Initial import of the CDE 2.1.30 sources from the Open Group.

cde/programs/dtmail/libDtMail/Common/BigMalloc.C

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+/*
+ *+SNOTICE
+ *
+ *
+ *	$XConsortium: BigMalloc.C /main/4 1996/04/21 19:47:03 drk $
+ *
+ *	RESTRICTED CONFIDENTIAL INFORMATION:
+ *	
+ *	The information in this document is subject to special
+ *	restrictions in a confidential disclosure agreement bertween
+ *	HP, IBM, Sun, USL, SCO and Univel.  Do not distribute this
+ *	document outside HP, IBM, Sun, USL, SCO, or Univel wihtout
+ *	Sun's specific written approval.  This documment and all copies
+ *	and derivative works thereof must be returned or destroyed at
+ *	Sun's request.
+ *
+ *	Copyright 1993 Sun Microsystems, Inc.  All rights reserved.
+ *
+ *+ENOTICE
+ */
+
+#include <stdio.h>
+#include <string.h>
+#include <unistd.h>
+#include <stdlib.h>
+#include <fcntl.h>
+
+#if defined(NEED_MMAP_WRAPPER)
+extern "C" {
+#endif
+
+#include <sys/mman.h>
+
+#if defined(NEED_MMAP_WRAPPER)
+}
+#endif
+
+#include "BigMalloc.hh"
+
+BigMalloc::BigMalloc(unsigned int size)
+{
+    _size = size;
+
+#if defined(MMAP_NORESERVE)
+    _fd = open("/dev/zero", O_RDONLY);
+
+    _buffer = mmap(NULL, size * 4, (PROT_READ | PROT_WRITE),
+		   MAP_PRIVATE | MAP_NORESERVE, _fd, 0);
+#else
+    _buffer = malloc(size);
+#endif
+}
+
+BigMalloc::~BigMalloc(void)
+{
+#if defined(MAP_NORESERVE)
+    if (_buffer) {
+	munmap((char *)_buffer, _size * 4);
+    }
+
+    if (_fd >= 0) {
+	close(_fd);
+    }
+#else
+    free(_buffer);
+#endif
+}
+
+void
+BigMalloc::Realloc(unsigned int size)
+{
+#if defined(MAP_NORESERVE)
+    if (size < (_size * 4)) {
+	return;
+    }
+
+    unsigned int additional = (size * 4) - (_size * 4);
+
+    char * new_buf;
+    new_buf = mmap(((char *)_buffer) + (_size * 4), additional, 
+		   (PROT_READ | PROT_WRITE),
+		   MAP_FIXED | MAP_PRIVATE | MAP_NORESERVE, _fd, (_size * 4));
+
+    if (new_buf == (char *)-1) {
+	// Fixed mapping failed. We will have to map a new region and copy.
+	//
+    	new_buf = mmap(NULL, size * 4, (PROT_READ | PROT_WRITE),
+		       MAP_PRIVATE | MAP_NORESERVE, _fd, 0);
+
+	memcpy(new_buf, _buffer, _size * 4);
+	munmap((char *)_buffer, _size * 4);
+    }
+
+    _buffer = new_buf;
+    _size = size;
+#else
+    _size = size;
+    _buffer = realloc(_buffer, _size);
+#endif
+
+}
+
+BigMalloc::operator char*(void)
+{
+    return((char *)_buffer);
+}