WIP

tar/verify/headers.go

@@ -0,0 +1,23 @@
+package verify
+
+import "time"
+
+// PosixHeader is the structure from a POSIX tar header, to be marshalled from
+// the tar stream, and available for on-disk comparison and verification
+type PosixHeader struct {
+	Name     string    `json:"name,omitempty"`
+	Mode     uint32    `json:"mode,omitempty"`
+	UID      uint32    `json:"uid,omitempty"`
+	GID      uint32    `json:"gid,omitempty"`
+	Size     int       `json:"size,omitempty"`
+	Mtime    time.Time `json:"mtime,omitempty"`
+	Checksum []byte    `json:"chksum,omitempty"`
+	LinkName string    `json:"linkname,omitempty"`
+	Magic    []byte    `json:"magic,omitempty"`
+	Version  string    `json:"version,omitempty"`
+	Uname    string    `json:"uname,omitempty"`
+	Gname    string    `json:"gname,omitempty"`
+	DevMajor int       `json:"devmajor,omitempty"`
+	DevMinor int       `json:"devminor,omitempty"`
+	Prefix   string    `json:"prefix,omitempty"`
+}

tar/verify/verify.go

@@ -0,0 +1,34 @@
+package verify
+
+import "fmt"
+
+// CheckType is how the on disk attributes will be verified against the
+// recorded header information
+type CheckType int
+
+// Check types for customizing how fuzzy or strict on-disk verification will be
+// handled
+const (
+	CheckDigest CheckType = iota
+	CheckFileSize
+	CheckFileMode
+	CheckFileUser
+	CheckFileGroup
+	CheckFileMtime
+	CheckFileDevice
+	CheckFileLink
+	CheckFileCaps
+)
+
+var (
+	// DefaultChecks is the default for verfication steps against each
+	// storage.VerficationEntry
+	DefaultChecks = CheckDigest | CheckFileAttributes
+	// CheckFileAttributes are the group of file attribute checks done
+	CheckFileAttributes = CheckFileSize | CheckFileMode | CheckFileUser |
+		CheckFileGroup | CheckFileMtime | CheckFileDevice | CheckFileCaps |
+		CheckFileLink
+
+	// ErrNotSupportedPlatform is when the platform does not support given features
+	ErrNotSupportedPlatform = fmt.Errorf("platform does not support this feature")
+)

tar/verify/xattrs_linux.go

@@ -0,0 +1,114 @@
+package verify
+
+/*
+Lgetxattr and Lsetxattr are copied directly from https://github.com/docker/docker
+  ./pkg/system/xattr_linux.go commit 7e420ad8502089e66ce0ade92bf70574f894f287
+  Apache License Version 2.0, January 2004 https://www.apache.org/licenses/
+  Copyright 2013-2015 Docker, Inc.
+*/
+
+import (
+	"bytes"
+	"syscall"
+	"unsafe"
+)
+
+/*
+func main() {
+	for _, arg := range os.Args[1:] {
+		keys, err := Listxattr(arg)
+		if err != nil {
+			fmt.Println(err)
+			continue
+		}
+		if len(keys) > 0 {
+			fmt.Printf("%s : %q\n", arg, keys)
+			for _, key := range keys {
+				buf, err := Lgetxattr(arg, key)
+				if err != nil {
+					fmt.Printf("  ERROR: %s\n", err)
+					continue
+				}
+				fmt.Printf("  %s = %s\n", key, string(buf))
+			}
+		}
+	}
+}
+*/
+
+// Listxattr is a helper around the syscall.Listxattr
+func Listxattr(path string) ([]string, error) {
+	buf := make([]byte, 1024)
+	sz, err := syscall.Listxattr(path, buf)
+	if err == syscall.ENODATA {
+		return nil, nil
+	}
+	if err == syscall.ERANGE && sz > 0 {
+		buf = make([]byte, sz)
+		sz, err = syscall.Listxattr(path, buf)
+	}
+	keys := []string{}
+	for _, key := range bytes.Split(bytes.TrimSpace(buf), []byte{0x0}) {
+		if string(key) != "" {
+			keys = append(keys, string(key))
+		}
+	}
+	return keys, nil
+}
+
+// Lgetxattr retrieves the value of the extended attribute identified by attr
+// and associated with the given path in the file system.
+// It will returns a nil slice and nil error if the xattr is not set.
+func Lgetxattr(path string, attr string) ([]byte, error) {
+	pathBytes, err := syscall.BytePtrFromString(path)
+	if err != nil {
+		return nil, err
+	}
+	attrBytes, err := syscall.BytePtrFromString(attr)
+	if err != nil {
+		return nil, err
+	}
+
+	dest := make([]byte, 128)
+	destBytes := unsafe.Pointer(&dest[0])
+	sz, _, errno := syscall.Syscall6(syscall.SYS_LGETXATTR, uintptr(unsafe.Pointer(pathBytes)), uintptr(unsafe.Pointer(attrBytes)), uintptr(destBytes), uintptr(len(dest)), 0, 0)
+	if errno == syscall.ENODATA {
+		return nil, nil
+	}
+	if errno == syscall.ERANGE {
+		dest = make([]byte, sz)
+		destBytes := unsafe.Pointer(&dest[0])
+		sz, _, errno = syscall.Syscall6(syscall.SYS_LGETXATTR, uintptr(unsafe.Pointer(pathBytes)), uintptr(unsafe.Pointer(attrBytes)), uintptr(destBytes), uintptr(len(dest)), 0, 0)
+	}
+	if errno != 0 {
+		return nil, errno
+	}
+
+	return dest[:sz], nil
+}
+
+var _zero uintptr
+
+// Lsetxattr sets the value of the extended attribute identified by attr
+// and associated with the given path in the file system.
+func Lsetxattr(path string, attr string, data []byte, flags int) error {
+	pathBytes, err := syscall.BytePtrFromString(path)
+	if err != nil {
+		return err
+	}
+	attrBytes, err := syscall.BytePtrFromString(attr)
+	if err != nil {
+		return err
+	}
+	var dataBytes unsafe.Pointer
+	if len(data) > 0 {
+		dataBytes = unsafe.Pointer(&data[0])
+	} else {
+		dataBytes = unsafe.Pointer(&_zero)
+	}
+	_, _, errno := syscall.Syscall6(syscall.SYS_LSETXATTR, uintptr(unsafe.Pointer(pathBytes)), uintptr(unsafe.Pointer(attrBytes)), uintptr(dataBytes), uintptr(len(data)), uintptr(flags), 0)
+	if errno != 0 {
+		return errno
+	}
+	return nil
+}

tar/verify/xattrs_unsupported.go

@@ -0,0 +1,13 @@
+// +build !linux
+
+package verify
+
+// Lgetxattr is not supported on platforms other than linux.
+func Lgetxattr(path string, attr string) ([]byte, error) {
+	return nil, ErrNotSupportedPlatform
+}
+
+// Lsetxattr is not supported on platforms other than linux.
+func Lsetxattr(path string, attr string, data []byte, flags int) error {
+	return ErrNotSupportedPlatform
+}