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 Högskolan
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
39 typedef struct emem_storage{
40 unsigned char *base;
41 size_t size;
42 size_t len;
43 unsigned char *ptr;
44 }emem_storage;
45
46 static ssize_t
emem_fetch(krb5_storage * sp,void * data,size_t size)47 emem_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
57 static ssize_t
emem_store(krb5_storage * sp,const void * data,size_t size)58 emem_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
81 static off_t
emem_seek(krb5_storage * sp,off_t offset,int whence)82 emem_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
108 static int
emem_trunc(krb5_storage * sp,off_t offset)109 emem_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
141 static void
emem_free(krb5_storage * sp)142 emem_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
165 KRB5_LIB_FUNCTION krb5_storage * KRB5_LIB_CALL
krb5_storage_emem(void)166 krb5_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