/usr/share/gocode/src/github.com/jacobsa/bazilfuse/mount_linux.go is in golang-github-jacobsa-bazilfuse-dev 0.0~git20150622-2.
This file is owned by root:root, with mode 0o644.
The actual contents of the file can be viewed below.
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import (
"bufio"
"fmt"
"io"
"log"
"net"
"os"
"os/exec"
"sync"
"syscall"
)
func lineLogger(wg *sync.WaitGroup, prefix string, r io.ReadCloser) {
defer wg.Done()
scanner := bufio.NewScanner(r)
for scanner.Scan() {
switch line := scanner.Text(); line {
case `fusermount: failed to open /etc/fuse.conf: Permission denied`:
// Silence this particular message, it occurs way too
// commonly and isn't very relevant to whether the mount
// succeeds or not.
continue
default:
log.Printf("%s: %s", prefix, line)
}
}
if err := scanner.Err(); err != nil {
log.Printf("%s, error reading: %v", prefix, err)
}
}
func mount(dir string, conf *mountConfig, ready chan<- struct{}, errp *error) (fusefd *os.File, err error) {
// linux mount is never delayed
close(ready)
fds, err := syscall.Socketpair(syscall.AF_FILE, syscall.SOCK_STREAM, 0)
if err != nil {
return nil, fmt.Errorf("socketpair error: %v", err)
}
writeFile := os.NewFile(uintptr(fds[0]), "fusermount-child-writes")
defer writeFile.Close()
readFile := os.NewFile(uintptr(fds[1]), "fusermount-parent-reads")
defer readFile.Close()
cmd := exec.Command(
"fusermount",
"-o", conf.getOptions(),
"--",
dir,
)
cmd.Env = append(os.Environ(), "_FUSE_COMMFD=3")
cmd.ExtraFiles = []*os.File{writeFile}
var wg sync.WaitGroup
stdout, err := cmd.StdoutPipe()
if err != nil {
return nil, fmt.Errorf("setting up fusermount stderr: %v", err)
}
stderr, err := cmd.StderrPipe()
if err != nil {
return nil, fmt.Errorf("setting up fusermount stderr: %v", err)
}
if err := cmd.Start(); err != nil {
return nil, fmt.Errorf("fusermount: %v", err)
}
wg.Add(2)
go lineLogger(&wg, "mount helper output", stdout)
go lineLogger(&wg, "mount helper error", stderr)
wg.Wait()
if err := cmd.Wait(); err != nil {
return nil, fmt.Errorf("fusermount: %v", err)
}
c, err := net.FileConn(readFile)
if err != nil {
return nil, fmt.Errorf("FileConn from fusermount socket: %v", err)
}
defer c.Close()
uc, ok := c.(*net.UnixConn)
if !ok {
return nil, fmt.Errorf("unexpected FileConn type; expected UnixConn, got %T", c)
}
buf := make([]byte, 32) // expect 1 byte
oob := make([]byte, 32) // expect 24 bytes
_, oobn, _, _, err := uc.ReadMsgUnix(buf, oob)
scms, err := syscall.ParseSocketControlMessage(oob[:oobn])
if err != nil {
return nil, fmt.Errorf("ParseSocketControlMessage: %v", err)
}
if len(scms) != 1 {
return nil, fmt.Errorf("expected 1 SocketControlMessage; got scms = %#v", scms)
}
scm := scms[0]
gotFds, err := syscall.ParseUnixRights(&scm)
if err != nil {
return nil, fmt.Errorf("syscall.ParseUnixRights: %v", err)
}
if len(gotFds) != 1 {
return nil, fmt.Errorf("wanted 1 fd; got %#v", gotFds)
}
f := os.NewFile(uintptr(gotFds[0]), "/dev/fuse")
return f, nil
}
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