From 20f0d60db4fb5083779c4c9182bbc692f7d2bac5 Mon Sep 17 00:00:00 2001 From: Tom Tromey Date: Fri, 5 Oct 2018 14:54:35 -0600 Subject: [PATCH] Avoid crash when calling warning too early I noticed that if you pass the name of an existing file (not a directory) as the argument to --data-directory, gdb will crash: $ ./gdb -nx --data-directory ./gdb ../../binutils-gdb/gdb/target.c:590:56: runtime error: member call on null pointer of type 'struct target_ops' This was later reported as PR gdb/23838. This happens because warning ends up calling target_supports_terminal_ours, which calls current_top_target, which returns nullptr this early. This fixes the problem by handling this case specially in target_supports_terminal_ours. I also changed target_supports_terminal_ours to return bool. gdb/ChangeLog 2018-11-08 Tom Tromey PR gdb/23555: PR gdb/23838: * target.h (target_supports_terminal_ours): Return bool. * target.c (target_supports_terminal_ours): Handle case where current_top_target returns nullptr. Return bool. gdb/testsuite/ChangeLog 2018-11-08 Tom Tromey PR gdb/23555: PR gdb/23838: * gdb.base/warning.exp: New file. --- gdb/ChangeLog | 8 +++++++ gdb/target.c | 10 +++++++-- gdb/target.h | 2 +- gdb/testsuite/ChangeLog | 6 +++++ gdb/testsuite/gdb.base/warning.exp | 36 ++++++++++++++++++++++++++++++ 5 files changed, 59 insertions(+), 3 deletions(-) create mode 100644 gdb/testsuite/gdb.base/warning.exp diff --git a/gdb/ChangeLog b/gdb/ChangeLog index be1b3d8c7ef..3a4db38e05e 100644 --- a/gdb/ChangeLog +++ b/gdb/ChangeLog @@ -1,3 +1,11 @@ +2018-11-08 Tom Tromey + + PR gdb/23555: + PR gdb/23838: + * target.h (target_supports_terminal_ours): Return bool. + * target.c (target_supports_terminal_ours): Handle case where + current_top_target returns nullptr. Return bool. + 2018-11-08 Joel Brobecker * aarch64-tdep.c (aapcs_is_vfp_call_or_return_candidate_1): diff --git a/gdb/target.c b/gdb/target.c index 2d98954b54a..9404025104f 100644 --- a/gdb/target.c +++ b/gdb/target.c @@ -584,10 +584,16 @@ target_terminal::info (const char *arg, int from_tty) /* See target.h. */ -int +bool target_supports_terminal_ours (void) { - return current_top_target ()->supports_terminal_ours (); + /* This can be called before there is any target, so we must check + for nullptr here. */ + target_ops *top = current_top_target (); + + if (top == nullptr) + return false; + return top->supports_terminal_ours (); } static void diff --git a/gdb/target.h b/gdb/target.h index a3000c80c64..6f4b73bf009 100644 --- a/gdb/target.h +++ b/gdb/target.h @@ -1577,7 +1577,7 @@ extern int target_remove_breakpoint (struct gdbarch *gdbarch, /* Return true if the target stack has a non-default "terminal_ours" method. */ -extern int target_supports_terminal_ours (void); +extern bool target_supports_terminal_ours (void); /* Kill the inferior process. Make it go away. */ diff --git a/gdb/testsuite/ChangeLog b/gdb/testsuite/ChangeLog index e0bb8382aa9..a0e614fbde0 100644 --- a/gdb/testsuite/ChangeLog +++ b/gdb/testsuite/ChangeLog @@ -1,3 +1,9 @@ +2018-11-08 Tom Tromey + + PR gdb/23555: + PR gdb/23838: + * gdb.base/warning.exp: New file. + 2018-11-08 Jan Beulich * testsuite/gdb.arch/i386-avx512.c, diff --git a/gdb/testsuite/gdb.base/warning.exp b/gdb/testsuite/gdb.base/warning.exp new file mode 100644 index 00000000000..53067f48d5c --- /dev/null +++ b/gdb/testsuite/gdb.base/warning.exp @@ -0,0 +1,36 @@ +# Copyright 2018 Free Software Foundation, Inc. + +# This program is free software; you can redistribute it and/or modify +# it under the terms of the GNU General Public License as published by +# the Free Software Foundation; either version 3 of the License, or +# (at your option) any later version. +# +# This program is distributed in the hope that it will be useful, +# but WITHOUT ANY WARRANTY; without even the implied warranty of +# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the +# GNU General Public License for more details. +# +# You should have received a copy of the GNU General Public License +# along with this program. If not, see . + +# Test that an early warning does not cause a crash. + +if {[is_remote host]} { + unsupported "warning.exp can only run on local host" + return +} + +set tname [standard_temp_file warning] +set fd [open $tname w] +puts $fd "anything" +close $fd + +set save $INTERNAL_GDBFLAGS +set INTERNAL_GDBFLAGS "-nw -nx -data-directory $tname" + +gdb_start + +# Make sure gdb started up. +gdb_test "echo 23\\n" "23" + +set INTERNAL_GDBFLAGS $save -- 2.30.2