Applied, thank you
On Sun, Apr 11, 2021 at 7:44 AM urmum-69 <urmu...@snopyta.org> wrote:
>
> This patch changes the functions used to update timestamps in touch.
>
> Before, utimes() and lutimes() were used, which had certain
> disadvantages.
> They are unable to handle nanosecond timestamps, and implementations of
> certain features like -a and -m require running stat() in a loop.
>
> Almost all implementations of utimes() and lutimes() are wrappers for
> utimensat(), this is the case for glibc, ulibc and musl libc.
> ---
> I forgot to initialize the nanoseconds of timebuf[x].tv_nsec, so if a
> date was specified, random values would be passed to utimes(), causing
> undefined behavior.
>
> This patch should be applied on top of Xabier Oneca's patches to
> implement the -a and -m options in touch.
>
> coreutils/touch.c | 57 +++++++++++++++++------------------------------
> 1 file changed, 20 insertions(+), 37 deletions(-)
>
> diff --git a/coreutils/touch.c b/coreutils/touch.c
> index 8af602b5e..a12501616 100644
> --- a/coreutils/touch.c
> +++ b/coreutils/touch.c
> @@ -25,7 +25,6 @@
> //config: depends on TOUCH
> //config: help
> //config: Enable touch to have the -h option.
> -//config: This requires libc support for lutimes() function.
> //config:
> //config:config FEATURE_TOUCH_SUSV3
> //config: bool "Add support for SUSV3 features (-a -d -m -t -r)"
> @@ -98,7 +97,7 @@ int touch_main(int argc UNUSED_PARAM, char **argv)
> OPT_h = (1 << 6) * ENABLE_FEATURE_TOUCH_NODEREF,
> };
> /* NULL = use current time */
> - const struct timeval *newtime = NULL;
> + const struct timespec *newtime = NULL;
> #if ENABLE_LONG_OPTS
> static const char touch_longopts[] ALIGN1 =
> /* name, has_arg, val */
> @@ -112,12 +111,12 @@ int touch_main(int argc UNUSED_PARAM, char **argv)
> char *reference_file = NULL;
> char *date_str = NULL;
> /* timebuf[0] is atime, timebuf[1] is mtime */
> - struct timeval timebuf[2];
> - timebuf[1].tv_usec = timebuf[0].tv_usec = 0;
> + struct timespec timebuf[2];
> + timebuf[0].tv_nsec = timebuf[1].tv_nsec = UTIME_NOW;
> #else
> # define reference_file NULL
> # define date_str NULL
> -# define timebuf ((struct timeval*)NULL)
> +# define timebuf ((struct timespec*)NULL)
> #endif
>
> /* -d and -t both set time. In coreutils,
> @@ -144,10 +143,8 @@ int touch_main(int argc UNUSED_PARAM, char **argv)
> xstat(reference_file, &stbuf);
> timebuf[0].tv_sec = stbuf.st_atime;
> timebuf[1].tv_sec = stbuf.st_mtime;
> - /* Can use .st_mtim.tv_nsec
> - * (or is it .st_mtimensec?? see date.c)
> - * to set microseconds too.
> - */
> + timebuf[0].tv_nsec = stbuf.st_atim.tv_nsec;
> + timebuf[1].tv_nsec = stbuf.st_mtim.tv_nsec;
> newtime = timebuf;
> }
>
> @@ -166,39 +163,25 @@ int touch_main(int argc UNUSED_PARAM, char **argv)
> t = validate_tm_time(date_str, &tm_time);
>
> timebuf[1].tv_sec = timebuf[0].tv_sec = t;
> + timebuf[1].tv_nsec = timebuf[0].tv_nsec = 0;
> newtime = timebuf;
> }
>
> - if ((opts & (OPT_a | OPT_m)) && !newtime) {
> - time(&timebuf[0].tv_sec);
> - timebuf[1].tv_sec = timebuf[0].tv_sec;
> + if ((opts & OPT_a) && !(opts & OPT_m)) {
> + timebuf[1].tv_nsec = UTIME_OMIT;
> + newtime = timebuf;
> + }
> + if ((opts & OPT_m) && !(opts & OPT_a)) {
> + timebuf[0].tv_nsec = UTIME_OMIT;
> newtime = timebuf;
> }
>
> do {
> - int result;
> -
> - if (opts & (OPT_a | OPT_m)) {
> - /* Save original times */
> - struct stat stbuf;
> - if(stat(*argv, &stbuf) == 0) {
> - /* As we must set both times, we lose original
> - * file time microseconds.
> - * Can use .st_mtim.tv_nsec
> - * (or is it .st_mtimensec?? see date.c)
> - * to set microseconds too.
> - * Also, utimensat(2) allows to omit one of
> the
> - * times to be set. But it is SUSv4.
> - */
> - if (!(opts & OPT_a))
> - timebuf[0].tv_sec = stbuf.st_atime;
> - if (!(opts & OPT_m))
> - timebuf[1].tv_sec = stbuf.st_mtime;
> - }
> - }
> -
> - result = (ENABLE_FEATURE_TOUCH_NODEREF && (opts & OPT_h) ?
> lutimes : utimes)(*argv, newtime);
> -
> + int result =
> +#if ENABLE_FEATURE_TOUCH_NODEREF
> + (opts & OPT_h) ? utimensat(AT_FDCWD, *argv, newtime,
> AT_SYMLINK_NOFOLLOW) :
> +#endif
> + utimensat(AT_FDCWD, *argv, newtime, 0);
> if (result != 0) {
> if (errno == ENOENT) { /* no such file? */
> if (opts & OPT_c) {
> @@ -208,9 +191,9 @@ int touch_main(int argc UNUSED_PARAM, char **argv)
> /* Try to create the file */
> fd = open(*argv, O_RDWR | O_CREAT, 0666);
> if (fd >= 0) {
> - xclose(fd);
> if (reference_file || date_str)
> - utimes(*argv, newtime);
> + futimens(fd, newtime);
> + xclose(fd);
> continue;
> }
> }
> --
> 2.31.1
>
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