Injecting more "const" declarations into code which does not change

pointed data.
I ran gcc -Wcast-qual on storage/maria, this identified un-needed casts,
a couple of functions which said they had a const parameter though
they changed the pointed content! This is fixed here. Some suspicious
places receive a comment.
The original intention of running -Wcast-qual was to find what code
changes R-tree keys: I added const words, but hidden casts
like those of int2store (casts target to (uint16*)) removed const
checking; -Wcast-qual helped find those hidden casts.
Log handler does not change the content pointed by LEX_STRING::str it
receives, so we now use a struct which has a const inside, to emphasize
this and be able to pass "const uchar*" buffers to log handler
without fear of their content being changed by it.
One-line fix for a merge glitch (when merging from MyISAM).


include/m_string.h:
  As Maria's log handler uses LEX_STRING but never changes the content
  pointed by LEX_STRING::str, and assigns uchar* into this member most
  of the time, we introduce a new struct LEX_CUSTRING
  (C const U unsigned) for the log handler.
include/my_global.h:
  In macros which read pointed content: use const pointers so that
  gcc -Wcast-qual does not warn about casting a const pointer to non-const.
include/my_handler.h:
  In macros which read pointed content: use const pointers so that
  gcc -Wcast-qual does not warn about casting a const pointer to non-const.
  ha_find_null() does not change *a.
include/my_sys.h:
  insert_dynamic() does not change *element.
include/myisampack.h:
  In macros which read pointed content: use const pointers so that
  gcc -Wcast-qual does not warn about casting a const pointer to non-const.
mysys/array.c:
  insert_dynamic() does not change *element
mysys/my_handler.c:
  ha_find_null() does not change *a
storage/maria/ma_bitmap.c:
  Log handler receives const strings now
storage/maria/ma_blockrec.c:
  Log handler receives const strings now.
  _ma_apply_undo_row_delete/update() do change *header.
storage/maria/ma_blockrec.h:
  correct prototype
storage/maria/ma_check.c:
  Log handler receives const strings now. Un-needed casts
storage/maria/ma_checkpoint.c:
  Log handler receives const strings now
storage/maria/ma_checksum.c:
  unneeded cast
storage/maria/ma_commit.c:
  Log handler receives const strings now
storage/maria/ma_create.c:
  Log handler receives const strings now
storage/maria/ma_dbug.c:
  fixing warning of gcc -Wcast-qual
storage/maria/ma_delete.c:
  Log handler receives const strings now
storage/maria/ma_delete_all.c:
  Log handler receives const strings now
storage/maria/ma_delete_table.c:
  Log handler receives const strings now
storage/maria/ma_dynrec.c:
  fixing some warnings of gcc -Wcast-qual. Unneeded casts removed.
  Comment about function which lies.
storage/maria/ma_ft_parser.c:
  fix for warnings of gcc -Wcast-qual, removing unneeded casts
storage/maria/ma_ft_update.c:
  less casts, comment
storage/maria/ma_key.c:
  less casts, stay const (warnings of gcc -Wcast-qual)
storage/maria/ma_key_recover.c:
  Log handler receives const strings now
storage/maria/ma_loghandler.c:
  Log handler receives const strings now
storage/maria/ma_loghandler.h:
  Log handler receives const strings now
storage/maria/ma_loghandler_lsn.h:
  In macros which read pointed content: use const pointers so that
  gcc -Wcast-qual does not warn about casting a const pointer to non-const.
storage/maria/ma_page.c:
  Log handler receives const strings now; more const
storage/maria/ma_recovery.c:
  Log handler receives const strings now
storage/maria/ma_rename.c:
  Log handler receives const strings now
storage/maria/ma_rt_index.c:
  more const, to emphasize that functions don't change pointed content.
  best_key= NULL was forgotten during merge from MyISAM a few days ago,
  was causing a Valgrind warning
storage/maria/ma_rt_index.h:
  new proto
storage/maria/ma_rt_key.c:
  more const
storage/maria/ma_rt_key.h:
  new proto
storage/maria/ma_rt_mbr.c:
  more const for functions which deserve it
storage/maria/ma_rt_mbr.h:
  new prototype
storage/maria/ma_rt_split.c:
  make const what is not changed.
storage/maria/ma_search.c:
  un-needed casts, more const
storage/maria/ma_sp_key.c:
  more const
storage/maria/ma_unique.c:
  un-needed casts.
storage/maria/ma_write.c:
  Log handler receives const strings now
storage/maria/maria_def.h:
  some more const
storage/maria/unittest/ma_test_loghandler-t.c:
  Log handler receives const strings now
storage/maria/unittest/ma_test_loghandler_first_lsn-t.c:
  Log handler receives const strings now
storage/maria/unittest/ma_test_loghandler_max_lsn-t.c:
  Log handler receives const strings now
storage/maria/unittest/ma_test_loghandler_multigroup-t.c:
  Log handler receives const strings now
storage/maria/unittest/ma_test_loghandler_multithread-t.c:
  Log handler receives const strings now
storage/maria/unittest/ma_test_loghandler_noflush-t.c:
  Log handler receives const strings now
storage/maria/unittest/ma_test_loghandler_nologs-t.c:
  Log handler receives const strings now
storage/maria/unittest/ma_test_loghandler_pagecache-t.c:
  Log handler receives const strings now
storage/maria/unittest/ma_test_loghandler_purge-t.c:
  Log handler receives const strings now

1 files changed, 15 insertions, 9 deletions

diff --git a/storage/maria/ma_dynrec.c b/storage/maria/ma_dynrec.c
index daf170b4cbe..4c124a31221 100644
--- a/storage/maria/ma_dynrec.c
+++ b/storage/maria/ma_dynrec.c
@@ -318,7 +318,11 @@ my_bool _ma_delete_dynamic_record(MARIA_HA *info,
 }
 
 
-	/* Write record to data-file */
+/**
+  Write record to data-file.
+
+  @todo it's cheating: it casts "const uchar*" to uchar*.
+*/
 
 static my_bool write_dynamic_record(MARIA_HA *info, const uchar *record,
                                     ulong reclength)
@@ -943,7 +947,8 @@ uint _ma_rec_pack(MARIA_HA *info, register uchar *to,
                   register const uchar *from)
 {
   uint		length,new_length,flag,bit,i;
-  uchar		*pos,*end,*startpos,*packpos;
+  const uchar   *pos,*end;
+  uchar         *startpos,*packpos;
   enum en_fieldtype type;
   reg3 MARIA_COLUMNDEF *column;
   MARIA_BLOB	*blob;
@@ -984,7 +989,7 @@ uint _ma_rec_pack(MARIA_HA *info, register uchar *to,
       }
       else if (type == FIELD_SKIP_ZERO)
       {
-	if (memcmp((uchar*) from, maria_zero_string, length) == 0)
+	if (memcmp(from, maria_zero_string, length) == 0)
 	  flag|=bit;
 	else
 	{
@@ -995,7 +1000,7 @@ uint _ma_rec_pack(MARIA_HA *info, register uchar *to,
       else if (type == FIELD_SKIP_ENDSPACE ||
 	       type == FIELD_SKIP_PRESPACE)
       {
-	pos= (uchar*) from; end= (uchar*) from + length;
+	pos= from; end= from + length;
 	if (type == FIELD_SKIP_ENDSPACE)
 	{					/* Pack trailing spaces */
 	  while (end > from && *(end-1) == ' ')
@@ -1032,7 +1037,7 @@ uint _ma_rec_pack(MARIA_HA *info, register uchar *to,
 	uint tmp_length;
         if (pack_length == 1)
         {
-          tmp_length= (uint) *(uchar*) from;
+          tmp_length= (uint) *from;
           *to++= *from;
         }
         else
@@ -1080,7 +1085,8 @@ my_bool _ma_rec_check(MARIA_HA *info,const uchar *record, uchar *rec_buff,
                       ha_checksum checksum)
 {
   uint		length,new_length,flag,bit,i;
-  uchar		*pos,*end,*packpos,*to;
+  const uchar   *pos,*end;
+  uchar         *packpos,*to;
   enum en_fieldtype type;
   reg3 MARIA_COLUMNDEF *column;
   DBUG_ENTER("_ma_rec_check");
@@ -1107,7 +1113,7 @@ my_bool _ma_rec_check(MARIA_HA *info,const uchar *record, uchar *rec_buff,
       }
       else if (type == FIELD_SKIP_ZERO)
       {
-	if (memcmp((uchar*) record, maria_zero_string, length) == 0)
+	if (memcmp(record, maria_zero_string, length) == 0)
 	{
 	  if (!(flag & bit))
 	    goto err;
@@ -1118,7 +1124,7 @@ my_bool _ma_rec_check(MARIA_HA *info,const uchar *record, uchar *rec_buff,
       else if (type == FIELD_SKIP_ENDSPACE ||
 	       type == FIELD_SKIP_PRESPACE)
       {
-	pos= (uchar*) record; end= (uchar*) record + length;
+	pos= record; end= record + length;
 	if (type == FIELD_SKIP_ENDSPACE)
 	{					/* Pack trailing spaces */
 	  while (end > record && *(end-1) == ' ')
@@ -1155,7 +1161,7 @@ my_bool _ma_rec_check(MARIA_HA *info,const uchar *record, uchar *rec_buff,
 	uint tmp_length;
         if (pack_length == 1)
         {
-          tmp_length= (uint) *(uchar*) record;
+          tmp_length= (uint) *record;
           to+= 1+ tmp_length;
           continue;
         }