github.com/hugh712/snapd@v0.0.0-20200910133618-1a99902bd583/osutil/sys_linux.go (about) 1 // -*- Mode: Go; indent-tabs-mode: t -*- 2 3 /* 4 * Copyright (C) 2018 Canonical Ltd 5 * 6 * This program is free software: you can redistribute it and/or modify 7 * it under the terms of the GNU General Public License version 3 as 8 * published by the Free Software Foundation. 9 * 10 * This program is distributed in the hope that it will be useful, 11 * but WITHOUT ANY WARRANTY; without even the implied warranty of 12 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the 13 * GNU General Public License for more details. 14 * 15 * You should have received a copy of the GNU General Public License 16 * along with this program. If not, see <http://www.gnu.org/licenses/>. 17 * 18 */ 19 20 package osutil 21 22 import ( 23 "syscall" 24 "unsafe" 25 ) 26 27 // Symlinkat is a direct pass-through to the symlinkat(2) system call. 28 func Symlinkat(target string, dirfd int, linkpath string) error { 29 targetPtr, err := syscall.BytePtrFromString(target) 30 if err != nil { 31 return err 32 } 33 linkpathPtr, err := syscall.BytePtrFromString(linkpath) 34 if err != nil { 35 return err 36 } 37 _, _, errno := syscall.Syscall(syscall.SYS_SYMLINKAT, uintptr(unsafe.Pointer(targetPtr)), uintptr(dirfd), uintptr(unsafe.Pointer(linkpathPtr))) 38 if errno != 0 { 39 return errno 40 } 41 return nil 42 } 43 44 // Readlinkat is a direct pass-through to the readlinkat(2) system call. 45 func Readlinkat(dirfd int, path string, buf []byte) (n int, err error) { 46 var zero uintptr 47 48 pathPtr, err := syscall.BytePtrFromString(path) 49 if err != nil { 50 return 0, err 51 } 52 var bufPtr unsafe.Pointer 53 if len(buf) > 0 { 54 bufPtr = unsafe.Pointer(&buf[0]) 55 } else { 56 bufPtr = unsafe.Pointer(&zero) 57 } 58 r0, _, errno := syscall.Syscall6(syscall.SYS_READLINKAT, uintptr(dirfd), uintptr(unsafe.Pointer(pathPtr)), uintptr(bufPtr), uintptr(len(buf)), 0, 0) 59 n = int(r0) 60 if errno != 0 { 61 return 0, errno 62 } 63 return n, nil 64 }