https://github.com/torvalds/linux
Revision 1741937d475d91ed95abb37f07e8571e23b9a7fe authored by Dmitry V. Levin on 26 April 2017, 13:50:00 UTC, committed by Al Viro on 27 April 2017, 01:19:05 UTC
The comment asserting that the value of struct statx_timestamp.tv_nsec must be negative when statx_timestamp.tv_sec is negative, is wrong, as could be seen from the following example: #define _FILE_OFFSET_BITS 64 #include <assert.h> #include <fcntl.h> #include <stdio.h> #include <sys/stat.h> #include <unistd.h> #include <asm/unistd.h> #include <linux/stat.h> int main(void) { static const struct timespec ts[2] = { { .tv_nsec = UTIME_OMIT }, { .tv_sec = -2, .tv_nsec = 42 } }; assert(utimensat(AT_FDCWD, ".", ts, 0) == 0); struct stat st; assert(stat(".", &st) == 0); printf("st_mtim.tv_sec = %lld, st_mtim.tv_nsec = %lu\n", (long long) st.st_mtim.tv_sec, (unsigned long) st.st_mtim.tv_nsec); struct statx stx; assert(syscall(__NR_statx, AT_FDCWD, ".", 0, 0, &stx) == 0); printf("stx_mtime.tv_sec = %lld, stx_mtime.tv_nsec = %lu\n", (long long) stx.stx_mtime.tv_sec, (unsigned long) stx.stx_mtime.tv_nsec); return 0; } It expectedly prints: st_mtim.tv_sec = -2, st_mtim.tv_nsec = 42 stx_mtime.tv_sec = -2, stx_mtime.tv_nsec = 42 The more generic comment asserting that the value of struct statx_timestamp.tv_nsec might be negative is confusing to say the least. It contradicts both the struct stat.st_[acm]time_nsec tradition and struct timespec.tv_nsec requirements in utimensat syscall. If statx syscall ever returns a stx_[acm]time containing a negative tv_nsec that cannot be passed unmodified to utimensat syscall, it will cause an immense confusion. Fix this source of confusion by changing the type of struct statx_timestamp.tv_nsec from __s32 to __u32. Fixes: a528d35e8bfc ("statx: Add a system call to make enhanced file info available") Signed-off-by: Dmitry V. Levin <ldv@altlinux.org> Signed-off-by: David Howells <dhowells@redhat.com> cc: linux-api@vger.kernel.org cc: mtk.manpages@gmail.com Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
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Tip revision: 1741937d475d91ed95abb37f07e8571e23b9a7fe authored by Dmitry V. Levin on 26 April 2017, 13:50:00 UTC
uapi: change the type of struct statx_timestamp.tv_nsec to unsigned
uapi: change the type of struct statx_timestamp.tv_nsec to unsigned
Tip revision: 1741937
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certs | ||
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net | ||
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.cocciconfig | -rw-r--r-- | 59 bytes |
.get_maintainer.ignore | -rw-r--r-- | 31 bytes |
.gitattributes | -rw-r--r-- | 30 bytes |
.gitignore | -rw-r--r-- | 1.3 KB |
.mailmap | -rw-r--r-- | 7.9 KB |
COPYING | -rw-r--r-- | 18.3 KB |
CREDITS | -rw-r--r-- | 96.0 KB |
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MAINTAINERS | -rw-r--r-- | 389.4 KB |
Makefile | -rw-r--r-- | 57.8 KB |
README | -rw-r--r-- | 722 bytes |
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