PDS3 reader - trouble with long label arrays

[thare]

Looks like a change to the PVL parser nasakeywordhandler.cpp may have introduced a problem with some PDS3 labels. It doesn't appear to be line length issue but a keyword array length issue.

The example header MI_MAP_02_S77E077S78E078SC_OriginalHeader.img (detached from the image to keep it small), will be successfully read using GDAL 2.1.x and lower (gdalinfo). However in 2.2.0 and 2.2.1 it will fail to read.

The example header MI_MAP_02_S77E077S78E078SC_HeaderLinesStripped.img has been stripped of the now offending array keywords so that GDAL 2.2.x works again.

The *.diff file just shows the offending header lines which are now breaking the 2.2.x support.

I tried to nail down the problem by scouring the pdsdataset.cpp and nasakeywordhandler.cpp but I don't see the impacting change...? ​https://trac.osgeo.org/gdal/changeset?old_path=%2Ftags%2F2.1.4%2Fgdal%2Ffrmts%2Fpds%2Fnasakeywordhandler.cpp&old=39612&new_path=%2Ftags%2F2.2.1%2Fgdal%2Ffrmts%2Fpds%2Fnasakeywordhandler.cpp&new=39612

I am hoping 2.2.x can be fixed to again support MI_MAP_02_S77E077S78E078SC_OriginalHeader.img

thanks - Trent

[thare]

header which no longer has support as of 2.2.x

[thare]

Header with lines remove to get back 2.2.x support

[thare]

Difference of the two headers to show the lines

[Even Rouault]

In 39616:

PDS: fix parsing of labels with nested list constructs (fixes #6970)

[Even Rouault]

In 39617:

PDS: fix parsing of labels with nested list constructs (fixes #6970)

[Even Rouault]

Thanks for the initial analysis. That helped narrowing things. I've added a new test case to avoid future regression on such constructs.