package syscallcompat import ( "syscall" "golang.org/x/sys/unix" ) // PATH_MAX is the maximum allowed path length on Linux. // It is not defined on Darwin, so we use the Linux value. const PATH_MAX = 4096 // Readlinkat is a convenience wrapper around unix.Readlinkat() that takes // care of buffer sizing. Implemented like os.Readlink(). func Readlinkat(dirfd int, path string) (string, error) { // Allocate the buffer exponentially like os.Readlink does. for bufsz := 128; ; bufsz *= 2 { buf := make([]byte, bufsz) n, err := unix.Readlinkat(dirfd, path, buf) if err != nil { return "", err } if n < bufsz { return string(buf[0:n]), nil } } } // Faccessat exists both in Linux and in MacOS 10.10+, but the Linux version // DOES NOT support any flags. Emulate AT_SYMLINK_NOFOLLOW like glibc does. func Faccessat(dirfd int, path string, mode uint32) error { var st unix.Stat_t err := Fstatat(dirfd, path, &st, unix.AT_SYMLINK_NOFOLLOW) if err != nil { return err } if st.Mode&syscall.S_IFMT == syscall.S_IFLNK { // Pretend that a symlink is always accessible return nil } return unix.Faccessat(dirfd, path, mode, 0) } // Linkat exists both in Linux and in MacOS 10.10+. func Linkat(olddirfd int, oldpath string, newdirfd int, newpath string, flags int) (err error) { return unix.Linkat(olddirfd, oldpath, newdirfd, newpath, flags) }