minio/cmd/posix-dirent_namelen_linux.go
Harshavardhana a8296445ad
Safely use unsafe.Pointer to avoid crashes on ARM (#8027)
Refactor the Dirent parsing code such that when we
calculate offsets are correct based on the platform
This PR fixes a silent potential crash on ARM
architecture.
2019-08-09 08:54:11 -07:00

44 lines
1.3 KiB
Go

// +build linux,!appengine
/*
* MinIO Cloud Storage, (C) 2019 MinIO, Inc.
*
* Licensed under the Apache License, Version 2.0 (the "License");
* you may not use this file except in compliance with the License.
* You may obtain a copy of the License at
*
* http://www.apache.org/licenses/LICENSE-2.0
*
* Unless required by applicable law or agreed to in writing, software
* distributed under the License is distributed on an "AS IS" BASIS,
* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
* See the License for the specific language governing permissions and
* limitations under the License.
*/
package cmd
import (
"bytes"
"fmt"
"syscall"
"unsafe"
)
func direntNamlen(dirent *syscall.Dirent) (uint64, error) {
const fixedHdr = uint16(unsafe.Offsetof(syscall.Dirent{}.Name))
nameBuf := (*[unsafe.Sizeof(dirent.Name)]byte)(unsafe.Pointer(&dirent.Name[0]))
const nameBufLen = uint16(len(nameBuf))
limit := dirent.Reclen - fixedHdr
if limit > nameBufLen {
limit = nameBufLen
}
// Avoid bugs in long file names
// https://github.com/golang/tools/commit/5f9a5413737ba4b4f692214aebee582b47c8be74
nameLen := bytes.IndexByte(nameBuf[:limit], 0)
if nameLen < 0 {
return 0, fmt.Errorf("failed to find terminating 0 byte in dirent")
}
return uint64(nameLen), nil
}