[PATCH] Don't truncate the history file when history size is unlimited

[Pedro Alves]

On 06/09/2015 08:27 PM, Patrick Palka wrote:
> We still do not handle "set history size unlimited" correctly.  In
> particular, after writing to the history file, we truncate the history
> even if it is unlimited.

Whoops.

> 
> This patch makes sure that we do not call history_truncate_file() if the
> history is not stifled (i.e. if it's unlimited).  This bug causes the
> history file to be truncated to zero on exit when one has "set history
> size unlimited" in their gdbinit file.  Although this code exists in GDB
> 7.8 it is masked by a pre-existing bug that's been only fixed in GDB 7.9
> (PR gdb/17820).
> 
> I tried to make a test to check that the history does not get truncated
> on exit when the history size is unlimited, but I could not get the test
> to work properly.

How so?

> Also I could not figure out a good way to create a
> temporary file (to act as the history file) in tcl versions earlier than
> 8.6.  I am not sure if it's worth the effort to add a test.

Not sure I follow.  Why do you need a temporary file?
You can leave the file in the build/test dir.  In fact, that's
encouraged, to make it easier to debug the test on failures.
You can instead delete a stale file from a previous run at the
start of the (new) run.

> (Apparently I did not test my changes to history file handling
> extensively enough.  Sorry..)

Don't stress about it.  But, it does show out that having a test
would be useful.  So I think it's worth the effort.

The code changes look OK to me.

Thanks,
Pedro Alves