114 lines
2.2 KiB
Go
114 lines
2.2 KiB
Go
package cnf
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import (
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"errors"
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"fmt"
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"os"
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"path/filepath"
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)
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// ErrUnknownExtension is raised when encountering an unknown extension
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var ErrUnknownExtension = errors.New("unknown extension format")
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// ErrUnknownFormat is raised when the format cannot be guessed from the content of the file
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var ErrUnknownFormat = errors.New("cannot infer format from content")
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// Load the current file and create the configuration format accordingly
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func Load(path string) (ConfigurationFormat, error) {
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var confFormat ConfigurationFormat
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// 1. check file
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if _, err := os.Stat(path); os.IsNotExist(err) {
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return nil, fmt.Errorf("cannot find file '%s'", path)
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}
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// 2. Try to load from extension
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extension := filepath.Ext(path)
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if len(extension) > 0 {
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confFormat = loadFromExtension(extension)
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if confFormat == nil {
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return nil, ErrUnknownExtension
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}
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// open file
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file, err := os.Open(path)
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if err != nil {
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return nil, err
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}
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defer file.Close()
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// parse
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_, err = confFormat.ReadFrom(file)
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if err == nil {
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return confFormat, nil
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}
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// return nil, fmt.Errorf("cannot parse file as '%s' | %s", extension, err)
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}
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// 4. Try to guess from the content
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confFormat, err := loadFromContent(path)
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if err != nil {
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return nil, err
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}
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if confFormat == nil {
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return nil, ErrUnknownFormat
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}
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return confFormat, nil
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}
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func loadFromExtension(ext string) ConfigurationFormat {
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// select configuration or fail if not known
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switch ext {
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case ".json":
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return new(json)
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case ".ini", ".conf":
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return new(ini)
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case ".yaml":
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return new(yaml)
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case ".nginx":
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return new(nginx)
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default:
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return nil
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}
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}
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func loadFromContent(path string) (ConfigurationFormat, error) {
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// 3. open file
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file, err := os.Open(path)
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if err != nil {
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return nil, err
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}
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defer file.Close()
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// extensions ordered by strictness of the language's syntax
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extensions := []string{".json", ".nginx", ".yaml", ".ini"}
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// try to load each available extension
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for _, ext := range extensions {
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file.Seek(0, 0)
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// load parser
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c := loadFromExtension(ext)
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if c == nil {
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continue
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}
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// parse
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_, err := c.ReadFrom(file)
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if err == nil {
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return c, nil
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}
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}
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return nil, ErrUnknownFormat
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}
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