Background execution + pagination aborts readline/gdb
authorPedro Alves <palves@redhat.com>
Mon, 14 Jul 2014 18:55:32 +0000 (19:55 +0100)
committerPedro Alves <palves@redhat.com>
Mon, 14 Jul 2014 19:32:13 +0000 (20:32 +0100)
commit0017922d0292d8c374584f6100874580659c9973
tree9c1351f0579064eba450871f0f7555e53ccc6b34
parent94696ad31c3fac4a3bc17391e42362d83be1fb56
Background execution + pagination aborts readline/gdb

If pagination occurs as result of output sent as response to a target
event while the target is executing in the background, subsequent
input aborts readline/gdb:

 $ gdb program
 ...
 (gdb) continue&
 Continuing.
 (gdb)
 ---Type <return> to continue, or q <return> to quit---
 *return*
 ---Type <return> to continue, or q <return> to quit---
 Breakpoint 2, after_sleep () at paginate-bg-execution.c:21
 ---Type <return> to continue, or q <return> to quit---
 21        return; /* after sleep */
 p 1
 readline: readline_callback_read_char() called with no handler!
 *abort/SIGABRT*
 $

gdb_readline_wrapper_line removes the handler after a line is
processed.  Usually, we'll end up re-displaying the prompt, and that
reinstalls the handler.  But if the output is coming out of handling
a stop event, we don't re-display the prompt, and nothing restores the
handler.  So the next input wakes up the event loop and calls into
readline, which aborts.

We should do better with the prompt handling while the target is
running (I think we should coordinate with readline, and
hide/redisplay it around output), but that's a more invasive change
better done post 7.8, so this patch is conservative and just
reinstalls the handler as soon as we're out of the readline line
callback.

gdb/
2014-07-14  Pedro Alves  <palves@redhat.com>

PR gdb/17072
* top.c (gdb_readline_wrapper_line): Tweak comment.
(gdb_readline_wrapper_cleanup): If readline is enabled, reinstall
the input handler callback.

gdb/testsuite/
2014-07-14  Pedro Alves  <palves@redhat.com>

PR gdb/17072
* gdb.base/paginate-bg-execution.c: New file.
* gdb.base/paginate-bg-execution.exp: New file.
gdb/ChangeLog
gdb/testsuite/ChangeLog
gdb/testsuite/gdb.base/paginate-bg-execution.c [new file with mode: 0644]
gdb/testsuite/gdb.base/paginate-bg-execution.exp [new file with mode: 0644]
gdb/top.c