[musl] Re: [PATCH v3] add renameat2 linux syscall wrapper

[T A <tony.ambardar@gmail.com>]

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Hi Rich,

I think this v3 patch addressed all your suggestions. Are any other
improvements needed?

Thanks,
Tony

On Mon, May 6, 2024, 20:28 Tony Ambardar <tony.ambardar@gmail.com> wrote:

> This syscall is available since Linux 3.15 and also implemented in glibc
> from version 2.28. It is commonly used in filesystem or security contexts.
>
> Constants RENAME_NOREPLACE, RENAME_EXCHANGE, RENAME_WHITEOUT are guarded by
> _GNU_SOURCE as with glibc.
>
> Signed-off-by: Tony Ambardar <Tony.Ambardar@gmail.com>
> ---
> v2 -> v3:
>  * call SYS_renameat first if applicable
>  * drop unneeded error code handling
>
> v1 -> v2:
>  * align related constants
>  * drop 'int' from 'unsigned int'
>  * add fallback to SYS_renameat where applicable
> ---
>  include/stdio.h       |  7 +++++++
>  src/linux/renameat2.c | 11 +++++++++++
>  2 files changed, 18 insertions(+)
>  create mode 100644 src/linux/renameat2.c
>
> diff --git a/include/stdio.h b/include/stdio.h
> index cb858618..4ea4c170 100644
> --- a/include/stdio.h
> +++ b/include/stdio.h
> @@ -158,6 +158,13 @@ char *ctermid(char *);
>  #define L_ctermid 20
>  #endif
>
> +#if defined(_GNU_SOURCE)
> +#define RENAME_NOREPLACE (1 << 0)
> +#define RENAME_EXCHANGE  (1 << 1)
> +#define RENAME_WHITEOUT  (1 << 2)
> +
> +int renameat2(int, const char *, int, const char *, unsigned);
> +#endif
>
>  #if defined(_XOPEN_SOURCE) || defined(_GNU_SOURCE) \
>   || defined(_BSD_SOURCE)
> diff --git a/src/linux/renameat2.c b/src/linux/renameat2.c
> new file mode 100644
> index 00000000..b8060388
> --- /dev/null
> +++ b/src/linux/renameat2.c
> @@ -0,0 +1,11 @@
> +#define _GNU_SOURCE
> +#include <stdio.h>
> +#include "syscall.h"
> +
> +int renameat2(int oldfd, const char *old, int newfd, const char *new,
> unsigned flags)
> +{
> +#ifdef SYS_renameat
> +       if (!flags) return syscall(SYS_renameat, oldfd, old, newfd, new);
> +#endif
> +       return syscall(SYS_renameat2, oldfd, old, newfd, new, flags);
> +}
> --
> 2.34.1

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