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/*
* Copyright (C) 2007 Rich Waters <raw@goodhumans.com>
*
* This file is part of lib_mysqludf_preg.
*
* lib_mysqudf_preg is free software; you can redistribute it and/or modify
* it under the terms of the GNU Lesser General Public License as published by
* the Free Software Foundation; either version 3 of the License, or
* (at your option) any later version.
*
* lib_mysqludf_preg 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, see <http://www.gnu.org/licenses/>.
*/
/** @file ghmysql.c
*
* @brief Provides some functions that are shared by the various
* gh udf functions.
*
*/
#include "ghmysql.h"
/**
* @fn char *ghstrndup( char *s , int l )
*
* @brief safe strndup
*
* @param s - bytes to copy
* @param l - number of bytes to copy
*
* @return ptr - to newly allocate memory
* @return NULL - if memory not available
*
* @details - This function copies the given number of bytes from the given
* buffer into a newly allocated memory area. It then adds a '\\0' to the
* end. This function shouldn't be necessary, but since many call rely on
* null-termination instead of lengths, this creates things that can be
* passed to those functions safely.
*/
char *ghstrndup( char *s , int l )
{
char *colval = NULL ;
colval = malloc( l + 1 ) ;
if( !colval )
{
fprintf( stderr , "Not enough memory: %d\n" , l ) ;
return NULL ;
}
memcpy( colval , s , l ) ;
colval[ l ] = '\0';
return colval ;
}
/**
* @fn char *ghargdup( UDF_ARGS *args,int i )
*
* @brief extract argument as a newly allocated null-terminated memory area
*
* @param args - args from the UDF function call
* @param i - offset of argument to extract.
*
* @return pointer - to newly allocate memory if successful
* @return NULL - if arg is NULL or not enough memory
*
*/
char *ghargdup( UDF_ARGS *args,int i )
{
int l ;
char *s ;
char *colval = NULL ;
if( (l=args->lengths[i] ) && (s=args->args[i]) )
{
colval = ghstrndup( s , l ) ;
}
return colval ;
}
/**
* @fn char *ghargdups( UDF_ARGS *args,int i , unsigned long *l)
*
* @brief extract argument as a newly allocated null-terminated memory area,
* and set the length to the size of that area
*
* @param args - args from the UDF function call
* @param i - offset of argument to extract.
* @param l - store the length of the argument here
*
* @return pointer - to newly allocate memory if successful
*
* @details This is useful for guaranteeing not to have NULL as an argument
*/
char *ghargdups( UDF_ARGS *args , int i , unsigned long *l)
{
if( !(*l=args->lengths[ i ]))
{
return strdup( "" ) ;
}
else if( !args->args[i]) {
*l = 0 ;
return strdup( "" ) ;
}
else {
return ghargdup( args , i ) ;
}
}
/**
* @fn char *ghargIsNull( UDF_ARGS *args,int argNum)
*
* @brief is the given argument NULL
*
* @param args - args from the UDF function call
* @param i - the argument to test
*
* @return int - 1 if the argument is NULL, 0 otherwise
*
* @details - this only returns true if the arg is specified as NULL
* when in the mysql statement. This does not return true if the
* NULL results from evaluating a column. The purpose of this function
* in so that init functions can differentiate NULL constants from
* NULL meaning that there are no constant arguments. This is important
* because there is better error handling in the API for init functions
* than mains.
*/
int ghargIsNullConstant(UDF_ARGS *args, int argNum)
{
if( args->arg_count > argNum && !args->args[argNum] &&
!strncmp( args->attributes[argNum], "NULL" , 4 ) ) {
return 1 ;
}
return 0 ;
}
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