Rearrange the file tree.

[u/mdw/catacomb] / base / lmem.h

diff --git a/base/lmem.h b/base/lmem.h
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+/* -*-c-*-
+ *
+ * Locked memory allocation
+ *
+ * (c) 1999 Straylight/Edgeware
+ */
+
+/*----- Licensing notice --------------------------------------------------*
+ *
+ * This file is part of Catacomb.
+ *
+ * Catacomb is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU Library General Public License as
+ * published by the Free Software Foundation; either version 2 of the
+ * License, or (at your option) any later version.
+ *
+ * Catacomb is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU Library General Public License for more details.
+ *
+ * You should have received a copy of the GNU Library General Public
+ * License along with Catacomb; if not, write to the Free
+ * Software Foundation, Inc., 59 Temple Place - Suite 330, Boston,
+ * MA 02111-1307, USA.
+ */
+
+#ifndef CATACOMB_LMEM_H
+#define CATACOMB_LMEM_H
+
+#ifdef __cplusplus
+  extern "C" {
+#endif
+
+/*----- Header files ------------------------------------------------------*/
+
+#include <stddef.h>
+
+#include <mLib/arena.h>
+#include <mLib/dstr.h>
+
+/*----- Data structures ---------------------------------------------------*/
+
+/* --- Block list --- *
+ *
+ * The block list is kept in normal memory, to avoid wasting precious locked
+ * memory.  Entries are sorted into ascending address order to make
+ * coalescing free blocks easier.  All blocks, free or not, are included in
+ * the list.
+ */
+
+typedef struct l_node {
+  struct l_node *next;                 /* Next free block in chain */
+  char *p;                             /* Pointer to the block */
+  size_t sz;                           /* Size of the block */
+  unsigned f;                          /* Various flags */
+} l_node;
+
+#define LF_ALLOC 1u
+
+/* --- Locked memory buffer state --- */
+
+typedef struct lmem {
+  arena a;                             /* Arena header block */
+  unsigned f;                          /* Various flags */
+  char *p;                             /* Pointer to locked buffer */
+  l_node *l;                           /* Pointer to block list */
+  size_t sz;                           /* Size of locked buffer */
+  size_t free;                         /* Size of free area */
+  int err; char *emsg;                 /* Error indicators */
+} lmem;
+
+#define LF_LOCKED 1u
+
+/*----- Functions provided ------------------------------------------------*/
+
+/* --- @l_init@ --- *
+ *
+ * Arguments:  @lmem *lm@ = pointer to locked memory descriptor
+ *             @size_t sz@ = size of locked memory area requested
+ *
+ * Returns:    Zero if everything is fine, @+1@ if some insecure memory was
+ *             allocated, and @-1@ if everything went horribly wrong.
+ *
+ * Use:                Initializes the locked memory manager.  This function is safe
+ *             to call in a privileged program; privileges should usually be
+ *             dropped after allocating the locked memory block.
+ *
+ *             You must call @sub_init@ before allocating locked memory
+ *             buffers.
+ */
+
+extern int l_init(lmem */*lm*/, size_t /*sz*/);
+
+/* --- @l_alloc@ --- *
+ *
+ * Arguments:  @lmem *lm@ = pointer to locked memory descriptor
+ *             @size_t sz@ = size requested
+ *
+ * Returns:    Pointer to allocated memory.
+ *
+ * Use:                Allocates @sz@ bytes of locked memory.
+ */
+
+extern void *l_alloc(lmem */*lm*/, size_t /*sz*/);
+
+/* --- @l_free@ --- *
+ *
+ * Arguments:  @lmem *lm@ = pointer to locked memory descriptor
+ *             @void *p@ = pointer to block
+ *
+ * Returns:    ---
+ *
+ * Use:                Releases a block of locked memory.
+ */
+
+extern void l_free(lmem */*lm*/, void */*p*/);
+
+/* --- @l_purge@ --- *
+ *
+ * Arguments:  @lmem *lm@ = pointer to locked memory descriptor
+ *
+ * Returns:    ---
+ *
+ * Use:                Purges all the free blocks in the buffer, and clears all of
+ *             the locked memory.  Memory is not freed back to the system.
+ */
+
+extern void l_purge(lmem */*lm*/);
+
+/* --- @l_destroy@ --- *
+ *
+ * Arguments:  @lmem *lm@ = pointer to locked memory descriptor
+ *
+ * Returns:    ---
+ *
+ * Use:                Disposes of a locked memory arena permanently.
+ */
+
+extern void l_destroy(lmem */*lm*/);
+
+/* --- @l_report@ --- *
+ *
+ * Arguments:  @lmem *lm@ = pointer to locked memory descriptor
+ *             @dstr *d@ = string to write the error message on
+ *
+ * Returns:    Zero if the buffer is fine, @+1@ if there was a problem
+ *             getting locked memory but insecure stuff could be allocated,
+ *             and @-1@ if not even insecure memory could be found.
+ *
+ * Use:                Returns a user-digestable explanation for the state of a
+ *             locked memory buffer.  If the return code is zero, no message
+ *             is emitted to the string @d@.
+ */
+
+extern int l_report(lmem */*lm*/, dstr */*d*/);
+
+/*----- That's all, folks -------------------------------------------------*/
+
+#ifdef __cplusplus
+  }
+#endif
+
+#endif