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
  37 typedef struct emem_storage{
  38     unsigned char *base;
  39     size_t size;
  40     size_t len;
  41     unsigned char *ptr;
  42 }emem_storage;
  43
  44 static ssize_t
  45 emem_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
  55 static ssize_t
  56 emem_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
  78 static off_t
  79 emem_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
 105 static int
 106 emem_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
 138 static void
 139 emem_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
 161 KRB5_LIB_FUNCTION krb5_storage * KRB5_LIB_CALL
 162 krb5_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 }