_dbus_header_load: Operate on the entire string, not a substring

This function worked with a (string,position,length) triple, but it
turns out to only have one caller, which tells it to look at the
entire string anyway. It'll be easier to document if all the offsets
start from 0.

Bug: https://bugs.freedesktop.org/show_bug.cgi?id=100317
Reviewed-by: Philip Withnall <withnall@endlessm.com>
Signed-off-by: Simon McVittie <smcv@collabora.com>

3 files changed, 14 insertions, 19 deletions

diff --git a/dbus/dbus-marshal-header.c b/dbus/dbus-marshal-header.c
index 74b39cdc9..c5b1a24f0 100644
--- a/dbus/dbus-marshal-header.c
+++ b/dbus/dbus-marshal-header.c
@@ -961,9 +961,7 @@ load_and_validate_field (DBusHeader     *header,
  * @param fields_array_len claimed length of fields array
  * @param body_len claimed length of body
  * @param header_len claimed length of header
- * @param str a string
- * @param start start of header, 8-aligned
- * @param len length of string to look at
+ * @param str a string starting with the header
  * @returns #FALSE if no memory or data was invalid, #TRUE otherwise
  */
 dbus_bool_t
@@ -974,9 +972,7 @@ _dbus_header_load (DBusHeader        *header,
                    int                fields_array_len,
                    int                header_len,
                    int                body_len,
-                   const DBusString  *str,
-                   int                start,
-                   int                len)
+                   const DBusString  *str)
 {
   int leftover;
   DBusValidity v;
@@ -988,12 +984,14 @@ _dbus_header_load (DBusHeader        *header,
   int padding_start;
   int padding_len;
   int i;
+  int len;
+
+  len = _dbus_string_get_length (str);
 
-  _dbus_assert (start == (int) _DBUS_ALIGN_VALUE (start, 8));
   _dbus_assert (header_len <= len);
   _dbus_assert (_dbus_string_get_length (&header->data) == 0);
 
-  if (!_dbus_string_copy_len (str, start, header_len, &header->data, 0))
+  if (!_dbus_string_copy_len (str, 0, header_len, &header->data, 0))
     {
       _dbus_verbose ("Failed to copy buffer into new header\n");
       *validity = DBUS_VALIDITY_UNKNOWN_OOM_ERROR;
@@ -1002,14 +1000,14 @@ _dbus_header_load (DBusHeader        *header,
 
   if (mode == DBUS_VALIDATION_MODE_WE_TRUST_THIS_DATA_ABSOLUTELY)
     {
-      leftover = len - header_len - body_len - start;
+      leftover = len - header_len - body_len;
     }
   else
     {
       v = _dbus_validate_body_with_reason (&_dbus_header_signature_str, 0,
                                            byte_order,
                                            &leftover,
-                                           str, start, len);
+                                           str, 0, len);
       
       if (v != DBUS_VALID)
         {
@@ -1021,9 +1019,9 @@ _dbus_header_load (DBusHeader        *header,
   _dbus_assert (leftover < len);
 
   padding_len = header_len - (FIRST_FIELD_OFFSET + fields_array_len);
-  padding_start = start + FIRST_FIELD_OFFSET + fields_array_len;
-  _dbus_assert (start + header_len == (int) _DBUS_ALIGN_VALUE (padding_start, 8));
-  _dbus_assert (start + header_len == padding_start + padding_len);
+  padding_start = FIRST_FIELD_OFFSET + fields_array_len;
+  _dbus_assert (header_len == (int) _DBUS_ALIGN_VALUE (padding_start, 8));
+  _dbus_assert (header_len == padding_start + padding_len);
 
   if (mode != DBUS_VALIDATION_MODE_WE_TRUST_THIS_DATA_ABSOLUTELY)
     {
@@ -1049,7 +1047,7 @@ _dbus_header_load (DBusHeader        *header,
   _dbus_type_reader_init (&reader,
                           byte_order,
                           &_dbus_header_signature_str, 0,
-                          str, start);
+                          str, 0);
 
   /* BYTE ORDER */
   _dbus_assert (_dbus_type_reader_get_current_type (&reader) == DBUS_TYPE_BYTE);
diff --git a/dbus/dbus-marshal-header.h b/dbus/dbus-marshal-header.h
index c8c011290..895cf63ba 100644
--- a/dbus/dbus-marshal-header.h
+++ b/dbus/dbus-marshal-header.h
@@ -119,9 +119,7 @@ dbus_bool_t   _dbus_header_load                   (DBusHeader        *header,
                                                    int                fields_array_len,
                                                    int                header_len,
                                                    int                body_len,
-                                                   const DBusString  *str,
-                                                   int                start,
-                                                   int                len);
+                                                   const DBusString  *str);
 void          _dbus_header_byteswap               (DBusHeader        *header,
                                                    int                new_order);
 DBUS_PRIVATE_EXPORT
diff --git a/dbus/dbus-message.c b/dbus/dbus-message.c
index 43b3a9fba..0d985a827 100644
--- a/dbus/dbus-message.c
+++ b/dbus/dbus-message.c
@@ -4430,8 +4430,7 @@ load_message (DBusMessageLoader *loader,
                           fields_array_len,
                           header_len,
                           body_len,
-                          &loader->data, 0,
-                          _dbus_string_get_length (&loader->data)))
+                          &loader->data))
     {
       _dbus_verbose ("Failed to load header for new message code %d\n", validity);