github.com/google/go-safeweb@v0.0.0-20231219055052-64d8cfc90fbb/safehttp/plugins/htmlinject/embed_1_16.go (about)

     1  // Copyright 2020 Google LLC
     2  //
     3  // Licensed under the Apache License, Version 2.0 (the "License");
     4  // you may not use this file except in compliance with the License.
     5  // You may obtain a copy of the License at
     6  //
     7  //	https://www.apache.org/licenses/LICENSE-2.0
     8  //
     9  // Unless required by applicable law or agreed to in writing, software
    10  // distributed under the License is distributed on an "AS IS" BASIS,
    11  // WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
    12  // See the License for the specific language governing permissions and
    13  // limitations under the License.
    14  
    15  //go:build go1.16
    16  // +build go1.16
    17  
    18  package htmlinject
    19  
    20  import (
    21  	"embed"
    22  	"fmt"
    23  	"io"
    24  	"io/fs"
    25  	"path/filepath"
    26  
    27  	"github.com/google/safehtml/template"
    28  	"github.com/google/safehtml/template/uncheckedconversions"
    29  )
    30  
    31  // LoadGlobEmbed is like LoadGlob but works on an embedded filesystem.
    32  func LoadGlobEmbed(tpl *template.Template, lcfg LoadConfig, pattern template.TrustedSource, fsys embed.FS) (*template.Template, error) {
    33  	return loadGlobFS(tpl, lcfg, pattern, fsys)
    34  }
    35  
    36  // TODO(clap): the rest of this file is a copy-paste of a lot of code. Unify this code path with that
    37  // once we decide to drop support for Go version before 1.16 and we can use fs everywhere.
    38  
    39  func loadGlobFS(tpl *template.Template, lcfg LoadConfig, pattern template.TrustedSource, fsys embed.FS) (*template.Template, error) {
    40  	filenames, err := fs.Glob(fsys, pattern.String())
    41  	if err != nil {
    42  		return nil, err
    43  	}
    44  	if len(filenames) == 0 {
    45  		return nil, fmt.Errorf("pattern matches no files: %#q", pattern.String())
    46  	}
    47  	var tts []template.TrustedSource
    48  	for _, fn := range filenames {
    49  		// The pattern expanded from a trusted source, so the expansion is still trusted.
    50  		tts = append(tts, uncheckedconversions.TrustedSourceFromStringKnownToSatisfyTypeContract(fn))
    51  	}
    52  	return loadFilesFS(tpl, lcfg, fsys, tts...)
    53  }
    54  
    55  func loadFilesFS(tpl *template.Template, lcfg LoadConfig, fsys fs.FS, filenames ...template.TrustedSource) (*template.Template, error) {
    56  	// The naming juggling below is quite odd but is kept for consistency.
    57  	if len(filenames) == 0 {
    58  		return nil, fmt.Errorf("no files named in call to LoadFiles")
    59  	}
    60  	for _, fnts := range filenames {
    61  		fn := fnts.String()
    62  		f, err := fsys.Open(fn)
    63  		if err != nil {
    64  			return nil, err
    65  		}
    66  		b, err := io.ReadAll(f)
    67  		if err != nil {
    68  			return nil, err
    69  		}
    70  		name := filepath.Base(fn)
    71  		var t *template.Template
    72  		if tpl == nil {
    73  			tpl = template.New(name)
    74  		}
    75  		if name == tpl.Name() {
    76  			t = tpl
    77  		} else {
    78  			t = tpl.New(name)
    79  		}
    80  		// We are loading a file from a TrustedSource, so this conversion is safe.
    81  		tts := uncheckedconversions.TrustedTemplateFromStringKnownToSatisfyTypeContract(string(b))
    82  		_, err = LoadTrustedTemplate(t, lcfg, tts)
    83  		if err != nil {
    84  			return nil, err
    85  		}
    86  	}
    87  	return tpl, nil
    88  }