* [musl] [PATCH v2] pass AT_NO_AUTOMOUNT when emulating fstatat via statx
@ 2023-10-07 18:02 Alexey Izbyshev
2023-10-07 21:09 ` Rich Felker
0 siblings, 1 reply; 2+ messages in thread
From: Alexey Izbyshev @ 2023-10-07 18:02 UTC (permalink / raw)
To: musl
AT_NO_AUTOMOUNT is implied for stat/lstat/fstatat syscalls since Linux
3.1 [1]. However, this is not the case for statx syscall, which defaults
to automounting, so this flag must be passed explicitly when statx is
used to implement stat-like functions.
This change affects only arches which use 32-bit seconds in struct kstat,
as well as out-of-tree/future ports to arches which lack SYS_fstatat.
[1] https://git.kernel.org/torvalds/c/b6c8069d3577481390b3f24a8434ad72a3235594
---
Fixed the wrong statement about affected arches in the commit message.
---
src/stat/fstatat.c | 1 +
1 file changed, 1 insertion(+)
diff --git a/src/stat/fstatat.c b/src/stat/fstatat.c
index 04506375d897..9eed063b26bc 100644
--- a/src/stat/fstatat.c
+++ b/src/stat/fstatat.c
@@ -36,6 +36,7 @@ static int fstatat_statx(int fd, const char *restrict path, struct stat *restric
{
struct statx stx;
+ flag |= AT_NO_AUTOMOUNT;
int ret = __syscall(SYS_statx, fd, path, flag, 0x7ff, &stx);
if (ret) return ret;
--
2.39.2
^ permalink raw reply [flat|nested] 2+ messages in thread
* Re: [musl] [PATCH v2] pass AT_NO_AUTOMOUNT when emulating fstatat via statx
2023-10-07 18:02 [musl] [PATCH v2] pass AT_NO_AUTOMOUNT when emulating fstatat via statx Alexey Izbyshev
@ 2023-10-07 21:09 ` Rich Felker
0 siblings, 0 replies; 2+ messages in thread
From: Rich Felker @ 2023-10-07 21:09 UTC (permalink / raw)
To: musl
On Sat, Oct 07, 2023 at 09:02:18PM +0300, Alexey Izbyshev wrote:
> AT_NO_AUTOMOUNT is implied for stat/lstat/fstatat syscalls since Linux
> 3.1 [1]. However, this is not the case for statx syscall, which defaults
> to automounting, so this flag must be passed explicitly when statx is
> used to implement stat-like functions.
>
> This change affects only arches which use 32-bit seconds in struct kstat,
> as well as out-of-tree/future ports to arches which lack SYS_fstatat.
>
> [1] https://git.kernel.org/torvalds/c/b6c8069d3577481390b3f24a8434ad72a3235594
> ---
> Fixed the wrong statement about affected arches in the commit message.
Indeed, statx is always used on 32-bit archs. 32-bit archs with no
legacy 32-bit kernel timespec struct (i.e. rv32) don't have the legacy
stat syscalls either.
> ---
> src/stat/fstatat.c | 1 +
> 1 file changed, 1 insertion(+)
>
> diff --git a/src/stat/fstatat.c b/src/stat/fstatat.c
> index 04506375d897..9eed063b26bc 100644
> --- a/src/stat/fstatat.c
> +++ b/src/stat/fstatat.c
> @@ -36,6 +36,7 @@ static int fstatat_statx(int fd, const char *restrict path, struct stat *restric
> {
> struct statx stx;
>
> + flag |= AT_NO_AUTOMOUNT;
> int ret = __syscall(SYS_statx, fd, path, flag, 0x7ff, &stx);
> if (ret) return ret;
>
> --
> 2.39.2
I think this is ok. I recall noticing something about this when
initially adding it but not being sure what behavior the legacy stat
syscall would give or whether it's "right". But short of a very good
reason to differ from the kernel default (which would then require
changing other archs to match), I think we just need to make it
consistent with what happens on other archs.
Rich
^ permalink raw reply [flat|nested] 2+ messages in thread
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2023-10-07 18:02 [musl] [PATCH v2] pass AT_NO_AUTOMOUNT when emulating fstatat via statx Alexey Izbyshev
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