Setting single value in the string with VM > 1 results in an incorrect string

[Oleh]

Hi,

I've recently encountered DCMTK behavior that looks like a bug to me, and I can't find similar threads or existing tickets.

Scenario:
* Start with any valid DICOM data set
* Add element 0020, 0032 - Image Position (VR: Decimal string, VM - 3). For example set it to "-1\-2\-3" (padding is ommited)
* Try to replace only middle value - either by calling putOFStringAtPos("2", 1) or via similar call to the putFloat64

Expected result: value is changed to the "-1\2\-3"
actual: value is "1\2-3"

Note: similar issue happens with other tags, like 0020,0037 for the intermediate positions
Looking at the sources of DCMTK, I think the problem is in the

Code: Select all

OFCondition DcmByteString::putOFStringAtPos

implementation

in the very end, it contains:

Code: Select all

       else
        {
            str = str.replace(leftPos+1, rightPos - leftPos, stringVal);
        }

which is called for such intermediate replacements.

but the second parameter should be rightPos - leftPos - 1, otherwise it overwrites characted at the rightPos, which is the next backslash.

[Michael Onken]

This simply looks like a bug, we are looking into it. Thank you for reporting!

BR Michael

[Michael Onken]

Hi,

your report and patch have been correct, thanks again

I submitted a patch along with some test code to the DCMTK repository which will be available on the public mirrors within the next days.

BR Michael

[Oleh]

Perfect,

Thank you!

[J. Riesmeier]

Here it is.