[PATCH] v4l-utils: use openat when available

[PATCH] v4l-utils: use openat when available

[Riku Voipio]

New architectures such as 64-Bit arm build kernels without legacy
system calls - Such as the the no-at system calls. Thus, use
SYS_openat whenever it is available.

Signed-off-by: Riku Voipio <riku.voipio@linaro.org>
---
 lib/libv4lconvert/libv4lsyscall-priv.h |    5 +++++
 1 file changed, 5 insertions(+)

diff --git a/lib/libv4lconvert/libv4lsyscall-priv.h b/lib/libv4lconvert/libv4lsyscall-priv.h
index 2dac49a..cdd38bc 100644
--- a/lib/libv4lconvert/libv4lsyscall-priv.h
+++ b/lib/libv4lconvert/libv4lsyscall-priv.h
@@ -72,8 +72,13 @@ typedef off_t __off_t;
 
 #ifndef CONFIG_SYS_WRAPPER
 
+#ifdef SYS_openat
+#define SYS_OPEN(file, oflag, mode) \
+	syscall(SYS_openat, AT_FDCWD, (const char *)(file), (int)(oflag), (mode_t)(mode))
+#else
 #define SYS_OPEN(file, oflag, mode) \
 	syscall(SYS_open, (const char *)(file), (int)(oflag), (mode_t)(mode))
+#endif
 #define SYS_CLOSE(fd) \
 	syscall(SYS_close, (int)(fd))
 #define SYS_IOCTL(fd, cmd, arg) \
-- 
1.7.10.4

Re: [PATCH] v4l-utils: use openat when available

[Gregor Jasny]

Hello,

On 1/22/13 5:37 PM, Riku Voipio wrote:
> New architectures such as 64-Bit arm build kernels without legacy
> system calls - Such as the the no-at system calls. Thus, use
> SYS_openat whenever it is available.

> +#ifdef SYS_openat
> +#define SYS_OPEN(file, oflag, mode) \
> +	syscall(SYS_openat, AT_FDCWD, (const char *)(file), (int)(oflag), (mode_t)(mode))
> +#else
>  #define SYS_OPEN(file, oflag, mode) \
>  	syscall(SYS_open, (const char *)(file), (int)(oflag), (mode_t)(mode))
> +#endif

This would reduce compatibility to Linux >= 2.6.16 where openat was
introduced. How about testing for absence of SYS_open instead? Or fall
back to SYS_open if SYS_openat is not implemented?

Thanks,
Gregor