store_emem.c revision 302408 
1/*
2 * Copyright (c) 1997 - 2002 Kungliga Tekniska H��gskolan
3 * (Royal Institute of Technology, Stockholm, Sweden).
4 * All rights reserved.
5 *
6 * Redistribution and use in source and binary forms, with or without
7 * modification, are permitted provided that the following conditions
8 * are met:
9 *
10 * 1. Redistributions of source code must retain the above copyright
11 *    notice, this list of conditions and the following disclaimer.
12 *
13 * 2. Redistributions in binary form must reproduce the above copyright
14 *    notice, this list of conditions and the following disclaimer in the
15 *    documentation and/or other materials provided with the distribution.
16 *
17 * 3. Neither the name of the Institute nor the names of its contributors
18 *    may be used to endorse or promote products derived from this software
19 *    without specific prior written permission.
20 *
21 * THIS SOFTWARE IS PROVIDED BY THE INSTITUTE AND CONTRIBUTORS ``AS IS'' AND
22 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
23 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
24 * ARE DISCLAIMED.  IN NO EVENT SHALL THE INSTITUTE OR CONTRIBUTORS BE LIABLE
25 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
26 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
27 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
28 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
29 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
30 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
31 * SUCH DAMAGE.
32 */
33
34#include "krb5_locl.h"
35#include "store-int.h"
36
37typedef struct emem_storage{
38    unsigned char *base;
39    size_t size;
40    size_t len;
41    unsigned char *ptr;
42}emem_storage;
43
44static ssize_t
45emem_fetch(krb5_storage *sp, void *data, size_t size)
46{
47    emem_storage *s = (emem_storage*)sp->data;
48    if((size_t)(s->base + s->len - s->ptr) < size)
49	size = s->base + s->len - s->ptr;
50    memmove(data, s->ptr, size);
51    sp->seek(sp, size, SEEK_CUR);
52    return size;
53}
54
55static ssize_t
56emem_store(krb5_storage *sp, const void *data, size_t size)
57{
58    emem_storage *s = (emem_storage*)sp->data;
59    if(size > (size_t)(s->base + s->size - s->ptr)){
60	void *base;
61	size_t sz, off;
62	off = s->ptr - s->base;
63	sz = off + size;
64	if (sz < 4096)
65	    sz *= 2;
66	base = realloc(s->base, sz);
67	if(base == NULL)
68	    return -1;
69	s->size = sz;
70	s->base = base;
71	s->ptr = (unsigned char*)base + off;
72    }
73    memmove(s->ptr, data, size);
74    sp->seek(sp, size, SEEK_CUR);
75    return size;
76}
77
78static off_t
79emem_seek(krb5_storage *sp, off_t offset, int whence)
80{
81    emem_storage *s = (emem_storage*)sp->data;
82    switch(whence){
83    case SEEK_SET:
84	if((size_t)offset > s->size)
85	    offset = s->size;
86	if(offset < 0)
87	    offset = 0;
88	s->ptr = s->base + offset;
89	if((size_t)offset > s->len)
90	    s->len = offset;
91	break;
92    case SEEK_CUR:
93	sp->seek(sp,s->ptr - s->base + offset, SEEK_SET);
94	break;
95    case SEEK_END:
96	sp->seek(sp, s->len + offset, SEEK_SET);
97	break;
98    default:
99	errno = EINVAL;
100	return -1;
101    }
102    return s->ptr - s->base;
103}
104
105static int
106emem_trunc(krb5_storage *sp, off_t offset)
107{
108    emem_storage *s = (emem_storage*)sp->data;
109    /*
110     * If offset is larget then current size, or current size is
111     * shrunk more then half of the current size, adjust buffer.
112     */
113    if (offset == 0) {
114	free(s->base);
115	s->size = 0;
116	s->base = NULL;
117	s->ptr = NULL;
118    } else if ((size_t)offset > s->size || (s->size / 2) > (size_t)offset) {
119	void *base;
120	size_t off;
121	off = s->ptr - s->base;
122	base = realloc(s->base, offset);
123	if(base == NULL)
124	    return ENOMEM;
125	if ((size_t)offset > s->size)
126	    memset((char *)base + s->size, 0, offset - s->size);
127	s->size = offset;
128	s->base = base;
129	s->ptr = (unsigned char *)base + off;
130    }
131    s->len = offset;
132    if ((s->ptr - s->base) > offset)
133	s->ptr = s->base + offset;
134    return 0;
135}
136
137
138static void
139emem_free(krb5_storage *sp)
140{
141    emem_storage *s = sp->data;
142    memset(s->base, 0, s->len);
143    free(s->base);
144}
145
146/**
147 * Create a elastic (allocating) memory storage backend. Memory is
148 * allocated on demand. Free returned krb5_storage with
149 * krb5_storage_free().
150 *
151 * @return A krb5_storage on success, or NULL on out of memory error.
152 *
153 * @ingroup krb5_storage
154 *
155 * @sa krb5_storage_from_mem()
156 * @sa krb5_storage_from_readonly_mem()
157 * @sa krb5_storage_from_fd()
158 * @sa krb5_storage_from_data()
159 */
160
161KRB5_LIB_FUNCTION krb5_storage * KRB5_LIB_CALL
162krb5_storage_emem(void)
163{
164    krb5_storage *sp;
165    emem_storage *s;
166
167    sp = malloc(sizeof(krb5_storage));
168    if (sp == NULL)
169	return NULL;
170
171    s = malloc(sizeof(*s));
172    if (s == NULL) {
173	free(sp);
174	return NULL;
175    }
176    sp->data = s;
177    sp->flags = 0;
178    sp->eof_code = HEIM_ERR_EOF;
179    s->size = 1024;
180    s->base = malloc(s->size);
181    if (s->base == NULL) {
182	free(sp);
183	free(s);
184	return NULL;
185    }
186    s->len = 0;
187    s->ptr = s->base;
188    sp->fetch = emem_fetch;
189    sp->store = emem_store;
190    sp->seek = emem_seek;
191    sp->trunc = emem_trunc;
192    sp->free = emem_free;
193    sp->max_alloc = UINT_MAX/8;
194    return sp;
195}
196