hugo/tpl/os/os.go

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// Copyright 2017 The Hugo Authors. All rights reserved.
//
// 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 os provides template functions for interacting with the operating
// system.
package os
import (
"errors"
"fmt"
"os"
_os "os"
"github.com/gohugoio/hugo/deps"
"github.com/spf13/afero"
"github.com/spf13/cast"
)
// New returns a new instance of the os-namespaced template functions.
func New(d *deps.Deps) *Namespace {
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var rfs afero.Fs
if d.Fs != nil {
rfs = d.Fs.WorkingDir
if d.PathSpec != nil && d.PathSpec.BaseFs != nil {
rfs = afero.NewReadOnlyFs(afero.NewCopyOnWriteFs(d.PathSpec.BaseFs.Content.Fs, d.Fs.WorkingDir))
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}
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}
return &Namespace{
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readFileFs: rfs,
deps: d,
}
}
// Namespace provides template functions for the "os" namespace.
type Namespace struct {
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readFileFs afero.Fs
deps *deps.Deps
}
// Getenv retrieves the value of the environment variable named by the key.
// It returns the value, which will be empty if the variable is not present.
func (ns *Namespace) Getenv(key interface{}) (string, error) {
skey, err := cast.ToStringE(key)
if err != nil {
return "", nil
}
return _os.Getenv(skey), nil
}
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// readFile reads the file named by filename in the given filesystem
// and returns the contents as a string.
// There is a upper size limit set at 1 megabytes.
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func readFile(fs afero.Fs, filename string) (string, error) {
if filename == "" {
return "", errors.New("readFile needs a filename")
}
if info, err := fs.Stat(filename); err == nil {
if info.Size() > 1000000 {
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return "", fmt.Errorf("file %q is too big", filename)
}
} else {
if os.IsNotExist(err) {
return "", fmt.Errorf("file %q does not exist", filename)
}
return "", err
}
b, err := afero.ReadFile(fs, filename)
if err != nil {
return "", err
}
return string(b), nil
}
// ReadFile reads the file named by filename relative to the configured WorkingDir.
// It returns the contents as a string.
// There is an upper size limit set at 1 megabytes.
func (ns *Namespace) ReadFile(i interface{}) (string, error) {
s, err := cast.ToStringE(i)
if err != nil {
return "", err
}
if ns.deps.PathSpec != nil {
s = ns.deps.PathSpec.RelPathify(s)
}
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return readFile(ns.readFileFs, s)
}
// ReadDir lists the directory contents relative to the configured WorkingDir.
func (ns *Namespace) ReadDir(i interface{}) ([]_os.FileInfo, error) {
path, err := cast.ToStringE(i)
if err != nil {
return nil, err
}
list, err := afero.ReadDir(ns.deps.Fs.WorkingDir, path)
if err != nil {
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return nil, fmt.Errorf("failed to read directory %q: %s", path, err)
}
return list, nil
}
// FileExists checks whether a file exists under the given path.
func (ns *Namespace) FileExists(i interface{}) (bool, error) {
path, err := cast.ToStringE(i)
if err != nil {
return false, err
}
if path == "" {
return false, errors.New("fileExists needs a path to a file")
}
status, err := afero.Exists(ns.readFileFs, path)
if err != nil {
return false, err
}
return status, nil
}
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// Stat returns the os.FileInfo structure describing file.
func (ns *Namespace) Stat(i interface{}) (_os.FileInfo, error) {
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path, err := cast.ToStringE(i)
if err != nil {
return nil, err
}
if path == "" {
return nil, errors.New("fileStat needs a path to a file")
}
r, err := ns.readFileFs.Stat(path)
if err != nil {
return nil, err
}
return r, nil
}