1/*	$NetBSD: store_emem.c,v 1.3 2023/06/19 21:41:44 christos Exp $	*/
2
3/*
4 * Copyright (c) 1997 - 2002 Kungliga Tekniska H��gskolan
5 * (Royal Institute of Technology, Stockholm, Sweden).
6 * All rights reserved.
7 *
8 * Redistribution and use in source and binary forms, with or without
9 * modification, are permitted provided that the following conditions
10 * are met:
11 *
12 * 1. Redistributions of source code must retain the above copyright
13 *    notice, this list of conditions and the following disclaimer.
14 *
15 * 2. Redistributions in binary form must reproduce the above copyright
16 *    notice, this list of conditions and the following disclaimer in the
17 *    documentation and/or other materials provided with the distribution.
18 *
19 * 3. Neither the name of the Institute nor the names of its contributors
20 *    may be used to endorse or promote products derived from this software
21 *    without specific prior written permission.
22 *
23 * THIS SOFTWARE IS PROVIDED BY THE INSTITUTE AND CONTRIBUTORS ``AS IS'' AND
24 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
25 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
26 * ARE DISCLAIMED.  IN NO EVENT SHALL THE INSTITUTE OR CONTRIBUTORS BE LIABLE
27 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
28 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
29 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
30 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
31 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
32 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
33 * SUCH DAMAGE.
34 */
35
36#include "krb5_locl.h"
37#include "store-int.h"
38
39typedef struct emem_storage{
40    unsigned char *base;
41    size_t size;
42    size_t len;
43    unsigned char *ptr;
44}emem_storage;
45
46static ssize_t
47emem_fetch(krb5_storage *sp, void *data, size_t size)
48{
49    emem_storage *s = (emem_storage*)sp->data;
50    if((size_t)(s->base + s->len - s->ptr) < size)
51	size = s->base + s->len - s->ptr;
52    memmove(data, s->ptr, size);
53    sp->seek(sp, size, SEEK_CUR);
54    return size;
55}
56
57static ssize_t
58emem_store(krb5_storage *sp, const void *data, size_t size)
59{
60    emem_storage *s = (emem_storage*)sp->data;
61    if(size > (size_t)(s->base + s->size - s->ptr)){
62	void *base;
63	size_t sz, off;
64	off = s->ptr - s->base;
65	sz = off + size;
66	if (sz < 4096)
67	    sz *= 2;
68	base = realloc(s->base, sz);
69	if(base == NULL)
70	    return -1;
71	s->size = sz;
72	s->base = base;
73	s->ptr = (unsigned char*)base + off;
74    }
75    if (size)
76        memmove(s->ptr, data, size);
77    sp->seek(sp, size, SEEK_CUR);
78    return size;
79}
80
81static off_t
82emem_seek(krb5_storage *sp, off_t offset, int whence)
83{
84    emem_storage *s = (emem_storage*)sp->data;
85    switch(whence){
86    case SEEK_SET:
87	if((size_t)offset > s->size)
88	    offset = s->size;
89	if(offset < 0)
90	    offset = 0;
91	s->ptr = s->base + offset;
92	if((size_t)offset > s->len)
93	    s->len = offset;
94	break;
95    case SEEK_CUR:
96	sp->seek(sp,s->ptr - s->base + offset, SEEK_SET);
97	break;
98    case SEEK_END:
99	sp->seek(sp, s->len + offset, SEEK_SET);
100	break;
101    default:
102	errno = EINVAL;
103	return -1;
104    }
105    return s->ptr - s->base;
106}
107
108static int
109emem_trunc(krb5_storage *sp, off_t offset)
110{
111    emem_storage *s = (emem_storage*)sp->data;
112    /*
113     * If offset is larget then current size, or current size is
114     * shrunk more then half of the current size, adjust buffer.
115     */
116    if (offset == 0) {
117	free(s->base);
118	s->size = 0;
119	s->base = NULL;
120	s->ptr = NULL;
121    } else if ((size_t)offset > s->size || (s->size / 2) > (size_t)offset) {
122	void *base;
123	size_t off;
124	off = s->ptr - s->base;
125	base = realloc(s->base, offset);
126	if(base == NULL)
127	    return ENOMEM;
128	if ((size_t)offset > s->size)
129	    memset((char *)base + s->size, 0, offset - s->size);
130	s->size = offset;
131	s->base = base;
132	s->ptr = (unsigned char *)base + off;
133    }
134    s->len = offset;
135    if ((s->ptr - s->base) > offset)
136	s->ptr = s->base + offset;
137    return 0;
138}
139
140
141static void
142emem_free(krb5_storage *sp)
143{
144    emem_storage *s = sp->data;
145    memset(s->base, 0, s->len);
146    free(s->base);
147}
148
149/**
150 * Create a elastic (allocating) memory storage backend. Memory is
151 * allocated on demand. Free returned krb5_storage with
152 * krb5_storage_free().
153 *
154 * @return A krb5_storage on success, or NULL on out of memory error.
155 *
156 * @ingroup krb5_storage
157 *
158 * @sa krb5_storage_from_mem()
159 * @sa krb5_storage_from_readonly_mem()
160 * @sa krb5_storage_from_fd()
161 * @sa krb5_storage_from_data()
162 * @sa krb5_storage_from_socket()
163 */
164
165KRB5_LIB_FUNCTION krb5_storage * KRB5_LIB_CALL
166krb5_storage_emem(void)
167{
168    krb5_storage *sp;
169    emem_storage *s;
170
171    sp = malloc(sizeof(krb5_storage));
172    if (sp == NULL)
173	return NULL;
174
175    s = malloc(sizeof(*s));
176    if (s == NULL) {
177	free(sp);
178	return NULL;
179    }
180    sp->data = s;
181    sp->flags = 0;
182    sp->eof_code = HEIM_ERR_EOF;
183    s->size = 1024;
184    s->base = malloc(s->size);
185    if (s->base == NULL) {
186	free(sp);
187	free(s);
188	return NULL;
189    }
190    s->len = 0;
191    s->ptr = s->base;
192    sp->fetch = emem_fetch;
193    sp->store = emem_store;
194    sp->seek = emem_seek;
195    sp->trunc = emem_trunc;
196    sp->fsync = NULL;
197    sp->free = emem_free;
198    sp->max_alloc = UINT_MAX/8;
199    return sp;
200}
201