implement remove and rename feature for fat32

filesystem/ext4/ext4.go

@@ -804,6 +804,14 @@
 	}, nil
 }
 
+func (fs *FileSystem) RemoveFile(p string) error {
+	return fmt.Errorf("not implemented")
+}
+
+func (fs *FileSystem) RenameFile(p, newFileName string) error {
+	return fmt.Errorf("not implemented")
+}
+
 // Label read the volume label
 func (fs *FileSystem) Label() string {
 	if fs.superblock == nil {

filesystem/fat32/directory.go

@@ -1,6 +1,7 @@
 package fat32
 
 import (
+	"fmt"
 	"time"
 )
 
@@ -41,7 +42,7 @@
 func (d *Directory) createEntry(name string, cluster uint32, dir bool) (*directoryEntry, error) {
 	// is it a long filename or a short filename?
 	var isLFN bool
-	// TODO: convertLfnSfn does not calculate if the short name conflicts and thus shoukld increment the last character
+	// TODO: convertLfnSfn does not calculate if the short name conflicts and thus should increment the last character
 	//       that should happen here, once we can look in the directory entry
 	shortName, extension, isLFN, _ := convertLfnSfn(name)
 	lfn := ""
@@ -70,6 +71,75 @@
 	return &entry, nil
 }
 
+// removeEntry removes an entry in the given directory
+func (d *Directory) removeEntry(name string) error {
+	// is it a long filename or a short filename?
+	var isLFN bool
+	// TODO: convertLfnSfn does not calculate if the short name conflicts and thus should increment the last character
+	//       that should happen here, once we can look in the directory entry
+	_, _, isLFN, _ = convertLfnSfn(name)
+	lfn := ""
+	if isLFN {
+		lfn = name
+	}
+
+	removeEntryIndex := -1
+	for i, entry := range d.entries {
+		if entry.filenameLong == lfn { // || entry.filenameShort == shortName  do not compare SFN, since it is not incremented correctly
+			removeEntryIndex = i
+		}
+	}
+
+	if removeEntryIndex == -1 {
+		return fmt.Errorf("cannot find entry for name %s", name)
+	}
+
+	// remove the entry from the list
+	d.entries = append(d.entries[:removeEntryIndex], d.entries[removeEntryIndex+1:]...)
+
+	return nil
+}
+
+// renameEntry renames an entry in the given directory, and returns the handle to it
+func (d *Directory) renameEntry(oldFileName, newFileName string) error {
+	// is it a long filename or a short filename?
+	var isLFN bool
+	// TODO: convertLfnSfn does not calculate if the short name conflicts and thus should increment the last character
+	//       that should happen here, once we can look in the directory entry
+	_, _, isLFN, _ = convertLfnSfn(oldFileName)
+	lfn := ""
+	if isLFN {
+		lfn = oldFileName
+	}
+
+	var newEntries []*directoryEntry
+	var isReplaced = false
+	for _, entry := range d.entries {
+		if entry.filenameLong == newFileName {
+			return fmt.Errorf("file with name %s already exists", newFileName)
+		}
+		if entry.filenameLong == lfn { //  || entry.filenameShort == shortName  do not compare SFN, since it is not incremented correctly
+			shortName, extension, isLFN, _ := convertLfnSfn(newFileName)
+			if isLFN {
+				lfn = newFileName
+			}
+			entry.filenameLong = lfn
+			entry.filenameShort = shortName
+			entry.fileExtension = extension
+			entry.modifyTime = time.Now()
+			isReplaced = true
+		}
+		newEntries = append(newEntries, entry)
+	}
+	if !isReplaced {
+		return fmt.Errorf("cannot find file entry for %s", oldFileName)
+	}
+
+	d.entries = newEntries
+
+	return nil
+}
+
 // createVolumeLabel create a volume label entry in the given directory, and return the handle to it
 func (d *Directory) createVolumeLabel(name string) (*directoryEntry, error) {
 	// allocate a slot for the new filename in the existing directory

filesystem/fat32/fat32.go

@@ -599,6 +599,124 @@ func (fs *FileSystem) OpenFile(p string, flag int) (filesystem.File, error) {
 	}, nil
 }
 
+// RemoveFile removes a file from the filesystem
+//
+// returns an error if the file does not exist or cannot be removed
+func (fs *FileSystem) RemoveFile(p string) error {
+	// get the path
+	dir := path.Dir(p)
+	filename := path.Base(p)
+	// if the dir == filename, then it is just /
+	if dir == filename {
+		return fmt.Errorf("cannot remove directory %s as file", p)
+	}
+	// get the directory entries
+	parentDir, entries, err := fs.readDirWithMkdir(dir, false)
+	if err != nil {
+		return fmt.Errorf("could not read directory entries for %s", dir)
+	}
+	// we now know that the directory exists, see if the file exists
+	var targetEntry *directoryEntry
+	for _, e := range entries {
+		shortName := e.filenameShort
+		if e.fileExtension != "" {
+			shortName += "." + e.fileExtension
+		}
+		if e.filenameLong != filename && shortName != filename {
+			continue
+		}
+		// cannot do anything with directories
+		if e.isSubdirectory {
+			return fmt.Errorf("cannot open directory %s as file", p)
+		}
+		// if we got this far, we have found the file
+		targetEntry = e
+	}
+
+	// see if the file exists
+	// if the file does not exist, and is not opened for os.O_CREATE, return an error
+	if targetEntry == nil {
+		return fmt.Errorf("target file %s does not exist", p)
+	}
+	err = parentDir.removeEntry(filename)
+	if err != nil {
+		return fmt.Errorf("failed to remove file %s: %v", p, err)
+	}
+
+	// we need to make sure that clusters are removed which may not be used anymore
+	_, err = fs.allocateSpace(uint64(parentDir.fileSize), parentDir.clusterLocation)
+	if err != nil {
+		return fmt.Errorf("failed to allocate clusters: %v", err)
+	}
+
+	// write the directory entries to disk
+	err = fs.writeDirectoryEntries(parentDir)
+	if err != nil {
+		return fmt.Errorf("error writing directory file %s to disk: %v", p, err)
+	}
+
+	return nil
+}
+
+// RenameFile removes a file from the filesystem
+//
+// returns an error if the file does not exist or cannot be renamed
+func (fs *FileSystem) RenameFile(p, newFileName string) error {
+	// get the path
+	dir := path.Dir(p)
+	filename := path.Base(p)
+	// if the dir == filename, then it is just /
+	if dir == filename {
+		return fmt.Errorf("cannot rename directory %s as file", p)
+	}
+	// get the directory entries
+	parentDir, entries, err := fs.readDirWithMkdir(dir, false)
+	if err != nil {
+		return fmt.Errorf("could not read directory entries for %s", dir)
+	}
+	// we now know that the directory exists, see if the file exists
+	var targetEntry *directoryEntry
+	for _, e := range entries {
+		shortName := e.filenameShort
+		if e.fileExtension != "" {
+			shortName += "." + e.fileExtension
+		}
+		if e.filenameLong != filename && shortName != filename {
+			continue
+		}
+		// cannot do anything with directories
+		if e.isSubdirectory {
+			return fmt.Errorf("cannot open directory %s as file", p)
+		}
+		// if we got this far, we have found the file
+		targetEntry = e
+	}
+
+	// see if the file exists
+	// if the file does not exist, and is not opened for os.O_CREATE, return an error
+	if targetEntry == nil {
+		return fmt.Errorf("target file %s does not exist", p)
+	}
+	err = parentDir.renameEntry(filename, newFileName)
+	if err != nil {
+		return fmt.Errorf("failed to rename file %s: %v", p, err)
+	}
+
+	// we need to make sure that clusters are removed which may not be used anymore
+	_, err = fs.allocateSpace(uint64(parentDir.fileSize), parentDir.clusterLocation)
+	if err != nil {
+		return fmt.Errorf("failed to allocate clusters: %v", err)
+	}
+
+	// write the directory entries to disk
+	err = fs.writeDirectoryEntries(parentDir)
+	if err != nil {
+		return fmt.Errorf("error writing directory file %s to disk: %v", p, err)
+	}
+
+	return nil
+}
+
 // Label get the label of the filesystem from the secial file in the root directory.
 // The label stored in the boot sector is ignored to mimic Windows behavior which
 // only stores and reads the label from the special file in the root directory.
@@ -748,7 +866,7 @@ func (fs *FileSystem) mkSubdir(parent *Directory, name string) (*directoryEntry,
 }
 
 func (fs *FileSystem) writeDirectoryEntries(dir *Directory) error {
-	// we need to save the entries of theparent
+	// we need to save the entries of the parent
 	b, err := dir.entriesToBytes(fs.bytesPerCluster)
 	if err != nil {
 		return fmt.Errorf("could not create a valid byte stream for a FAT32 Entries: %v", err)