Updated vendor pkg: github.com/danieljoos/wincred

This includes the following changes:
- Removed need for `C`
- Added some null checks to avoid possible panics
- `List` returns an empty list instead of an error, in case no credentials
  are installed on the system

Signed-off-by: Daniel Joos <daniel@joosweb.de>

vendor/github.com/danieljoos/wincred/conversion.go

@@ -1,7 +1,6 @@
 package wincred
 
 import (
-	"C"
 	"encoding/binary"
 	"reflect"
 	"syscall"
@@ -10,6 +9,8 @@ import (
 	"unsafe"
 )
 
+var nullPointer = unsafe.Pointer(uintptr(0))
+
 // Create a Go string using a pointer to a zero-terminated UTF 16 encoded string.
 // See github.com/AllenDang/w32
 func utf16PtrToString(wstr *uint16) string {
@@ -36,8 +37,22 @@ func utf16ToByte(wstr []uint16) (result []byte) {
 	return
 }
 
+// Copies the given C byte array to a Go byte array (see `C.GoBytes`)
+func goBytes(src unsafe.Pointer, len uint32) []byte {
+	if src == nullPointer {
+		return []byte{}
+	}
+	slice := (*[1 << 30]byte)(src)[0:len]
+	rv := make([]byte, len)
+	copy(rv, slice)
+	return rv[:]
+}
+
 // Convert the given CREDENTIAL struct to a more usable structure
 func nativeToCredential(cred *nativeCREDENTIAL) (result *Credential) {
+	if unsafe.Pointer(cred) == nullPointer {
+		return nil
+	}
 	result = new(Credential)
 	result.Comment = utf16PtrToString(cred.Comment)
 	result.TargetName = utf16PtrToString(cred.TargetName)
@@ -45,7 +60,7 @@ func nativeToCredential(cred *nativeCREDENTIAL) (result *Credential) {
 	result.UserName = utf16PtrToString(cred.UserName)
 	result.LastWritten = time.Unix(0, cred.LastWritten.Nanoseconds())
 	result.Persist = CredentialPersistence(cred.Persist)
-	result.CredentialBlob = C.GoBytes(unsafe.Pointer(cred.CredentialBlob), C.int(cred.CredentialBlobSize))
+	result.CredentialBlob = goBytes(unsafe.Pointer(cred.CredentialBlob), cred.CredentialBlobSize)
 	result.Attributes = make([]CredentialAttribute, cred.AttributeCount)
 	attrSliceHeader := reflect.SliceHeader{
 		Data: cred.Attributes,
@@ -56,7 +71,7 @@ func nativeToCredential(cred *nativeCREDENTIAL) (result *Credential) {
 	for i, attr := range attrSlice {
 		resultAttr := &result.Attributes[i]
 		resultAttr.Keyword = utf16PtrToString(attr.Keyword)
-		resultAttr.Value = C.GoBytes(unsafe.Pointer(attr.Value), C.int(attr.ValueSize))
+		resultAttr.Value = goBytes(unsafe.Pointer(attr.Value), attr.ValueSize)
 	}
 	return result
 }
@@ -64,6 +79,9 @@ func nativeToCredential(cred *nativeCREDENTIAL) (result *Credential) {
 // Convert the given Credential object back to a CREDENTIAL struct, which can be used for calling the
 // Windows APIs
 func nativeFromCredential(cred *Credential) (result *nativeCREDENTIAL) {
+	if cred == nil {
+		return nil
+	}
 	result = new(nativeCREDENTIAL)
 	result.Flags = 0
 	result.Type = 0

vendor/github.com/danieljoos/wincred/native.go

@@ -1,7 +1,6 @@
 package wincred
 
 import (
-	"C"
 	"syscall"
 	"unsafe"
 )
@@ -9,13 +8,18 @@ import (
 var (
 	modadvapi32 = syscall.NewLazyDLL("advapi32.dll")
 
-	procCredRead      = modadvapi32.NewProc("CredReadW")
-	procCredWrite     = modadvapi32.NewProc("CredWriteW")
-	procCredDelete    = modadvapi32.NewProc("CredDeleteW")
-	procCredFree      = modadvapi32.NewProc("CredFree")
-	procCredEnumerate = modadvapi32.NewProc("CredEnumerateW")
+	procCredRead      proc = modadvapi32.NewProc("CredReadW")
+	procCredWrite     proc = modadvapi32.NewProc("CredWriteW")
+	procCredDelete    proc = modadvapi32.NewProc("CredDeleteW")
+	procCredFree      proc = modadvapi32.NewProc("CredFree")
+	procCredEnumerate proc = modadvapi32.NewProc("CredEnumerateW")
 )
 
+// Interface for syscall.Proc: helps testing
+type proc interface {
+	Call(a ...uintptr) (r1, r2 uintptr, lastErr error)
+}
+
 // http://msdn.microsoft.com/en-us/library/windows/desktop/aa374788(v=vs.85).aspx
 type nativeCREDENTIAL struct {
 	Flags              uint32
@@ -50,6 +54,8 @@ const (
 	naCRED_TYPE_DOMAIN_VISIBLE_PASSWORD nativeCRED_TYPE = 0x4
 	naCRED_TYPE_GENERIC_CERTIFICATE     nativeCRED_TYPE = 0x5
 	naCRED_TYPE_DOMAIN_EXTENDED         nativeCRED_TYPE = 0x6
+
+	naERROR_NOT_FOUND = "Element not found."
 )
 
 // http://msdn.microsoft.com/en-us/library/windows/desktop/aa374804(v=vs.85).aspx

vendor/github.com/danieljoos/wincred/wincred.go

@@ -70,5 +70,11 @@ func (t *DomainPassword) SetPassword(pw string) {
 
 // List the contents of the Credentials store
 func List() ([]*Credential, error) {
-	return nativeCredEnumerate("", true)
+	creds, err := nativeCredEnumerate("", true)
+	if err != nil && err.Error() == naERROR_NOT_FOUND {
+		// Ignore ERROR_NOT_FOUND and return an empty list instead
+		creds = []*Credential{}
+		err = nil
+	}
+	return creds, err
 }