I have a iOS app. I allocate 2d memory and then deallocate using free function. Is this the right way to free? Recently I had crash pointing to free statement. Should I be releasing buf[i] in loop?
+(int**) initArr:(int) Nr:( int) Nc
{
int ** buf;
buf = calloc(Nr,sizeof(int*));
for(int i = 0; i < Nr; i++)
{
buf[i] = calloc(Nc,sizeof(int));
}
//Funny Processing
//Release
for(int i = 0; i < Nr; i++)
free(buf[i]);
free(buf);
}
Here is the error message
2 libsystem_c.dylib 0x328b87ec _sigtramp + 48
3 libsystem_c.dylib 0x328ae20e pthread_kill + 54
4 libsystem_c.dylib 0x328a729e abort + 94
5 libsystem_c.dylib 0x32862380 free + 380
6 MyApp 0x0009be52 +[clsGlobalHelper resizeImageAvg:::] (clsGlobalHelper.m:300)
Related
I use backtrace and backtrace_symbols to collect the call stack when my app crashed.
void InstallSignalHandler(void)
{
signal(SIGHUP, SignalExceptionHandler);
signal(SIGINT, SignalExceptionHandler);
signal(SIGQUIT, SignalExceptionHandler);
signal(SIGABRT, SignalExceptionHandler);
signal(SIGILL, SignalExceptionHandler);
signal(SIGSEGV, SignalExceptionHandler);
signal(SIGFPE, SignalExceptionHandler);
signal(SIGBUS, SignalExceptionHandler);
signal(SIGPIPE, SignalExceptionHandler);
}
void SignalExceptionHandler(int signal)
{
NSMutableString *mstr = [[NSMutableString alloc] init];
[mstr appendString:#"Stack:\n"];
void* callstack[128];
int i, frames = backtrace(callstack, 128);
char** strs = backtrace_symbols(callstack, frames);
for (i = 0; i <frames; ++i) {
[mstr appendFormat:#"%s\n", strs[i]];
}
NSLog(#"%#", mstr);
free(strs);
}
When I check the log in console, I just find the log miss the function that caused the crash.The function is:
+ (void)testCrash
{
int *nullPointer = NULL;
*nullPointer = 2019;
}
And the log in console is:
0 TestApp 0x0000000101d1e040 SignalExceptionHandler + 160
1 libsystem_platform.dylib 0x000000011002bb5d _sigtramp + 29
2 ??? 0x0000000000000000 0x0 + 0
3 TestApp 0x00000001019bbc6f __39+[MyCrashTesting showInViewController:]_block_invoke + 303
4 UIKit 0x000000010b09a559 -[UIAlertController _invokeHandlersForAction:] + 105
5 UIKit 0x000000010b09af5e __103-[UIAlertController _dismissAnimated:triggeringAction:triggeredByPopoverDimmingView:dismissCompletion:]_block_invoke.461 + 16
6 UIKit 0x000000010ae42ca2 -[UIPresentationController transitionDidFinish:] + 1346
7 UIKit 0x000000010ae46b12 __56-[UIPresentationController runTransitionForCurrentState]_block_invoke.436 + 183
8 UIKit 0x000000010ba2a3b4 -[_UIViewControllerTransitionContext c
I have thought the function name "testCrash" should be in the top of the log. Does I do something wrong?
Since this is a very simple method with no arguments and no ARC heavylifting inside clang the Objective-C compiler is able to do an optimization (-O1 is enough to achieve that) of removing the message runtime call.
You can prevent this behavior with:
+ (void)testCrash __attribute__((optnone))
{
int *nullPointer = NULL;
*nullPointer = 2019;
}
The lesson learnt here is you should never rely on particular stacktrace to achieve something during your program execution. Diagnostics is fine as long as you understand the optimizing principles you've just encountered.
I am seeing a crash in a very simple code snippet. The crash occurs when cv::Mat::deallocate attempts to free unallocated memory. I even simplified the code ride down to the point where it is useless, but I still see the crash.
boost::shared_ptr<cv::Mat> mask = ...;
cv::Mat thresholdedImage = cv::Mat::zeros(mask->size(), CV_32FC1);
cv::Mat dummyMask = cv::Mat::zeros(mask->size(), CV_32FC1);
cv::threshold(dummyMask, thresholdedImage, 0.5, 1, cv::THRESH_BINARY);
int nonzeroCount = cv::countNonZero(thresholdedImage);
Here is the backtrace:
1 libsystem_c.dylib 0x00007fff93aa49a3 abort + 129
2 libsystem_malloc.dylib 0x00007fff92ec91cb free + 428
3 MyLib.dylib 0x0000000135b45d7c cv::StdMatAllocator::deallocate(cv::UMatData*) const + 60
4 MyLib.dylib 0x0000000135b0240c cv::Mat::deallocate() + 28
5 MyLib.dylib 0x0000000135ba9362 cv::countNonZero(cv::_InputArray const&) + 802
Am I missing something obvious here?
I'm seeing a segfault from using NSLog and specifically, it is on a 64 bit device, with a SEGV_ACCERR. I'm new to iOS, so i'm a little confused.
Here's the stack trace:
Exception Type: SIGSEGV
Exception Codes: SEGV_ACCERR at 0x108074000
Crashed Thread: 0
Thread 0 Crashed:
0 libsystem_platform.dylib 0x00000001826ea31c _platform_memmove + 300
1 libsystem_asl.dylib 0x00000001825289a4 asl_string_append_no_encoding_len + 92
2 libsystem_asl.dylib 0x0000000182522fc8 asl_string_new + 108
3 libsystem_asl.dylib 0x0000000182522df4 asl_msg_to_string_raw + 68
4 libsystem_asl.dylib 0x00000001825228dc _asl_send_message + 828
5 libsystem_asl.dylib 0x00000001825224fc asl_send + 8
6 CoreFoundation 0x0000000182a6fa1c __CFLogCString + 568
7 CoreFoundation 0x0000000182a6f7ac _CFLogvEx2 + 300
8 CoreFoundation 0x0000000182a6fc14 _CFLogvEx3 + 152
9 Foundation 0x0000000183435dd8 _NSLogv + 128
10 Foundation 0x000000018336ae04 NSLog + 28
Here is the code that calls this:
NSString *truncated = [NSString stringWithUTF8String:buffer];
// Using original NSLog to print.
#undef NSLog
NSLog(#"%#", truncated);
and it crashes from my NSLog call.
where buffer is just a char buffer.
My questions specifically are:
Is it even possible to crash from using Apple's provided NSLog? Or is my stack trace wrong?
What does SEG_ACCERR even mean in this context?
How could i go about finding if this was caused by a bad memory issue or not?
Is something blowing up with the asl file under multiple threads?
How should i approach debugging this?
Any help would be greatly appreciated! Thanks!
You say that buffer is a char buffer. If that is the case, you should initialize the string like this
NSString *truncated = [[NSString alloc] initWithBytes:buffer
length:len NSUTF8StringEncoding];
where len is the length of the characters in the buffer.
I have recorded a crash of my app, but the last line in my app (5 Control) points just to the method begin. How do I know in which line the problem is?
0 CoreFoundation 0x185f0af50 __exceptionPreprocess + 132
1 libobjc.A.dylib 0x1924141fc objc_exception_throw + 60
2 CoreFoundation 0x185f0fc04 -[NSObject(NSObject) doesNotRecognizeSelector:] + 220
3 CoreFoundation 0x185f0d930 ___forwarding___ + 912
4 CoreFoundation 0x185e2d5dc _CF_forwarding_prep_0 + 92
5 Control 0x10005acb4 -[PaymillPaymentService handleTransactionListRequest:] (PaymillPaymentService.m:211)
6 Foundation 0x186a7416c __103+[__NSOperationInternal _observeValueForKeyPath:ofObject:changeKind:oldValue:newValue:indexes:context:]_block_invoke96 + 28
7 libdispatch.dylib 0x1929ec014 _dispatch_call_block_and_release + 24
8 libdispatch.dylib 0x1929ebfd4 _dispatch_client_callout + 16
9 libdispatch.dylib 0x1929f32b8 _dispatch_root_queue_drain + 556
10 libdispatch.dylib 0x1929f34fc _dispatch_worker_thread2 + 76
11 libsystem_pthread.dylib 0x192b816bc _pthread_wqthread + 356
12 libsystem_pthread.dylib 0x192b8154c start_wqthread + 4
Here the [lengthy] method code. I see a couple of places where I can add the check but how to I know it for sure that I fixed the issue? The problem is sporadical and I cannot reproduce it easily.
- (void)handleTransactionListRequest:(ServiceRequest *)serviceRequest
{
LRURLRequestOperation* operation = serviceRequest.operation;
NSHTTPURLResponse *response = (NSHTTPURLResponse *)operation.URLResponse;
if (response.statusCode == 200)
{
if (operation.responseData)
{
NSError *parserError = nil;
NSDictionary *data = [NSJSONSerialization JSONObjectWithData:operation.responseData options:0 error:&parserError];
//NSLog(#"%#", data);
if (!parserError)
{
NSArray* transactions = [data objectForKey:#"data"];
if (0 == serviceRequest.currentOffset)
{
NSNumber* totalCountObj = [data objectForKey:#"data_count"];
serviceRequest.totalCount = [totalCountObj intValue];
}
int loadedCount = 0;
if (transactions)
{
for (id object in transactions)
{
TransactionInfo* info = [self createTransactionFrom:object];
[serviceRequest.transactionList addTransaction:info];
[info release];
loadedCount++;
}
}
if (loadedCount + serviceRequest.currentOffset >= serviceRequest.totalCount)
{
if ([serviceRequest.delegate respondsToSelector:#selector(transactionListLoadingComplete:)])
[serviceRequest.delegate transactionListLoadingComplete:serviceRequest];
serviceRequest.transactionList.timeStamp = [[NSDate date] timeIntervalSince1970];
NSLog(#"COMPLETE: %d transaction loaded ", serviceRequest.totalCount);
}
else
{
serviceRequest.currentOffset += loadedCount;
bool needToContinue = YES;
if ([serviceRequest.delegate respondsToSelector:#selector(transactionListLoadingContinue:)])
needToContinue = [serviceRequest.delegate transactionListLoadingContinue];
if (needToContinue)
{
[self continueRetrievingTransactionListFor:serviceRequest];
NSLog(#"CONTINUE: %d of %d loaded ", serviceRequest.currentOffset, serviceRequest.totalCount);
}
}
return; // all OK cases
}
}
}
if ([serviceRequest.delegate respondsToSelector:#selector(transactionListLoadingFailed:with:)])
[serviceRequest.delegate transactionListLoadingFailed:serviceRequest with:response.statusCode];
NSLog(#"ERROR: Loading Transactions Response Code: %ld", (long)response.statusCode);
}
Short Answer:
You are sending a message to an object that cannot validly respond to it. The stack trace is telling you that when you make the call [PaymillPaymentService handleTransactionListRequest:] that PaymillPaymentService cannot accept handleTransactionListRequest.
Long answer:
Look at the stack trace here:
5 Control 0x10005acb4 -[PaymillPaymentService handleTransactionListRequest:] (PaymillPaymentService.m:211)
This is telling you that in the file PaymillPaymentService.m on line 211 you are sending PaymillPaymentService the message handleTransactionListRequest to which it cannot validly respond. In your discussion with rmaddy, Hot Licks, and Paulc11 you mentioned that line 211 is the function entry for handleTransactionListRequest (in whatever file it resides). If that's the case it is coincidental.
If you want further follow up you need to post PaymillPaymentService.m and ensure that you include all the line numbers.
The crash log is below.
Do you know any particular reason why might [UIScrollView removeFromSuperview] can crash? The scrollview contains view hierarchy with different types of UIViews. I also finds that the ad hoc version crash often not the debug version. I could not find any reason for that.
Same viewcontroller is loaded in a different flow in iPhone that works fine. But in iPad it crashes.
In iPad, in a container view controller, only viewcontroler.view is loaded.
Incident Identifier: EE102239-34D1-4BE7-8B52-41F74AB26203
CrashReporter Key: 2b11ea2a01ac5618e199ffc5a1e1f321600bb6a9
Hardware Model: iPad3,4
Version: ??? (???)
Code Type: ARM (Native)
Parent Process: launchd [1]
Date/Time: 2013-06-18 15:19:16.132 +0200
OS Version: iOS 6.1.3 (10B329)
Report Version: 104
Exception Type: EXC_BAD_ACCESS (SIGSEGV)
Exception Codes: KERN_INVALID_ADDRESS at 0x00000000
Crashed Thread: 0
Thread 0 name: Dispatch queue: com.apple.main-thread
Thread 0 Crashed:
0 libobjc.A.dylib 0x3bab7070 prepareForMethodLookup + 20
1 libobjc.A.dylib 0x3bab6fb2 lookUpMethod + 42
2 libobjc.A.dylib 0x3bab6f7e _class_lookupMethodAndLoadCache3 + 14
3 libobjc.A.dylib 0x3bab6638 objc_msgSend_uncached + 24
4 QuartzCore 0x357f2a72 CA::Layer::contents_visibility_changed(CA::Transaction*, bool) + 50
5 QuartzCore 0x357f29de CA::Layer::mark_visible(CA::Transaction*, bool) + 190
6 QuartzCore 0x357f29b2 CA::Layer::mark_visible(CA::Transaction*, bool) + 146
7 QuartzCore 0x357f29b2 CA::Layer::mark_visible(CA::Transaction*, bool) + 146
8 QuartzCore 0x357f29b2 CA::Layer::mark_visible(CA::Transaction*, bool) + 146
9 QuartzCore 0x357f29b2 CA::Layer::mark_visible(CA::Transaction*, bool) + 146
10 QuartzCore 0x357f28d2 CA::Layer::update_removed_sublayer(CA::Transaction*, unsigned int) + 18
11 QuartzCore 0x357f255a CA::Layer::remove_sublayer(CA::Transaction*, CALayer*) + 130
12 QuartzCore 0x357f246a CA::Layer::remove_from_superlayer() + 34
13 UIKit 0x35a6e92c -[UIView(Hierarchy) removeFromSuperview] + 144
14 UIKit 0x35b857bc -[UIScrollView removeFromSuperview] + 60
15 MyApp 0x000bde8a -[iPadNavigationController vcAnimationDone] (iPadNavigationController.m:400)
16 UIKit 0x35a55ab6 -[UIViewAnimationState sendDelegateAnimationDidStop:finished:] + 154
17 UIKit 0x35aca8f8 -[UIViewAnimationState animationDidStop:finished:] + 44
18 QuartzCore 0x35801304 CA::Layer::run_animation_callbacks(void*) + 204
19 libdispatch.dylib 0x3bed55d8 _dispatch_client_callout + 20
20 libdispatch.dylib 0x3bed8e40 _dispatch_main_queue_callback_4CF + 224
21 CoreFoundation 0x33c051ac __CFRunLoopRun + 1284
22 CoreFoundation 0x33b78238 CFRunLoopRunSpecific + 352
23 CoreFoundation 0x33b780c4 CFRunLoopRunInMode + 100
24 GraphicsServices 0x37733336 GSEventRunModal + 70
25 UIKit 0x35a942b4 UIApplicationMain + 1116
A few line from the code (as asked),
previous = showing;
showing = [ vc retain ];
showing.view.frame = startFrameIn;
[ container addSubview:showing.view ];
CGContextRef context = UIGraphicsGetCurrentContext();
[ UIView beginAnimations:nil context:context ];
[ UIView setAnimationDelegate:self ];
[ UIView setAnimationDidStopSelector:#selector(vcAnimationDone) ];
[ UIView setAnimationCurve:UIViewAnimationCurveEaseOut ];
[ UIView setAnimationDuration:0.4 ];
previous.view.frame = endFrameOut;
showing.view.frame = detailFrame;
[ UIView commitAnimations ];
}
- (void) vcAnimationDone {
if ( previous != nil ) {
if (previous.view.superview != nil) {
[previous.view removeFromSuperview];
}
[ previous release ];
previous = nil;
}
A very probable reason is that you are overreleasing your scrollview or one of the views inside it.
Calling removeFromSuperview then deallocates the view instead of simply decreasing the retain count.
Actually, if you are still stuck with non-ARC project, Static Code Analysis is very useful for this kind of bug. Retain/release balancing issues are hard to pin down, and nearly impossible with incomplete method so I suggest you post the full method body if possible.
Thanks everyone for your answers, tips and tricks. However one thing I want share with you is the cause of the crash. I found that the crash was at different thread in different times. I had several views loaded with button pressing/menu in my iPad app. Some of the button pressing fetch data from web service. So I was bit confused to get the cuase of crash, animation, or url connection etc... I tried with enabled NSZombie objects, but it did not show any information.
Then I tried with Guard Malloc. This only runs in Simulator. And magically I found the code point of crash. I have function to convert a hex string into data. There I have line of code to make a C string null terminated. where I assigned 0 at the last index. and that makes the crash!
tmpCh[count] = 0;
I do not why, but probably it takes some time in the memory management procedure in iOS so it crash at different thread at different times. But with Guard malloc in Simulator, it always point out here and when I rewrite the code, the crash is gone.
/* Converts a hex string to bytes.
Precondition:
. The hex string can be separated by space or not.
. the string length without space or 0x, must be even. 2 symbols for one byte/char
. sample input: 23 3A F1 OR 233AF1
*/
+ (NSData *) dataFromHexString:(NSString*)hexString
{
if (hexString.length < 1) {
return nil;
}
char * tmpCh = (char *) malloc([hexString length] * sizeof(char));
int count = 0;
for (int k=0; k<hexString.length;k++) {
char c = [hexString characterAtIndex:k];
if (c == (char)0x20) { //skip space
continue;
}
if (c == '0') { // skip 0x
if(k+1 < hexString.length){
if ([hexString characterAtIndex:k+1] == 'x'
|| [hexString characterAtIndex:k+1] == 'X' )
{
k = k + 1;
continue;
}
}
}
tmpCh[count] = c;
count++;
}
tmpCh[count] = 0; // make null terminated string
if (count % 2) {
return nil;
}
NSString *temp = [[NSString alloc] initWithUTF8String:tmpCh];
free(tmpCh);
if ([temp length] % 2 != 0) {
return nil;
}
NSMutableData *result = [[NSMutableData alloc] init];
unsigned char byte;
char hexChars[3] = {0};
for (int i=0; i < (temp.length/2); i++) {
hexChars[0] = [temp characterAtIndex:i*2];
hexChars[1] = [temp characterAtIndex:i*2+1];
if (![Util isValidChar:hexChars[0]] || ![Util isValidChar:hexChars[1]]) {
return nil;
}
byte = strtol(hexChars, NULL, 16);
[result appendBytes:&byte length:1];
}
NSData * data = [NSData dataWithData:result];
[result release];
return data;
}