mirror of
https://github.com/cuigh/swirl
synced 2024-12-28 14:51:57 +00:00
82 lines
2.5 KiB
Go
82 lines
2.5 KiB
Go
package compose
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import (
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"bufio"
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"bytes"
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"fmt"
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"os"
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"strings"
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"unicode"
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"unicode/utf8"
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)
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// ParseEnvFile reads a file with environment variables enumerated by lines
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//
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// ``Environment variable names used by the utilities in the Shell and
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// Utilities volume of IEEE Std 1003.1-2001 consist solely of uppercase
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// letters, digits, and the '_' (underscore) from the characters defined in
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// Portable Character Set and do not begin with a digit. *But*, other
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// characters may be permitted by an implementation; applications shall
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// tolerate the presence of such names.''
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// -- http://pubs.opengroup.org/onlinepubs/009695399/basedefs/xbd_chap08.html
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//
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// As of #16585, it's up to application inside docker to validate or not
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// environment variables, that's why we just strip leading whitespace and
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// nothing more.
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func ParseEnvFile(filename string) ([]string, error) {
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fh, err := os.Open(filename)
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if err != nil {
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return []string{}, err
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}
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defer fh.Close()
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lines := []string{}
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scanner := bufio.NewScanner(fh)
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currentLine := 0
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utf8bom := []byte{0xEF, 0xBB, 0xBF}
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for scanner.Scan() {
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scannedBytes := scanner.Bytes()
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if !utf8.Valid(scannedBytes) {
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return []string{}, fmt.Errorf("env file %s contains invalid utf8 bytes at line %d: %v", filename, currentLine+1, scannedBytes)
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}
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// We trim UTF8 BOM
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if currentLine == 0 {
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scannedBytes = bytes.TrimPrefix(scannedBytes, utf8bom)
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}
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// trim the line from all leading whitespace first
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line := strings.TrimLeftFunc(string(scannedBytes), unicode.IsSpace)
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currentLine++
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// line is not empty, and not starting with '#'
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if len(line) > 0 && !strings.HasPrefix(line, "#") {
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data := strings.SplitN(line, "=", 2)
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// trim the front of a variable, but nothing else
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variable := strings.TrimLeft(data[0], whiteSpaces)
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if strings.ContainsAny(variable, whiteSpaces) {
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return []string{}, ErrBadEnvVariable{fmt.Sprintf("variable '%s' has white spaces", variable)}
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}
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if len(data) > 1 {
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// pass the value through, no trimming
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lines = append(lines, fmt.Sprintf("%s=%s", variable, data[1]))
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} else {
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// if only a pass-through variable is given, clean it up.
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lines = append(lines, fmt.Sprintf("%s=%s", strings.TrimSpace(line), os.Getenv(line)))
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}
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}
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}
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return lines, scanner.Err()
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}
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var whiteSpaces = " \t"
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// ErrBadEnvVariable typed error for bad environment variable
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type ErrBadEnvVariable struct {
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msg string
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}
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func (e ErrBadEnvVariable) Error() string {
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return fmt.Sprintf("poorly formatted environment: %s", e.msg)
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}
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