fs: simplify readFileHeader by using defer statements

.gitignore

@@ -2,6 +2,7 @@ tags
 *.pprof
 *.fasthttp.gz
 *.fasthttp.br
+*.fasthttp.zst
 .idea
 .vscode
 .DS_Store

brotli_test.go

@@ -91,14 +91,14 @@ func testBrotliCompressSingleCase(s string) error {
 	if err != nil {
 		return fmt.Errorf("unexpected error: %w. s=%q", err, s)
 	}
+	defer releaseBrotliReader(zr)
 	body, err := io.ReadAll(zr)
 	if err != nil {
 		return fmt.Errorf("unexpected error: %w. s=%q", err, s)
 	}
 	if string(body) != s {
 		return fmt.Errorf("unexpected string after decompression: %q. Expecting %q", body, s)
 	}
-	releaseBrotliReader(zr)
 	return nil
 }
 

compress_test.go

@@ -173,14 +173,14 @@ func testGzipCompressSingleCase(s string) error {
 	if err != nil {
 		return fmt.Errorf("unexpected error: %w. s=%q", err, s)
 	}
+	defer releaseGzipReader(zr)
 	body, err := io.ReadAll(zr)
 	if err != nil {
 		return fmt.Errorf("unexpected error: %w. s=%q", err, s)
 	}
 	if string(body) != s {
 		return fmt.Errorf("unexpected string after decompression: %q. Expecting %q", body, s)
 	}
-	releaseGzipReader(zr)
 	return nil
 }
 

fs.go

@@ -16,9 +16,6 @@ import (
 	"sync"
 	"time"
 
-	"github.com/andybalholm/brotli"
-	"github.com/klauspost/compress/gzip"
-	"github.com/klauspost/compress/zstd"
 	"github.com/valyala/bytebufferpool"
 )
 
@@ -1632,28 +1629,28 @@ func (h *fsHandler) newFSFile(f fs.File, fileInfo fs.FileInfo, compressed bool,
 
 func readFileHeader(f io.Reader, compressed bool, fileEncoding string) ([]byte, error) {
 	r := f
-	var (
-		br  *brotli.Reader
-		zr  *gzip.Reader
-		zsr *zstd.Decoder
-	)
 	if compressed {
-		var err error
 		switch fileEncoding {
 		case "br":
-			if br, err = acquireBrotliReader(f); err != nil {
+			br, err := acquireBrotliReader(f)
+			if err != nil {
 				return nil, err
 			}
+			defer releaseBrotliReader(br)
 			r = br
 		case "gzip":
-			if zr, err = acquireGzipReader(f); err != nil {
+			zr, err := acquireGzipReader(f)
+			if err != nil {
 				return nil, err
 			}
+			defer releaseGzipReader(zr)
 			r = zr
 		case "zstd":
-			if zsr, err = acquireZstdReader(f); err != nil {
+			zsr, err := acquireZstdReader(f)
+			if err != nil {
 				return nil, err
 			}
+			defer releaseZstdReader(zsr)
 			r = zsr
 		}
 	}
@@ -1671,18 +1668,6 @@ func readFileHeader(f io.Reader, compressed bool, fileEncoding string) ([]byte,
 		return nil, err
 	}
 
-	if br != nil {
-		releaseBrotliReader(br)
-	}
-
-	if zr != nil {
-		releaseGzipReader(zr)
-	}
-
-	if zsr != nil {
-		releaseZstdReader(zsr)
-	}
-
 	return data, err
 }
 

fs_test.go

@@ -263,6 +263,35 @@ func TestServeFileCompressed(t *testing.T) {
 	if !bytes.Equal(body, expectedBody) {
 		t.Fatalf("unexpected body %q. expecting %q", body, expectedBody)
 	}
+
+	// request compressed zstd file
+	ctx.Request.Reset()
+	ctx.Request.SetRequestURI("http://foobar.com/baz")
+	ctx.Request.Header.Set(HeaderAcceptEncoding, "zstd")
+	ServeFile(&ctx, "fs.go")
+
+	s = ctx.Response.String()
+	br = bufio.NewReader(bytes.NewBufferString(s))
+	if err = resp.Read(br); err != nil {
+		t.Fatalf("unexpected error: %v", err)
+	}
+
+	ce = resp.Header.ContentEncoding()
+	if string(ce) != "zstd" {
+		t.Fatalf("Unexpected 'Content-Encoding' %q. Expecting %q", ce, "zstd")
+	}
+
+	body, err = resp.BodyUnzstd()
+	if err != nil {
+		t.Fatalf("unexpected error: %v", err)
+	}
+	expectedBody, err = getFileContents("/fs.go")
+	if err != nil {
+		t.Fatalf("unexpected error: %v", err)
+	}
+	if !bytes.Equal(body, expectedBody) {
+		t.Fatalf("unexpected body %q. expecting %q", body, expectedBody)
+	}
 }
 
 func TestServeFileUncompressed(t *testing.T) {

zstd_test.go

@@ -90,13 +90,13 @@ func testZstdCompressSingleCase(s string) error {
 	if err != nil {
 		return fmt.Errorf("unexpected error: %w. s=%q", err, s)
 	}
+	defer releaseZstdReader(zr)
 	body, err := io.ReadAll(zr)
 	if err != nil {
 		return fmt.Errorf("unexpected error: %w. s=%q", err, s)
 	}
 	if string(body) != s {
 		return fmt.Errorf("unexpected string after decompression: %q. Expecting %q", body, s)
 	}
-	releaseZstdReader(zr)
 	return nil
 }