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110 lines
3.0 KiB
Go
110 lines
3.0 KiB
Go
// -*- Mode: Go; indent-tabs-mode: t -*-
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/*
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* Copyright (C) 2017 Canonical Ltd
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*
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* This program is free software: you can redistribute it and/or modify
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* it under the terms of the GNU General Public License version 3 as
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* published by the Free Software Foundation.
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*
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* This program is distributed in the hope that it will be useful,
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* but WITHOUT ANY WARRANTY; without even the implied warranty of
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* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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* GNU General Public License for more details.
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*
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* You should have received a copy of the GNU General Public License
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* along with this program. If not, see <http://www.gnu.org/licenses/>.
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*
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*/
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package sys
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import (
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"os"
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"syscall"
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"unsafe"
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)
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// FlagID can be passed to chown-ish functions to mean "no change",
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// and can be returned from getuid-ish functions to mean "not found".
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const FlagID = 1<<32 - 1
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// UserID is the type of the system's user identifiers (in C, uid_t).
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//
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// We give it its own explicit type so you don't have to remember that
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// it's a uint32 (which lead to the bug this package fixes in the
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// first place)
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type UserID uint32
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// GroupID is the type of the system's group identifiers (in C, gid_t).
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type GroupID uint32
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// uid_t is an unsigned 32-bit integer in linux right now.
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// so syscall.Gete?[ug]id are wrong, and break in 32 bits
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// (see https://github.com/golang/go/issues/22739)
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func Getuid() UserID {
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return UserID(getid(_SYS_GETUID))
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}
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func Geteuid() UserID {
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return UserID(getid(_SYS_GETEUID))
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}
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func Getgid() GroupID {
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return GroupID(getid(_SYS_GETGID))
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}
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func Getegid() GroupID {
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return GroupID(getid(_SYS_GETEGID))
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}
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func getid(id uintptr) uint32 {
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// these are documented as not failing, but see golang#22924
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r0, _, errno := syscall.RawSyscall(id, 0, 0, 0)
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if errno != 0 {
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return uint32(-errno)
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}
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return uint32(r0)
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}
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func Chown(f *os.File, uid UserID, gid GroupID) error {
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return Fchown(int(f.Fd()), uid, gid)
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}
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func Fchown(fd int, uid UserID, gid GroupID) error {
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_, _, errno := syscall.Syscall(syscall.SYS_FCHOWN, uintptr(fd), uintptr(uid), uintptr(gid))
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if errno == 0 {
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return nil
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}
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return errno
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}
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func ChownPath(path string, uid UserID, gid GroupID) error {
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AT_FDCWD := -100 // also written as -0x64 in ztypes_linux_*.go (but -100 in sys_linux_*.s, and /usr/include/linux/fcntl.h)
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return FchownAt(uintptr(AT_FDCWD), path, uid, gid, 0)
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}
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func FchownAt(dirfd uintptr, path string, uid UserID, gid GroupID, flags int) error {
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p0, err := syscall.BytePtrFromString(path)
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if err != nil {
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return err
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}
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_, _, errno := syscall.Syscall6(_SYS_FCHOWNAT, dirfd, uintptr(unsafe.Pointer(p0)), uintptr(uid), uintptr(gid), uintptr(flags), 0)
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if errno == 0 {
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return nil
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}
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return errno
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}
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// As of Go 1.9, the O_PATH constant does not seem to be declared
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// uniformly over all archtiectures.
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const O_PATH = 0x200000
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func FcntlGetFl(fd int) (int, error) {
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flags, _, errno := syscall.Syscall(syscall.SYS_FCNTL, uintptr(fd), uintptr(syscall.F_GETFL), 0)
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if errno != 0 {
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return 0, errno
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}
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return int(flags), nil
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}
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