Re: [PATCH v2 1/2] tools/nolibc: Add dirfd()

["Thomas Weißschuh" <linux@weissschuh.net>]

On 2026-10-07 14:29:12+0900, Daniel Palmer wrote:
> This is useful for things like fstatat() on children of a directory
> opened with opendir().
> 
> At the same time use the new internal helper to replace the two places
> that are converting the DIR pointer back into an fd.
> 
> Signed-off-by: Daniel Palmer <daniel@thingy.jp>
> ---
>  tools/include/nolibc/dirent.h | 38 +++++++++++++++++++++++++++--------
>  1 file changed, 30 insertions(+), 8 deletions(-)
> 
> diff --git a/tools/include/nolibc/dirent.h b/tools/include/nolibc/dirent.h
> index 4e02ef25e72d..d282ea8eb5d3 100644
> --- a/tools/include/nolibc/dirent.h
> +++ b/tools/include/nolibc/dirent.h
> @@ -27,6 +27,18 @@ typedef struct {
>  	char dummy[1];
>  } DIR;
>  
> +/* Internal dirfd() that does not set errno */
> +static __attribute__((unused))
> +int __nolibc_dirfd(DIR *dirp)
> +{
> +	intptr_t i = (intptr_t)dirp;
> +
> +	if (i >= 0)
> +		return -1;
> +
> +	return ~i;
> +}

I'm fine with keeping __nolibc_dirfd(), but the diffs would be nicer if
it was introduced in a dedicated commit.

> +
>  static __attribute__((unused))
>  DIR *fdopendir(int fd)
>  {
> @@ -49,15 +61,27 @@ DIR *opendir(const char *name)
>  }
>  
>  static __attribute__((unused))
> -int closedir(DIR *dirp)
> +int dirfd(DIR *dirp)
>  {
> -	intptr_t i = (intptr_t)dirp;
> +	int fd = __nolibc_dirfd(dirp);
>  
> -	if (i >= 0) {
> +	if (fd < 0) {
>  		SET_ERRNO(EBADF);
>  		return -1;
>  	}
> -	return close(~i);
> +
> +	return fd;
> +}

(...)