ExceptionUtils.m

//
//  ExceptionUtils.m
//  MYUtilities
//
//  Created by Jens Alfke on 1/5/08.
//  Copyright 2008-2013 Jens Alfke. All rights reserved.
//  See BSD license at bottom of file.
//

#import "ExceptionUtils.h"

#import "MYLogging.h"
#import "Test.h"

#include <pthread.h>

#if !__has_feature(objc_arc)
#error This source file must be compiled with ARC
#endif


#ifndef MYWarn
#define MYWarn NSLog
#endif


static void (*sExceptionReporter)(NSException*);

void MYSetExceptionReporter( void (*reporter)(NSException*) )
{
    sExceptionReporter = reporter;
}

void MYReportException( NSException *x, NSString *where, ... )
{
    va_list args;
    va_start(args,where);
    where = [[NSString alloc] initWithFormat: where arguments: args];
    va_end(args);
    MYWarn(@"Exception caught in %@:\n\t%@\n%@",where,x,x.my_callStack);
    if( sExceptionReporter )
        sExceptionReporter(x);
}


@implementation NSException (MYUtilities)


- (NSArray*) my_callStackReturnAddresses
{
    // On 10.5 or later, can get the backtrace:
    if( [self respondsToSelector: @selector(callStackReturnAddresses)] )
        return [self valueForKey: @"callStackReturnAddresses"];
    else
        return nil;
}

- (NSArray*) my_callStackReturnAddressesSkipping: (unsigned)skip limit: (unsigned)limit
{
    NSArray *addresses = [self my_callStackReturnAddresses];
    if( addresses ) {
        unsigned n = (unsigned) [addresses count];
        skip = MIN(skip,n);
        limit = MIN(limit,n-skip);
        addresses = [addresses subarrayWithRange: NSMakeRange(skip,limit)];
    }
    return addresses;
}


- (NSString*) my_callStack
{
    NSMutableString* result = [NSMutableString string];
    unsigned lines = 0;
    for (NSString* line in [self callStackSymbols]) {
        NSString* symbol = @"";
        if (line.length > 40) {
            NSRange space = [line rangeOfString: @" " options: 0 range: NSMakeRange(41, line.length - 41)];
            if (space.length > 0)
                symbol = [line substringFromIndex: NSMaxRange(space)];
        }
        // Skip  frames that are part of the exception/assertion handling itself:
        if( [symbol hasPrefix: @"-[NSAssertionHandler"] || [symbol hasPrefix: @"+[NSException"]
                || [symbol hasPrefix: @"-[NSException"] || [symbol hasPrefix: @"_AssertFailed"]
                || [symbol hasPrefix: @"__exception"] || [symbol hasPrefix: @"objc_"] )
            continue;
        if( result.length )
            [result appendString: @"\n"];
        [result appendString: @"\t"];
        [result appendString: line];
        // Don't show the "__start" frame below "main":
        if( [symbol hasPrefix: @"main "] || [symbol hasPrefix: @"start "] )
            break;
        if (++lines >= 15) {
            [result appendString: @"\n\t..."];
            break;
        }
    }
    return result;
}

@end




#ifdef NSAppKitVersionNumber10_4 // only enable this in a project that uses AppKit

@implementation MYExceptionReportingApplication


static void report( NSException *x ) {
    [NSApp reportException: x];
}

- (instancetype) init
{
    self = [super init];
    if (self != nil) {
        MYSetExceptionReporter(&report);
    }
    return self;
}


- (void)reportException:(NSException *)x
{
    [super reportException: x];
    [self performSelector: @selector(_showExceptionAlert:) withObject: x afterDelay: 0.0];
    MYSetExceptionReporter(NULL);     // ignore further exceptions till alert is dismissed
}

- (void) _showExceptionAlert: (NSException*)x
{
    NSString *stack = [x my_callStack] ?:@"";

    NSAlert* alert = [NSAlert new];
    alert.alertStyle = NSCriticalAlertStyle;
    alert.messageText =  @"Internal Error!";
    alert.informativeText = $sprintf(@"Uncaught exception: %@\n%@\n\n%@\n\n"
                                     "Please report this bug (you can copy & paste the text).",
                                     [x name], [x reason], stack);
    [alert addButtonWithTitle: @"Continue"];
    [alert addButtonWithTitle: @"Quit"];

    if( [alert runModal] == NSAlertSecondButtonReturn )
        exit(1);
    MYSetExceptionReporter(&report);
}

@end

#endif




#if DEBUG

#include <assert.h>
#include <stdbool.h>
#include <sys/types.h>
#include <unistd.h>
#include <sys/sysctl.h>
#include <pthread.h>


// Returns true if the current process is being debugged (either
// running under the debugger or has a debugger attached post facto).
// Copied from <https://developer.apple.com/library/content/qa/qa1361/_index.html>
bool MYIsDebuggerAttached(void)
{
    // Important: Because the definition of the kinfo_proc structure (in <sys/sysctl.h>) is
    // conditionalized by __APPLE_API_UNSTABLE, you should restrict use of the above code to the
    // debug build of your program.

    int                 junk;
    int                 mib[4];
    struct kinfo_proc   info;
    size_t              size;

    // Initialize the flags so that, if sysctl fails for some bizarre
    // reason, we get a predictable result.

    info.kp_proc.p_flag = 0;

    // Initialize mib, which tells sysctl the info we want, in this case
    // we're looking for information about a specific process ID.

    mib[0] = CTL_KERN;
    mib[1] = KERN_PROC;
    mib[2] = KERN_PROC_PID;
    mib[3] = getpid();

    // Call sysctl.

    size = sizeof(info);
    junk = sysctl(mib, sizeof(mib) / sizeof(*mib), &info, &size, NULL, 0);
    assert(junk == 0);

    // We're being debugged if the P_TRACED flag is set.

    return ( (info.kp_proc.p_flag & P_TRACED) != 0 );
}

#endif


#if !TARGET_CPU_X86_64 && !TARGET_CPU_X86
void _MYBreakpoint() {
    pthread_kill(pthread_self(), SIGINT);
}
#endif



/*
 Copyright (c) 2008-2013, Jens Alfke <jens@mooseyard.com>. 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.
 
 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 OWNER OR CONTRI-
 BUTORS 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.
 */