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   1 /* -*-c-*-
   2  *
   3  * $Id: lmem.h,v 1.4 2000/12/06 20:33:27 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 1.4  2000/12/06 20:33:27  mdw
  34  * Make flags be macros rather than enumerations, to ensure that they're
  35  * unsigned.
  36  *
  37  * Revision 1.3  2000/07/29 21:58:15  mdw
  38  * (l_destroy): New function for destroying locked memory blocks.
  39  *
  40  * Revision 1.2  2000/06/17 11:29:38  mdw
  41  * Add arena support.
  42  *
  43  * Revision 1.1  1999/12/22 16:02:52  mdw
  44  * Interface to allocating `locked' memory (which isn't paged out).
  45  *
  46  */
  47
  48 #ifndef CATACOMB_LMEM_H
  49 #define CATACOMB_LMEM_H
  50
  51 #ifdef __cplusplus
  52   extern "C" {
  53 #endif
  54
  55 /*----- Header files ------------------------------------------------------*/
  56
  57 #include <stddef.h>
  58
  59 #include <mLib/arena.h>
  60 #include <mLib/dstr.h>
  61
  62 /*----- Data structures ---------------------------------------------------*/
  63
  64 /* --- Block list --- *
  65  *
  66  * The block list is kept in normal memory, to avoid wasting precious locked
  67  * memory.  Entries are sorted into ascending address order to make
  68  * coalescing free blocks easier.  All blocks, free or not, are included in
  69  * the list.
  70  */
  71
  72 typedef struct l_node {
  73   struct l_node *next;                  /* Next free block in chain */
  74   char *p;                              /* Pointer to the block */
  75   size_t sz;                            /* Size of the block */
  76   unsigned f;                           /* Various flags */
  77 } l_node;
  78
  79 #define LF_ALLOC 1u
  80
  81 /* --- Locked memory buffer state --- */
  82
  83 typedef struct lmem {
  84   arena a;                              /* Arena header block */
  85   unsigned f;                           /* Various flags */
  86   char *p;                              /* Pointer to locked buffer */
  87   l_node *l;                            /* Pointer to block list */
  88   size_t sz;                            /* Size of locked buffer */
  89   size_t free;                          /* Size of free area */
  90   int err; char *emsg;                  /* Error indicators */
  91 } lmem;
  92
  93 #define LF_LOCKED 1u
  94
  95 /*----- Functions provided ------------------------------------------------*/
  96
  97 /* --- @l_init@ --- *
  98  *
  99  * Arguments:   @lmem *lm@ = pointer to locked memory descriptor
 100  *              @size_t sz@ = size of locked memory area requested
 101  *
 102  * Returns:     Zero if everything is fine, @+1@ if some insecure memory was
 103  *              allocated, and @-1@ if everything went horribly wrong.
 104  *
 105  * Use:         Initializes the locked memory manager.  This function is safe
 106  *              to call in a privileged program; privileges should usually be
 107  *              dropped after allocating the locked memory block.
 108  *
 109  *              You must call @sub_init@ before allocating locked memory
 110  *              buffers.
 111  */
 112
 113 extern int l_init(lmem */*lm*/, size_t /*sz*/);
 114
 115 /* --- @l_alloc@ --- *
 116  *
 117  * Arguments:   @lmem *lm@ = pointer to locked memory descriptor
 118  *              @size_t sz@ = size requested
 119  *
 120  * Returns:     Pointer to allocated memory.
 121  *
 122  * Use:         Allocates @sz@ bytes of locked memory.
 123  */
 124
 125 extern void *l_alloc(lmem */*lm*/, size_t /*sz*/);
 126
 127 /* --- @l_free@ --- *
 128  *
 129  * Arguments:   @lmem *lm@ = pointer to locked memory descriptor
 130  *              @void *p@ = pointer to block
 131  *
 132  * Returns:     ---
 133  *
 134  * Use:         Releases a block of locked memory.
 135  */
 136
 137 extern void l_free(lmem */*lm*/, void */*p*/);
 138
 139 /* --- @l_purge@ --- *
 140  *
 141  * Arguments:   @lmem *lm@ = pointer to locked memory descriptor
 142  *
 143  * Returns:     ---
 144  *
 145  * Use:         Purges all the free blocks in the buffer, and clears all of
 146  *              the locked memory.  Memory is not freed back to the system.
 147  */
 148
 149 extern void l_purge(lmem */*lm*/);
 150
 151 /* --- @l_destroy@ --- *
 152  *
 153  * Arguments:   @lmem *lm@ = pointer to locked memory descriptor
 154  *
 155  * Returns:     ---
 156  *
 157  * Use:         Disposes of a locked memory arena permanently.
 158  */
 159
 160 extern void l_destroy(lmem */*lm*/);
 161
 162 /* --- @l_report@ --- *
 163  *
 164  * Arguments:   @lmem *lm@ = pointer to locked memory descriptor
 165  *              @dstr *d@ = string to write the error message on
 166  *
 167  * Returns:     Zero if the buffer is fine, @+1@ if there was a problem
 168  *              getting locked memory but insecure stuff could be allocated,
 169  *              and @-1@ if not even insecure memory could be found.
 170  *
 171  * Use:         Returns a user-digestable explanation for the state of a
 172  *              locked memory buffer.  If the return code is zero, no message
 173  *              is emitted to the string @d@.
 174  */
 175
 176 extern int l_report(lmem */*lm*/, dstr */*d*/);
 177
 178 /*----- That's all, folks -------------------------------------------------*/
 179
 180 #ifdef __cplusplus
 181   }
 182 #endif
 183
 184 #endif