github.com/kovansky/hugo@v0.92.3-0.20220224232819-63076e4ff19f/tpl/os/os.go (about) 1 // Copyright 2017 The Hugo Authors. All rights reserved. 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 // http://www.apache.org/licenses/LICENSE-2.0 7 // 8 // Unless required by applicable law or agreed to in writing, software 9 // distributed under the License is distributed on an "AS IS" BASIS, 10 // WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. 11 // See the License for the specific language governing permissions and 12 // limitations under the License. 13 14 // Package os provides template functions for interacting with the operating 15 // system. 16 package os 17 18 import ( 19 "errors" 20 "fmt" 21 _os "os" 22 "path/filepath" 23 24 "github.com/gohugoio/hugo/deps" 25 "github.com/spf13/afero" 26 "github.com/spf13/cast" 27 ) 28 29 // New returns a new instance of the os-namespaced template functions. 30 func New(d *deps.Deps) *Namespace { 31 return &Namespace{ 32 readFileFs: afero.NewReadOnlyFs(afero.NewCopyOnWriteFs(d.PathSpec.BaseFs.Content.Fs, d.PathSpec.BaseFs.Work)), 33 workFs: d.PathSpec.BaseFs.Work, 34 deps: d, 35 } 36 } 37 38 // Namespace provides template functions for the "os" namespace. 39 type Namespace struct { 40 readFileFs afero.Fs 41 workFs afero.Fs 42 deps *deps.Deps 43 } 44 45 // Getenv retrieves the value of the environment variable named by the key. 46 // It returns the value, which will be empty if the variable is not present. 47 func (ns *Namespace) Getenv(key interface{}) (string, error) { 48 skey, err := cast.ToStringE(key) 49 if err != nil { 50 return "", nil 51 } 52 53 if err = ns.deps.ExecHelper.Sec().CheckAllowedGetEnv(skey); err != nil { 54 return "", err 55 } 56 57 return _os.Getenv(skey), nil 58 } 59 60 // readFile reads the file named by filename in the given filesystem 61 // and returns the contents as a string. 62 func readFile(fs afero.Fs, filename string) (string, error) { 63 filename = filepath.Clean(filename) 64 if filename == "" || filename == "." || filename == string(_os.PathSeparator) { 65 return "", errors.New("invalid filename") 66 } 67 68 b, err := afero.ReadFile(fs, filename) 69 if err != nil { 70 return "", err 71 } 72 73 return string(b), nil 74 } 75 76 // ReadFile reads the file named by filename relative to the configured WorkingDir. 77 // It returns the contents as a string. 78 // There is an upper size limit set at 1 megabytes. 79 func (ns *Namespace) ReadFile(i interface{}) (string, error) { 80 s, err := cast.ToStringE(i) 81 if err != nil { 82 return "", err 83 } 84 85 if ns.deps.PathSpec != nil { 86 s = ns.deps.PathSpec.RelPathify(s) 87 } 88 89 return readFile(ns.readFileFs, s) 90 } 91 92 // ReadDir lists the directory contents relative to the configured WorkingDir. 93 func (ns *Namespace) ReadDir(i interface{}) ([]_os.FileInfo, error) { 94 path, err := cast.ToStringE(i) 95 if err != nil { 96 return nil, err 97 } 98 99 list, err := afero.ReadDir(ns.workFs, path) 100 if err != nil { 101 return nil, fmt.Errorf("failed to read directory %q: %s", path, err) 102 } 103 104 return list, nil 105 } 106 107 // FileExists checks whether a file exists under the given path. 108 func (ns *Namespace) FileExists(i interface{}) (bool, error) { 109 path, err := cast.ToStringE(i) 110 if err != nil { 111 return false, err 112 } 113 114 if path == "" { 115 return false, errors.New("fileExists needs a path to a file") 116 } 117 118 status, err := afero.Exists(ns.readFileFs, path) 119 if err != nil { 120 return false, err 121 } 122 123 return status, nil 124 } 125 126 // Stat returns the os.FileInfo structure describing file. 127 func (ns *Namespace) Stat(i interface{}) (_os.FileInfo, error) { 128 path, err := cast.ToStringE(i) 129 if err != nil { 130 return nil, err 131 } 132 133 if path == "" { 134 return nil, errors.New("fileStat needs a path to a file") 135 } 136 137 r, err := ns.readFileFs.Stat(path) 138 if err != nil { 139 return nil, err 140 } 141 142 return r, nil 143 }