mmap() calls. > I changed return value checking of ioctl() calls. So I believe the > patch is correct. >From ioctl man page: RETURN VALUE Usually, on success zero is returned. A few ioctl() requests use the return value as an output parameter and return a non-negative value on success. On error, -1 is returned, and errno is set appropriately. So, at least on glibc, it will return -1 for errors, storing the error code at errno var, and 0 for OK. Several V4L2 applications do error checks with -1. So, if some non-glibc implementation is returning a different return value, that means that several V4L applications will not work properly. Do you know any case where ioctl is implemented on a different way? Cheers, Mauro. -- To unsubscribe from this list: send the line "unsubscribe linux-media" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
