[knc1]

Looking good so far (output when run by Q.A. script):

Spoiler:

both full blocks, test: c-w/r/c
Termination on block boundary.
Blocks: 3, plus Bytes: 0, Total skips: 0, Total bytes: 12288

both full blocks, test: c
Termination on block boundary.
Blocks: 3, plus Bytes: 0, Total skips: 3, Total bytes: 12288

both partial blocks, test: c-w/r/c
Termination on a partial block boundary
Blocks: 3, plus Bytes: 2048, Total skips: 0, Total bytes: 14336

both partial blocks, test: c
Termination with a partial block
Blocks: 3, plus Bytes: 2048, Total skips: 4, Total bytes: 14336

Following are Warnings because they might be intended usage
That is: Changing only an initial portion of the destination

both full blocks, *.src < *.dst, test: c-w/r/c
Warning: Early EOF on test03.src
Blocks: 2, plus Bytes: 0, Total skips: 0, Total bytes: 8192

both full blocks, *.src < *.dst, test: c
Warning: Early EOF on test03.src
Blocks: 2, plus Bytes: 0, Total skips: 2, Total bytes: 8192

both partial blocks, *.src < *.dst, test: c-w/r/c
Warning: Early EOF on test04.src, common bytes: w/r/c
Blocks: 2, plus Bytes: 2048, Total skips: 0, Total bytes: 10240

both partial blocks, *.src < *.dst, test: c
Warning: Early EOF on test04.src, common bytes: match
Blocks: 2, plus Bytes: 2048, Total skips: 3, Total bytes: 10240

Still need to test error paths, but should be done today.

Edit: Of course, it was a bigger job than just that due to think'os along the way.
**should**