John Howard
803f14d503
Signed-off-by: John Howard <jhoward@microsoft.com> Upstream-commit: bc503ca8ab2303066cc64d752ffff05100a9b267 Component: engine
79 lines
2.2 KiB
Go
79 lines
2.2 KiB
Go
package hcsshim
|
|
|
|
import (
|
|
"fmt"
|
|
"syscall"
|
|
"unsafe"
|
|
|
|
"github.com/Sirupsen/logrus"
|
|
)
|
|
|
|
// PrepareLayer finds a mounted read-write layer matching layerId and enables the
|
|
// the filesystem filter for use on that layer. This requires the paths to all
|
|
// parent layers, and is necessary in order to view or interact with the layer
|
|
// as an actual filesystem (reading and writing files, creating directories, etc).
|
|
// Disabling the filter must be done via UnprepareLayer.
|
|
func PrepareLayer(info DriverInfo, layerId string, parentLayerPaths []string) error {
|
|
title := "hcsshim::PrepareLayer "
|
|
logrus.Debugf(title+"flavour %d layerId %s", info.Flavour, layerId)
|
|
|
|
// Load the DLL and get a handle to the procedure we need
|
|
dll, proc, err := loadAndFind(procPrepareLayer)
|
|
if dll != nil {
|
|
defer dll.Release()
|
|
}
|
|
if err != nil {
|
|
return err
|
|
}
|
|
|
|
// Generate layer descriptors
|
|
layers, err := layerPathsToDescriptors(parentLayerPaths)
|
|
if err != nil {
|
|
err = fmt.Errorf(title+"- Failed to generate layer descriptors ", err)
|
|
return err
|
|
}
|
|
|
|
// Convert layerId to uint16 pointer for calling the procedure
|
|
layerIdp, err := syscall.UTF16PtrFromString(layerId)
|
|
if err != nil {
|
|
err = fmt.Errorf(title+"- Failed conversion of layerId %s to pointer %s", layerId, err)
|
|
logrus.Error(err)
|
|
return err
|
|
}
|
|
|
|
// Convert info to API calling convention
|
|
infop, err := convertDriverInfo(info)
|
|
if err != nil {
|
|
err = fmt.Errorf(title+"- Failed conversion info struct %s", err)
|
|
logrus.Error(err)
|
|
return err
|
|
}
|
|
|
|
var layerDescriptorsp *WC_LAYER_DESCRIPTOR
|
|
if len(layers) > 0 {
|
|
layerDescriptorsp = &(layers[0])
|
|
} else {
|
|
layerDescriptorsp = nil
|
|
}
|
|
|
|
// Call the procedure itself.
|
|
r1, _, _ := proc.Call(
|
|
uintptr(unsafe.Pointer(&infop)),
|
|
uintptr(unsafe.Pointer(layerIdp)),
|
|
uintptr(unsafe.Pointer(layerDescriptorsp)),
|
|
uintptr(len(layers)))
|
|
use(unsafe.Pointer(&infop))
|
|
use(unsafe.Pointer(layerIdp))
|
|
use(unsafe.Pointer(layerDescriptorsp))
|
|
|
|
if r1 != 0 {
|
|
err = fmt.Errorf(title+"- Win32 API call returned error r1=%d err=%s layerId=%s flavour=%d",
|
|
r1, syscall.Errno(r1), layerId, info.Flavour)
|
|
logrus.Error(err)
|
|
return err
|
|
}
|
|
|
|
logrus.Debugf(title+"succeeded flavour=%d layerId=%s", info.Flavour, layerId)
|
|
return nil
|
|
}
|