This bug was found by Chris Siebenmann. Here is a detailed post about it: https://utcc.utoronto.ca/~cks/space/blog/sysadmin/TarFindingTruncateBug
I did not find this bug, I am just reporting it. Steps to reproduce: - create a large sparse file - start tar so that it archives the file - while it works on the file, use ftruncate() to reduce file size. - tar continues running forever generating infinite output Probable location of the bug: sparse_dump_region() function in sparse.c
