From 7f0f9fd3657b566616a661ce9c0eb9c4485b247f Mon Sep 17 00:00:00 2001
From: Conrad Hoffmann <ch@bitfehler.net>
Date: Mon, 31 Oct 2022 12:24:32 +0100
Subject: [PATCH] Implement If-Match handling

---
 storage/filesystem.go | 25 +++++++++++++++++++++++--
 1 file changed, 23 insertions(+), 2 deletions(-)

diff --git a/storage/filesystem.go b/storage/filesystem.go
index ee46863..7da8ea7 100644
--- a/storage/filesystem.go
+++ b/storage/filesystem.go
@@ -10,6 +10,7 @@ import (
 	"io"
 	"io/fs"
 	"io/ioutil"
+	"net/http"
 	"os"
 	"path"
 	"path/filepath"
@@ -428,9 +429,19 @@ func (b *filesystemBackend) PutAddressObject(ctx context.Context, objPath string
 	flags := os.O_RDWR | os.O_CREATE | os.O_TRUNC
 	if opts.IfNoneMatch {
 		flags |= os.O_EXCL
+	} else if opts.IfMatch == "*" {
+		flags &= ^os.O_CREATE
+	} else if opts.IfMatch != "" {
+		etag, err := etagForFile(localPath)
+		if err != nil {
+			return "", webdav.NewHTTPError(http.StatusPreconditionFailed, err)
+		}
+		if opts.IfMatch != etag {
+			err = fmt.Errorf("If-Match does not match current ETag (%s/%s)", opts.IfMatch, etag)
+			return "", webdav.NewHTTPError(http.StatusPreconditionFailed, err)
+		}
 	}
 
-	// TODO handle IfMatch
 	f, err := os.OpenFile(localPath, flags, 0666)
 	if os.IsExist(err) {
 		return "", carddav.NewPreconditionError(carddav.PreconditionNoUIDConflict)
@@ -608,9 +619,19 @@ func (b *filesystemBackend) PutCalendarObject(ctx context.Context, objPath strin
 	flags := os.O_RDWR | os.O_CREATE | os.O_TRUNC
 	if opts.IfNoneMatch {
 		flags |= os.O_EXCL
+	} else if opts.IfMatch == "*" {
+		flags &= ^os.O_CREATE
+	} else if opts.IfMatch != "" {
+		etag, err := etagForFile(localPath)
+		if err != nil {
+			return "", webdav.NewHTTPError(http.StatusPreconditionFailed, err)
+		}
+		if opts.IfMatch != etag {
+			err = fmt.Errorf("If-Match does not match current ETag (%s/%s)", opts.IfMatch, etag)
+			return "", webdav.NewHTTPError(http.StatusPreconditionFailed, err)
+		}
 	}
 
-	// TODO handle IfMatch
 	f, err := os.OpenFile(localPath, flags, 0666)
 	if os.IsExist(err) {
 		return "", caldav.NewPreconditionError(caldav.PreconditionNoUIDConflict)