Unpredictable segfault occurring during resizing of images for export
Chris Williams
I've been developing a plugin for Aperture that resizes the exported images to a maximum longest edge of 1280px, before sending them off to an FTP server, and I've come across an unusual segfault during the resizing phase.
Initially the segfault occured when processing a RAW (.RW2) image (although others had previously exported fine).
Thinking the problem was due to RAW image files in particular, I removed them from my export list and then tried again. Again a segfault resulted when processing a JPG file.
Both errors seem to be related to CGColorSpace, and occur during a CGImageSourceCreateImageAtInde
It's not consistent when and where it happens, and has only been apparent on largish exports (400+) images and so my guess is that must be doing something wrong with memory management somewhere.
If anyone has a clue on what is happening here, or has seen this before, any help would be greatly appreciated!
Best regards,
Chris.
Stack trace on RAW file:
====================
Exception Type: EXC_BAD_ACCESS (SIGSEGV)
Exception Codes: 0x000000000000000d, 0x0000000000000000
Crashed Thread: 14
<snip>
Thread 14 Crashed:
0 com.apple.CoreGraphics 0x00007fff868cc88a CGColorSpaceGetType + 18
1 com.apple.ImageIO.framework 0x00007fff88f12936 CGImagePlusSetGeometry + 564
2 com.apple.ImageIO.framework 0x00007fff88f126e7 CGImagePluginSetImageBlockProc + 168
3 com.apple.RawCamera.bundle 0x00007fff83d371b4 GetRawPluginsInfo + 138788
4 com.apple.RawCamera.bundle 0x00007fff83d386a1 GetRawPluginsInfo + 144145
5 com.apple.RawCamera.bundle 0x00007fff83d3e6f9 GetRawPluginsInfo + 168809
6 com.apple.RawCamera.bundle 0x00007fff83d35557 GetRawPluginsInfo + 131527
7 com.apple.ImageIO.framework 0x00007fff88f10124 makeImagePlus + 511
8 com.apple.ImageIO.framework 0x00007fff88f145ec CGImageSourceCreateImageAtIndex + 216
9 ...taproofs.export.Instaproofs 0x0000000125559b64 -[Instaproofs exportManagerShouldWriteImageData:toRelativePath:forImageAtIndex:] + 163
10 com.apple.Aperture 0x000000010059c257 0x100000000 + 5882455
11 com.apple.Aperture 0x000000010021574b 0x100000000 + 2185035
12 com.apple.proxtcore 0x00000001015c3328 0x1015be000 + 21288
13 com.apple.proxtcore 0x00000001015c2c70 0x1015be000 + 19568
14 com.apple.proxtcore 0x00000001015c1726 0x1015be000 + 14118
15 com.apple.Foundation 0x00007fff8473c0a5 __NSThread__main__ + 1429
16 libSystem.B.dylib 0x00007fff85328536 _pthread_start + 331
17 libSystem.B.dylib 0x00007fff853283e9 thread_start + 13
Stack trace on JPG file
=========================================================
Exception Type: EXC_BAD_ACCESS (SIGSEGV)
Exception Codes: KERN_INVALID_ADDRESS at 0x00000000850ff685
Crashed Thread: 14
Application Specific Information:
objc_msgSend() selector name: retain
<snip>
Thread 14 Crashed:
0 libobjc.A.dylib 0x934b6eec objc_msgSend + 44
1 com.apple.CoreGraphics 0x920ab2f7 CGColorSpaceRetain + 22
2 com.apple.CoreGraphics 0x920aae42 CGColorSpaceCreateWithIndex + 762
3 com.apple.ImageIO.framework 0x92ea8a41 initImageJPEG + 4982
4 com.apple.ImageIO.framework 0x92ea76c1 _CGImagePluginInitJPEG + 69
5 com.apple.ImageIO.framework 0x92e8f6fd makeImagePlus + 715
6 com.apple.ImageIO.framework 0x92e95c0a CGImageSourceCreateImageAtIndex + 176
7 ...taproofs.export.Instaproofs 0x1f54cff8 -[Instaproofs exportManagerShouldWriteImageData:toRelativePath:forImageAtIndex:] + 167
8 com.apple.Aperture 0x00554a92 0x1000 + 5585554
9 com.apple.Aperture 0x001f7002 0x1000 + 2056194
10 com.apple.proxtcore 0x0125e5b3 0x1258000 + 26035
11 com.apple.proxtcore 0x0125ddb6 0x1258000 + 23990
12 com.apple.proxtcore 0x0125d831 0x1258000 + 22577
13 com.apple.proxtcore 0x0125bf46 0x1258000 + 16198
14 com.apple.Foundation 0x909d6bf0 -[NSThread main] + 45
15 com.apple.Foundation 0x909d6ba0 __NSThread__main__ + 1499
16 libSystem.B.dylib 0x95be285d _pthread_start + 345
17 libSystem.B.dylib 0x95be26e2 thread_start + 34
Chris Williams
- (BOOL)exportManagerShouldWriteImageData:(NSData *)imageData
toRelativePath:(NSString *)path forImageAtIndex:(unsigned)index
{
NSUInteger width, height;
NSUInteger longestEdge;
double scaleFactor;
BOOL longestEdgeIsWidth;
NSString *resizedImagePath = [path copy];
NSLog(@"Examining: %@", resizedImagePath);
CGImageRef resizedImageRef = NULL;
CFURLRef baseURLRef =
CFURLCreateWithFileSystemPath(kCFAllocatorDefault,
(CFStringRef)_exportPath, kCFURLPOSIXPathStyle, true);
// Create our full size CGImage from the provided data
CGImageSourceRef imageSourceRef =
CGImageSourceCreateWithData((CFDataRef)imageData, NULL);
if (imageSourceRef != NULL) {
CGImageRef fullSizeImageRef =
CGImageSourceCreateImageAtIndex(imageSourceRef, 0, NULL);
CFRelease(imageSourceRef);
CGContextRef context = NULL;
width = CGImageGetWidth(fullSizeImageRef);
height = CGImageGetHeight(fullSizeImageRef);
if (width > height) {
longestEdge = width;
longestEdgeIsWidth = YES;
}
else {
longestEdge = height;
longestEdgeIsWidth=NO;
}
if (longestEdge >1280) {
NSLog(@" and resizing....");
scaleFactor = 1280.0/longestEdge;
NSUInteger newWidth = round(width*scaleFactor);
NSUInteger newHeight = round(height*scaleFactor);
CGColorSpaceRef colorspace = CGImageGetColorSpace(fullSizeImageRef);
void * bitmapData;
int bitmapBytesPerRow = (newWidth * 4);
int bitmapByteCount = (bitmapBytesPerRow * newHeight);
bitmapData = malloc( bitmapByteCount );
context = CGBitmapContextCreate(bitmapData, newWidth,
newHeight, 8,bitmapBytesPerRow, colorspace,
kCGImageAlphaNoneSkipFirst);
CGContextDrawImage(context, CGRectMake(0, 0, newWidth,
newHeight), fullSizeImageRef);
resizedImageRef= CGBitmapContextCreateImage(context);
CFRelease(fullSizeImageRef);
CFRelease(colorspace);
CFRelease(context);
free(bitmapData);
}
else {
//Image is within requirements, simply use a copy.
resizedImageRef = CGImageCreateCopy(fullSizeImageRef);
CFRelease(fullSizeImageRef);
}
resizedImagePath = [resizedImagePath stringByDeletingPathExtension];
resizedImagePath = [resizedImagePath stringByAppendingPathExtension:@"jpg"];
NSDictionary* image_dict = [_exportManager propertiesForImageAtIndex:index];
NSString* project_name = [[image_dict
objectForKey:kExportKeyProjectName] retain];
CFURLRef resizedFileURLRef =
CFURLCreateWithFileSystemPathRelativeToBase(kCFAllocatorDefault,
(CFStringRef)resizedImagePath, kCFURLPOSIXPathStyle, false,
baseURLRef);
CGImageDestinationRef imageDestinationRef =
CGImageDestinationCreateWithURL(resizedFileURLRef, kUTTypeJPEG, 1,
NULL);
NSMutableDictionary *imageProperties = [[NSMutableDictionary alloc] init];
[imageProperties setObject:[NSNumber numberWithInt:1]
forKey:(NSString *)kCGImageDestinationLossyCompressionQuality];
CGImageDestinationAddImage(imageDestinationRef, resizedImageRef,
(CFDictionaryRef) imageProperties);
CGImageDestinationFinalize(imageDestinationRef);
CFRelease(imageDestinationRef);
[imageProperties release];
CFRelease(resizedImageRef);
NSNumber *fileSize = [self sizeOfFileAtPath:(NSURL*) resizedFileURLRef];
NSString* fileRefString = [self fileSystemStringOfPath:(NSURL
*)resizedFileURLRef];
CFRelease(resizedFileURLRef);
CFRelease(baseURLRef);
totalBytes += [fileSize longValue];
// Increment the current progress
[self lockProgress];
exportProgress.currentValue++;
[self unlockProgress];}
return NO;
}
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Clarence Locke
The CGImageGetColorSpace() function does not follow the Create Rule <http://developer.apple.com/library/mac/#documentation/CoreFoundation/Conceptual/CFMemoryMgmt/Concepts/Ownership.html>, so you should _not_ be calling CFRelease(colorSpace) — you've over-released the object.
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Chris Williams
You're a lifesaver :) Thank you so much! That seems to have fixed it.
Best regards,
Chris.