[libsecret/wip/dueno/simple-item: 7/9] secret-value: Add secret_value_unref_to_password

[Daiki Ueno <dueno src gnome org>]

commit 85565d26d394dd612735b96b4f440ce0bac8f5cd
Author: Daiki Ueno <dueno src gnome org>
Date:   Thu Jun 20 06:55:56 2019 +0200

    secret-value: Add secret_value_unref_to_password
    
    This adds the secret_value_unref_to_password function that
    unreferences and returns the stored secret in non-pageable memory.
    This is supposed to be used with secret_password_lookup_binary*
    functions.

 docs/reference/libsecret/libsecret-sections.txt |  1 +
 libsecret/secret-value.c                        | 38 +++++++++++++++++++++----
 libsecret/secret-value.h                        |  3 ++
 3 files changed, 36 insertions(+), 6 deletions(-)
---
diff --git a/docs/reference/libsecret/libsecret-sections.txt b/docs/reference/libsecret/libsecret-sections.txt
index d8f9509..f811b9d 100644
--- a/docs/reference/libsecret/libsecret-sections.txt
+++ b/docs/reference/libsecret/libsecret-sections.txt
@@ -333,6 +333,7 @@ secret_value_get_text
 secret_value_get_content_type
 secret_value_ref
 secret_value_unref
+secret_value_unref_to_password
 <SUBSECTION Standard>
 SECRET_TYPE_VALUE
 secret_value_get_type
diff --git a/libsecret/secret-value.c b/libsecret/secret-value.c
index ca891cb..ce4ebee 100644
--- a/libsecret/secret-value.c
+++ b/libsecret/secret-value.c
@@ -256,38 +256,64 @@ is_password_value (SecretValue *value)
        return FALSE;
 }
 
+/**
+ * secret_value_unref_to_password:
+ * @value: the value
+ * @length: the length of the secret
+ *
+ * Unreference a #SecretValue and steal the secret data in
+ * #SecretValue as nonpageable memory.
+ *
+ * Returns: (transfer full): a new password string stored in nonpageable memory
+ *          which must be freed with secret_password_free() when done
+ */
 gchar *
-_secret_value_unref_to_password (SecretValue *value)
+secret_value_unref_to_password (SecretValue *value,
+                               gsize *length)
 {
        SecretValue *val = value;
        gchar *result;
 
        g_return_val_if_fail (value != NULL, NULL);
 
-       if (!is_password_value (value)) {
-               secret_value_unref (value);
-               return NULL;
-       }
-
        if (g_atomic_int_dec_and_test (&val->refs)) {
                if (val->destroy == egg_secure_free) {
                        result = val->secret;
+                       if (length)
+                               *length = val->length;
 
                } else {
                        result = egg_secure_strndup (val->secret, val->length);
                        if (val->destroy)
                                (val->destroy) (val->secret);
+                       if (length)
+                               *length = val->length;
                }
                g_free (val->content_type);
                g_slice_free (SecretValue, val);
 
        } else {
                result = egg_secure_strndup (val->secret, val->length);
+               if (length)
+                       *length = val->length;
        }
 
        return result;
 }
 
+gchar *
+_secret_value_unref_to_password (SecretValue *value)
+{
+       g_return_val_if_fail (value != NULL, NULL);
+
+       if (!is_password_value (value)) {
+               secret_value_unref (value);
+               return NULL;
+       }
+
+       return secret_value_unref_to_password (value, NULL);
+}
+
 gchar *
 _secret_value_unref_to_string (SecretValue *value)
 {
diff --git a/libsecret/secret-value.h b/libsecret/secret-value.h
index 43b0e09..7699c08 100644
--- a/libsecret/secret-value.h
+++ b/libsecret/secret-value.h
@@ -51,6 +51,9 @@ SecretValue *       secret_value_ref               (SecretValue *value);
 
 void                secret_value_unref             (gpointer value);
 
+gchar *             secret_value_unref_to_password (SecretValue *value,
+                                                   gsize *length);
+
 G_DEFINE_AUTOPTR_CLEANUP_FUNC (SecretValue, secret_value_unref)
 
 G_END_DECLS