On 11/06/2021 17.59, Jia He wrote:

After the behaviour of specifier '%pD' is changed to print full path
of struct file, the related test cases are also updated.

Given the string is prepended from the end of the buffer, the check
of "wrote beyond the nul-terminator" should be skipped.

Sorry, that is far from enough justification.

I should probably have split the "wrote beyond nul-terminator" check in two:

One that checks whether any memory beyond the buffer given to
vsnprintf() was touched (including all the padding, but possibly more
for the cases where we pass a known-too-short buffer), symmetric to the
"wrote before buffer" check.

And then another that checks the area between the '\0' and the end of
the given buffer - I suppose that it's fair game for vsnprintf to use
all of that as scratch space, and for that it could be ok to add that
boolean knob.

Rasmus