2ceef01afe
Add faccessat(2) with a hack for symlink, because the
kernel does not actually looks at the passed flags.
From man 2 faccessat:
C library/kernel differences
The raw faccessat() system call takes only the first three argu‐
ments. The AT_EACCESS and AT_SYMLINK_NOFOLLOW flags are actually
implemented within the glibc wrapper function for faccessat().
41 lines
1.1 KiB
Go
41 lines
1.1 KiB
Go
package syscallcompat
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import (
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"syscall"
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"golang.org/x/sys/unix"
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)
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// Readlinkat exists both in Linux and in MacOS 10.10+. We may add an
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// emulated version for users on older MacOS versions if there is
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// demand.
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// Buffer allocation is handled internally, unlike the bare unix.Readlinkat.
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func Readlinkat(dirfd int, path string) (string, error) {
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// Allocate the buffer exponentially like os.Readlink does.
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for bufsz := 128; ; bufsz *= 2 {
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buf := make([]byte, bufsz)
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n, err := unix.Readlinkat(dirfd, path, buf)
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if err != nil {
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return "", err
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}
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if n < bufsz {
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return string(buf[0:n]), nil
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}
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}
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}
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// Faccessat exists both in Linux and in MacOS 10.10+, but the Linux version
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// DOES NOT support any flags. Emulate AT_SYMLINK_NOFOLLOW like glibc does.
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func Faccessat(dirfd int, path string, mode uint32) error {
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var st unix.Stat_t
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err := Fstatat(dirfd, path, &st, unix.AT_SYMLINK_NOFOLLOW)
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if err != nil {
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return err
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}
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if st.Mode&syscall.S_IFMT == syscall.S_IFLNK {
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// Pretend that a symlink is always accessible
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return nil
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}
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return unix.Faccessat(dirfd, path, mode, 0)
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}
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