templates: fix inconsistent nested includes (#4452)

modules/caddyhttp/templates/frontmatter_fuzz.go

@@ -12,6 +12,7 @@
 // See the License for the specific language governing permissions and
 // limitations under the License.
 
+//go:build gofuzz
 // +build gofuzz
 
 package templates

modules/caddyhttp/templates/tplcontext.go

@@ -91,7 +91,12 @@ func (c TemplateContext) OriginalReq() http.Request {
 // trusted files. If it is not trusted, be sure to use escaping functions
 // in your template.
 func (c TemplateContext) funcInclude(filename string, args ...interface{}) (string, error) {
-	bodyBuf, err := c.readFileToBuffer(filename)
+
+	bodyBuf := bufPool.Get().(*bytes.Buffer)
+	bodyBuf.Reset()
+	defer bufPool.Put(bodyBuf)
+
+	err := c.readFileToBuffer(filename, bodyBuf)
 
 	if err != nil {
 		return "", err
@@ -107,28 +112,24 @@ func (c TemplateContext) funcInclude(filename string, args ...interface{}) (stri
 	return bodyBuf.String(), nil
 }
 
-// readFileToBuffer returns the contents of filename relative to root as a buffer
-func (c TemplateContext) readFileToBuffer(filename string) (*bytes.Buffer, error) {
+// readFileToBuffer reads a file into a buffer
+func (c TemplateContext) readFileToBuffer(filename string, bodyBuf *bytes.Buffer) error {
 	if c.Root == nil {
-		return nil, fmt.Errorf("root file system not specified")
+		return fmt.Errorf("root file system not specified")
 	}
 
 	file, err := c.Root.Open(filename)
 	if err != nil {
-		return nil, err
+		return err
 	}
 	defer file.Close()
 
-	bodyBuf := bufPool.Get().(*bytes.Buffer)
-	bodyBuf.Reset()
-	defer bufPool.Put(bodyBuf)
-
 	_, err = io.Copy(bodyBuf, file)
 	if err != nil {
-		return nil, err
+		return err
 	}
 
-	return bodyBuf, nil
+	return nil
 }
 
 // funcHTTPInclude returns the body of a virtual (lightweight) request
@@ -185,7 +186,12 @@ func (c TemplateContext) funcHTTPInclude(uri string) (string, error) {
 // {{ template }} from the standard template library. If the imported file has
 // no {{ define }} blocks, the name of the import will be the path
 func (c *TemplateContext) funcImport(filename string) (string, error) {
-	bodyBuf, err := c.readFileToBuffer(filename)
+
+	bodyBuf := bufPool.Get().(*bytes.Buffer)
+	bodyBuf.Reset()
+	defer bufPool.Put(bodyBuf)
+
+	err := c.readFileToBuffer(filename, bodyBuf)
 	if err != nil {
 		return "", err
 	}

modules/caddyhttp/templates/tplcontext_test.go

@@ -18,6 +18,7 @@ import (
 	"bytes"
 	"context"
 	"fmt"
+	"io/ioutil"
 	"net/http"
 	"os"
 	"path/filepath"
@@ -187,6 +188,95 @@ func TestImport(t *testing.T) {
 	}
 }
 
+func TestNestedInclude(t *testing.T) {
+	for i, test := range []struct {
+		child      string
+		childFile  string
+		parent     string
+		parentFile string
+		shouldErr  bool
+		expect     string
+		child2     string
+		child2File string
+	}{
+		{
+			// include in parent
+			child:      `{{ include "file1" }}`,
+			childFile:  "file0",
+			parent:     `{{ $content := "file2" }}{{ $p := include $content}}`,
+			parentFile: "file1",
+			shouldErr:  false,
+			expect:     ``,
+			child2:     `This shouldn't show`,
+			child2File: "file2",
+		},
+	} {
+		context := getContextOrFail(t)
+		var absFilePath string
+		var absFilePath0 string
+		var absFilePath1 string
+		var buf *bytes.Buffer
+		var err error
+
+		// create files and for test case
+		if test.parentFile != "" {
+			absFilePath = filepath.Join(fmt.Sprintf("%s", context.Root), test.parentFile)
+			if err := ioutil.WriteFile(absFilePath, []byte(test.parent), os.ModePerm); err != nil {
+				os.Remove(absFilePath)
+				t.Fatalf("Test %d: Expected no error creating file, got: '%s'", i, err.Error())
+			}
+		}
+		if test.childFile != "" {
+			absFilePath0 = filepath.Join(fmt.Sprintf("%s", context.Root), test.childFile)
+			if err := ioutil.WriteFile(absFilePath0, []byte(test.child), os.ModePerm); err != nil {
+				os.Remove(absFilePath0)
+				t.Fatalf("Test %d: Expected no error creating file, got: '%s'", i, err.Error())
+			}
+		}
+		if test.child2File != "" {
+			absFilePath1 = filepath.Join(fmt.Sprintf("%s", context.Root), test.child2File)
+			if err := ioutil.WriteFile(absFilePath1, []byte(test.child2), os.ModePerm); err != nil {
+				os.Remove(absFilePath0)
+				t.Fatalf("Test %d: Expected no error creating file, got: '%s'", i, err.Error())
+			}
+		}
+
+		buf = bufPool.Get().(*bytes.Buffer)
+		buf.Reset()
+		defer bufPool.Put(buf)
+		buf.WriteString(test.child)
+		err = context.executeTemplateInBuffer(test.childFile, buf)
+
+		if err != nil {
+			if !test.shouldErr {
+				t.Errorf("Test %d: Expected no error, got: '%s'", i, err)
+			}
+		} else if test.shouldErr {
+			t.Errorf("Test %d: Expected error but had none", i)
+		} else if buf.String() != test.expect {
+			//
+			t.Errorf("Test %d: Expected '%s' but got '%s'", i, test.expect, buf.String())
+
+		}
+
+		if absFilePath != "" {
+			if err := os.Remove(absFilePath); err != nil && !os.IsNotExist(err) {
+				t.Fatalf("Test %d: Expected no error removing temporary test file, got: %v", i, err)
+			}
+		}
+		if absFilePath0 != "" {
+			if err := os.Remove(absFilePath0); err != nil && !os.IsNotExist(err) {
+				t.Fatalf("Test %d: Expected no error removing temporary test file, got: %v", i, err)
+			}
+		}
+		if absFilePath1 != "" {
+			if err := os.Remove(absFilePath1); err != nil && !os.IsNotExist(err) {
+				t.Fatalf("Test %d: Expected no error removing temporary test file, got: %v", i, err)
+			}
+		}
+	}
+}
+
 func TestInclude(t *testing.T) {
 	for i, test := range []struct {
 		fileContent string