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Undo changes in case of failure to create file/dir/symlink

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File/dir/symlink creation is multi-step and may leave state behind in
case of failure in one of the steps. Added best effort attempt to
clean up.

PiperOrigin-RevId: 228286612
Change-Id: Ib03c27cd3d3e4f44d0352edc6ee212a53412d7f1
This commit is contained in:
Fabricio Voznika
2019-01-07 23:02:19 -08:00
committed by Shentubot
parent dc4849e49c
commit 5ce542ecc7
2 changed files with 30 additions and 7 deletions
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runsc/fsgofer/BUILD
+1
View File
@@ -18,6 +18,7 @@ go_library(
"//pkg/log",
"//pkg/p9",
"//pkg/syserr",
"//runsc/specutils",
"@org_golang_x_sys//unix:go_default_library",
],
)
runsc/fsgofer/fsgofer.go
+29 -7
View File
@@ -35,6 +35,7 @@ import (
"gvisor.googlesource.com/gvisor/pkg/fd"
"gvisor.googlesource.com/gvisor/pkg/log"
"gvisor.googlesource.com/gvisor/pkg/p9"
"gvisor.googlesource.com/gvisor/runsc/specutils"
)
const (
@@ -379,19 +380,20 @@ func (l *localFile) Create(name string, mode p9.OpenFlags, perm p9.FileMode, uid
if err != nil {
return nil, nil, p9.QID{}, 0, extractErrno(err)
}
if err := fchown(fd, uid, gid); err != nil {
cu := specutils.MakeCleanup(func() {
syscall.Close(fd)
if e := syscall.Unlinkat(l.controlFD(), name); e != nil {
log.Warningf("error unlinking file %q after failed chown: %v", name, e)
// Best effort attempt to remove the file in case of failure.
if err := syscall.Unlinkat(l.controlFD(), name); err != nil {
log.Warningf("error unlinking file %q after failure: %v", path.Join(l.hostPath, name), err)
}
})
defer cu.Clean()
if err := fchown(fd, uid, gid); err != nil {
return nil, nil, p9.QID{}, 0, extractErrno(err)
}
stat, err := stat(fd)
if err != nil {
syscall.Close(fd)
if e := syscall.Unlinkat(l.controlFD(), name); e != nil {
log.Warningf("error unlinking file %q after failed stat: %v", name, e)
}
return nil, nil, p9.QID{}, 0, extractErrno(err)
}
@@ -404,6 +406,8 @@ func (l *localFile) Create(name string, mode p9.OpenFlags, perm p9.FileMode, uid
openedFile: f,
mode: mode,
}
cu.Release()
return newFDMaybe(c.openedFile), c, l.attachPoint.makeQID(stat), 0, nil
}
@@ -420,6 +424,13 @@ func (l *localFile) Mkdir(name string, perm p9.FileMode, uid p9.UID, gid p9.GID)
if err := syscall.Mkdirat(l.controlFD(), name, uint32(perm.Permissions())); err != nil {
return p9.QID{}, extractErrno(err)
}
cu := specutils.MakeCleanup(func() {
// Best effort attempt to remove the dir in case of failure.
if err := unix.Unlinkat(l.controlFD(), name, unix.AT_REMOVEDIR); err != nil {
log.Warningf("error unlinking dir %q after failure: %v", path.Join(l.hostPath, name), err)
}
})
defer cu.Clean()
// Open directory to change ownership and stat it.
flags := syscall.O_DIRECTORY | syscall.O_RDONLY | openFlags
@@ -436,6 +447,8 @@ func (l *localFile) Mkdir(name string, perm p9.FileMode, uid p9.UID, gid p9.GID)
if err != nil {
return p9.QID{}, extractErrno(err)
}
cu.Release()
return l.attachPoint.makeQID(stat), nil
}
@@ -759,6 +772,13 @@ func (l *localFile) Symlink(target, newName string, uid p9.UID, gid p9.GID) (p9.
if err := unix.Symlinkat(target, l.controlFD(), newName); err != nil {
return p9.QID{}, extractErrno(err)
}
cu := specutils.MakeCleanup(func() {
// Best effort attempt to remove the symlink in case of failure.
if err := syscall.Unlinkat(l.controlFD(), newName); err != nil {
log.Warningf("error unlinking file %q after failure: %v", path.Join(l.hostPath, newName), err)
}
})
defer cu.Clean()
// Open symlink to change ownership and stat it.
fd, err := syscall.Openat(l.controlFD(), newName, unix.O_PATH|openFlags, 0)
@@ -774,6 +794,8 @@ func (l *localFile) Symlink(target, newName string, uid p9.UID, gid p9.GID) (p9.
if err != nil {
return p9.QID{}, extractErrno(err)
}
cu.Release()
return l.attachPoint.makeQID(stat), nil
}