Port of #945 (#1343)

- Make sure we always cleanup the temp directory on error.
- Complain about it having an error prone API shape.

mediaapi/fileutils/fileutils.go

@@ -16,6 +16,7 @@ package fileutils
 
 import (
 	"bufio"
+	"context"
 	"crypto/sha256"
 	"encoding/base64"
 	"fmt"
@@ -27,6 +28,7 @@ import (
 
 	"github.com/matrix-org/dendrite/internal/config"
 	"github.com/matrix-org/dendrite/mediaapi/types"
+	"github.com/matrix-org/util"
 	log "github.com/sirupsen/logrus"
 )
 
@@ -104,15 +106,23 @@ func RemoveDir(dir types.Path, logger *log.Entry) {
 	}
 }
 
-// WriteTempFile writes to a new temporary file
-func WriteTempFile(reqReader io.Reader, maxFileSizeBytes config.FileSizeBytes, absBasePath config.Path) (hash types.Base64Hash, size types.FileSizeBytes, path types.Path, err error) {
+// WriteTempFile writes to a new temporary file.
+// The file is deleted if there was an error while writing.
+func WriteTempFile(
+	ctx context.Context, reqReader io.Reader, maxFileSizeBytes config.FileSizeBytes, absBasePath config.Path,
+) (hash types.Base64Hash, size types.FileSizeBytes, path types.Path, err error) {
 	size = -1
-
+	logger := util.GetLogger(ctx)
 	tmpFileWriter, tmpFile, tmpDir, err := createTempFileWriter(absBasePath)
 	if err != nil {
 		return
 	}
-	defer (func() { err = tmpFile.Close() })()
+	defer func() {
+		err2 := tmpFile.Close()
+		if err == nil {
+			err = err2
+		}
+	}()
 
 	// The amount of data read is limited to maxFileSizeBytes. At this point, if there is more data it will be truncated.
 	limitedReader := io.LimitReader(reqReader, int64(maxFileSizeBytes))
@@ -123,11 +133,13 @@ func WriteTempFile(reqReader io.Reader, maxFileSizeBytes config.FileSizeBytes, a
 	teeReader := io.TeeReader(limitedReader, hasher)
 	bytesWritten, err := io.Copy(tmpFileWriter, teeReader)
 	if err != nil && err != io.EOF {
+		RemoveDir(tmpDir, logger)
 		return
 	}
 
 	err = tmpFileWriter.Flush()
 	if err != nil {
+		RemoveDir(tmpDir, logger)
 		return
 	}