The My iPad application encounters a message EXC_BAD_ACCESSin a call in the CGPDFContextClosefollowing way. This happens only for certain pages, and only for one document so far (unfortunately, this is our help document).
- (CGPDFDocumentRef)newSinglePageDocumentFromDocument:(CGPDFDocumentRef)document page:(NSInteger)pageNumber
{
CGPDFDocumentRef sourceDocument = CGPDFDocumentRetain(document);
CGPDFDocumentRef newDocument = NULL;
CFMutableDataRef consumerData = CFDataCreateMutable(kCFAllocatorDefault, 0);
CGDataConsumerRef contextConsumer = CGDataConsumerCreateWithCFData(consumerData);
CGPDFPageRef page = CGPDFDocumentGetPage(sourceDocument, pageNumber);
const CGRect mediaBox = CGPDFPageGetBoxRect(page, kCGPDFCropBox);
CGContextRef ctx = CGPDFContextCreate(contextConsumer, &mediaBox, NULL);
if (ctx)
{
if (page)
{
CGPDFContextBeginPage(ctx, NULL);
CGContextDrawPDFPage(ctx, page);
CGPDFContextEndPage(ctx);
}
CGPDFContextClose(ctx);
CGContextRelease(ctx);
CGDataProviderRef provider = CGDataProviderCreateWithCFData((CFDataRef)consumerData);
newDocument = CGPDFDocumentCreateWithProvider(provider);
CGDataProviderRelease(provider);
}
CGDataConsumerRelease(contextConsumer);
CFRelease(consumerData);
CGPDFDocumentRelease(sourceDocument);
return newDocument;
}
A document that cannot be opened can be opened by Preview on Mac. I cannot visually identify something different between pages that fail and those that succeed.
Can anyone see what is wrong with the code, or suggestions to solve the problem?
EDIT: EXC_BAD_ACCESS is thrown inside the CGPDFContextClose method, see below:
0x00e93d0e <+0000> push %ebp
0x00e93d0f <+0001> mov %esp,%ebp
0x00e93d11 <+0003> sub $0x18,%esp
0x00e93d14 <+0006> call 0xe93d19 <CGPDFContextClose+11>
0x00e93d19 <+0011> pop %eax
0x00e93d1a <+0012> mov 0x8(%ebp),%ecx
0x00e93d1d <+0015> test %ecx,%ecx
0x00e93d1f <+0017> je 0xe93d30 <CGPDFContextClose+34>
0x00e93d21 <+0019> cmpl $0x43545854,0x8(%ecx)
0x00e93d28 <+0026> jne 0xe93d30 <CGPDFContextClose+34>
0x00e93d2a <+0028> cmpl $0x1,0x10(%ecx)
0x00e93d2e <+0032> je 0xe93d4e <CGPDFContextClose+64>
0x00e93d30 <+0034> mov %ecx,0x8(%esp)
0x00e93d34 <+0038> lea 0xc393b(%eax),%ecx
0x00e93d3a <+0044> mov %ecx,0x4(%esp)
0x00e93d3e <+0048> lea 0xad9eb(%eax),%ecx
0x00e93d44 <+0054> mov %ecx,(%esp)
0x00e93d47 <+0057> call 0xe7176c <CGPostError>
0x00e93d4c <+0062> jmp 0xe93d59 <CGPDFContextClose+75>
0x00e93d4e <+0064> mov 0x18(%ecx),%eax
0x00e93d51 <+0067> mov %eax,(%esp)
0x00e93d54 <+0070> call 0xdb25af <CGContextDelegateFinalize>
0x00e93d59 <+0075> add $0x18,%esp //EXC_BAD_ACCESS thrown here
0x00e93d5c <+0078> pop %ebp
0x00e93d5d <+0079> ret