From 5d4f6342b0467f924ef4cd4190c82dc570a49d7e Mon Sep 17 00:00:00 2001
From: Simon Ser <contact@emersion.fr>
Date: Mon, 16 Dec 2024 19:13:30 +0100
Subject: [PATCH] webdav: add support for If-Match/If-None-Match in DELETE

---
 fs_local.go | 49 ++++++++++++++++++++++++++++++++-----------------
 server.go   | 11 +++++++++--
 webdav.go   |  5 +++++
 3 files changed, 46 insertions(+), 19 deletions(-)

diff --git a/fs_local.go b/fs_local.go
index c2cfd46..ed66dd0 100644
--- a/fs_local.go
+++ b/fs_local.go
@@ -114,33 +114,43 @@ func (fs LocalFileSystem) ReadDir(ctx context.Context, name string, recursive bo
 	return l, errFromOS(err)
 }
 
-func (fs LocalFileSystem) Create(ctx context.Context, name string, body io.ReadCloser, opts *CreateOptions) (fi *FileInfo, created bool, err error) {
-	p, err := fs.localPath(name)
-	if err != nil {
-		return nil, false, err
-	}
-	fi, _ = fs.Stat(ctx, name)
-	created = fi == nil
+func checkConditionalMatches(fi *FileInfo, ifMatch, ifNoneMatch ConditionalMatch) error {
 	etag := ""
 	if fi != nil {
 		etag = fi.ETag
 	}
 
-	if opts.IfMatch.IsSet() {
-		if ok, err := opts.IfMatch.MatchETag(etag); err != nil {
-			return nil, false, NewHTTPError(http.StatusBadRequest, err)
+	if ifMatch.IsSet() {
+		if ok, err := ifMatch.MatchETag(etag); err != nil {
+			return NewHTTPError(http.StatusBadRequest, err)
 		} else if !ok {
-			return nil, false, NewHTTPError(http.StatusPreconditionFailed, fmt.Errorf("If-Match condition failed"))
+			return NewHTTPError(http.StatusPreconditionFailed, fmt.Errorf("If-Match condition failed"))
 		}
 	}
-	if opts.IfNoneMatch.IsSet() {
-		if ok, err := opts.IfNoneMatch.MatchETag(etag); err != nil {
-			return nil, false, NewHTTPError(http.StatusBadRequest, err)
+
+	if ifNoneMatch.IsSet() {
+		if ok, err := ifNoneMatch.MatchETag(etag); err != nil {
+			return NewHTTPError(http.StatusBadRequest, err)
 		} else if ok {
-			return nil, false, NewHTTPError(http.StatusPreconditionFailed, fmt.Errorf("If-None-Match condition failed"))
+			return NewHTTPError(http.StatusPreconditionFailed, fmt.Errorf("If-None-Match condition failed"))
 		}
 	}
 
+	return nil
+}
+
+func (fs LocalFileSystem) Create(ctx context.Context, name string, body io.ReadCloser, opts *CreateOptions) (fi *FileInfo, created bool, err error) {
+	p, err := fs.localPath(name)
+	if err != nil {
+		return nil, false, err
+	}
+	fi, _ = fs.Stat(ctx, name)
+	created = fi == nil
+
+	if err := checkConditionalMatches(fi, opts.IfMatch, opts.IfNoneMatch); err != nil {
+		return nil, false, err
+	}
+
 	wc, err := os.Create(p)
 	if err != nil {
 		return nil, false, errFromOS(err)
@@ -164,7 +174,7 @@ func (fs LocalFileSystem) Create(ctx context.Context, name string, body io.ReadC
 	return fi, created, err
 }
 
-func (fs LocalFileSystem) RemoveAll(ctx context.Context, name string) error {
+func (fs LocalFileSystem) RemoveAll(ctx context.Context, name string, opts *RemoveAllOptions) error {
 	p, err := fs.localPath(name)
 	if err != nil {
 		return err
@@ -172,10 +182,15 @@ func (fs LocalFileSystem) RemoveAll(ctx context.Context, name string) error {
 
 	// WebDAV semantics are that it should return a "404 Not Found" error in
 	// case the resource doesn't exist. We need to Stat before RemoveAll.
-	if _, err = os.Stat(p); err != nil {
+	fi, err := fs.Stat(ctx, name)
+	if err != nil {
 		return errFromOS(err)
 	}
 
+	if err := checkConditionalMatches(fi, opts.IfMatch, opts.IfNoneMatch); err != nil {
+		return err
+	}
+
 	return errFromOS(os.RemoveAll(p))
 }
 
diff --git a/server.go b/server.go
index b5ba8f4..3d73209 100644
--- a/server.go
+++ b/server.go
@@ -18,7 +18,7 @@ type FileSystem interface {
 	Stat(ctx context.Context, name string) (*FileInfo, error)
 	ReadDir(ctx context.Context, name string, recursive bool) ([]FileInfo, error)
 	Create(ctx context.Context, name string, body io.ReadCloser, opts *CreateOptions) (fileInfo *FileInfo, created bool, err error)
-	RemoveAll(ctx context.Context, name string) error
+	RemoveAll(ctx context.Context, name string, opts *RemoveAllOptions) error
 	Mkdir(ctx context.Context, name string) error
 	Copy(ctx context.Context, name, dest string, options *CopyOptions) (created bool, err error)
 	Move(ctx context.Context, name, dest string, options *MoveOptions) (created bool, err error)
@@ -226,7 +226,14 @@ func (b *backend) Put(w http.ResponseWriter, r *http.Request) error {
 }
 
 func (b *backend) Delete(r *http.Request) error {
-	return b.FileSystem.RemoveAll(r.Context(), r.URL.Path)
+	ifNoneMatch := ConditionalMatch(r.Header.Get("If-None-Match"))
+	ifMatch := ConditionalMatch(r.Header.Get("If-Match"))
+
+	opts := RemoveAllOptions{
+		IfNoneMatch: ifNoneMatch,
+		IfMatch:     ifMatch,
+	}
+	return b.FileSystem.RemoveAll(r.Context(), r.URL.Path, &opts)
 }
 
 func (b *backend) Mkcol(r *http.Request) error {
diff --git a/webdav.go b/webdav.go
index eb5c742..ca16d4c 100644
--- a/webdav.go
+++ b/webdav.go
@@ -24,6 +24,11 @@ type CreateOptions struct {
 	IfNoneMatch ConditionalMatch
 }
 
+type RemoveAllOptions struct {
+	IfMatch     ConditionalMatch
+	IfNoneMatch ConditionalMatch
+}
+
 type CopyOptions struct {
 	NoRecursive bool
 	NoOverwrite bool