vendor: Add dependencies for discosrv

vendor/github.com/cznic/fileutil/fileutil_linux.go

@@ -0,0 +1,96 @@
+// Copyright (c) 2014 The fileutil Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style
+// license that can be found in the LICENSE file.
+
+// +build !arm
+
+package fileutil
+
+import (
+	"bytes"
+	"io"
+	"io/ioutil"
+	"os"
+	"strconv"
+	"syscall"
+)
+
+func n(s []byte) byte {
+	for i, c := range s {
+		if c < '0' || c > '9' {
+			s = s[:i]
+			break
+		}
+	}
+	v, _ := strconv.Atoi(string(s))
+	return byte(v)
+}
+
+func init() {
+	b, err := ioutil.ReadFile("/proc/sys/kernel/osrelease")
+	if err != nil {
+		panic(err)
+	}
+
+	tokens := bytes.Split(b, []byte("."))
+	if len(tokens) > 3 {
+		tokens = tokens[:3]
+	}
+	switch len(tokens) {
+	case 3:
+		// Supported since kernel 2.6.38
+		if bytes.Compare([]byte{n(tokens[0]), n(tokens[1]), n(tokens[2])}, []byte{2, 6, 38}) < 0 {
+			puncher = func(*os.File, int64, int64) error { return nil }
+		}
+	case 2:
+		if bytes.Compare([]byte{n(tokens[0]), n(tokens[1])}, []byte{2, 7}) < 0 {
+			puncher = func(*os.File, int64, int64) error { return nil }
+		}
+	default:
+		puncher = func(*os.File, int64, int64) error { return nil }
+	}
+}
+
+var puncher = func(f *os.File, off, len int64) error {
+	const (
+		/*
+			/usr/include/linux$ grep FL_ falloc.h
+		*/
+		_FALLOC_FL_KEEP_SIZE  = 0x01 // default is extend size
+		_FALLOC_FL_PUNCH_HOLE = 0x02 // de-allocates range
+	)
+
+	_, _, errno := syscall.Syscall6(
+		syscall.SYS_FALLOCATE,
+		uintptr(f.Fd()),
+		uintptr(_FALLOC_FL_KEEP_SIZE|_FALLOC_FL_PUNCH_HOLE),
+		uintptr(off),
+		uintptr(len),
+		0, 0)
+	if errno != 0 {
+		return os.NewSyscallError("SYS_FALLOCATE", errno)
+	}
+	return nil
+}
+
+// PunchHole deallocates space inside a file in the byte range starting at
+// offset and continuing for len bytes. No-op for kernels < 2.6.38 (or < 2.7).
+func PunchHole(f *os.File, off, len int64) error {
+	return puncher(f, off, len)
+}
+
+// Fadvise predeclares an access pattern for file data.  See also 'man 2
+// posix_fadvise'.
+func Fadvise(f *os.File, off, len int64, advice FadviseAdvice) error {
+	_, _, errno := syscall.Syscall6(
+		syscall.SYS_FADVISE64,
+		uintptr(f.Fd()),
+		uintptr(off),
+		uintptr(len),
+		uintptr(advice),
+		0, 0)
+	return os.NewSyscallError("SYS_FADVISE64", errno)
+}
+
+// IsEOF reports whether err is an EOF condition.
+func IsEOF(err error) bool { return err == io.EOF }