Merge pull request #553 from peterverraedt/marshal-extended

Marshal extended data if file info supports it

Author: puellanivis

attrs.go

@@ -69,6 +69,20 @@ func fileInfoFromStat(stat *FileStat, name string) os.FileInfo {
 	}
 }
 
+// FileInfoUidGid extends os.FileInfo and adds callbacks for Uid and Gid retrieval,
+// as an alternative to *syscall.Stat_t objects on unix systems.
+type FileInfoUidGid interface {
+	os.FileInfo
+	Uid() uint32
+	Gid() uint32
+}
+
+// FileInfoUidGid extends os.FileInfo and adds a callbacks for extended data retrieval.
+type FileInfoExtendedData interface {
+	os.FileInfo
+	Extended() []StatExtended
+}
+
 func fileStatFromInfo(fi os.FileInfo) (uint32, *FileStat) {
 	mtime := fi.ModTime().Unix()
 	atime := mtime
@@ -86,5 +100,22 @@ func fileStatFromInfo(fi os.FileInfo) (uint32, *FileStat) {
 	// os specific file stat decoding
 	fileStatFromInfoOs(fi, &flags, fileStat)
 
+	// The call above will include the sshFileXferAttrUIDGID in case
+	// the os.FileInfo can be casted to *syscall.Stat_t on unix.
+	// If fi implements FileInfoUidGid, retrieve Uid, Gid from it instead.
+	if fiExt, ok := fi.(FileInfoUidGid); ok {
+		flags |= sshFileXferAttrUIDGID
+		fileStat.UID = fiExt.Uid()
+		fileStat.GID = fiExt.Gid()
+	}
+
+	// if fi implements FileInfoExtendedData, retrieve extended data from it
+	if fiExt, ok := fi.(FileInfoExtendedData); ok {
+		fileStat.Extended = fiExt.Extended()
+		if len(fileStat.Extended) > 0 {
+			flags |= sshFileXferAttrExtended
+		}
+	}
+
 	return flags, fileStat
 }

ls_formatting.go

@@ -60,6 +60,13 @@ func runLs(idLookup NameLookupFileLister, dirent os.FileInfo) string {
 		uid = lsFormatID(sys.UID)
 		gid = lsFormatID(sys.GID)
 	default:
+		if fiExt, ok := dirent.(FileInfoUidGid); ok {
+			uid = lsFormatID(fiExt.Uid())
+			gid = lsFormatID(fiExt.Gid())
+
+			break
+		}
+
 		numLinks, uid, gid = lsLinksUIDGID(dirent)
 	}
 

packet.go

@@ -71,6 +71,15 @@ func marshalFileInfo(b []byte, fi os.FileInfo) []byte {
 		b = marshalUint32(b, fileStat.Mtime)
 	}
 
+	if flags&sshFileXferAttrExtended != 0 {
+		b = marshalUint32(b, uint32(len(fileStat.Extended)))
+
+		for _, attr := range fileStat.Extended {
+			b = marshalString(b, attr.ExtType)
+			b = marshalString(b, attr.ExtData)
+		}
+	}
+
 	return b
 }
 

request-interfaces.go

@@ -75,7 +75,7 @@ type StatVFSFileCmder interface {
 // Note in cases of an error, the error text will be sent to the client.
 // Called for Methods: List, Stat, Readlink
 //
-// Since Filelist returns an os.FileInfo, this can make it non-ideal for impelmenting Readlink.
+// Since Filelist returns an os.FileInfo, this can make it non-ideal for implementing Readlink.
 // This is because the Name receiver method defined by that interface defines that it should only return the base name.
 // However, Readlink is required to be capable of returning essentially any arbitrary valid path relative or absolute.
 // In order to implement this more expressive requirement, implement [ReadlinkFileLister] which will then be used instead.
@@ -131,11 +131,19 @@ type NameLookupFileLister interface {
 	LookupGroupName(string) string
 }
 
-// ListerAt does for file lists what io.ReaderAt does for files.
-// ListAt should return the number of entries copied and an io.EOF
-// error if at end of list. This is testable by comparing how many you
-// copied to how many could be copied (eg. n < len(ls) below).
+// ListerAt does for file lists what io.ReaderAt does for files, i.e. a []os.FileInfo buffer is passed to the ListAt function
+// and the entries that are populated in the buffer will be passed to the client.
+//
+// ListAt should return the number of entries copied and an io.EOF error if at end of list.
+// This is testable by comparing how many you copied to how many could be copied (eg. n < len(ls) below).
 // The copy() builtin is best for the copying.
+//
+// Uid and gid information will on unix systems be retrieved from [os.FileInfo.Sys]
+// if this function returns a [syscall.Stat_t] when called on a populated entry.
+// Alternatively, if the entry implements [FileInfoUidGid], it will be used for uid and gid information.
+//
+// If a populated entry implements [FileInfoExtendedData], extended attributes will also be returned to the client.
+//
 // Note in cases of an error, the error text will be sent to the client.
 type ListerAt interface {
 	ListAt([]os.FileInfo, int64) (int, error)