Disallow bad combination of arguments in keygen grind (#17251)

* Use constant for outfile sentinel value

* Require --use-mnemonic flag when --no-outfile flag passed to keygen grind

clap-utils/src/input_parsers.rs

@@ -17,6 +17,9 @@ use {
     std::{str::FromStr, sync::Arc},
 };
 
+// Sentinel value used to indicate to write to screen instead of file
+pub const STDOUT_OUTFILE_TOKEN: &str = "-";
+
 // Return parsed values from matches at `name`
 pub fn values_of<T>(matches: &ArgMatches<'_>, name: &str) -> Option<Vec<T>>
 where

clap-utils/src/keypair.rs

@@ -1,6 +1,6 @@
 use {
     crate::{
-        input_parsers::pubkeys_sigs_of,
+        input_parsers::{pubkeys_sigs_of, STDOUT_OUTFILE_TOKEN},
         offline::{SIGNER_ARG, SIGN_ONLY_ARG},
         ArgConstant,
     },
@@ -235,7 +235,7 @@ pub(crate) fn parse_signer_source<S: AsRef<str>>(
                 }
             } else {
                 match source {
-                    "-" => Ok(SignerSource::new(SignerSourceKind::Stdin)),
+                    STDOUT_OUTFILE_TOKEN => Ok(SignerSource::new(SignerSourceKind::Stdin)),
                     ASK_KEYWORD => Ok(SignerSource::new_legacy(SignerSourceKind::Prompt)),
                     _ => match Pubkey::from_str(source) {
                         Ok(pubkey) => Ok(SignerSource::new(SignerSourceKind::Pubkey(pubkey))),
@@ -632,7 +632,7 @@ mod tests {
     #[test]
     fn test_parse_signer_source() {
         assert!(matches!(
-            parse_signer_source("-").unwrap(),
+            parse_signer_source(STDOUT_OUTFILE_TOKEN).unwrap(),
             SignerSource {
                 kind: SignerSourceKind::Stdin,
                 derivation_path: None,

keygen/src/keygen.rs

@@ -5,6 +5,7 @@ use clap::{
     Arg, ArgMatches, SubCommand,
 };
 use solana_clap_utils::{
+    input_parsers::STDOUT_OUTFILE_TOKEN,
     input_validators::{is_parsable, is_prompt_signer_source},
     keypair::{
         keypair_from_path, keypair_from_seed_phrase, prompt_passphrase, signer_from_path,
@@ -105,6 +106,9 @@ fn no_outfile_arg<'a, 'b>() -> Arg<'a, 'b> {
     Arg::with_name(NO_OUTFILE_ARG.name)
         .long(NO_OUTFILE_ARG.long)
         .conflicts_with_all(&["outfile", "silent"])
+        // Require a seed phrase to avoid generating a keypair
+        // but having no way to get the private key
+        .requires("use_mnemonic")
         .help(NO_OUTFILE_ARG.help)
 }
 
@@ -151,7 +155,7 @@ fn output_keypair(
     outfile: &str,
     source: &str,
 ) -> Result<(), Box<dyn error::Error>> {
-    if outfile == "-" {
+    if outfile == STDOUT_OUTFILE_TOKEN {
         let mut stdout = std::io::stdout();
         write_keypair(&keypair, &mut stdout)?;
     } else {
@@ -550,7 +554,7 @@ fn do_main(matches: &ArgMatches<'_>) -> Result<(), Box<dyn error::Error>> {
             };
 
             match outfile {
-                Some("-") => (),
+                Some(STDOUT_OUTFILE_TOKEN) => (),
                 Some(outfile) => check_for_overwrite(&outfile, &matches),
                 None => (),
             }
@@ -592,7 +596,7 @@ fn do_main(matches: &ArgMatches<'_>) -> Result<(), Box<dyn error::Error>> {
                 path.to_str().unwrap()
             };
 
-            if outfile != "-" {
+            if outfile != STDOUT_OUTFILE_TOKEN {
                 check_for_overwrite(&outfile, &matches);
             }