1/*
2 * Copyright (c) 1997 - 2002 Kungliga Tekniska Högskolan
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 = (size_t)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	if (offset > SIZE_T_MAX)
123	    return ENOMEM;
124	base = realloc(s->base, (size_t)offset);
125	if(base == NULL)
126	    return ENOMEM;
127	if ((size_t)offset > s->size)
128	    memset((char *)base + s->size, 0, offset - s->size);
129	s->size = (size_t)offset;
130	s->base = base;
131	s->ptr = (unsigned char *)base + off;
132    }
133    s->len = (size_t)offset;
134    if ((s->ptr - s->base) > offset)
135	s->ptr = s->base + offset;
136    return 0;
137}
138
139
140static void
141emem_free(krb5_storage *sp)
142{
143    emem_storage *s = sp->data;
144    memset(s->base, 0, s->len);
145    free(s->base);
146}
147
148/**
149 * Create a elastic (allocating) memory storage backend. Memory is
150 * allocated on demand. Free returned krb5_storage with
151 * krb5_storage_free().
152 *
153 * @return A krb5_storage on success, or NULL on out of memory error.
154 *
155 * @ingroup krb5_storage
156 *
157 * @sa krb5_storage_from_mem()
158 * @sa krb5_storage_from_readonly_mem()
159 * @sa krb5_storage_from_fd()
160 * @sa krb5_storage_from_data()
161 */
162
163KRB5_LIB_FUNCTION krb5_storage * KRB5_LIB_CALL
164krb5_storage_emem(void)
165{
166    krb5_storage *sp;
167    emem_storage *s;
168
169    sp = malloc(sizeof(krb5_storage));
170    if (sp == NULL)
171	return NULL;
172
173    s = malloc(sizeof(*s));
174    if (s == NULL) {
175	free(sp);
176	return NULL;
177    }
178    sp->data = s;
179    sp->flags = 0;
180    sp->eof_code = HEIM_ERR_EOF;
181    s->size = 1024;
182    s->base = malloc(s->size);
183    if (s->base == NULL) {
184	free(sp);
185	free(s);
186	return NULL;
187    }
188    s->len = 0;
189    s->ptr = s->base;
190    sp->fetch = emem_fetch;
191    sp->store = emem_store;
192    sp->seek = emem_seek;
193    sp->trunc = emem_trunc;
194    sp->free = emem_free;
195    sp->max_alloc = UINT_MAX/8;
196    return sp;
197}
198