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Improve docs of more system calls

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This change also found a few POSIX compliance bugs with errnos. Another
bug was discovered where, on Windows, pread() and pwrite() could modify
the file position in cases where ReadFile() returned an error e.g. when
seeking past the end of file. We also have more tests!
This commit is contained in:
Justine Tunney 2022-10-02 22:14:33 -07:00
parent af24c19db3
commit ccbae7799e
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GPG key ID: BE714B4575D6E328
39 changed files with 589 additions and 175 deletions
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67
libc/calls/utimensat.c
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@ -30,54 +30,43 @@
#include "libc/zipos/zipos.internal.h"
/**
* Sets atime/mtime on file, the modern way.
* Sets access/modified time on file, the modern way.
*
* This is two functions in one. If `path` is null then this function
* becomes the same as `futimens(dirfd, ts)`.
* XNU only has microsecond (1e-6) accuracy and there's no
* `dirfd`-relative support. Windows only has hectonanosecond (1e-7)
* accuracy. RHEL5 is somewhat broken so utimes() is recommended if
* portability to old versions of Linux is desired.
*
* XNU and RHEL5 only have microsecond accuracy and there's no `dirfd`
* relative support.
*
* @param dirfd should AT_FDCWD
* @param ts is atime/mtime, or null for current time
* @param flags can have AT_SYMLINK_NOFOLLOW
* @raise ENOSYS on RHEL5 if path is NULL
* @raise EINVAL if flags had unrecognized bits
* @raise EINVAL if path is NULL and flags has AT_SYMLINK_NOFOLLOW
* @raise EBADF if dirfd isn't a valid fd or AT_FDCWD
* @raise EFAULT if path or ts memory was invalid
* @raise EROFS if file system is read-only
* @raise ENAMETOOLONG
* @raise EPERM
* @param dirfd is usually `AT_FDCWD`
* @param path is filename whose timestamps should be modified
* @param ts is {access, modified} timestamps, or null for current time
* @param flags can have `AT_SYMLINK_NOFOLLOW` when `path` is specified
* @return 0 on success, or -1 w/ errno
* @raise EINVAL if `flags` had an unrecognized value
* @raise EPERM if pledge() is in play without `fattr` promise
* @raise EACCES if unveil() is in play and `path` isn't unveiled
* @raise ENOTSUP if `path` is a zip filesystem path or `dirfd` is zip
* @raise EINVAL if `ts` specifies a nanosecond value that's out of range
* @raise ENAMETOOLONG if symlink-resolved `path` length exceeds `PATH_MAX`
* @raise ENAMETOOLONG if component in `path` exists longer than `NAME_MAX`
* @raise EBADF if `dirfd` isn't a valid fd or `AT_FDCWD`
* @raise EFAULT if `path` or `ts` memory was invalid
* @raise EROFS if `path` is on read-only filesystem
* @raise ENOSYS on bare metal
* @see futimens()
* @asyncsignalsafe
* @threadsafe
*/
int utimensat(int dirfd, const char *path, const struct timespec ts[2],
int flags) {
int rc;
if (IsAsan() && ((dirfd == AT_FDCWD && !__asan_is_valid(path, 1)) ||
(ts && (!__asan_is_valid_timespec(ts + 0) ||
!__asan_is_valid_timespec(ts + 1))))) {
rc = efault(); // bad memory
} else if ((flags & ~AT_SYMLINK_NOFOLLOW)) {
rc = einval(); // unsupported flag
} else if (!path && flags) {
rc = einval(); // futimens() doesn't take flags
} else if ((path || __isfdkind(dirfd, kFdZip)) && _weaken(__zipos_notat) &&
(rc = __zipos_notat(dirfd, path)) == -1) {
STRACE("zipos utimensat not supported yet");
} else if (!IsWindows()) {
rc = sys_utimensat(dirfd, path, ts, flags);
if (!path) {
rc = efault(); // linux kernel abi behavior isn't supported
} else {
rc = sys_utimensat_nt(dirfd, path, ts, flags);
}
if (ts) {
STRACE("utimensat(%s, %#s, {{%,ld, %,ld}, {%,ld, %,ld}}, %#b) → %d% m",
DescribeDirfd(dirfd), path, ts[0].tv_sec, ts[0].tv_nsec,
ts[1].tv_sec, ts[1].tv_nsec, flags, rc);
} else {
STRACE("utimensat(%s, %#s, 0, %#b) → %d% m", DescribeDirfd(dirfd), path,
flags, rc);
rc = __utimens(dirfd, path, ts, flags);
}
STRACE("utimensat(%s, %#s, {%s, %s}, %#o) → %d% m", DescribeDirfd(dirfd),
path, DescribeTimespec(0, ts), DescribeTimespec(0, ts ? ts + 1 : 0),
flags, rc);
return rc;
}