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/* Copyright (C) 2006 MySQL AB
This program is free software; you can redistribute it and/or modify
it under the terms of the GNU General Public License as published by
the Free Software Foundation; version 2 of the License.
This program is distributed in the hope that it will be useful,
but WITHOUT ANY WARRANTY; without even the implied warranty of
MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
GNU General Public License for more details.
You should have received a copy of the GNU General Public License
along with this program; if not, write to the Free Software
Foundation, Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA */
#include <drizzled/common_includes.h>
#include <drizzled/item_func.h>
#include <drizzled/item_strfunc.h>
#include <drizzled/error.h>
#include <zlib.h>
class Item_func_compress: public Item_str_func
{
String buffer;
public:
Item_func_compress():Item_str_func(){}
void fix_length_and_dec(){max_length= (args[0]->max_length*120)/100+12;}
const char *func_name() const{return "compress";}
String *val_str(String *) ;
};
String *Item_func_compress::val_str(String *str)
{
int err= Z_OK, code;
ulong new_size;
String *res;
Byte *body;
char *tmp, *last_char;
assert(fixed == 1);
if (!(res= args[0]->val_str(str)))
{
null_value= 1;
return 0;
}
null_value= 0;
if (res->is_empty()) return res;
/*
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.
We assume here that the buffer can't grow more than .25 %.
*/
new_size= res->length() + res->length() / 5 + 12;
// Check new_size overflow: new_size <= res->length()
if (((uint32_t) (new_size+5) <= res->length()) ||
buffer.realloc((uint32_t) new_size + 4 + 1))
{
null_value= 1;
return 0;
}
body= ((Byte*)buffer.ptr()) + 4;
// As far as we have checked res->is_empty() we can use ptr()
if ((err= compress(body, &new_size,
(const Bytef*)res->ptr(), res->length())) != Z_OK)
{
code= err==Z_MEM_ERROR ? ER_ZLIB_Z_MEM_ERROR : ER_ZLIB_Z_BUF_ERROR;
push_warning(current_session, DRIZZLE_ERROR::WARN_LEVEL_ERROR, code, ER(code));
null_value= 1;
return 0;
}
tmp= (char*)buffer.ptr(); // int4store is a macro; avoid side effects
int4store(tmp, res->length() & 0x3FFFFFFF);
/* This is to ensure that things works for CHAR fields, which trim ' ': */
last_char= ((char*)body)+new_size-1;
if (*last_char == ' ')
{
*++last_char= '.';
new_size++;
}
buffer.length((uint32_t)new_size + 4);
return &buffer;
}
Item_func* create_compressudf_item(MEM_ROOT* m)
{
return new (m) Item_func_compress();
}
static struct udf_func compressudf = {
{ C_STRING_WITH_LEN("compress") },
create_compressudf_item
};
static int compressudf_plugin_init(void *p)
{
udf_func **f = (udf_func**) p;
*f= &compressudf;
return 0;
}
static int compressudf_plugin_deinit(void *p)
{
udf_func *udff = (udf_func *) p;
(void)udff;
return 0;
}
mysql_declare_plugin(compress)
{
DRIZZLE_UDF_PLUGIN,
"compress",
"1.0",
"Stewart Smith",
"UDF for compress()",
PLUGIN_LICENSE_GPL,
compressudf_plugin_init, /* Plugin Init */
compressudf_plugin_deinit, /* Plugin Deinit */
NULL, /* status variables */
NULL, /* system variables */
NULL /* config options */
}
mysql_declare_plugin_end;
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