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Copy pathlock_nix.go
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102 lines (90 loc) · 2.79 KB
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//go:build !windows && !plan9 && !solaris
// +build !windows,!plan9,!solaris
// Copyright (c) 2015-2021 MinIO, Inc.
//
// This file is part of MinIO Object Storage stack
//
// This program is free software: you can redistribute it and/or modify
// it under the terms of the GNU Affero General Public License as published by
// the Free Software Foundation, either version 3 of the License, or
// (at your option) any later version.
//
// This program is distributed in the hope that it will be useful
// but WITHOUT ANY WARRANTY; without even the implied warranty of
// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
// GNU Affero General Public License for more details.
//
// You should have received a copy of the GNU Affero General Public License
// along with this program. If not, see <http://www.gnu.org/licenses/>.
package lock
import (
"os"
"syscall"
)
// Internal function implements support for both
// blocking and non blocking lock type.
func lockedOpenFile(path string, flag int, perm os.FileMode, lockType int) (*LockedFile, error) {
switch flag {
case syscall.O_RDONLY:
lockType |= syscall.LOCK_SH
case syscall.O_WRONLY:
fallthrough
case syscall.O_RDWR:
fallthrough
case syscall.O_WRONLY | syscall.O_CREAT:
fallthrough
case syscall.O_RDWR | syscall.O_CREAT:
lockType |= syscall.LOCK_EX
default:
return nil, &os.PathError{
Op: "open",
Path: path,
Err: syscall.EINVAL,
}
}
f, err := os.OpenFile(path, flag|syscall.O_SYNC, perm)
if err != nil {
return nil, err
}
if err = syscall.Flock(int(f.Fd()), lockType); err != nil {
f.Close()
if err == syscall.EWOULDBLOCK {
err = ErrAlreadyLocked
}
return nil, err
}
st, err := os.Stat(path)
if err != nil {
f.Close()
return nil, err
}
if st.IsDir() {
f.Close()
return nil, &os.PathError{
Op: "open",
Path: path,
Err: syscall.EISDIR,
}
}
return &LockedFile{File: f}, nil
}
// TryLockedOpenFile - tries a new write lock, functionality
// it is similar to LockedOpenFile with with syscall.LOCK_EX
// mode but along with syscall.LOCK_NB such that the function
// doesn't wait forever but instead returns if it cannot
// acquire a write lock.
func TryLockedOpenFile(path string, flag int, perm os.FileMode) (*LockedFile, error) {
return lockedOpenFile(path, flag, perm, syscall.LOCK_NB)
}
// LockedOpenFile - initializes a new lock and protects
// the file from concurrent access across mount points.
// This implementation doesn't support all the open
// flags and shouldn't be considered as replacement
// for os.OpenFile().
func LockedOpenFile(path string, flag int, perm os.FileMode) (*LockedFile, error) {
return lockedOpenFile(path, flag, perm, 0)
}
// Open - Call os.OpenFile
func Open(path string, flag int, perm os.FileMode) (*os.File, error) {
return os.OpenFile(path, flag, perm)
}