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Make Attach no longer a special snowflake

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fsgofer.attachPoint.Attach has a bunch of funky special logic to create a RW
file or connect a socket rather than creating a standard control file like
localFile.Walk.

This is unecessary and error-prone, as the attach point still has to go through
Open or Connect which will properly convert the control file to something
usable. As such, switch the logic to be equivalent to a simple Walk.

Updates #235

PiperOrigin-RevId: 274827872
This commit is contained in:
Michael Pratt
2019-10-15 10:01:22 -07:00
committed by gVisor bot
parent bfa0bb24dd
commit a295616326
1 changed files with 13 additions and 44 deletions
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runsc/fsgofer/fsgofer.go
+13 -44
View File
@@ -21,7 +21,6 @@
package fsgofer
import (
"errors"
"fmt"
"io"
"math"
@@ -126,13 +125,6 @@ func NewAttachPoint(prefix string, c Config) (p9.Attacher, error) {
// Attach implements p9.Attacher.
func (a *attachPoint) Attach() (p9.File, error) {
// dirFD (1st argument) is ignored because 'prefix' is always absolute.
stat, err := statAt(-1, a.prefix)
if err != nil {
return nil, fmt.Errorf("stat file %q, err: %v", a.prefix, err)
}
// Acquire the attach point lock.
a.attachedMu.Lock()
defer a.attachedMu.Unlock()
@@ -140,47 +132,24 @@ func (a *attachPoint) Attach() (p9.File, error) {
return nil, fmt.Errorf("attach point already attached, prefix: %s", a.prefix)
}
// Hold the file descriptor we are converting into a p9.File.
var f *fd.FD
// Apply the S_IFMT bitmask so we can detect file type appropriately.
switch fmtStat := stat.Mode & syscall.S_IFMT; fmtStat {
case syscall.S_IFSOCK:
// Check to see if the CLI option has been set to allow the UDS mount.
if !a.conf.HostUDS {
return nil, errors.New("host UDS support is disabled")
}
// Attempt to open a connection. Bubble up the failures.
f, err = fd.DialUnix(a.prefix)
if err != nil {
return nil, err
}
default:
// Default to Read/Write permissions.
mode := syscall.O_RDWR
// If the configuration is Read Only or the mount point is a directory,
// set the mode to Read Only.
if a.conf.ROMount || fmtStat == syscall.S_IFDIR {
mode = syscall.O_RDONLY
}
// Open the mount point & capture the FD.
f, err = fd.Open(a.prefix, openFlags|mode, 0)
if err != nil {
return nil, fmt.Errorf("unable to open file %q, err: %v", a.prefix, err)
}
f, err := openAnyFile(a.prefix, func(mode int) (*fd.FD, error) {
return fd.Open(a.prefix, openFlags|mode, 0)
})
if err != nil {
return nil, fmt.Errorf("unable to open %q: %v", a.prefix, err)
}
// Return a localFile object to the caller with the UDS FD included.
rv, err := newLocalFile(a, f, a.prefix, stat)
stat, err := stat(f.FD())
if err != nil {
return nil, err
return nil, fmt.Errorf("unable to stat %q: %v", a.prefix, err)
}
lf, err := newLocalFile(a, f, a.prefix, stat)
if err != nil {
return nil, fmt.Errorf("unable to create localFile %q: %v", a.prefix, err)
}
a.attached = true
return rv, nil
return lf, nil
}
// makeQID returns a unique QID for the given stat buffer.