fileserver: configure plain browse time format (#8084)

caddytest/integration/caddyfile_adapt/file_server_plain_time_format.caddyfiletest

@@ -0,0 +1,36 @@
+:80
+
+file_server {
+	browse {
+		plain_time_format "2006-01-02 15:04:05 MST"
+	}
+}
+----------
+{
+	"apps": {
+		"http": {
+			"servers": {
+				"srv0": {
+					"listen": [
+						":80"
+					],
+					"routes": [
+						{
+							"handle": [
+								{
+									"browse": {
+										"plain_time_format": "2006-01-02 15:04:05 MST"
+									},
+									"handler": "file_server",
+									"hide": [
+										"./Caddyfile"
+									]
+								}
+							]
+						}
+					]
+				}
+			}
+		}
+	}
+}

caddytest/integration/caddyfile_adapt/file_server_plain_time_format_empty_argument.caddyfiletest

@@ -0,0 +1,9 @@
+:80
+
+file_server {
+	browse {
+		plain_time_format ""
+	}
+}
+----------
+plain_time_format requires a non-empty time layout argument

caddytest/integration/caddyfile_adapt/file_server_plain_time_format_extra_arguments.caddyfiletest

@@ -0,0 +1,9 @@
+:80
+
+file_server {
+	browse {
+		plain_time_format 2006-01-02 15:04:05 MST
+	}
+}
+----------
+plain_time_format accepts exactly one time layout argument; enclose layouts containing spaces in quotes

caddytest/integration/caddyfile_adapt/file_server_plain_time_format_missing_argument.caddyfiletest

@@ -0,0 +1,9 @@
+:80
+
+file_server {
+	browse {
+		plain_time_format
+	}
+}
+----------
+plain_time_format is missing a time layout argument

modules/caddyhttp/fileserver/browse.go

@@ -69,10 +69,17 @@ type Browse struct {
 
 	// FileLimit limits the number of up to n DirEntry values in directory order.
 	FileLimit int `json:"file_limit,omitempty"`
+
+	// PlainTimeFormat specifies the Go time layout used for modification
+	// times in plain-text directory listings. The default layout is
+	// `January 2, 2006 at 15:04:05`. See
+	// [Go's time layout documentation](https://pkg.go.dev/time#pkg-constants).
+	PlainTimeFormat string `json:"plain_time_format,omitempty"`
 }
 
 const (
-	defaultDirEntryLimit = 10000
+	defaultDirEntryLimit   = 10000
+	defaultPlainTimeFormat = "January 2, 2006 at 15:04:05"
 )
 
 func (fsrv *FileServer) serveBrowse(fileSystem fs.FS, root, dirPath string, w http.ResponseWriter, r *http.Request, next caddyhttp.Handler) error {
@@ -167,11 +174,19 @@ func (fsrv *FileServer) serveBrowse(fileSystem fs.FS, root, dirPath string, w ht
 			return caddyhttp.Error(http.StatusInternalServerError, err)
 		}
 
+		// Use the configured time format if specified, otherwise use the default
+		plainTimeFormat := defaultPlainTimeFormat
+		if fsrv.Browse.PlainTimeFormat != "" {
+			plainTimeFormat = fsrv.Browse.PlainTimeFormat
+		}
+
 		// Actual files
 		for _, item := range listing.Items {
 			//nolint:gosec // not sure how this could be XSS unless you lose control of the file system (like aren't sanitizing) and client ignores Content-Type of text/plain
 			if _, err := fmt.Fprintf(writer, "%s\t%s\t%s\n",
-				item.Name, item.HumanSize(), item.HumanModTime("January 2, 2006 at 15:04:05"),
+				item.Name,
+				item.HumanSize(),
+				item.HumanModTime(plainTimeFormat),
 			); err != nil {
 				return caddyhttp.Error(http.StatusInternalServerError, err)
 			}

modules/caddyhttp/fileserver/browse_test.go

@@ -0,0 +1,88 @@
+// Copyright 2015 Matthew Holt and The Caddy Authors
+//
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+//     http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+
+package fileserver
+
+import (
+	"context"
+	"net/http"
+	"net/http/httptest"
+	"os"
+	"path/filepath"
+	"strings"
+	"testing"
+	"time"
+
+	"github.com/caddyserver/caddy/v2"
+	"github.com/caddyserver/caddy/v2/modules/caddyhttp"
+)
+
+func TestBrowsePlainTimeFormat(t *testing.T) {
+	root := t.TempDir()
+	filename := filepath.Join(root, "example.txt")
+	if err := os.WriteFile(filename, nil, 0o600); err != nil {
+		t.Fatal(err)
+	}
+	modTime := time.Date(2024, time.January, 2, 3, 4, 5, 0, time.UTC)
+	if err := os.Chtimes(filename, modTime, modTime); err != nil {
+		t.Fatal(err)
+	}
+
+	for _, tc := range []struct {
+		name        string
+		layout      string
+		wantModTime string
+	}{
+		{
+			name:        "default",
+			wantModTime: "January 2, 2024 at 03:04:05",
+		},
+		{
+			name:        "custom",
+			layout:      "2006-01-02T15:04:05Z07:00",
+			wantModTime: "2024-01-02T03:04:05Z",
+		},
+	} {
+		t.Run(tc.name, func(t *testing.T) {
+			fsrv := FileServer{
+				Root: root,
+				Browse: &Browse{
+					PlainTimeFormat: tc.layout,
+				},
+			}
+			ctx, _ := caddy.NewContext(caddy.Context{Context: context.Background()})
+			if err := fsrv.Provision(ctx); err != nil {
+				t.Fatal(err)
+			}
+
+			req := httptest.NewRequest(http.MethodGet, "http://example.com/", nil)
+			req.Header.Set("Accept", "text/plain")
+			originalReq := *req
+			reqCtx := context.WithValue(req.Context(), caddy.ReplacerCtxKey, caddy.NewReplacer())
+			reqCtx = context.WithValue(reqCtx, caddyhttp.OriginalRequestCtxKey, originalReq)
+			req = req.WithContext(reqCtx)
+
+			w := httptest.NewRecorder()
+			if err := fsrv.ServeHTTP(w, req, nil); err != nil {
+				t.Fatal(err)
+			}
+			if got := w.Header().Get("Content-Type"); got != "text/plain; charset=utf-8" {
+				t.Fatalf("Content-Type = %q, want %q", got, "text/plain; charset=utf-8")
+			}
+			if !strings.Contains(w.Body.String(), tc.wantModTime) {
+				t.Fatalf("response body does not contain modification time %q:\n%s", tc.wantModTime, w.Body.String())
+			}
+		})
+	}
+}

modules/caddyhttp/fileserver/caddyfile.go

@@ -56,7 +56,12 @@ func parseCaddyfile(h httpcaddyfile.Helper) (caddyhttp.MiddlewareHandler, error)
 //	    root          <path>
 //	    hide          <files...>
 //	    index         <files...>
-//	    browse        [<template_file>]
+//	    browse        [<template_file>] {
+//	        reveal_symlinks
+//	        sort              <options...>
+//	        file_limit        <limit>
+//	        plain_time_format <layout>
+//	    }
 //	    precompressed <formats...>
 //	    status        <status>
 //	    disable_canonical_uris
@@ -147,6 +152,21 @@ func (fsrv *FileServer) UnmarshalCaddyfile(d *caddyfile.Dispenser) error {
 						return d.Err("file_limit is already enabled")
 					}
 					fsrv.Browse.FileLimit = val
+				case "plain_time_format":
+					plainTimeFormat := d.RemainingArgs()
+					if len(plainTimeFormat) == 0 {
+						return d.Err("plain_time_format is missing a time layout argument")
+					}
+					if len(plainTimeFormat) > 1 {
+						return d.Err("plain_time_format accepts exactly one time layout argument; enclose layouts containing spaces in quotes")
+					}
+					if plainTimeFormat[0] == "" {
+						return d.Err("plain_time_format requires a non-empty time layout argument")
+					}
+					if fsrv.Browse.PlainTimeFormat != "" {
+						return d.Err("plain_time_format is already set")
+					}
+					fsrv.Browse.PlainTimeFormat = plainTimeFormat[0]
 				default:
 					return d.Errf("unknown subdirective '%s'", d.Val())
 				}