This file is indexed.

/usr/share/gocode/src/github.com/hanwen/go-fuse/fuse/mount_linux.go is in golang-github-hanwen-go-fuse-dev 0.0~git20171124.0.14c3015-4.

This file is owned by root:root, with mode 0o644.

The actual contents of the file can be viewed below.

  1
  2
  3
  4
  5
  6
  7
  8
  9
 10
 11
 12
 13
 14
 15
 16
 17
 18
 19
 20
 21
 22
 23
 24
 25
 26
 27
 28
 29
 30
 31
 32
 33
 34
 35
 36
 37
 38
 39
 40
 41
 42
 43
 44
 45
 46
 47
 48
 49
 50
 51
 52
 53
 54
 55
 56
 57
 58
 59
 60
 61
 62
 63
 64
 65
 66
 67
 68
 69
 70
 71
 72
 73
 74
 75
 76
 77
 78
 79
 80
 81
 82
 83
 84
 85
 86
 87
 88
 89
 90
 91
 92
 93
 94
 95
 96
 97
 98
 99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
// Copyright 2016 the Go-FUSE Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.

package fuse

import (
	"bytes"
	"fmt"
	"os"
	"os/exec"
	"path"
	"strings"
	"syscall"
	"unsafe"
)

func unixgramSocketpair() (l, r *os.File, err error) {
	fd, err := syscall.Socketpair(syscall.AF_UNIX, syscall.SOCK_SEQPACKET, 0)
	if err != nil {
		return nil, nil, os.NewSyscallError("socketpair",
			err.(syscall.Errno))
	}
	l = os.NewFile(uintptr(fd[0]), "socketpair-half1")
	r = os.NewFile(uintptr(fd[1]), "socketpair-half2")
	return
}

// Create a FUSE FS on the specified mount point.  The returned
// mount point is always absolute.
func mount(mountPoint string, opts *MountOptions, ready chan<- error) (fd int, err error) {
	local, remote, err := unixgramSocketpair()
	if err != nil {
		return
	}

	defer local.Close()
	defer remote.Close()

	bin, err := fusermountBinary()
	if err != nil {
		return 0, err
	}

	cmd := []string{bin, mountPoint}
	if s := opts.optionsStrings(); len(s) > 0 {
		cmd = append(cmd, "-o", strings.Join(s, ","))
	}
	proc, err := os.StartProcess(bin,
		cmd,
		&os.ProcAttr{
			Env:   []string{"_FUSE_COMMFD=3"},
			Files: []*os.File{os.Stdin, os.Stdout, os.Stderr, remote}})

	if err != nil {
		return
	}

	w, err := proc.Wait()
	if err != nil {
		return
	}
	if !w.Success() {
		err = fmt.Errorf("fusermount exited with code %v\n", w.Sys())
		return
	}

	fd, err = getConnection(local)
	if err != nil {
		return -1, err
	}

	// golang sets CLOEXEC on file descriptors when they are
	// acquired through normal operations (e.g. open).
	// Buf for fd, we have to set CLOEXEC manually
	syscall.CloseOnExec(fd)

	close(ready)
	return fd, err
}

func unmount(mountPoint string) (err error) {
	if os.Geteuid() == 0 {
		return syscall.Unmount(mountPoint, 0)
	}
	bin, err := fusermountBinary()
	if err != nil {
		return err
	}
	errBuf := bytes.Buffer{}
	cmd := exec.Command(bin, "-u", mountPoint)
	cmd.Stderr = &errBuf
	err = cmd.Run()
	if errBuf.Len() > 0 {
		return fmt.Errorf("%s (code %v)\n",
			errBuf.String(), err)
	}
	return err
}

func getConnection(local *os.File) (int, error) {
	var data [4]byte
	control := make([]byte, 4*256)

	// n, oobn, recvflags, from, errno  - todo: error checking.
	_, oobn, _, _,
		err := syscall.Recvmsg(
		int(local.Fd()), data[:], control[:], 0)
	if err != nil {
		return 0, err
	}

	message := *(*syscall.Cmsghdr)(unsafe.Pointer(&control[0]))
	fd := *(*int32)(unsafe.Pointer(uintptr(unsafe.Pointer(&control[0])) + syscall.SizeofCmsghdr))

	if message.Type != 1 {
		return 0, fmt.Errorf("getConnection: recvmsg returned wrong control type: %d", message.Type)
	}
	if oobn <= syscall.SizeofCmsghdr {
		return 0, fmt.Errorf("getConnection: too short control message. Length: %d", oobn)
	}
	if fd < 0 {
		return 0, fmt.Errorf("getConnection: fd < 0: %d", fd)
	}
	return int(fd), nil
}

// lookPathFallback - search binary in PATH and, if that fails,
// in fallbackDir. This is useful if PATH is possible empty.
func lookPathFallback(file string, fallbackDir string) (string, error) {
	binPath, err := exec.LookPath(file)
	if err == nil {
		return binPath, nil
	}

	abs := path.Join(fallbackDir, file)
	return exec.LookPath(abs)
}

func fusermountBinary() (string, error) {
	return lookPathFallback("fusermount", "/bin")
}

func umountBinary() (string, error) {
	return lookPathFallback("umount", "/bin")
}