diff options
Diffstat (limited to 'vendor/github.com/Microsoft/go-winio/ea.go')
| -rw-r--r-- | vendor/github.com/Microsoft/go-winio/ea.go | 137 |
1 files changed, 137 insertions, 0 deletions
diff --git a/vendor/github.com/Microsoft/go-winio/ea.go b/vendor/github.com/Microsoft/go-winio/ea.go new file mode 100644 index 000000000..b37e930d6 --- /dev/null +++ b/vendor/github.com/Microsoft/go-winio/ea.go @@ -0,0 +1,137 @@ +package winio
+
+import (
+ "bytes"
+ "encoding/binary"
+ "errors"
+)
+
+type fileFullEaInformation struct {
+ NextEntryOffset uint32
+ Flags uint8
+ NameLength uint8
+ ValueLength uint16
+}
+
+var (
+ fileFullEaInformationSize = binary.Size(&fileFullEaInformation{})
+
+ errInvalidEaBuffer = errors.New("invalid extended attribute buffer")
+ errEaNameTooLarge = errors.New("extended attribute name too large")
+ errEaValueTooLarge = errors.New("extended attribute value too large")
+)
+
+// ExtendedAttribute represents a single Windows EA.
+type ExtendedAttribute struct {
+ Name string
+ Value []byte
+ Flags uint8
+}
+
+func parseEa(b []byte) (ea ExtendedAttribute, nb []byte, err error) {
+ var info fileFullEaInformation
+ err = binary.Read(bytes.NewReader(b), binary.LittleEndian, &info)
+ if err != nil {
+ err = errInvalidEaBuffer
+ return
+ }
+
+ nameOffset := fileFullEaInformationSize
+ nameLen := int(info.NameLength)
+ valueOffset := nameOffset + int(info.NameLength) + 1
+ valueLen := int(info.ValueLength)
+ nextOffset := int(info.NextEntryOffset)
+ if valueLen+valueOffset > len(b) || nextOffset < 0 || nextOffset > len(b) {
+ err = errInvalidEaBuffer
+ return
+ }
+
+ ea.Name = string(b[nameOffset : nameOffset+nameLen])
+ ea.Value = b[valueOffset : valueOffset+valueLen]
+ ea.Flags = info.Flags
+ if info.NextEntryOffset != 0 {
+ nb = b[info.NextEntryOffset:]
+ }
+ return
+}
+
+// DecodeExtendedAttributes decodes a list of EAs from a FILE_FULL_EA_INFORMATION
+// buffer retrieved from BackupRead, ZwQueryEaFile, etc.
+func DecodeExtendedAttributes(b []byte) (eas []ExtendedAttribute, err error) {
+ for len(b) != 0 {
+ ea, nb, err := parseEa(b)
+ if err != nil {
+ return nil, err
+ }
+
+ eas = append(eas, ea)
+ b = nb
+ }
+ return
+}
+
+func writeEa(buf *bytes.Buffer, ea *ExtendedAttribute, last bool) error {
+ if int(uint8(len(ea.Name))) != len(ea.Name) {
+ return errEaNameTooLarge
+ }
+ if int(uint16(len(ea.Value))) != len(ea.Value) {
+ return errEaValueTooLarge
+ }
+ entrySize := uint32(fileFullEaInformationSize + len(ea.Name) + 1 + len(ea.Value))
+ withPadding := (entrySize + 3) &^ 3
+ nextOffset := uint32(0)
+ if !last {
+ nextOffset = withPadding
+ }
+ info := fileFullEaInformation{
+ NextEntryOffset: nextOffset,
+ Flags: ea.Flags,
+ NameLength: uint8(len(ea.Name)),
+ ValueLength: uint16(len(ea.Value)),
+ }
+
+ err := binary.Write(buf, binary.LittleEndian, &info)
+ if err != nil {
+ return err
+ }
+
+ _, err = buf.Write([]byte(ea.Name))
+ if err != nil {
+ return err
+ }
+
+ err = buf.WriteByte(0)
+ if err != nil {
+ return err
+ }
+
+ _, err = buf.Write(ea.Value)
+ if err != nil {
+ return err
+ }
+
+ _, err = buf.Write([]byte{0, 0, 0}[0 : withPadding-entrySize])
+ if err != nil {
+ return err
+ }
+
+ return nil
+}
+
+// EncodeExtendedAttributes encodes a list of EAs into a FILE_FULL_EA_INFORMATION
+// buffer for use with BackupWrite, ZwSetEaFile, etc.
+func EncodeExtendedAttributes(eas []ExtendedAttribute) ([]byte, error) {
+ var buf bytes.Buffer
+ for i := range eas {
+ last := false
+ if i == len(eas)-1 {
+ last = true
+ }
+
+ err := writeEa(&buf, &eas[i], last)
+ if err != nil {
+ return nil, err
+ }
+ }
+ return buf.Bytes(), nil
+}
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