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   1 /* -*-c-*-
   2  *
   3  * $Id: lmem.h,v 1.5 2004/04/08 01:36:15 mdw Exp $
   4  *
   5  * Locked memory allocation
   6  *
   7  * (c) 1999 Straylight/Edgeware
   8  */
   9
  10 /*----- Licensing notice --------------------------------------------------*
  11  *
  12  * This file is part of Catacomb.
  13  *
  14  * Catacomb is free software; you can redistribute it and/or modify
  15  * it under the terms of the GNU Library General Public License as
  16  * published by the Free Software Foundation; either version 2 of the
  17  * License, or (at your option) any later version.
  18  *
  19  * Catacomb is distributed in the hope that it will be useful,
  20  * but WITHOUT ANY WARRANTY; without even the implied warranty of
  21  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  22  * GNU Library General Public License for more details.
  23  *
  24  * You should have received a copy of the GNU Library General Public
  25  * License along with Catacomb; if not, write to the Free
  26  * Software Foundation, Inc., 59 Temple Place - Suite 330, Boston,
  27  * MA 02111-1307, USA.
  28  */
  29
  30 #ifndef CATACOMB_LMEM_H
  31 #define CATACOMB_LMEM_H
  32
  33 #ifdef __cplusplus
  34   extern "C" {
  35 #endif
  36
  37 /*----- Header files ------------------------------------------------------*/
  38
  39 #include <stddef.h>
  40
  41 #include <mLib/arena.h>
  42 #include <mLib/dstr.h>
  43
  44 /*----- Data structures ---------------------------------------------------*/
  45
  46 /* --- Block list --- *
  47  *
  48  * The block list is kept in normal memory, to avoid wasting precious locked
  49  * memory.  Entries are sorted into ascending address order to make
  50  * coalescing free blocks easier.  All blocks, free or not, are included in
  51  * the list.
  52  */
  53
  54 typedef struct l_node {
  55   struct l_node *next;                  /* Next free block in chain */
  56   char *p;                              /* Pointer to the block */
  57   size_t sz;                            /* Size of the block */
  58   unsigned f;                           /* Various flags */
  59 } l_node;
  60
  61 #define LF_ALLOC 1u
  62
  63 /* --- Locked memory buffer state --- */
  64
  65 typedef struct lmem {
  66   arena a;                              /* Arena header block */
  67   unsigned f;                           /* Various flags */
  68   char *p;                              /* Pointer to locked buffer */
  69   l_node *l;                            /* Pointer to block list */
  70   size_t sz;                            /* Size of locked buffer */
  71   size_t free;                          /* Size of free area */
  72   int err; char *emsg;                  /* Error indicators */
  73 } lmem;
  74
  75 #define LF_LOCKED 1u
  76
  77 /*----- Functions provided ------------------------------------------------*/
  78
  79 /* --- @l_init@ --- *
  80  *
  81  * Arguments:   @lmem *lm@ = pointer to locked memory descriptor
  82  *              @size_t sz@ = size of locked memory area requested
  83  *
  84  * Returns:     Zero if everything is fine, @+1@ if some insecure memory was
  85  *              allocated, and @-1@ if everything went horribly wrong.
  86  *
  87  * Use:         Initializes the locked memory manager.  This function is safe
  88  *              to call in a privileged program; privileges should usually be
  89  *              dropped after allocating the locked memory block.
  90  *
  91  *              You must call @sub_init@ before allocating locked memory
  92  *              buffers.
  93  */
  94
  95 extern int l_init(lmem */*lm*/, size_t /*sz*/);
  96
  97 /* --- @l_alloc@ --- *
  98  *
  99  * Arguments:   @lmem *lm@ = pointer to locked memory descriptor
 100  *              @size_t sz@ = size requested
 101  *
 102  * Returns:     Pointer to allocated memory.
 103  *
 104  * Use:         Allocates @sz@ bytes of locked memory.
 105  */
 106
 107 extern void *l_alloc(lmem */*lm*/, size_t /*sz*/);
 108
 109 /* --- @l_free@ --- *
 110  *
 111  * Arguments:   @lmem *lm@ = pointer to locked memory descriptor
 112  *              @void *p@ = pointer to block
 113  *
 114  * Returns:     ---
 115  *
 116  * Use:         Releases a block of locked memory.
 117  */
 118
 119 extern void l_free(lmem */*lm*/, void */*p*/);
 120
 121 /* --- @l_purge@ --- *
 122  *
 123  * Arguments:   @lmem *lm@ = pointer to locked memory descriptor
 124  *
 125  * Returns:     ---
 126  *
 127  * Use:         Purges all the free blocks in the buffer, and clears all of
 128  *              the locked memory.  Memory is not freed back to the system.
 129  */
 130
 131 extern void l_purge(lmem */*lm*/);
 132
 133 /* --- @l_destroy@ --- *
 134  *
 135  * Arguments:   @lmem *lm@ = pointer to locked memory descriptor
 136  *
 137  * Returns:     ---
 138  *
 139  * Use:         Disposes of a locked memory arena permanently.
 140  */
 141
 142 extern void l_destroy(lmem */*lm*/);
 143
 144 /* --- @l_report@ --- *
 145  *
 146  * Arguments:   @lmem *lm@ = pointer to locked memory descriptor
 147  *              @dstr *d@ = string to write the error message on
 148  *
 149  * Returns:     Zero if the buffer is fine, @+1@ if there was a problem
 150  *              getting locked memory but insecure stuff could be allocated,
 151  *              and @-1@ if not even insecure memory could be found.
 152  *
 153  * Use:         Returns a user-digestable explanation for the state of a
 154  *              locked memory buffer.  If the return code is zero, no message
 155  *              is emitted to the string @d@.
 156  */
 157
 158 extern int l_report(lmem */*lm*/, dstr */*d*/);
 159
 160 /*----- That's all, folks -------------------------------------------------*/
 161
 162 #ifdef __cplusplus
 163   }
 164 #endif
 165
 166 #endif