rano/config/dotenv/write.go

package dotenv

import (
	"fmt"
	"os"
	"sort"
	"strconv"
	"strings"
)

//
// ported from https://github.com/joho/godotenv/blob/main/godotenv.go
//

const doubleQuoteSpecialChars = "\\\n\r\"!$`"

// Write serializes the given environment and writes it to a file.
func Write(envMap map[string]string, filename string) error {
	content, err := marshal(envMap)
	if err != nil {
		return err
	}
	file, err := os.Create(filename)
	if err != nil {
		return err
	}
	defer file.Close()
	_, err = file.WriteString(content + "\n")
	if err != nil {
		return err
	}
	return file.Sync()
}

// marshal outputs the given environment as a dotenv-formatted environment file.
// Each line is in the format: KEY="VALUE" where VALUE is backslash-escaped.
func marshal(envMap map[string]string) (string, error) {
	lines := make([]string, 0, len(envMap))
	for k, v := range envMap {
		if d, err := strconv.Atoi(v); err == nil {
			lines = append(lines, fmt.Sprintf(`%s=%d`, k, d))
		} else {
			lines = append(lines, fmt.Sprintf(`%s="%s"`, k, doubleQuoteEscape(v)))
		}
	}
	sort.Strings(lines)
	return strings.Join(lines, "\n"), nil
}

func doubleQuoteEscape(line string) string {
	for _, c := range doubleQuoteSpecialChars {
		toReplace := "\\" + string(c)
		if c == '\n' {
			toReplace = `\n`
		}
		if c == '\r' {
			toReplace = `\r`
		}
		line = strings.Replace(line, string(c), toReplace, -1)
	}
	return line
}