WL#3817: Simplify string / memory area types and make things more consistent (first part)

The following type conversions was done:

- Changed byte to uchar
- Changed gptr to uchar*
- Change my_string to char *
- Change my_size_t to size_t
- Change size_s to size_t

Removed declaration of byte, gptr, my_string, my_size_t and size_s. 

Following function parameter changes was done:
- All string functions in mysys/strings was changed to use size_t
  instead of uint for string lengths.
- All read()/write() functions changed to use size_t (including vio).
- All protocoll functions changed to use size_t instead of uint
- Functions that used a pointer to a string length was changed to use size_t*
- Changed malloc(), free() and related functions from using gptr to use void *
  as this requires fewer casts in the code and is more in line with how the
  standard functions work.
- Added extra length argument to dirname_part() to return the length of the
  created string.
- Changed (at least) following functions to take uchar* as argument:
  - db_dump()
  - my_net_write()
  - net_write_command()
  - net_store_data()
  - DBUG_DUMP()
  - decimal2bin() & bin2decimal()
- Changed my_compress() and my_uncompress() to use size_t. Changed one
  argument to my_uncompress() from a pointer to a value as we only return
  one value (makes function easier to use).
- Changed type of 'pack_data' argument to packfrm() to avoid casts.
- Changed in readfrm() and writefrom(), ha_discover and handler::discover()
  the type for argument 'frmdata' to uchar** to avoid casts.
- Changed most Field functions to use uchar* instead of char* (reduced a lot of
  casts).
- Changed field->val_xxx(xxx, new_ptr) to take const pointers.

Other changes:
- Removed a lot of not needed casts
- Added a few new cast required by other changes
- Added some cast to my_multi_malloc() arguments for safety (as string lengths
  needs to be uint, not size_t).
- Fixed all calls to hash-get-key functions to use size_t*. (Needed to be done
  explicitely as this conflict was often hided by casting the function to
  hash_get_key).
- Changed some buffers to memory regions to uchar* to avoid casts.
- Changed some string lengths from uint to size_t.
- Changed field->ptr to be uchar* instead of char*. This allowed us to
  get rid of a lot of casts.
- Some changes from true -> TRUE, false -> FALSE, unsigned char -> uchar
- Include zlib.h in some files as we needed declaration of crc32()
- Changed MY_FILE_ERROR to be (size_t) -1.
- Changed many variables to hold the result of my_read() / my_write() to be
  size_t. This was needed to properly detect errors (which are
  returned as (size_t) -1).
- Removed some very old VMS code
- Changed packfrm()/unpackfrm() to not be depending on uint size
  (portability fix)
- Removed windows specific code to restore cursor position as this
  causes slowdown on windows and we should not mix read() and pread()
  calls anyway as this is not thread safe. Updated function comment to
  reflect this. Changed function that depended on original behavior of
  my_pwrite() to itself restore the cursor position (one such case).
- Added some missing checking of return value of malloc().
- Changed definition of MOD_PAD_CHAR_TO_FULL_LENGTH to avoid 'long' overflow.
- Changed type of table_def::m_size from my_size_t to ulong to reflect that
  m_size is the number of elements in the array, not a string/memory
  length.
- Moved THD::max_row_length() to table.cc (as it's not depending on THD).
  Inlined max_row_length_blob() into this function.
- More function comments
- Fixed some compiler warnings when compiled without partitions.
- Removed setting of LEX_STRING() arguments in declaration (portability fix).
- Some trivial indentation/variable name changes.
- Some trivial code simplifications:
  - Replaced some calls to alloc_root + memcpy to use
    strmake_root()/strdup_root().
  - Changed some calls from memdup() to strmake() (Safety fix)
  - Simpler loops in client-simple.c

include/myisam.h

@@ -227,7 +227,7 @@ typedef struct st_mi_decode_tree	/* Decode huff-table */
 {
   uint16 *table;
   uint	 quick_table_bits;
-  byte	 *intervalls;
+  uchar	 *intervalls;
 } MI_DECODE_TREE;
 
 
@@ -259,7 +259,7 @@ typedef struct st_columndef		/* column information */
 /* invalidator function reference for Query Cache */
 typedef void (* invalidator_by_filename)(const char * filename);
 
-extern my_string myisam_log_filename;		/* Name of logfile */
+extern char * myisam_log_filename;		/* Name of logfile */
 extern ulong myisam_block_size;
 extern ulong myisam_concurrent_insert;
 extern my_bool myisam_flush,myisam_delay_key_write,myisam_single_user;
@@ -269,26 +269,26 @@ extern ulong myisam_bulk_insert_tree_size, myisam_data_pointer_size;
 	/* Prototypes for myisam-functions */
 
 extern int mi_close(struct st_myisam_info *file);
-extern int mi_delete(struct st_myisam_info *file,const byte *buff);
+extern int mi_delete(struct st_myisam_info *file,const uchar *buff);
 extern struct st_myisam_info *mi_open(const char *name,int mode,
 				      uint wait_if_locked);
 extern int mi_panic(enum ha_panic_function function);
-extern int mi_rfirst(struct st_myisam_info *file,byte *buf,int inx);
-extern int mi_rkey(MI_INFO *info, byte *buf, int inx, const byte *key,
+extern int mi_rfirst(struct st_myisam_info *file,uchar *buf,int inx);
+extern int mi_rkey(MI_INFO *info, uchar *buf, int inx, const uchar *key,
                    key_part_map keypart_map, enum ha_rkey_function search_flag);
-extern int mi_rlast(struct st_myisam_info *file,byte *buf,int inx);
-extern int mi_rnext(struct st_myisam_info *file,byte *buf,int inx);
-extern int mi_rnext_same(struct st_myisam_info *info, byte *buf);
-extern int mi_rprev(struct st_myisam_info *file,byte *buf,int inx);
-extern int mi_rrnd(struct st_myisam_info *file,byte *buf, my_off_t pos);
+extern int mi_rlast(struct st_myisam_info *file,uchar *buf,int inx);
+extern int mi_rnext(struct st_myisam_info *file,uchar *buf,int inx);
+extern int mi_rnext_same(struct st_myisam_info *info, uchar *buf);
+extern int mi_rprev(struct st_myisam_info *file,uchar *buf,int inx);
+extern int mi_rrnd(struct st_myisam_info *file,uchar *buf, my_off_t pos);
 extern int mi_scan_init(struct st_myisam_info *file);
-extern int mi_scan(struct st_myisam_info *file,byte *buf);
-extern int mi_rsame(struct st_myisam_info *file,byte *record,int inx);
-extern int mi_rsame_with_pos(struct st_myisam_info *file,byte *record,
+extern int mi_scan(struct st_myisam_info *file,uchar *buf);
+extern int mi_rsame(struct st_myisam_info *file,uchar *record,int inx);
+extern int mi_rsame_with_pos(struct st_myisam_info *file,uchar *record,
 			     int inx, my_off_t pos);
-extern int mi_update(struct st_myisam_info *file,const byte *old,
-		     byte *new_record);
-extern int mi_write(struct st_myisam_info *file,byte *buff);
+extern int mi_update(struct st_myisam_info *file,const uchar *old,
+		     uchar *new_record);
+extern int mi_write(struct st_myisam_info *file,uchar *buff);
 extern my_off_t mi_position(struct st_myisam_info *file);
 extern int mi_status(struct st_myisam_info *info, MI_ISAMINFO *x, uint flag);
 extern int mi_lock_database(struct st_myisam_info *file,int lock_type);
@@ -307,7 +307,7 @@ extern ha_rows mi_records_in_range(MI_INFO *info, int inx,
 extern int mi_log(int activate_log);
 extern int mi_is_changed(struct st_myisam_info *info);
 extern int mi_delete_all_rows(struct st_myisam_info *info);
-extern ulong _mi_calc_blob_length(uint length , const byte *pos);
+extern ulong _mi_calc_blob_length(uint length , const uchar *pos);
 extern uint mi_get_pointer_length(ulonglong file_length, uint def);
 
 /* this is used to pass to mysql_myisamchk_table -- by Sasha Pachev */
@@ -474,8 +474,8 @@ int chk_size(MI_CHECK *param, MI_INFO *info);
 int chk_key(MI_CHECK *param, MI_INFO *info);
 int chk_data_link(MI_CHECK *param, MI_INFO *info,int extend);
 int mi_repair(MI_CHECK *param, register MI_INFO *info,
-	      my_string name, int rep_quick);
-int mi_sort_index(MI_CHECK *param, register MI_INFO *info, my_string name);
+	      char * name, int rep_quick);
+int mi_sort_index(MI_CHECK *param, register MI_INFO *info, char * name);
 int mi_repair_by_sort(MI_CHECK *param, register MI_INFO *info,
 		      const char * name, int rep_quick);
 int mi_repair_parallel(MI_CHECK *param, register MI_INFO *info,
@@ -494,7 +494,7 @@ void update_key_parts(MI_KEYDEF *keyinfo, ulong *rec_per_key_part,
                       ulonglong records);
 int filecopy(MI_CHECK *param, File to,File from,my_off_t start,
 	     my_off_t length, const char *type);
-int movepoint(MI_INFO *info,byte *record,my_off_t oldpos,
+int movepoint(MI_INFO *info,uchar *record,my_off_t oldpos,
 	      my_off_t newpos, uint prot_key);
 int write_data_suffix(SORT_INFO *sort_info, my_bool fix_datafile);
 int test_if_almost_full(MI_INFO *info);