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// The sym command encrypts or decrypts files with a password.
//
// Sym has two subcommands, enc and dec, which perform encryption and
// decryption. The encryption key is derived from the user's password using
// argon2, and the data is then encrypted using AES-256 in chunks of 1MiB.
//
// Run sym -h for detailed usage information.
package main
import (
"flag"
"fmt"
"os"
"path/filepath"
)
type subcommand interface {
registerFlags(*flag.FlagSet)
run(...string) error
}
func whichSubcommand(name string) (subcommand, bool) {
switch name {
case "enc":
return &encryptOptions{
passwordIn: termReadPassword,
passwordOut: os.Stderr,
stdin: os.Stdin,
stdout: os.Stdout,
}, true
case "dec":
return &decryptOptions{
passwordIn: termReadPassword,
stdin: os.Stdin,
stdout: os.Stdout,
}, true
default:
return nil, false
}
}
func run(args []string) error {
name := filepath.Base(args[0])
cmd, ok := whichSubcommand(name)
if !ok {
flag.Usage = func() {
fmt.Fprintf(os.Stderr, `usage: sym <subcommand> [OPTION]... [FILE]...
Encrypt or decrypt files using a password.
Subcommands:
enc encrypt
dec decrypt
Try sym <subcommand> -h for command-specific help.
Pro tip: use "ln sym enc" or "ln sym dec" to create shortcuts for each subcommand.
`)
}
flag.CommandLine.Parse(args[1:])
args = flag.Args()
if len(args) == 0 {
return fmt.Errorf("missing subcommand (use sym -h for help)")
}
subcommand := filepath.Base(args[0])
name = "sym " + subcommand
cmd, ok = whichSubcommand(subcommand)
if !ok {
return fmt.Errorf("invalid subcommand %q", args[0])
}
}
fs := flag.NewFlagSet(name, flag.ExitOnError)
cmd.registerFlags(fs)
fs.Parse(args[1:])
return cmd.run(fs.Args()...)
}
func main() {
if err := run(os.Args); err != nil {
fmt.Fprintln(os.Stderr, err)
os.Exit(1)
}
}
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