--- /dev/null
+++ Libc/Libc-498/gen/backtrace.c
@@ -0,0 +1,141 @@
+/*
+ * Copyright (c) 2007 Apple Inc. All rights reserved.
+ *
+ * @APPLE_LICENSE_HEADER_START@
+ * 
+ * This file contains Original Code and/or Modifications of Original Code
+ * as defined in and that are subject to the Apple Public Source License
+ * Version 2.0 (the 'License'). You may not use this file except in
+ * compliance with the License. Please obtain a copy of the License at
+ * http://www.opensource.apple.com/apsl/ and read it before using this
+ * file.
+ * 
+ * The Original Code and all software distributed under the License are
+ * distributed on an 'AS IS' basis, WITHOUT WARRANTY OF ANY KIND, EITHER
+ * EXPRESS OR IMPLIED, AND APPLE HEREBY DISCLAIMS ALL SUCH WARRANTIES,
+ * INCLUDING WITHOUT LIMITATION, ANY WARRANTIES OF MERCHANTABILITY,
+ * FITNESS FOR A PARTICULAR PURPOSE, QUIET ENJOYMENT OR NON-INFRINGEMENT.
+ * Please see the License for the specific language governing rights and
+ * limitations under the License.
+ * 
+ * @APPLE_LICENSE_HEADER_END@
+ */
+
+#include <mach/vm_types.h>
+#include <sys/uio.h>
+
+#include <dlfcn.h>
+#include <stdlib.h>
+#include <stdio.h>
+#include <string.h>
+
+#include "stack_logging.h"
+#include "execinfo.h"
+
+int backtrace(void** buffer, int size) {
+	extern void _thread_stack_pcs(vm_address_t *buffer, unsigned max, unsigned *nb, unsigned skip);
+	unsigned int num_frames;
+	_thread_stack_pcs((vm_address_t*)buffer, size, &num_frames, 1);
+	while (num_frames >= 1 && buffer[num_frames-1] == NULL) num_frames -= 1;
+	return num_frames;
+}
+
+#if __LP64__
+#define _BACKTRACE_FORMAT "%-4d%-35s 0x%016x %s + %u"
+#define _BACKTRACE_FORMAT_SIZE 82
+#else
+#define _BACKTRACE_FORMAT "%-4d%-35s 0x%08x %s + %u"
+#define _BACKTRACE_FORMAT_SIZE 65
+#endif
+
+
+static int _backtrace_snprintf(char* buf, size_t size, int frame, const void* addr, const Dl_info* info) {
+	char symbuf[19];
+	const char* image = "???";
+	const char* symbol = symbuf;
+
+	if (info->dli_fname) {
+		image = strrchr(info->dli_fname, '/') + 1;
+		if (image == NULL) image = info->dli_fname;
+	}
+	
+	if (info->dli_sname) {
+		symbol = info->dli_sname;
+	} else {
+		snprintf(symbuf, sizeof(symbuf), "0x%x", info->dli_saddr);
+	}
+
+	return snprintf(buf, size,
+			_BACKTRACE_FORMAT,
+			frame,
+			image,
+			addr,
+			symbol,
+			addr - info->dli_saddr) + 1;
+}
+
+char** backtrace_symbols(void* const* buffer, int size) {
+	int i;
+	size_t total_bytes;
+	char** result;
+	char** ptrs;
+	intptr_t strs;
+	Dl_info* info = calloc(size, sizeof (Dl_info));
+	
+	if (info == NULL) return NULL;
+	
+	// Compute the total size for the block that is returned.
+	// The block will contain size number of pointers to the
+	// symbol descriptions.
+
+	total_bytes = sizeof(char*) * size;
+	
+	// Plus each symbol description
+	for (i = 0 ; i < size; ++i) {
+		dladdr(buffer[i], &info[i]);
+		total_bytes += _BACKTRACE_FORMAT_SIZE + 1;
+		if (info[i].dli_sname) total_bytes += strlen(info[i].dli_sname);
+	}
+	
+	result = (char**)malloc(total_bytes);
+	if (result == NULL) {
+		free(info);
+		return NULL;
+	}
+	
+	// Fill in the array of pointers and append the strings for
+	// each symbol description.
+	
+	ptrs = result;
+	strs = ((intptr_t)result) + sizeof(char*) * size;
+	
+	for (i = 0; i < size; ++i) {
+		ptrs[i] = (char*)strs;
+		strs += _backtrace_snprintf((char*)strs, total_bytes, i, buffer[i], &info[i]);
+	}
+	
+	free(info);
+	
+	return result;
+}
+
+void backtrace_symbols_fd(void* const* buffer, int size, int fd) {
+	int i;
+	char buf[BUFSIZ];
+	Dl_info info;
+	struct iovec iov[2];
+
+	iov[0].iov_base = buf;
+
+	iov[1].iov_base = "\n";
+	iov[1].iov_len = 1;
+
+	for (i = 0; i < size; ++i) {
+		memset(&info, 0, sizeof(info));
+		dladdr(buffer[i], &info);
+
+		iov[0].iov_len = _backtrace_snprintf(buf, sizeof(buf), i, buffer[i], &info);
+		
+		writev(fd, iov, 2);
+	}
+}