package readpassword import ( "bytes" "os" "github.com/rfjakob/gocryptfs/internal/exitcodes" "github.com/rfjakob/gocryptfs/internal/tlog" ) func readPassFile(passfile string) []byte { tlog.Info.Printf("passfile: reading from file %q", passfile) f, err := os.Open(passfile) if err != nil { tlog.Fatal.Printf("fatal: passfile: could not open %q: %v", passfile, err) os.Exit(exitcodes.ReadPassword) } defer f.Close() // +1 for an optional trailing newline, // +2 so we can detect if maxPasswordLen is exceeded. buf := make([]byte, maxPasswordLen+2) n, err := f.Read(buf) if err != nil { tlog.Fatal.Printf("fatal: passfile: could not read from %q: %v", passfile, err) os.Exit(exitcodes.ReadPassword) } buf = buf[:n] // Split into first line and "trailing garbage" lines := bytes.SplitN(buf, []byte("\n"), 2) if len(lines[0]) == 0 { tlog.Fatal.Printf("fatal: passfile: empty first line in %q", passfile) os.Exit(exitcodes.ReadPassword) } if len(lines[0]) > maxPasswordLen { tlog.Fatal.Printf("fatal: passfile: max password length (%d bytes) exceeded", maxPasswordLen) os.Exit(exitcodes.ReadPassword) } if len(lines) > 1 && len(lines[1]) > 0 { tlog.Warn.Printf("passfile: ignoring trailing garbage (%d bytes) after first line", len(lines[1])) } return lines[0] }