[uclibc-ng-devel] Re: Implement 'futimesat' function for architectures where Linux does not provide a futimesat syscall.

Recently I tried compiling QEMU user emulation with uClibc on Aarch64, and found the 'futimesat' symbol was missing (but still defined in headers). This emulation is similar to the 'lutimesat' emulation. Regards, Elliot.

From 60d600b56627cceace22da19ea3803aa7ab6bcf2 Mon Sep 17 00:00:00 2001 From: Elliot Thomas &lt;elliot(a)midnightspark.net&gt; Date: Mon, 6 Mar 2023 01:21:05 +0000 Subject: [PATCH] Emulate 'futimesat' when __NR_futimesat is not available. --- libc/sysdeps/linux/common/futimesat.c | 26 ++++++++++++++++++++++++-- 1 file changed, 24 insertions(+), 2 deletions(-) diff --git a/libc/sysdeps/linux/common/futimesat.c b/libc/sysdeps/linux/common/futimesat.c index bd73eae7e..fd19fea7c 100644 --- a/libc/sysdeps/linux/common/futimesat.c +++ b/libc/sysdeps/linux/common/futimesat.c @@ -11,6 +11,28 @@ #ifdef __NR_futimesat _syscall3(int, futimesat, int, fd, const char *, file, const struct timeval *, tvp) -#else -/* should add emulation with futimes() and /proc/self/fd/ ... */ +#elif defined __NR_utimensat +#include <errno.h> +#define __need_NULL +#include <stddef.h> + +int futimesat(int dirfd, const char *file, const struct timeval tvp[2]) +{ + struct timespec ts[2]; + + if (tvp != NULL) + { + if (tvp[0].tv_usec < 0 || tvp[0].tv_usec >= 1000000 + || tvp[1].tv_usec < 0 || tvp[1].tv_usec >= 1000000) + { + __set_errno(EINVAL); + return -1; + } + + TIMEVAL_TO_TIMESPEC(&tvp[0], &ts[0]); + TIMEVAL_TO_TIMESPEC(&tvp[1], &ts[1]); + } + + return utimensat(dirfd, file, tvp ? ts : NULL, 0); +} #endif -- 2.39.2

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