From db77480d979ba37be8c03584e8584e5f6a498608 Mon Sep 17 00:00:00 2001
From: Christian Hergert <chergert@redhat.com>
Date: Fri, 20 Sep 2024 16:14:17 -0700
Subject: [PATCH] glib/gvariant: use g_utf8_validate() for strlen

We can get the length of the string if we provide an out argument to
g_utf8_validate(). This avoids an extra strlen() when creating GVariant
for UTF-8 strings.

This is good for nearly 7% reduction of CPU samples when building
heavily string-based GVariant using GVariantBuilder as a benchmark.
---
 glib/gvariant.c | 36 +++++++++++++++++++++++++-----------
 1 file changed, 25 insertions(+), 11 deletions(-)

diff --git a/glib/gvariant.c b/glib/gvariant.c
index 8ea52d50a..4080ebf1c 100644
--- a/glib/gvariant.c
+++ b/glib/gvariant.c
@@ -1267,11 +1267,17 @@ g_variant_new_fixed_array (const GVariantType  *element_type,
 GVariant *
 g_variant_new_string (const gchar *string)
 {
-  g_return_val_if_fail (string != NULL, NULL);
-  g_return_val_if_fail (g_utf8_validate (string, -1, NULL), NULL);
+  const char *endptr = NULL;
 
-  return g_variant_new_from_trusted (G_VARIANT_TYPE_STRING,
-                                     string, strlen (string) + 1);
+  g_return_val_if_fail (string != NULL, NULL);
+
+  if G_LIKELY (g_utf8_validate (string, -1, &endptr))
+    return g_variant_new_from_trusted (G_VARIANT_TYPE_STRING,
+                                       string, endptr - string + 1);
+
+  g_critical ("g_variant_new_string(): requires valid UTF-8");
+
+  return NULL;
 }
 
 /**
@@ -1299,17 +1305,25 @@ g_variant_new_string (const gchar *string)
 GVariant *
 g_variant_new_take_string (gchar *string)
 {
-  GVariant *value;
-  GBytes *bytes;
+  const char *end = NULL;
 
   g_return_val_if_fail (string != NULL, NULL);
-  g_return_val_if_fail (g_utf8_validate (string, -1, NULL), NULL);
 
-  bytes = g_bytes_new_take (string, strlen (string) + 1);
-  value = g_variant_new_from_bytes (G_VARIANT_TYPE_STRING, bytes, TRUE);
-  g_bytes_unref (bytes);
+  if G_LIKELY (g_utf8_validate (string, -1, &end))
+    {
+      GVariant *value;
+      GBytes *bytes;
 
-  return value;
+      bytes = g_bytes_new_take (string, end - string + 1);
+      value = g_variant_new_from_bytes (G_VARIANT_TYPE_STRING, bytes, TRUE);
+      g_bytes_unref (bytes);
+
+      return value;
+    }
+
+  g_critical ("g_variant_new_take_string(): requires valid UTF-8");
+
+  return NULL;
 }
 
 /**