gdb's (or gdbserver's) own signal handling should not interfere with
the signal dispositions their spawned children inherit. However, it
currently does. For example, some paths in gdb cause SIGPIPE to be
set to SIG_IGN, and as consequence, the child starts with SIGPIPE to
set to SIG_IGN too, even though gdb was started with SIGPIPE set to
SIG_DFL.
This is because the exec family of functions does not reset the signal
disposition of signals that are set to SIG_IGN:
http://pubs.opengroup.org/onlinepubs/
7908799/xsh/execve.html
Signals set to the default action (SIG_DFL) in the calling process
image are set to the default action in the new process
image. Signals set to be ignored (SIG_IGN) by the calling process
image are set to be ignored by the new process image. Signals set to
be caught by the calling process image are set to the default action
in the new process image (see <signal.h>).
And neither does it reset signal masks or flags.
In order to be transparent, when spawning new child processes to debug
(with "run", etc.), reset signal actions and mask back to what was
originally inherited from gdb/gdbserver's parent, just before execing
the target program to debug.
gdb/ChangeLog:
2016-08-09 Pedro Alves <palves@redhat.com>
PR gdb/18653
* Makefile.in (SFILES): Add
common/signals-state-save-restore.c.
(HFILES_NO_SRCDIR): Add common/signals-state-save-restore.h.
(COMMON_OBS): Add signals-state-save-restore.o.
(signals-state-save-restore.o): New rule.
* configure: Regenerate.
* fork-child.c: Include "signals-state-save-restore.h".
(fork_inferior): Call restore_original_signals_state.
* main.c: Include "signals-state-save-restore.h".
(captured_main): Call save_original_signals_state.
* common/common.m4: Add sigaction to AC_CHECK_FUNCS checks.
* common/signals-state-save-restore.c: New file.
* common/signals-state-save-restore.h: New file.
gdb/gdbserver/ChangeLog:
2016-08-09 Pedro Alves <palves@redhat.com>
PR gdb/18653
* Makefile.in (OBS): Add signals-state-save-restore.o.
(signals-state-save-restore.o): New rule.
* config.in: Regenerate.
* configure: Regenerate.
* linux-low.c: Include "signals-state-save-restore.h".
(linux_create_inferior): Call
restore_original_signals_state.
* server.c: Include "dispositions-save-restore.h".
(captured_main): Call save_original_signals_state.
gdb/testsuite/ChangeLog:
2016-08-09 Pedro Alves <palves@redhat.com>
PR gdb/18653
* gdb.base/signals-state-child.c: New file.
* gdb.base/signals-state-child.exp: New file.
* gdb.gdb/selftest.exp (do_steps_and_nexts): Add new pattern.
+2016-08-09 Pedro Alves <palves@redhat.com>
+
+ PR gdb/18653
+ * Makefile.in (SFILES): Add
+ common/signals-state-save-restore.c.
+ (HFILES_NO_SRCDIR): Add common/signals-state-save-restore.h.
+ (COMMON_OBS): Add signals-state-save-restore.o.
+ (signals-state-save-restore.o): New rule.
+ * configure: Regenerate.
+ * fork-child.c: Include "signals-state-save-restore.h".
+ (fork_inferior): Call restore_original_signals_state.
+ * main.c: Include "signals-state-save-restore.h".
+ (captured_main): Call save_original_signals_state.
+ * common/common.m4: Add sigaction to AC_CHECK_FUNCS checks.
+ * common/signals-state-save-restore.c: New file.
+ * common/signals-state-save-restore.h: New file.
+
2016-08-09 Pedro Alves <palves@redhat.com>
* value.c (unpack_value_bitfield): Skip unpacking if the parent
target/waitstatus.c common/print-utils.c common/rsp-low.c \
common/errors.c common/common-debug.c common/common-exceptions.c \
common/btrace-common.c common/fileio.c common/common-regcache.c \
+ common/signals-state-save-restore.c \
$(SUBDIR_GCC_COMPILE_SRCS)
LINTFILES = $(SFILES) $(YYFILES) $(CONFIG_SRCS) init.c
common/common-regcache.h fbsd-tdep.h nat/linux-personality.h \
common/fileio.h nat/x86-linux.h nat/x86-linux-dregs.h nat/amd64-linux-siginfo.h\
nat/linux-namespaces.h arch/arm.h common/gdb_sys_time.h arch/aarch64-insn.h \
-tid-parse.h ser-event.h
+tid-parse.h ser-event.h \
+common/signals-state-save-restore.h
# Header files that already have srcdir in them, or which are in objdir.
build-id.o buildsym.o \
findcmd.o \
std-regs.o \
+ signals-state-save-restore.o \
signals.o \
exec.o reverse.o \
bcache.o objfiles.o observer.o minsyms.o maint.o demangle.o \
$(COMPILE) $(srcdir)/common/common-regcache.c
$(POSTCOMPILE)
+signals-state-save-restore.o: $(srcdir)/common/signals-state-save-restore.c
+ $(COMPILE) $(srcdir)/common/signals-state-save-restore.c
+ $(POSTCOMPILE)
+
#
# gdb/target/ dependencies
#
sys/un.h sys/wait.h dnl
thread_db.h wait.h)
- AC_CHECK_FUNCS([fdwalk getrlimit pipe pipe2 socketpair])
+ AC_CHECK_FUNCS([fdwalk getrlimit pipe pipe2 socketpair sigaction])
AC_CHECK_DECLS([strerror, strstr])
--- /dev/null
+/* Copyright (C) 2016 Free Software Foundation, Inc.
+
+ This file is part of GDB.
+
+ 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 <http://www.gnu.org/licenses/>. */
+
+#include "common-defs.h"
+#include "signals-state-save-restore.h"
+
+#include <signal.h>
+
+/* The original signal actions and mask. */
+
+#ifdef HAVE_SIGACTION
+static struct sigaction original_signal_actions[NSIG];
+
+/* Note that we use sigprocmask without worrying about threads because
+ the save/restore functions are called either from main, or after a
+ fork. In both cases, we know the calling process is single
+ threaded. */
+static sigset_t original_signal_mask;
+#endif
+
+/* See signals-state-save-restore.h. */
+
+void
+save_original_signals_state (void)
+{
+#ifdef HAVE_SIGACTION
+ int i;
+ int res;
+
+ res = sigprocmask (0, NULL, &original_signal_mask);
+ if (res == -1)
+ perror_with_name ("sigprocmask");
+
+ for (i = 1; i < NSIG; i++)
+ {
+ struct sigaction *oldact = &original_signal_actions[i];
+
+ res = sigaction (i, NULL, oldact);
+ if (res == -1 && errno == EINVAL)
+ {
+ /* Some signal numbers in the range are invalid. */
+ continue;
+ }
+ else if (res == -1)
+ perror_with_name ("sigaction");
+
+ /* If we find a custom signal handler already installed, then
+ this function was called too late. */
+ if (oldact->sa_handler != SIG_DFL && oldact->sa_handler != SIG_IGN)
+ internal_error (__FILE__, __LINE__, _("unexpected signal handler"));
+ }
+#endif
+}
+
+/* See signals-state-save-restore.h. */
+
+void
+restore_original_signals_state (void)
+{
+#ifdef HAVE_SIGACTION
+ int i;
+ int res;
+
+ for (i = 1; i < NSIG; i++)
+ {
+ res = sigaction (i, &original_signal_actions[i], NULL);
+ if (res == -1 && errno == EINVAL)
+ {
+ /* Some signal numbers in the range are invalid. */
+ continue;
+ }
+ else if (res == -1)
+ perror_with_name ("sigaction");
+ }
+
+ res = sigprocmask (SIG_SETMASK, &original_signal_mask, NULL);
+ if (res == -1)
+ perror_with_name ("sigprocmask");
+#endif
+}
--- /dev/null
+/* Copyright (C) 2016 Free Software Foundation, Inc.
+
+ This file is part of GDB.
+
+ 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 <http://www.gnu.org/licenses/>. */
+
+#ifndef COMMON_SIGNALS_STATE_SAVE_RESTORE_H
+#define COMMON_SIGNALS_STATE_SAVE_RESTORE_H
+
+/* Save/restore the signal actions of all signals, and the signal
+ mask.
+
+ Since the exec family of functions does not reset the signal
+ disposition of signals set to SIG_IGN, nor does it reset the signal
+ mask, in order to be transparent, when spawning new child processes
+ to debug (with "run", etc.), we must reset signal actions and mask
+ back to what was originally inherited from gdb/gdbserver's parent,
+ just before execing the target program to debug. */
+
+/* Save the signal state of all signals. */
+
+extern void save_original_signals_state (void);
+
+/* Restore the signal state of all signals. */
+
+extern void restore_original_signals_state (void);
+
+#endif /* COMMON_SIGNALS_STATE_SAVE_RESTORE_H */
done
- for ac_func in fdwalk getrlimit pipe pipe2 socketpair
+ for ac_func in fdwalk getrlimit pipe pipe2 socketpair sigaction
do :
as_ac_var=`$as_echo "ac_cv_func_$ac_func" | $as_tr_sh`
ac_fn_c_check_func "$LINENO" "$ac_func" "$as_ac_var"
#include "solib.h"
#include "filestuff.h"
#include "top.h"
-
+#include "signals-state-save-restore.h"
#include <signal.h>
/* This just gets used as a default if we can't find SHELL. */
saying "not parent". Sorry; you'll have to use print
statements! */
+ restore_original_signals_state ();
+
/* There is no execlpe call, so we have to set the environment
for our child in the global variable. If we've vforked, this
clobbers the parent, but environ is restored a few lines down
+2016-08-09 Pedro Alves <palves@redhat.com>
+
+ PR gdb/18653
+ * Makefile.in (OBS): Add signals-state-save-restore.o.
+ (signals-state-save-restore.o): New rule.
+ * config.in: Regenerate.
+ * configure: Regenerate.
+ * linux-low.c: Include "signals-state-save-restore.h".
+ (linux_create_inferior): Call
+ restore_original_signals_state.
+ * server.c: Include "dispositions-save-restore.h".
+ (captured_main): Call save_original_signals_state.
+
2016-08-05 Pedro Alves <palves@redhat.com>
* configure: Regenerate.
common-utils.o ptid.o buffer.o format.o filestuff.o dll.o notif.o \
tdesc.o print-utils.o rsp-low.o errors.o common-debug.o cleanups.o \
common-exceptions.o symbol.o btrace-common.o fileio.o common-regcache.o \
+ signals-state-save-restore.o \
$(XML_BUILTIN) $(DEPFILES) $(LIBOBJS)
GDBREPLAY_OBS = gdbreplay.o version.o
GDBSERVER_LIBS = @GDBSERVER_LIBS@
common-regcache.o: ../common/common-regcache.c
$(COMPILE) $<
$(POSTCOMPILE)
+signals-state-save-restore.o: ../common/signals-state-save-restore.c
+ $(COMPILE) $<
+ $(POSTCOMPILE)
# Arch object files rules form ../arch
/* Define to 1 if you have the <sgtty.h> header file. */
#undef HAVE_SGTTY_H
+/* Define to 1 if you have the `sigaction' function. */
+#undef HAVE_SIGACTION
+
/* Define to 1 if you have the <signal.h> header file. */
#undef HAVE_SIGNAL_H
done
- for ac_func in fdwalk getrlimit pipe pipe2 socketpair
+ for ac_func in fdwalk getrlimit pipe pipe2 socketpair sigaction
do :
as_ac_var=`$as_echo "ac_cv_func_$ac_func" | $as_tr_sh`
ac_fn_c_check_func "$LINENO" "$ac_func" "$as_ac_var"
#include "agent.h"
#include "tdesc.h"
#include "rsp-low.h"
-
+#include "signals-state-save-restore.h"
#include "nat/linux-nat.h"
#include "nat/linux-waitpid.h"
#include "gdb_wait.h"
}
}
+ restore_original_signals_state ();
+
execv (program, allargs);
if (errno == ENOENT)
execvp (program, allargs);
#include "notif.h"
#include "tdesc.h"
#include "rsp-low.h"
-
+#include "signals-state-save-restore.h"
#include <ctype.h>
#include <unistd.h>
#if HAVE_SIGNAL_H
opened by remote_prepare. */
notice_open_fds ();
+ save_original_signals_state ();
+
/* We need to know whether the remote connection is stdio before
starting the inferior. Inferiors created in this scenario have
stdin,stdout redirected. So do this here before we call
#include <signal.h>
#include "event-top.h"
#include "infrun.h"
+#include "signals-state-save-restore.h"
/* The selected interpreter. This will be used as a set command
variable, so it should always be malloc'ed - since
bfd_init ();
notice_open_fds ();
+ save_original_signals_state ();
make_cleanup (VEC_cleanup (cmdarg_s), &cmdarg_vec);
dirsize = 1;
+2016-08-09 Pedro Alves <palves@redhat.com>
+
+ PR gdb/18653
+ * gdb.base/signals-state-child.c: New file.
+ * gdb.base/signals-state-child.exp: New file.
+ * gdb.gdb/selftest.exp (do_steps_and_nexts): Add new pattern.
+
2016-08-09 Pedro Alves <palves@redhat.com>
* gdb.dwarf2/bitfield-parent-optimized-out.exp: New file.
--- /dev/null
+/* Copyright 2016 Free Software Foundation, Inc.
+
+ This file is part of GDB.
+
+ 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 <http://www.gnu.org/licenses/>. */
+
+#include <stdlib.h>
+#include <stdio.h>
+#include <signal.h>
+#include <assert.h>
+#include <errno.h>
+
+#ifndef OUTPUT_TXT
+# define OUTPUT_TXT "output.txt"
+#endif
+
+static void
+perror_and_exit (const char *s)
+{
+ perror (s);
+ exit (1);
+}
+
+int
+main (int argc, char **argv)
+{
+ int i;
+ FILE *out;
+ sigset_t sigset;
+ int res;
+
+ res = sigprocmask (0, NULL, &sigset);
+ if (res != 0)
+ perror_and_exit ("sigprocmask");
+
+ if (argc > 1)
+ out = stdout;
+ else
+ {
+ out = fopen (OUTPUT_TXT, "w");
+ if (out == NULL)
+ perror_and_exit ("fopen");
+ }
+
+ for (i = 1; i < NSIG; i++)
+ {
+ struct sigaction oldact;
+
+ fprintf (out, "signal %d: ", i);
+
+ res = sigaction (i, NULL, &oldact);
+ if (res == -1 && errno == EINVAL)
+ {
+ /* Some signal numbers in the range are invalid. E.g.,
+ signals 32 and 33 on GNU/Linux. */
+ fprintf (out, "invalid");
+ }
+ else if (res == -1)
+ {
+ perror_and_exit ("sigaction");
+ }
+ else
+ {
+ int m;
+
+ fprintf (out, "sigaction={sa_handler=", i);
+
+ if (oldact.sa_handler == SIG_DFL)
+ fprintf (out, "SIG_DFL");
+ else if (oldact.sa_handler == SIG_IGN)
+ fprintf (out, "SIG_IGN");
+ else
+ abort ();
+
+ fprintf (out, ", sa_mask=");
+ for (m = 1; m < NSIG; m++)
+ fprintf (out, "%c", sigismember (&oldact.sa_mask, m) ? '1' : '0');
+
+ fprintf (out, ", sa_flags=%d", oldact.sa_flags);
+
+ fprintf (out, "}, masked=%d", sigismember (&sigset, i));
+ }
+ fprintf (out, "\n");
+ }
+
+ if (out != stdout)
+ fclose (out);
+
+ return 0;
+}
--- /dev/null
+# Copyright 2016 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 <http://www.gnu.org/licenses/>.
+
+# Test that gdb's (or gdbserver's) own signal handling does not
+# interfere with the signal actions (dispositions, etc.) and mask
+# their spawned children inherit.
+#
+# - If gdb inherits some signal set to SIG_IGN, so should the
+# inferior, even if gdb itself chooses not to ignore the signal.
+#
+# - If gdb inherits some signal set to SIG_DFL, so should the inferior
+# even if gdb itself ignores that signal.
+#
+# This requires special support in gdb/gdbserver because the exec
+# family of functions does not reset the signal disposition of signals
+# that are set to SIG_IGN, nor signal masks and flags.
+
+standard_testfile
+
+set gdb_txt [standard_output_file gdb.txt]
+set standalone_txt [standard_output_file standalone.txt]
+remote_exec host "rm -f $gdb_txt"
+remote_exec host "rm -f $standalone_txt"
+
+set options [list debug "additional_flags=-DOUTPUT_TXT=\"$gdb_txt\""]
+if {[build_executable $testfile.exp $testfile $srcfile $options]} {
+ untested $testfile.exp
+ return -1
+}
+
+set options [list debug "additional_flags=-DOUTPUT_TXT=\"$standalone_txt\""]
+if {[build_executable $testfile.exp $testfile-standalone $srcfile $options]} {
+ untested $testfile.exp
+ return -1
+}
+
+# Run the program directly, and dump its initial signal actions and
+# mask in "standalone.txt".
+
+# Use remote_spawn instead of remote_exec, like how we spawn gdb.
+# This is in order to take the same code code paths in dejagnu
+# compared to when running the program through gdb. E.g., because
+# local_exec uses -ignore SIGHUP, while remote_spawn does not, if we
+# used remote_exec, the test program would start with SIGHUP ignored
+# when run standalone, but not when run through gdb.
+set res [remote_spawn host "$binfile-standalone"]
+if { $res < 0 || $res == "" } {
+ untested "spawning $binfile-standalone failed"
+ return 1
+} else {
+ pass "collect standalone signals state"
+}
+remote_close host
+
+# Now run the program through gdb, and dump its initial signal actions
+# and mask in "gdb.txt".
+
+clean_restart $binfile
+
+if { ! [ runto_main ] } then {
+ untested $testfile.exp
+ return -1
+}
+
+gdb_continue_to_end "collect signals state under gdb"
+
+# Diff the .txt files. They should be identical.
+gdb_test "shell diff -s $standalone_txt $gdb_txt" \
+ "Files .* are identical.*" \
+ "signals states are identical"
set description "next over notice_open_fds"
set command "next"
}
+ -re ".*save_original_signals_state ..;.*$gdb_prompt $" {
+ set description "next over save_original_signals_state"
+ set command "next"
+ }
-re ".*VEC_cleanup .cmdarg_s.*$gdb_prompt $" {
set description "next over cmdarg_s VEC_cleanup"
set command "next"
projects / deliverable / binutils-gdb.git / commitdiff
