rename all remaining packages to internal/ (#12418)

This is to ensure that there are no projects
that try to import `minio/minio/pkg` into
their own repo. Any such common packages should
go to `https://github.com/minio/pkg`

internal/lock/lock_nix.go

@@ -0,0 +1,101 @@
+// +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)
+}