From 4f5e5aad18426443aee81710fdf6b85bbf399e41 Mon Sep 17 00:00:00 2001
From: Rusty Russell <rusty@rustcorp.com.au>
Date: Tue, 13 Jan 2026 13:19:18 +1030
Subject: [PATCH] common: expose validate_mnemonic so the option can use it.

Signed-off-by: Rusty Russell <rusty@rustcorp.com.au>
---
 common/hsm_secret.c | 18 +++++++++---------
 common/hsm_secret.h |  8 ++++++++
 2 files changed, 17 insertions(+), 9 deletions(-)

diff --git a/common/hsm_secret.c b/common/hsm_secret.c
index 62348627f..253553973 100644
--- a/common/hsm_secret.c
+++ b/common/hsm_secret.c
@@ -29,7 +29,7 @@
 #define HSM_SECRET_PLAIN_SIZE 32
 
 /* Helper function to validate a mnemonic string */
-static bool validate_mnemonic(const char *mnemonic, enum hsm_secret_error *err)
+enum hsm_secret_error validate_mnemonic(const char *mnemonic)
 {
 	struct words *words;
 	bool ok;
@@ -44,12 +44,10 @@ static bool validate_mnemonic(const char *mnemonic, enum hsm_secret_error *err)
 	/* Wordlists can persist, so provide a common context! */
 	tal_wally_end(notleak_with_children(tal(NULL, char)));
 
-	if (!ok) {
-		*err = HSM_SECRET_ERR_INVALID_MNEMONIC;
-		return false;
-	}
+	if (!ok)
+		return HSM_SECRET_ERR_INVALID_MNEMONIC;
 
-	return true;
+	return HSM_SECRET_OK;
 }
 
 struct secret *get_encryption_key(const tal_t *ctx, const char *passphrase)
@@ -314,7 +312,8 @@ static struct hsm_secret *extract_mnemonic_secret(const tal_t *ctx,
 	}
 
 	/* Validate mnemonic */
-	if (!validate_mnemonic(hsms->mnemonic, err)) {
+	*err = validate_mnemonic(hsms->mnemonic);
+	if (*err != HSM_SECRET_OK) {
 		return tal_free(hsms);
 	}
 
@@ -464,8 +463,9 @@ const char *read_stdin_mnemonic(const tal_t *ctx, enum hsm_secret_error *err)
 	}
 
 	/* Validate mnemonic */
-	if (!validate_mnemonic(line, err)) {
-		return NULL;
+	*err = validate_mnemonic(line);
+	if (*err != HSM_SECRET_OK) {
+		return tal_free(line);
 	}
 
 	*err = HSM_SECRET_OK;
diff --git a/common/hsm_secret.h b/common/hsm_secret.h
index 740f2ebc0..1f6314e63 100644
--- a/common/hsm_secret.h
+++ b/common/hsm_secret.h
@@ -129,6 +129,14 @@ const char *hsm_secret_error_str(enum hsm_secret_error err);
  */
 enum hsm_secret_type detect_hsm_secret_type(const u8 *hsm_secret, size_t len);
 
+/**
+ * Check a BIP39 mnemonic is valid.
+ * @mnemonic - 12 words, single-space separated, nul terminate.
+ *
+ * Returns HSM_SECRET_ERR_INVALID_MNEMONIC or HSM_SECRET_OK.
+ */
+enum hsm_secret_error validate_mnemonic(const char *mnemonic);
+
 /**
  * Reads a BIP39 mnemonic from stdin with validation.
  * Returns a newly allocated string on success, NULL on error.