strngmem.c revision 7c478bd95313f5f23a4c958a745db2134aa03244
/*
* Copyright (c) 2000, 2001, 2002, 2003, 2004 by Martin C. Shepherd.
*
* All rights reserved.
*
* Permission is hereby granted, free of charge, to any person obtaining a
* copy of this software and associated documentation files (the
* "Software"), to deal in the Software without restriction, including
* without limitation the rights to use, copy, modify, merge, publish,
* to whom the Software is furnished to do so, provided that the above
* copyright notice(s) and this permission notice appear in all copies of
* the Software and that both the above copyright notice(s) and this
* permission notice appear in supporting documentation.
*
* THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS
* OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF
* MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT
* OF THIRD PARTY RIGHTS. IN NO EVENT SHALL THE COPYRIGHT HOLDER OR
* HOLDERS INCLUDED IN THIS NOTICE BE LIABLE FOR ANY CLAIM, OR ANY SPECIAL
* INDIRECT OR CONSEQUENTIAL DAMAGES, OR ANY DAMAGES WHATSOEVER RESULTING
* FROM LOSS OF USE, DATA OR PROFITS, WHETHER IN AN ACTION OF CONTRACT,
* NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING OUT OF OR IN CONNECTION
* WITH THE USE OR PERFORMANCE OF THIS SOFTWARE.
*
* Except as contained in this notice, the name of a copyright holder
* shall not be used in advertising or otherwise to promote the sale, use
* or other dealings in this Software without prior written authorization
* of the copyright holder.
*/
#pragma ident "%Z%%M% %I% %E% SMI"
#include <stdlib.h>
#include <stdio.h>
#include <errno.h>
#include "strngmem.h"
#include "freelist.h"
struct StringMem {
unsigned long nmalloc; /* The number of strings allocated with malloc */
};
/*.......................................................................
* Create a string free-list container and the first block of its free-list.
*
* Input:
* blocking_factor int The blocking_factor argument specifies how
* many strings of length SM_STRLEN
* bytes (see stringmem.h) are allocated in each
* free-list block.
* For example if blocking_factor=64 and
* SM_STRLEN=16, then each new
* free-list block will take 1K of memory.
* Output:
* return StringMem * The new free-list container, or NULL on
* error.
*/
{
/*
* Check arguments.
*/
if(blocking_factor < 1) {
return NULL;
};
/*
* Allocate the container.
*/
if(!sm) {
return NULL;
};
/*
* Before attempting any operation that might fail, initialize
* the container at least up to the point at which it can safely
* be passed to _del_StringMem().
*/
/*
* Allocate the free-list.
*/
/*
* Return the free-list container.
*/
return sm;
}
/*.......................................................................
* Delete a string free-list.
*
* Input:
* sm StringMem * The string free-list to be deleted, or NULL.
* force int If force==0 then _del_StringMem() will complain
* and refuse to delete the free-list if any
* of nodes have not been returned to the free-list.
* If force!=0 then _del_StringMem() will not check
* whether any nodes are still in use and will
* always delete the list.
* Output:
* return StringMem * Always NULL (even if the list couldn't be
* deleted).
*/
{
if(sm) {
/*
* Check whether any strings have not been returned to the free-list.
*/
return NULL;
};
/*
* Delete the free-list.
*/
/*
* Delete the container.
*/
};
return NULL;
}
/*.......................................................................
* Allocate an array of 'length' chars.
*
* Input:
* sm StringMem * The string free-list to allocate from.
* length size_t The length of the new string (including '\0').
* Output:
* return char * The new string or NULL on error.
*/
{
char *string; /* The string to be returned */
int was_malloc; /* True if malloc was used to allocate the string */
/*
* Check arguments.
*/
if(!sm)
return NULL;
if(length < 1)
length = 1;
/*
* Allocate the new node from the free list if possible.
*/
if(!string)
return NULL;
was_malloc = 0;
} else {
if(!string)
return NULL;
/*
* Count malloc allocations.
*/
was_malloc = 1;
};
/*
* Use the first byte of the string to record whether the string was
* allocated with malloc or from the free-list. Then return the rest
* of the string for use by the user.
*/
string[0] = (char) was_malloc;
return string + 1;
}
/*.......................................................................
* Free a string that was previously returned by _new_StringMemString().
*
* Input:
* sm StringMem * The free-list from which the string was originally
* allocated.
* s char * The string to be returned to the free-list, or NULL.
* Output:
* return char * Always NULL.
*/
{
int was_malloc; /* True if the string originally came from malloc() */
/*
* Is there anything to be deleted?
*/
if(s && sm) {
/*
* Retrieve the true string pointer. This is one less than the one
* returned by _new_StringMemString() because the first byte of the
* allocated memory is reserved by _new_StringMemString as a flag byte
* to say whether the memory was allocated from the free-list or directly
* from malloc().
*/
s--;
/*
* Get the origination flag.
*/
was_malloc = s[0];
if(was_malloc) {
free(s);
s = NULL;
} else {
};
};
return NULL;
}