src/libstatgrab/vector.c

/*
 * i-scream central monitoring system
 * http://www.i-scream.org
 * Copyright (C) 2000-2004 i-scream
 * 
 * This library 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 2.1 of the License, or (at your option) any later version.
 * 
 * This library 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
 * Lesser General Public License for more details.
 * 
 * You should have received a copy of the GNU Lesser General Public
 * License along with this library; if not, write to the Free Software
 * Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA
 * 02111-1307 USA
 *
 * $Id: vector.c,v 1.3 2004/04/05 00:45:17 ats Exp $
 */

#ifdef HAVE_CONFIG_H
#include "config.h"
#endif

#include <stdlib.h>

#include "vector.h"

void *statgrab_vector_resize(void *vector, vector_header *h, int count) {
        int new_count, i;

        /* Destroy any now-unused items.
         *
         * Note that there's an assumption here that making the vector smaller
         * will never fail; if it did, then we would have destroyed items here
         * but not actually got rid of the vector pointing to them before the
         * error return.) */
        if (count < h->used_count && h->destroy_fn != NULL) {
                for (i = count; i < h->used_count; i++) {
                        h->destroy_fn((void *) (vector + i * h->item_size));
                }
        }

        /* Round up the desired size to the next multiple of the block size. */
        new_count =  ((count - 1 + h->block_size) / h->block_size)
                     * h->block_size;

        /* Resize the vector if necessary. */
        if (new_count != h->alloc_count) {
                char *new_vector;

                new_vector = realloc(vector, new_count * h->item_size);
                if (new_vector == NULL && new_count != 0) {
                        /* Out of memory -- free the contents of the vector. */
                        statgrab_vector_resize(vector, h, 0);
                        h->error = -1;
                        return vector;
                }

                vector = new_vector;
                h->alloc_count = new_count;
        }

        /* Initialise any new items. */
        if (count > h->used_count && h->init_fn != NULL) {
                for (i = h->used_count; i < count; i++) {
                        h->init_fn((void *) (vector + i * h->item_size));
                }
        }

        h->used_count = count;
        h->error = 0;
        return vector;
}

Revision:	1.4
Committed:	Mon Apr 5 00:58:05 2004 UTC (20 years, 1 month ago) by ats
Content type:	text/plain
Branch:	MAIN
Changes since 1.3:	+10 -5 lines
Log Message:	Fix the strict-aliasing problem in a clean, sensible way that actually works. As a bonus, we now get a "value computed is not used" warning from GCC if we don't check the return value of VECTOR_RESIZE. (This is dubiously a bonus when it's being resized to 0, but it's not going to hurt to check even then -- we might support destructors failing in the future.)
#	User	Rev	Content
1	ats	1.1	/*
2			* i-scream central monitoring system
3			* http://www.i-scream.org
4			* Copyright (C) 2000-2004 i-scream
5			*
6			* This library is free software; you can redistribute it and/or
7			* modify it under the terms of the GNU Lesser General Public
8			* License as published by the Free Software Foundation; either
9			* version 2.1 of the License, or (at your option) any later version.
10			*
11			* This library is distributed in the hope that it will be useful,
12			* but WITHOUT ANY WARRANTY; without even the implied warranty of
13			* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
14			* Lesser General Public License for more details.
15			*
16			* You should have received a copy of the GNU Lesser General Public
17			* License along with this library; if not, write to the Free Software
18			* Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA
19			* 02111-1307 USA
20			*
21	ats	1.4	* $Id: vector.c,v 1.3 2004/04/05 00:45:17 ats Exp $
22	ats	1.1	*/
23
24			#ifdef HAVE_CONFIG_H
25			#include "config.h"
26			#endif
27
28			#include <stdlib.h>
29
30			#include "vector.h"
31
32	ats	1.3	void statgrab_vector_resize(void vector, vector_header *h, int count) {
33	ats	1.1	int new_count, i;
34
35	ats	1.4	/* Destroy any now-unused items.
36			*
37			* Note that there's an assumption here that making the vector smaller
38			* will never fail; if it did, then we would have destroyed items here
39			* but not actually got rid of the vector pointing to them before the
40			* error return.) */
41	ats	1.1	if (count < h->used_count && h->destroy_fn != NULL) {
42			for (i = count; i < h->used_count; i++) {
43	ats	1.3	h->destroy_fn((void ) (vector + i h->item_size));
44	ats	1.1	}
45			}
46
47			/* Round up the desired size to the next multiple of the block size. */
48			new_count = ((count - 1 + h->block_size) / h->block_size)
49			* h->block_size;
50
51			/* Resize the vector if necessary. */
52			if (new_count != h->alloc_count) {
53	ats	1.2	char *new_vector;
54	ats	1.1
55	ats	1.3	new_vector = realloc(vector, new_count * h->item_size);
56	ats	1.1	if (new_vector == NULL && new_count != 0) {
57			/* Out of memory -- free the contents of the vector. */
58			statgrab_vector_resize(vector, h, 0);
59	ats	1.4	h->error = -1;
60			return vector;
61	ats	1.1	}
62
63	ats	1.3	vector = new_vector;
64	ats	1.1	h->alloc_count = new_count;
65			}
66
67			/* Initialise any new items. */
68			if (count > h->used_count && h->init_fn != NULL) {
69			for (i = h->used_count; i < count; i++) {
70	ats	1.3	h->init_fn((void ) (vector + i h->item_size));
71	ats	1.1	}
72			}
73
74			h->used_count = count;
75	ats	1.4	h->error = 0;
76	ats	1.3	return vector;
77	ats	1.1	}
78