NSException+Backtrace.m

/*
 * NSException+Backtrace.h
 * Utilities
 * 
 * Created by Jim Dovey on 8/7/2010.
 * 
 * Copyright (c) 2010 Kobo, Inc.
 * All rights reserved.
 * 
 * Redistribution and use in source and binary forms, with or without
 * modification, are permitted provided that the following conditions
 * are met:
 * 
 * Redistributions of source code must retain the above copyright notice,
 * this list of conditions and the following disclaimer.
 * 
 * Redistributions in binary form must reproduce the above copyright
 * notice, this list of conditions and the following disclaimer in the
 * documentation and/or other materials provided with the distribution.
 * 
 * Neither the name of the project's author nor the names of its
 * contributors may be used to endorse or promote products derived from
 * this software without specific prior written permission.
 * 
 * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
 * "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
 * LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS
 * FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
 * HOLDER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
 * SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED
 * TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR
 * PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF
 * LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING
 * NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS
 * SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
 *
 */

#import <Foundation/Foundation.h>

@interface NSException (KBBacktrace)

- (NSArray *) kobo_symbolicBacktrace;

@end

///////////////////////////////////////////////////////////////////////////////

#import <execinfo.h>

static NSString * const kSymbolsKey = @"Kobo_callStackSymbols";

@implementation NSException (KBBacktrace)

- (NSArray *) kobo_symbolicBacktrace
{
	// Mac OS X 10.6 and iOS 4.0 provide this for us
	if ( [self respondsToSelector: @selector(callStackSymbols)] )
		return ( [self callStackSymbols] );
	
	NSArray * result = [[[NSThread currentThread] threadDictionary] objectForKey: kSymbolsKey];
	
	// on earlier versions, we have to do the work ourselves
	NSArray * addresses = [self callStackReturnAddresses];
	NSMutableArray * symbols = [[NSMutableArray alloc] initWithCapacity: [addresses count]];
	
	// get a list of void * addresses
	void ** addrs = (void **)NSZoneMalloc( [self zone], [addresses count] * sizeof(void *) );
	
	NSUInteger idx = 0;
	for ( id obj in addresses )
	{
		addrs[idx++] = (void *)[obj integerValue];
	}
	
	// now get the symbols
	char ** symstrs = backtrace_symbols(addrs, [addresses count]);
	for ( int i = 0; i < [addresses count]; i++ )
	{
		[symbols addObject: [NSString stringWithCString: symstrs[i] encoding: NSASCIIStringEncoding]];
	}
	
	result = [symbols copy];
	[symbols release];
	
	[[[NSThread currentThread] threadDictionary] setObject: result forKey: kSymbolsKey];
	return ( result );
}

@end