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1741937d47
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: a528d35e8b ("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>
174 lines
5.9 KiB
C
174 lines
5.9 KiB
C
#ifndef _UAPI_LINUX_STAT_H
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#define _UAPI_LINUX_STAT_H
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#include <linux/types.h>
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#if defined(__KERNEL__) || !defined(__GLIBC__) || (__GLIBC__ < 2)
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#define S_IFMT 00170000
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#define S_IFSOCK 0140000
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#define S_IFLNK 0120000
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#define S_IFREG 0100000
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#define S_IFBLK 0060000
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#define S_IFDIR 0040000
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#define S_IFCHR 0020000
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#define S_IFIFO 0010000
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#define S_ISUID 0004000
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#define S_ISGID 0002000
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#define S_ISVTX 0001000
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#define S_ISLNK(m) (((m) & S_IFMT) == S_IFLNK)
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#define S_ISREG(m) (((m) & S_IFMT) == S_IFREG)
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#define S_ISDIR(m) (((m) & S_IFMT) == S_IFDIR)
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#define S_ISCHR(m) (((m) & S_IFMT) == S_IFCHR)
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#define S_ISBLK(m) (((m) & S_IFMT) == S_IFBLK)
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#define S_ISFIFO(m) (((m) & S_IFMT) == S_IFIFO)
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#define S_ISSOCK(m) (((m) & S_IFMT) == S_IFSOCK)
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#define S_IRWXU 00700
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#define S_IRUSR 00400
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#define S_IWUSR 00200
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#define S_IXUSR 00100
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#define S_IRWXG 00070
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#define S_IRGRP 00040
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#define S_IWGRP 00020
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#define S_IXGRP 00010
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#define S_IRWXO 00007
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#define S_IROTH 00004
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#define S_IWOTH 00002
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#define S_IXOTH 00001
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#endif
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/*
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* Timestamp structure for the timestamps in struct statx.
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*
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* tv_sec holds the number of seconds before (negative) or after (positive)
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* 00:00:00 1st January 1970 UTC.
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*
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* tv_nsec holds a number of nanoseconds (0..999,999,999) after the tv_sec time.
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*
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* __reserved is held in case we need a yet finer resolution.
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*/
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struct statx_timestamp {
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__s64 tv_sec;
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__u32 tv_nsec;
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__s32 __reserved;
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};
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/*
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* Structures for the extended file attribute retrieval system call
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* (statx()).
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*
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* The caller passes a mask of what they're specifically interested in as a
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* parameter to statx(). What statx() actually got will be indicated in
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* st_mask upon return.
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*
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* For each bit in the mask argument:
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*
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* - if the datum is not supported:
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*
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* - the bit will be cleared, and
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*
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* - the datum will be set to an appropriate fabricated value if one is
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* available (eg. CIFS can take a default uid and gid), otherwise
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*
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* - the field will be cleared;
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*
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* - otherwise, if explicitly requested:
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*
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* - the datum will be synchronised to the server if AT_STATX_FORCE_SYNC is
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* set or if the datum is considered out of date, and
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*
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* - the field will be filled in and the bit will be set;
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*
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* - otherwise, if not requested, but available in approximate form without any
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* effort, it will be filled in anyway, and the bit will be set upon return
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* (it might not be up to date, however, and no attempt will be made to
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* synchronise the internal state first);
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*
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* - otherwise the field and the bit will be cleared before returning.
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*
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* Items in STATX_BASIC_STATS may be marked unavailable on return, but they
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* will have values installed for compatibility purposes so that stat() and
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* co. can be emulated in userspace.
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*/
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struct statx {
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/* 0x00 */
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__u32 stx_mask; /* What results were written [uncond] */
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__u32 stx_blksize; /* Preferred general I/O size [uncond] */
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__u64 stx_attributes; /* Flags conveying information about the file [uncond] */
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/* 0x10 */
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__u32 stx_nlink; /* Number of hard links */
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__u32 stx_uid; /* User ID of owner */
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__u32 stx_gid; /* Group ID of owner */
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__u16 stx_mode; /* File mode */
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__u16 __spare0[1];
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/* 0x20 */
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__u64 stx_ino; /* Inode number */
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__u64 stx_size; /* File size */
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__u64 stx_blocks; /* Number of 512-byte blocks allocated */
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__u64 stx_attributes_mask; /* Mask to show what's supported in stx_attributes */
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/* 0x40 */
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struct statx_timestamp stx_atime; /* Last access time */
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struct statx_timestamp stx_btime; /* File creation time */
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struct statx_timestamp stx_ctime; /* Last attribute change time */
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struct statx_timestamp stx_mtime; /* Last data modification time */
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/* 0x80 */
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__u32 stx_rdev_major; /* Device ID of special file [if bdev/cdev] */
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__u32 stx_rdev_minor;
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__u32 stx_dev_major; /* ID of device containing file [uncond] */
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__u32 stx_dev_minor;
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/* 0x90 */
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__u64 __spare2[14]; /* Spare space for future expansion */
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/* 0x100 */
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};
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/*
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* Flags to be stx_mask
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*
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* Query request/result mask for statx() and struct statx::stx_mask.
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*
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* These bits should be set in the mask argument of statx() to request
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* particular items when calling statx().
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*/
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#define STATX_TYPE 0x00000001U /* Want/got stx_mode & S_IFMT */
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#define STATX_MODE 0x00000002U /* Want/got stx_mode & ~S_IFMT */
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#define STATX_NLINK 0x00000004U /* Want/got stx_nlink */
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#define STATX_UID 0x00000008U /* Want/got stx_uid */
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#define STATX_GID 0x00000010U /* Want/got stx_gid */
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#define STATX_ATIME 0x00000020U /* Want/got stx_atime */
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#define STATX_MTIME 0x00000040U /* Want/got stx_mtime */
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#define STATX_CTIME 0x00000080U /* Want/got stx_ctime */
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#define STATX_INO 0x00000100U /* Want/got stx_ino */
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#define STATX_SIZE 0x00000200U /* Want/got stx_size */
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#define STATX_BLOCKS 0x00000400U /* Want/got stx_blocks */
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#define STATX_BASIC_STATS 0x000007ffU /* The stuff in the normal stat struct */
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#define STATX_BTIME 0x00000800U /* Want/got stx_btime */
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#define STATX_ALL 0x00000fffU /* All currently supported flags */
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#define STATX__RESERVED 0x80000000U /* Reserved for future struct statx expansion */
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/*
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* Attributes to be found in stx_attributes and masked in stx_attributes_mask.
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*
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* These give information about the features or the state of a file that might
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* be of use to ordinary userspace programs such as GUIs or ls rather than
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* specialised tools.
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*
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* Note that the flags marked [I] correspond to generic FS_IOC_FLAGS
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* semantically. Where possible, the numerical value is picked to correspond
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* also.
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*/
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#define STATX_ATTR_COMPRESSED 0x00000004 /* [I] File is compressed by the fs */
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#define STATX_ATTR_IMMUTABLE 0x00000010 /* [I] File is marked immutable */
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#define STATX_ATTR_APPEND 0x00000020 /* [I] File is append-only */
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#define STATX_ATTR_NODUMP 0x00000040 /* [I] File is not to be dumped */
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#define STATX_ATTR_ENCRYPTED 0x00000800 /* [I] File requires key to decrypt in fs */
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#define STATX_ATTR_AUTOMOUNT 0x00001000 /* Dir: Automount trigger */
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#endif /* _UAPI_LINUX_STAT_H */
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