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added compress/uncompress function

Browse Source 
sql/mysql_priv.h:
  added have_compress variable
sql/mysqld.cc:
  added have_compress variable
sql/set_var.cc:
  added have_compress variable
This commit is contained in:
unknown
2003-04-09 20:50:30 -04:00
parent 90527436fa
commit 75bdeb1b21
38 changed files with 332 additions and 2 deletions
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88
sql/item_strfunc.cc
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@ -2895,3 +2895,91 @@ String *Item_func_spatial_collection::val_str(String *str)
ret:
return null_value ? 0 : str;
}
#ifdef HAVE_COMPRESS
#include <zlib.h>
String *Item_func_compress::val_str(String *str)
{
String *res= args[0]->val_str(str);
int err= Z_OK;
int code;
/*
citation from zlib.h (comment for compress function):
Compresses the source buffer into the destination buffer. sourceLen is
the byte length of the source buffer. Upon entry, destLen is the total
size of the destination buffer, which must be at least 0.1% larger than
sourceLen plus 12 bytes.
Proportion 120/100 founded by Sinica with help of procedure
compress(compress(compress(...)))
I.e. zlib give number 'at least'..
*/
uLongf new_size= (uLongf)((res->length()*120)/100)+12;
buffer.realloc((uint32)new_size+sizeof(int32)+sizeof(char));
Byte *body= ((Byte*)buffer.c_ptr())+sizeof(int32);
err= compress(body, &new_size,(const Bytef*)res->c_ptr(), res->length());
if (err != Z_OK)
{
code= err==Z_MEM_ERROR ? ER_ZLIB_Z_MEM_ERROR : ER_ZLIB_Z_BUF_ERROR;
push_warning(current_thd,MYSQL_ERROR::WARN_LEVEL_ERROR,code,ER(code));
null_value= 1;
return 0;
}
int4store(buffer.c_ptr(),res->length());
buffer.length((uint32)new_size+sizeof(int32));
/* This is for the stupid char fields which trimm ' ': */
char *last_char= ((char*)body)+new_size-1;
if (*last_char == ' ')
{
*++last_char= '.';
new_size++;
}
buffer.length((uint32)new_size+sizeof(int32));
return &buffer;
}
String *Item_func_uncompress::val_str(String *str)
{
String *res= args[0]->val_str(str);
uLongf new_size= uint4korr(res->c_ptr());
int err= Z_OK;
uint code;
if (new_size > MAX_BLOB_WIDTH)
{
push_warning_printf(current_thd,MYSQL_ERROR::WARN_LEVEL_ERROR,
ER_TOO_BIG_FOR_UNCOMPRESS,
ER(ER_TOO_BIG_FOR_UNCOMPRESS),MAX_BLOB_WIDTH);
null_value= 1;
return 0;
}
buffer.realloc((uint32)new_size);
err= uncompress((Byte*)buffer.c_ptr(), &new_size,
((const Bytef*)res->c_ptr())+sizeof(int32),res->length());
if (err == Z_OK)
{
buffer.length((uint32)new_size);
return &buffer;
}
code= err==Z_BUF_ERROR ? ER_ZLIB_Z_BUF_ERROR :
err==Z_MEM_ERROR ? ER_ZLIB_Z_MEM_ERROR : ER_ZLIB_Z_DATA_ERROR;
push_warning(current_thd,MYSQL_ERROR::WARN_LEVEL_ERROR,code,ER(code));
null_value= 1;
return 0;
}
#endif