lib/krb5/store_emem.c

   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 #include <assert.h>
  37
  38 typedef struct emem_storage{
  39     unsigned char *base;
  40     size_t size;
  41     size_t len;
  42     unsigned char *ptr;
  43 }emem_storage;
  44
  45 static ssize_t
  46 emem_fetch(krb5_storage *sp, void *data, size_t size)
  47 {
  48     emem_storage *s = (emem_storage*)sp->data;
  49
  50     assert(data != NULL && s->ptr != NULL);
  51
  52     if((size_t)(s->base + s->len - s->ptr) < size)
  53         size = s->base + s->len - s->ptr;
  54     memmove(data, s->ptr, size);
  55     sp->seek(sp, size, SEEK_CUR);
  56     return size;
  57 }
  58
  59 static ssize_t
  60 emem_store(krb5_storage *sp, const void *data, size_t size)
  61 {
  62     emem_storage *s;
  63
  64     if (size == 0) {
  65         sp->seek(sp, 0, SEEK_CUR);
  66         return 0;
  67     }
  68
  69     s = (emem_storage*)sp->data;
  70
  71     assert(data != NULL);
  72
  73     if(size > (size_t)(s->base + s->size - s->ptr)){
  74         void *base;
  75         size_t sz, off;
  76         off = s->ptr - s->base;
  77         sz = off + size;
  78         if (sz < 4096)
  79             sz *= 2;
  80         base = realloc(s->base, sz);
  81         if(base == NULL)
  82             return -1;
  83         s->size = sz;
  84         s->base = base;
  85         s->ptr = (unsigned char*)base + off;
  86     }
  87     if (size)
  88         memmove(s->ptr, data, size);
  89     sp->seek(sp, size, SEEK_CUR);
  90     return size;
  91 }
  92
  93 static off_t
  94 emem_seek(krb5_storage *sp, off_t offset, int whence)
  95 {
  96     emem_storage *s = (emem_storage*)sp->data;
  97     switch(whence){
  98     case SEEK_SET:
  99         if((size_t)offset > s->size)
 100             offset = s->size;
 101         if(offset < 0)
 102             offset = 0;
 103         s->ptr = s->base + offset;
 104         if((size_t)offset > s->len)
 105             s->len = offset;
 106         break;
 107     case SEEK_CUR:
 108         sp->seek(sp,s->ptr - s->base + offset, SEEK_SET);
 109         break;
 110     case SEEK_END:
 111         sp->seek(sp, s->len + offset, SEEK_SET);
 112         break;
 113     default:
 114         errno = EINVAL;
 115         return -1;
 116     }
 117     return s->ptr - s->base;
 118 }
 119
 120 static int
 121 emem_trunc(krb5_storage *sp, off_t offset)
 122 {
 123     emem_storage *s = (emem_storage*)sp->data;
 124     /*
 125      * If offset is larget then current size, or current size is
 126      * shrunk more then half of the current size, adjust buffer.
 127      */
 128     if (offset == 0) {
 129         if (s->size > 1024) {
 130             void *base;
 131
 132             base = realloc(s->base, 1024);
 133             if (base) {
 134                 s->base = base;
 135                 s->size = 1024;
 136             }
 137         }
 138         s->len = 0;
 139         s->ptr = s->base;
 140     } else if ((size_t)offset > s->size || (s->size / 2) > (size_t)offset) {
 141         void *base;
 142         size_t off;
 143         off = s->ptr - s->base;
 144         base = realloc(s->base, offset);
 145         if(base == NULL)
 146             return ENOMEM;
 147         if ((size_t)offset > s->size)
 148             memset((char *)base + s->size, 0, offset - s->size);
 149         s->size = offset;
 150         s->base = base;
 151         s->ptr = (unsigned char *)base + off;
 152     }
 153     s->len = offset;
 154     if ((s->ptr - s->base) > offset)
 155         s->ptr = s->base + offset;
 156     return 0;
 157 }
 158
 159
 160 static void
 161 emem_free(krb5_storage *sp)
 162 {
 163     emem_storage *s = sp->data;
 164
 165     assert(s->base != NULL);
 166
 167     memset_s(s->base, s->len, 0, s->len);
 168     free(s->base);
 169 }
 170
 171 /**
 172  * Create a elastic (allocating) memory storage backend. Memory is
 173  * allocated on demand. Free returned krb5_storage with
 174  * krb5_storage_free().
 175  *
 176  * @return A krb5_storage on success, or NULL on out of memory error.
 177  *
 178  * @ingroup krb5_storage
 179  *
 180  * @sa krb5_storage_from_mem()
 181  * @sa krb5_storage_from_readonly_mem()
 182  * @sa krb5_storage_from_fd()
 183  * @sa krb5_storage_from_data()
 184  * @sa krb5_storage_from_socket()
 185  */
 186
 187 KRB5_LIB_FUNCTION krb5_storage * KRB5_LIB_CALL
 188 krb5_storage_emem(void)
 189 {
 190     krb5_storage *sp;
 191     emem_storage *s;
 192
 193     sp = malloc(sizeof(krb5_storage));
 194     if (sp == NULL)
 195         return NULL;
 196
 197     s = malloc(sizeof(*s));
 198     if (s == NULL) {
 199         free(sp);
 200         return NULL;
 201     }
 202     sp->data = s;
 203     sp->flags = 0;
 204     sp->eof_code = HEIM_ERR_EOF;
 205     s->size = 1024;
 206     s->base = calloc(1, s->size);
 207     if (s->base == NULL) {
 208         free(sp);
 209         free(s);
 210         return NULL;
 211     }
 212     s->len = 0;
 213     s->ptr = s->base;
 214     sp->fetch = emem_fetch;
 215     sp->store = emem_store;
 216     sp->seek = emem_seek;
 217     sp->trunc = emem_trunc;
 218     sp->fsync = NULL;
 219     sp->free = emem_free;
 220     sp->max_alloc = UINT32_MAX/64;
 221     return sp;
 222 }