NSData data corrupts if destroy source NSData

Originator:aironik
Number:rdar://14175384 Date Originated:2013-03-17
Status: Resolved:
Product:iOS SDK Product Version:7.0 beta 1
Classification:Serious Bug Reproducible:
 
Summary: -[NSData data] bytes value changes if source NSData object destroys.

Steps to Reproduce:

__strong NSData *dataRes = nil;
@autoreleasepool {
    // Create NSData:
    NSString *string = @"Some Data";
    NSData *data = [string dataUsingEncoding:NSUTF8StringEncoding];
    // data contains <536f6d65 20446174 61>

    // create new NSData object without copy
    NSData *data2 = [NSData dataWithBytesNoCopy:data.bytes length:[data length] freeWhenDone:NO];
    // data2 contains <536f6d65 20446174 61>

    // copy data object
    dataRes = [data2 copy]; // same result for dataRes = [NSData dataWithData:data2];
    // dataRes contains <536f6d65 20446174 61>
} // destroy source data object
// here dataRes contains other data e.g. <00000090 97868e20 61>

Expected Results:
data doesn't change value. For above example <536f6d65 20446174 61>

Actual Results:
data changes bytes value.

Regression:
occurs iOS7 beta 1

Notes:

Comments

Will probably be closed as behaves correctly

While I'm not sure about -copy, +dataWithData: is definitely a shallow copy. CFDataCreateCopy doesn't create a copy of the bytes if the source was immutable; I imagine NSData -copy doesn't either

By chaos42 at June 18, 2013, 7:05 p.m. (reply...)

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