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   1 /* -*-c-*-
   2  *
   3  * $Id: lmem.h,v 1.1 1999/12/22 16:02:52 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 /*----- Revision history --------------------------------------------------*
  31  *
  32  * $Log: lmem.h,v $
  33  * Revision 1.1  1999/12/22 16:02:52  mdw
  34  * Interface to allocating `locked' memory (which isn't paged out).
  35  *
  36  */
  37
  38 #ifndef CATACOMB_LMEM_H
  39 #define CATACOMB_LMEM_H
  40
  41 #ifdef __cplusplus
  42   extern "C" {
  43 #endif
  44
  45 /*----- Header files ------------------------------------------------------*/
  46
  47 #include <stddef.h>
  48
  49 #include <mLib/dstr.h>
  50
  51 /*----- Data structures ---------------------------------------------------*/
  52
  53 /* --- Block list --- *
  54  *
  55  * The block list is kept in normal memory, to avoid wasting precious locked
  56  * memory.  Entries are sorted into ascending address order to make
  57  * coalescing free blocks easier.  All blocks, free or not, are included in
  58  * the list.
  59  */
  60
  61 typedef struct l_node {
  62   struct l_node *next;                  /* Next free block in chain */
  63   char *p;                              /* Pointer to the block */
  64   size_t sz;                            /* Size of the block */
  65   unsigned f;                           /* Various flags */
  66 } l_node;
  67
  68 enum {
  69   LF_ALLOC = 1
  70 };
  71
  72 /* --- Locked memory buffer state --- */
  73
  74 typedef struct lmem {
  75   char *p;                              /* Pointer to locked buffer */
  76   l_node *l;                            /* Pointer to block list */
  77   size_t sz;                            /* Size of locked buffer */
  78   size_t free;                          /* Size of free area */
  79   int err; char *emsg;                  /* Error indicators */
  80 } lmem;
  81
  82 /*----- Functions provided ------------------------------------------------*/
  83
  84 /* --- @l_init@ --- *
  85  *
  86  * Arguments:   @lmem *lm@ = pointer to locked memory descriptor
  87  *              @size_t sz@ = size of locked memory area requested
  88  *
  89  * Returns:     Zero if everything is fine, @+1@ if some insecure memory was
  90  *              allocated, and @-1@ if everything went horribly wrong.
  91  *
  92  * Use:         Initializes the locked memory manager.  This function is safe
  93  *              to call in a privileged program; privileges should usually be
  94  *              dropped after allocating the locked memory block.
  95  *
  96  *              You must call @sub_init@ before allocating locked memory
  97  *              buffers.
  98  */
  99
 100 extern int l_init(lmem */*lm*/, size_t /*sz*/);
 101
 102 /* --- @l_alloc@ --- *
 103  *
 104  * Arguments:   @lmem *lm@ = pointer to locked memory descriptor
 105  *              @size_t sz@ = size requested
 106  *
 107  * Returns:     Pointer to allocated memory.
 108  *
 109  * Use:         Allocates @sz@ bytes of locked memory.
 110  */
 111
 112 extern void *l_alloc(lmem */*lm*/, size_t /*sz*/);
 113
 114 /* --- @l_free@ --- *
 115  *
 116  * Arguments:   @lmem *lm@ = pointer to locked memory descriptor
 117  *              @void *p@ = pointer to block
 118  *
 119  * Returns:     ---
 120  *
 121  * Use:         Releases a block of locked memory.
 122  */
 123
 124 extern void l_free(lmem */*lm*/, void */*p*/);
 125
 126 /* --- @l_purge@ --- *
 127  *
 128  * Arguments:   @lmem *lm@ = pointer to locked memory descriptor
 129  *
 130  * Returns:     ---
 131  *
 132  * Use:         Purges all the free blocks in the buffer, and clears all of
 133  *              the locked memory.  Memory is not freed back to the system.
 134  */
 135
 136 extern void l_purge(lmem */*lm*/);
 137
 138 /* --- @l_report@ --- *
 139  *
 140  * Arguments:   @lmem *lm@ = pointer to locked memory descriptor
 141  *              @dstr *d@ = string to write the error message on
 142  *
 143  * Returns:     Zero if the buffer is fine, @+1@ if there was a problem
 144  *              getting locked memory but insecure stuff could be allocated,
 145  *              and @-1@ if not even insecure memory could be found.
 146  *
 147  * Use:         Returns a user-digestable explanation for the state of a
 148  *              locked memory buffer.  If the return code is zero, no message
 149  *              is emitted to the string @d@.
 150  */
 151
 152 extern int l_report(lmem */*lm*/, dstr */*d*/);
 153
 154 /*----- That's all, folks -------------------------------------------------*/
 155
 156 #ifdef __cplusplus
 157   }
 158 #endif
 159
 160 #endif