Add helper API to write in a safer way

libfwupdplugin/fu-common.c

@@ -2179,6 +2179,115 @@ fu_common_read_uint32_safe (const guint8 *buf,
 	return TRUE;
 }
 
+/**
+ * fu_common_write_uint8_safe:
+ * @buf: source buffer
+ * @bufsz: maximum size of @buf, typically `sizeof(buf)`
+ * @offset: offset in bytes into @buf to write to
+ * @value: the value to write
+ * @error: A #GError or %NULL
+ *
+ * Write a value to a buffer in a safe way.
+ *
+ * You don't need to use this function in "obviously correct" cases, nor should
+ * you use it when performance is a concern. Only us it when you're not sure if
+ * malicious data from a device or firmware could cause memory corruption.
+ *
+ * Return value: %TRUE if @value was written, %FALSE otherwise
+ *
+ * Since: 1.5.8
+ **/
+gboolean
+fu_common_write_uint8_safe (guint8 *buf,
+			    gsize bufsz,
+			    gsize offset,
+			    guint8 value,
+			    GError **error)
+{
+	g_return_val_if_fail (buf != NULL, FALSE);
+	g_return_val_if_fail (error == NULL || *error == NULL, FALSE);
+
+	return fu_memcpy_safe (buf, bufsz, offset,		/* dst */
+			       &value, sizeof(value), 0x0,	/* src */
+			       sizeof(value), error);
+}
+
+/**
+ * fu_common_write_uint16_safe:
+ * @buf: source buffer
+ * @bufsz: maximum size of @buf, typically `sizeof(buf)`
+ * @offset: offset in bytes into @buf to write to
+ * @value: the value to write
+ * @endian: A #FuEndianType, e.g. %G_LITTLE_ENDIAN
+ * @error: A #GError or %NULL
+ *
+ * Write a value to a buffer using a specified endian in a safe way.
+ *
+ * You don't need to use this function in "obviously correct" cases, nor should
+ * you use it when performance is a concern. Only us it when you're not sure if
+ * malicious data from a device or firmware could cause memory corruption.
+ *
+ * Return value: %TRUE if @value was written, %FALSE otherwise
+ *
+ * Since: 1.5.8
+ **/
+gboolean
+fu_common_write_uint16_safe (guint8 *buf,
+			     gsize bufsz,
+			     gsize offset,
+			     guint16 value,
+			     FuEndianType endian,
+			     GError **error)
+{
+	guint8 tmp[2] = { 0x0 };
+
+	g_return_val_if_fail (buf != NULL, FALSE);
+	g_return_val_if_fail (error == NULL || *error == NULL, FALSE);
+
+	fu_common_write_uint16 (tmp, value, endian);
+	return fu_memcpy_safe (buf, bufsz, offset,	/* dst */
+			       tmp, sizeof(tmp), 0x0,	/* src */
+			       sizeof(tmp), error);
+}
+
+/**
+ * fu_common_write_uint32_safe:
+ * @buf: source buffer
+ * @bufsz: maximum size of @buf, typically `sizeof(buf)`
+ * @offset: offset in bytes into @buf to write to
+ * @value: the value to write
+ * @endian: A #FuEndianType, e.g. %G_LITTLE_ENDIAN
+ * @error: A #GError or %NULL
+ *
+ * Write a value to a buffer using a specified endian in a safe way.
+ *
+ * You don't need to use this function in "obviously correct" cases, nor should
+ * you use it when performance is a concern. Only us it when you're not sure if
+ * malicious data from a device or firmware could cause memory corruption.
+ *
+ * Return value: %TRUE if @value was written, %FALSE otherwise
+ *
+ * Since: 1.5.8
+ **/
+gboolean
+fu_common_write_uint32_safe (guint8 *buf,
+			     gsize bufsz,
+			     gsize offset,
+			     guint32 value,
+			     FuEndianType endian,
+			     GError **error)
+{
+	guint8 tmp[4] = { 0x0 };
+
+	g_return_val_if_fail (buf != NULL, FALSE);
+	g_return_val_if_fail (error == NULL || *error == NULL, FALSE);
+
+	fu_common_write_uint32 (tmp, value, endian);
+	return fu_memcpy_safe (buf, bufsz, offset,	/* dst */
+			       tmp, sizeof(tmp), 0x0,	/* src */
+			       sizeof(tmp), error);
+}
+
 /**
  * fu_byte_array_append_uint8:
  * @array: A #GByteArray

libfwupdplugin/fu-common.h

@@ -224,6 +224,26 @@ gboolean	 fu_common_read_uint32_safe	(const guint8	*buf,
 						 FuEndianType	 endian,
 						 GError		**error)
 						 G_GNUC_WARN_UNUSED_RESULT;
+gboolean	 fu_common_write_uint8_safe	(guint8		*buf,
+						 gsize		 bufsz,
+						 gsize		 offset,
+						 guint8		 value,
+						 GError		**error)
+						 G_GNUC_WARN_UNUSED_RESULT;
+gboolean	 fu_common_write_uint16_safe	(guint8		*buf,
+						 gsize		 bufsz,
+						 gsize		 offset,
+						 guint16	 value,
+						 FuEndianType	 endian,
+						 GError		**error)
+						 G_GNUC_WARN_UNUSED_RESULT;
+gboolean	 fu_common_write_uint32_safe	(guint8		*buf,
+						 gsize		 bufsz,
+						 gsize		 offset,
+						 guint32	 value,
+						 FuEndianType	 endian,
+						 GError		**error)
+						 G_GNUC_WARN_UNUSED_RESULT;
 
 void		 fu_byte_array_set_size		(GByteArray	*array,
 						 guint		 length);

libfwupdplugin/fwupdplugin.map

@@ -775,6 +775,9 @@ LIBFWUPDPLUGIN_1.5.8 {
   global:
     fu_bluez_device_notify_start;
     fu_bluez_device_notify_stop;
+    fu_common_write_uint16_safe;
+    fu_common_write_uint32_safe;
+    fu_common_write_uint8_safe;
     fu_device_get_backend_id;
     fu_device_set_backend_id;
     fu_plugin_add_possible_quirk_key;