X-Git-Url: https://git.distorted.org.uk/u/mdw/catacomb/blobdiff_plain/3636b349d37b4394e50e6f733bde63286a75e178..359df77829d85c6a415220fb4f21d5331323c79f:/lmem.h

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+/* -*-c-*-
+ *
+ * $Id: lmem.h,v 1.1 1999/12/22 16:02:52 mdw Exp $
+ *
+ * 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.
+ */
+
+/*----- Revision history --------------------------------------------------* 
+ *
+ * $Log: lmem.h,v $
+ * Revision 1.1  1999/12/22 16:02:52  mdw
+ * Interface to allocating `locked' memory (which isn't paged out).
+ *
+ */
+
+#ifndef CATACOMB_LMEM_H
+#define CATACOMB_LMEM_H
+
+#ifdef __cplusplus
+  extern "C" {
+#endif
+
+/*----- Header files ------------------------------------------------------*/
+
+#include <stddef.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;
+
+enum {
+  LF_ALLOC = 1
+};
+
+/* --- Locked memory buffer state --- */
+
+typedef struct lmem {
+  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;
+
+/*----- 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_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