Hello,
Thanks for all comments.
On 2019-02-24 11:33 a.m., Paul Eggert wrote:
Thanks for doing all that. Although Pádraig is not enthusiastic about a
shortcut like -p, I'm a bit warmer to it, as it's an important special
case to fix a wart in POSIX. No big deal either way.
For now I kept "-p", can be removed later of course.
The first patch includes Pádraig's recent suggestions (slightly modified).
The documentation should mention that SIGCHLD is special [...]
The documentation should say what happens if mutually-contradictory
options are specified, [...]
The documentation should echo this suggestion in
<http://pubs.opengroup.org/onlinepubs/9699919799/functions/exec.html>:
I've added those, and I welcome all improvements suggestion to
grammar/phrasing/etc.
> There should be options --block-signal[=SIG], --unblock-signal[=SIG],
> and --setmask-signal[=SIG] that affect the signal mask, which is also
> inherited by the child. These can be implemented via pthread_sigmask.
The second patch adds these new options (separated to ease review).
As for documentation - I'm not sure what to add beyond the basic
option description. When should these be used?
A third small patch adds "env ---list-signal-actions" and
"env --list-blocked-signals" - to ease diagnostics.
Might be worth adding for completeness (e.g., for users who
need to somehow know if SIGPIPE is being ignored by the shell
or not):
$ ( trap '' PIPE && src/env --list-signal-actions )
PIPE (13): ignore
Comments very welcomed,
- assaf
>From 02cba657e2f63c05f859daf18a7d1032fdc32c6f Mon Sep 17 00:00:00 2001
From: Assaf Gordon <assafgor...@gmail.com>
Date: Fri, 15 Feb 2019 12:31:48 -0700
Subject: [PATCH 1/3] env: new options
-p/--default-signal=SIG/--ignore-signal=SIG
New options to set signal handlers to default (SIG_DFL) or ignore
(SIG_IGN) This is useful to overcome POSIX limitation that shell must
not override inherited signal state, e.g. the second 'trap' here is
a no-op:
trap '' PIPE && sh -c 'trap - PIPE ; seq inf | head -n1'
Instead use:
trap '' PIPE && sh -c 'env -p seq inf | head -n1'
Similarly, the following will prevent CTRL-C from terminating the
program:
env --ignore-signal=INT seq inf > /dev/null
See https://bugs.gnu.org/34488#8 .
* NEWS: Mention new options.
* doc/coreutils.texi (env invocation): Document new options.
* man/env.x: Add example of --default-signal=SIG usage.
* src/env.c (signals): New global variable.
(shortopts,longopts): Add new options.
(usage): Print new options.
(parse_signal_params): Parse comma-separated list of signals, store in
signals variable.
(reset_signal_handlers): Set each signal to SIG_DFL/SIG_IGN.
(main): Process new options.
* src/local.mk (src_env_SOURCES): Add operand2sig.c.
* tests/misc/env-signal-handler.sh: New test.
* tests/local.mk (all_tests): Add new test.
---
NEWS | 3 +
doc/coreutils.texi | 58 ++++++++++++++++
man/env.x | 69 ++++++++++++++++++
src/env.c | 138 +++++++++++++++++++++++++++++++++++-
src/local.mk | 1 +
tests/local.mk | 1 +
tests/misc/env-signal-handler.sh | 146 +++++++++++++++++++++++++++++++++++++++
7 files changed, 415 insertions(+), 1 deletion(-)
create mode 100755 tests/misc/env-signal-handler.sh
diff --git a/NEWS b/NEWS
index e73cb52b8..ddbbaf138 100644
--- a/NEWS
+++ b/NEWS
@@ -81,6 +81,9 @@ GNU coreutils NEWS -*- outline -*-
test now supports the '-N FILE' unary operator (like e.g. bash) to check
whether FILE exists and has been modified since it was last read.
+ env now supports '--default-singal[=SIG]' and '--ignore-signal[=SIG]'
+ options to set signal handlers before executing a program.
+
** New commands
basenc is added to complement existing base64,base32 commands,
diff --git a/doc/coreutils.texi b/doc/coreutils.texi
index eb1848882..c2c202b28 100644
--- a/doc/coreutils.texi
+++ b/doc/coreutils.texi
@@ -17246,6 +17246,64 @@ chroot /chroot env --chdir=/srv true
env --chdir=/build FOO=bar timeout 5 true
@end example
+@item --default-signal[=@var{sig}]
+Reset signal @var{sig} to its default signal handler. Without @var{sig} all
+known signals are reset to their defaults. Multiple signals can be
+comma-separated. The following command runs @command{seq} with SIGINT and
+SIGPIPE set to their default (which is to terminate the program):
+
+@example
+env --default-signal=PIPE,INT seq 1000 | head -n1
+@end example
+
+In the following example:
+
+@example
+trap '' PIPE && sh -c 'trap - PIPE ; seq inf | head -n1'
+@end example
+
+The first trap command sets SIGPIPE to ignore. The second trap command
+ostensibly sets it back to its default, but POSIX mandates that the shell
+must not change inherited state of the signal - so it is a no-op.
+
+Using @option{--default-signal=PIPE} (or its shortcut @option{-p}) can be
+used to force the signal to its default behavior:
+
+@example
+trap '' PIPE && sh -c "env -p seq inf | head -n1'
+@end example
+
+
+@item --ignore-signal[=@var{sig}]
+Ignore signal @var{sig} when running a program. Without @var{sig} all
+known signals are set to ignore. Multiple signals can be
+comma-separated. The following command runs @command{seq} with SIGINT set
+to be ignored - pressing @kbd{Ctrl-C} will not terminate it:
+
+@example
+env --ignore-signal=INT seq inf > /dev/null
+@end example
+
+@samp{SIGCHLD} is special, in that @option{--ignore-signal=CHLD} might have
+no effect (POSIX says it's unspecified).
+
+Most operating systems do not allow ignoring @samp{SIGKILL}, @samp{SIGSTOP}
+(and possibly other signals). Attempting to ignore these signals will fail.
+
+Multiple (and contradictory) @option{--default-signal=SIG} and
+@option{--ignore-signal=SIG} options are processed left-to-right,
+with the latter taking precedence. In the follwing example, @samp{SIGPIPE} is
+set to default while @samp{SIGINT} is ignored:
+
+@example
+env --default-signal=INT,PIPE --ignore-signal=INT
+@end example
+
+
+@item -p
+Equivalent to @option{--default-signal=PIPE} - sets SIGPIPE to its default
+behavior (terminate a program upon @samp{SIGPIPE}).
+
@item -v
@itemx --debug
@opindex -v
diff --git a/man/env.x b/man/env.x
index 8eea79655..09c7f0f3a 100644
--- a/man/env.x
+++ b/man/env.x
@@ -37,3 +37,72 @@ parameter the script will likely fail with:
.RE
.PP
See the full documentation for more details.
+.PP
+.SS "\-\-default-signal[=SIG]" to 'untrap' a singal
+This option allows setting a signal handler to its default
+action. This is useful to reset a signal after setting it
+to 'ignore' using the shell's trap command.
+
+In the following example:
+.PP
+.RS
+.nf
+trap '' PIPE && sh \-c 'trap \- PIPE ; seq inf | head \-n1'
+.fi
+.RE
+.PP
+The first
+.B trap
+command sets SIGPIPE to ignore.
+The second
+.B trap
+command ostensibly sets it back to its default, but POSIX mandates that the
+shell must not change inherited state of the signal - so it is a no-op.
+.PP
+Using
+.B \-\-default-signal=PIPE
+(or its shortcut
+.B \-p
+)
+can be used to force the signal to its default behavior:
+.PP
+.RS
+.nf
+trap '' PIPE && sh \-c "env \-p seq inf | head \-n1'
+.fi
+.RE
+.PP
+.B SIGCHLD
+is special in that
+.B \-\-ignore\-signal=CHLD
+might have no effect (POSIX says it's unspecified).
+.PP
+Most operating systems do not allow ignoring
+.B SIGKILL, SIGSTOP
+(and possibly other signals).
+Attempting to ignore these signals will fail.
+.PP
+Multiple (and contradictory)
+.B \-\-default\-signal=SIG
+and
+.B \-\-ignore\-signal=SIG
+options are processed left-to-right, with the latter taking precedence.
+In the follwing example, SIGPIPE is set to default while SIGINT is ignored:
+.RS
+.nf
+env \-\-default\-signal=INT,PIPE \-\-ignore\-signal=INT
+.fi
+.RE
+
+[NOTES]
+POSIX's exec(2) pages says:
+.RS
+"many existing applications wrongly assume that they start with certain
+signals set to the default action and/or unblocked.... Therefore, it is best
+not to block or ignore signals across execs without explicit reason to do so,
+and especially not to block signals across execs of arbitrary (not closely
+cooperating) programs."
+.RE
+
+[SEE ALSO]
+sigaction(2), signal(7)
diff --git a/src/env.c b/src/env.c
index 3a1a3869e..bd9b68560 100644
--- a/src/env.c
+++ b/src/env.c
@@ -21,12 +21,15 @@
#include <sys/types.h>
#include <getopt.h>
#include <c-ctype.h>
+#include <signal.h>
#include <assert.h>
#include "system.h"
#include "die.h"
#include "error.h"
+#include "operand2sig.h"
#include "quote.h"
+#include "sig2str.h"
/* The official name of this program (e.g., no 'g' prefix). */
#define PROGRAM_NAME "env"
@@ -48,7 +51,27 @@ static bool dev_debug;
static char *varname;
static size_t vnlen;
-static char const shortopts[] = "+C:iS:u:v0 \t";
+/* Possible actions on each signal. */
+enum SIGNAL_MODE {
+ UNCHANGED = 0,
+ DEFAULT, /* Set to default handler (SIG_DFL). */
+ DEFAULT_NOERR, /* ditto, but ignore sigaction(2) errors. */
+ IGNORE, /* Set to ignore (SIG_IGN). */
+ IGNORE_NOERR /* ditto, but ignore sigaction(2) errors. */
+};
+static enum SIGNAL_MODE signals[SIGNUM_BOUND];
+
+
+
+static char const shortopts[] = "+C:ipS:u:v0 \t";
+
+/* For long options that have no equivalent short option, use a
+ non-character as a pseudo short option, starting with CHAR_MAX + 1. */
+enum
+{
+ DEFAULT_SIGNAL_OPTION = CHAR_MAX + 1,
+ IGNORE_SIGNAL_OPTION
+};
static struct option const longopts[] =
{
@@ -56,6 +79,8 @@ static struct option const longopts[] =
{"null", no_argument, NULL, '0'},
{"unset", required_argument, NULL, 'u'},
{"chdir", required_argument, NULL, 'C'},
+ {"default-signal", optional_argument, NULL, DEFAULT_SIGNAL_OPTION},
+ {"ignore-signal", optional_argument, NULL, IGNORE_SIGNAL_OPTION},
{"debug", no_argument, NULL, 'v'},
{"split-string", required_argument, NULL, 'S'},
{GETOPT_HELP_OPTION_DECL},
@@ -88,8 +113,19 @@ Set each NAME to VALUE in the environment and run COMMAND.\n\
-C, --chdir=DIR change working directory to DIR\n\
"), stdout);
fputs (_("\
+ --default-signal[=SIG] set signal SIG to its default action.\n\
+"), stdout);
+ fputs (_("\
+ --ignore-signal[=SIG] set signal SIG to be ignored.\n\
+"), stdout);
+ fputs (_("\
-S, --split-string=S process and split S into separate arguments;\n\
used to pass multiple arguments on shebang lines\n\
+"), stdout);
+ fputs (_("\
+ -p same as --default-signal=PIPE\n\
+"), stdout);
+ fputs (_("\
-v, --debug print verbose information for each processing step\n\
"), stdout);
fputs (HELP_OPTION_DESCRIPTION, stdout);
@@ -98,6 +134,13 @@ Set each NAME to VALUE in the environment and run COMMAND.\n\
\n\
A mere - implies -i. If no COMMAND, print the resulting environment.\n\
"), stdout);
+ fputs (_("\
+\n\
+SIG may be a signal name like 'PIPE', or a signal number like '13'.\n\
+Without SIG, all known signals are included. Multiple signals can be\n\
+comma-separated.\n\
+\n\
+"), stdout);
emit_ancillary_info (PROGRAM_NAME);
}
exit (status);
@@ -525,6 +568,87 @@ parse_split_string (const char* str, int /*out*/ *orig_optind,
*orig_optind = 0; /* tell getopt to restart from first argument */
}
+static void
+parse_signal_action_params (const char* optarg, bool set_default)
+{
+ char signame[SIG2STR_MAX];
+ char *opt_sig;
+ char *optarg_writable;
+
+ if (! optarg)
+ {
+ /* without an argument, reset all signals.
+ Some signals cannot be set to ignore or default (e.g., SIGKILL,
+ SIGSTOP on most OSes, and SIGCONT on AIX.) - so ignore errors. */
+ for (int i = 1 ; i < SIGNUM_BOUND; ++i)
+ if (sig2str (i, signame) == 0)
+ signals[i] = set_default ? DEFAULT_NOERR : IGNORE_NOERR;
+ return;
+ }
+
+ optarg_writable = xstrdup (optarg);
+
+ opt_sig = strtok (optarg_writable, ",");
+ while (opt_sig)
+ {
+ int signum = operand2sig (opt_sig, signame);
+ /* operand2sig accepts signal 0 (EXIT) - but we reject it. */
+ if (signum == 0)
+ error (0, 0, _("%s: invalid signal"), quote (opt_sig));
+ if (signum <= 0)
+ usage (exit_failure);
+
+ signals[signum] = set_default ? DEFAULT : IGNORE;
+
+ opt_sig = strtok (NULL, ",");
+ }
+
+ free (optarg_writable);
+}
+
+static void
+reset_signal_handlers (void)
+{
+ for (int i = 1; i < SIGNUM_BOUND; i++)
+ {
+ struct sigaction act;
+
+ if (signals[i] == UNCHANGED)
+ continue;
+
+ bool ignore_errors = (signals[i] == DEFAULT_NOERR
+ || signals[i] == IGNORE_NOERR);
+
+ bool set_to_default = (signals[i] == DEFAULT
+ || signals[i] == DEFAULT_NOERR);
+
+ int sig_err = sigaction (i, NULL, &act);
+
+ if (sig_err && !ignore_errors)
+ die (EXIT_CANCELED, errno,
+ _("failed to get signal action for signal %d"), i);
+
+ if (! sig_err)
+ {
+ act.sa_handler = set_to_default ? SIG_DFL : SIG_IGN;
+
+ if ((sig_err = sigaction (i, &act, NULL)) && !ignore_errors)
+ die (EXIT_CANCELED, errno,
+ _("failed to set signal action for signal %d"), i);
+ }
+
+ if (dev_debug)
+ {
+ char signame[SIG2STR_MAX];
+ sig2str (i, signame);
+ devmsg ("Reset signal %s (%d) to %s%s\n",
+ signame, i,
+ set_to_default ? "DEFAULT" : "IGNORE",
+ sig_err ? " (failure ignored)" : "");
+ }
+ }
+}
+
int
main (int argc, char **argv)
{
@@ -558,6 +682,16 @@ main (int argc, char **argv)
case '0':
opt_nul_terminate_output = true;
break;
+ case 'p':
+ /* alias to --default-signal=PIPE */
+ signals[SIGPIPE] = DEFAULT;
+ break;
+ case DEFAULT_SIGNAL_OPTION:
+ parse_signal_action_params (optarg, true);
+ break;
+ case IGNORE_SIGNAL_OPTION:
+ parse_signal_action_params (optarg, false);
+ break;
case 'C':
newdir = optarg;
break;
@@ -633,6 +767,8 @@ main (int argc, char **argv)
return EXIT_SUCCESS;
}
+ reset_signal_handlers ();
+
if (newdir)
{
devmsg ("chdir: %s\n", quoteaf (newdir));
diff --git a/src/local.mk b/src/local.mk
index ba219d530..a69d40521 100644
--- a/src/local.mk
+++ b/src/local.mk
@@ -356,6 +356,7 @@ src_coreutils_SOURCES = src/coreutils.c
src_cp_SOURCES = src/cp.c $(copy_sources) $(selinux_sources)
src_dir_SOURCES = src/ls.c src/ls-dir.c
+src_env_SOURCES = src/env.c src/operand2sig.c
src_vdir_SOURCES = src/ls.c src/ls-vdir.c
src_id_SOURCES = src/id.c src/group-list.c
src_groups_SOURCES = src/groups.c src/group-list.c
diff --git a/tests/local.mk b/tests/local.mk
index bcb61edc7..d67e4e80c 100644
--- a/tests/local.mk
+++ b/tests/local.mk
@@ -240,6 +240,7 @@ all_tests = \
tests/fmt/goal-option.sh \
tests/misc/echo.sh \
tests/misc/env.sh \
+ tests/misc/env-signal-handler.sh \
tests/misc/ptx.pl \
tests/misc/test.pl \
tests/misc/seq.pl \
diff --git a/tests/misc/env-signal-handler.sh b/tests/misc/env-signal-handler.sh
new file mode 100755
index 000000000..b5315499e
--- /dev/null
+++ b/tests/misc/env-signal-handler.sh
@@ -0,0 +1,146 @@
+#!/bin/sh
+# Test env --default-signal=PIPE feature.
+
+# Copyright (C) 2019 Free Software Foundation, Inc.
+
+# This program is free software: you can redistribute it and/or modify
+# it under the terms of the GNU General Public License as published by
+# the Free Software Foundation, either version 3 of the License, or
+# (at your option) any later version.
+
+# This program is distributed in the hope that it will be useful,
+# but WITHOUT ANY WARRANTY; without even the implied warranty of
+# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
+# GNU General Public License for more details.
+
+# You should have received a copy of the GNU General Public License
+# along with this program. If not, see <https://www.gnu.org/licenses/>.
+
+. "${srcdir=.}/tests/init.sh"; path_prepend_ ./src
+print_ver_ seq
+print_ver_ timeout
+print_ver_ test
+trap_sigpipe_or_skip_
+
+# Paraphrasing http://bugs.gnu.org/34488#8:
+# POSIX requires that sh started with an inherited ignored SIGPIPE must
+# silently ignore all attempts from within the shell to restore SIGPIPE
+# handling to child processes of the shell:
+#
+# $ (trap '' PIPE; bash -c 'trap - PIPE; seq inf | head -n1')
+# 1
+# seq: write error: Broken pipe
+#
+# With 'env --default-signal=PIPE', the signal handler can be reset to its
+# default.
+
+# Baseline Test - default signal handler
+# --------------------------------------
+# Ensure this results in a "broken pipe" error (the first 'trap'
+# sets SIGPIPE to ignore, and the second 'trap' becomes a no-op instead
+# of resetting SIGPIPE to its default). Upon a SIGPIPE 'seq' will not be
+# terminated, instead its write(2) call will return an error.
+(trap '' PIPE; sh -c 'trap - PIPE; seq 999999 2>err1t | head -n1 > out1')
+
+# The exact broken pipe message depends on the operating system, just ensure
+# there was a 'write error' message in stderr:
+sed 's/^\(seq: write error:\) .*/\1/' err1t > err1 || framework_failure_
+
+printf "1\n" > exp-out || framework_failure_
+printf "seq: write error:\n" > exp-err1 || framework_failure_
+
+compare exp-out out1 || framework_failure_
+compare exp-err1 err1 || framework_failure_
+
+
+# env test - default signal handler
+# ---------------------------------
+# With env resetting the signal handler to its defaults, there should be no
+# error message (because the default SIGPIPE action is to terminate the
+# 'seq' program):
+(trap '' PIPE;
+ env --default-signal=PIPE \
+ sh -c 'trap - PIPE; seq 999999 2>err2 | head -n1 > out2')
+
+compare exp-out out2 || fail=1
+compare /dev/null err2 || fail=1
+
+# env test - default signal handler (2)
+# -------------------------------------
+# Repeat the previous test, using "-p" (shortcut for --default-signal=PIPE):
+(trap '' PIPE;
+ env -p \
+ sh -c 'trap - PIPE; seq 999999 2>err3 | head -n1 > out3')
+
+compare exp-out out3 || fail=1
+compare /dev/null err3 || fail=1
+
+# env test - default signal handler (3)
+# -------------------------------------
+# Repeat the previous test, using --default-signal with no signal names,
+# i.e., all signals.
+(trap '' PIPE;
+ env --default-signal \
+ sh -c 'trap - PIPE; seq 999999 2>err4 | head -n1 > out4')
+
+compare exp-out out4 || fail=1
+compare /dev/null err4 || fail=1
+
+
+
+
+
+
+# Baseline test - ignore signal handler
+# -------------------------------------
+# Kill 'seq' after 1 second with SIGINT - it should terminate (as SIGINT's
+# default action is to terminate a program).
+# (The first 'env' is just to ensure timeout is not the shell's built-in.)
+env timeout --verbose --kill-after=1 --signal=INT 1 \
+ seq inf > /dev/null 2>err5
+
+printf "timeout: sending signal INT to command 'seq'\n" > exp-err5 \
+ || framework_failure_
+
+compare exp-err5 err5 || fail=1
+
+
+# env test - ignore signal handler
+# --------------------------------
+# Use env to silence (ignore) SIGINT - "seq" should continue running
+# after timeout sends SIGINT, and be killed after 1 second using SIGKILL.
+
+cat>exp-err6 <<EOF
+timeout: sending signal INT to command 'env'
+timeout: sending signal KILL to command 'env'
+EOF
+
+env timeout --verbose --kill-after=1 --signal=INT 1 \
+ env --ignore-signal=INT \
+ seq inf > /dev/null 2>err6t
+
+# check only the first two lines from stderr, which are printed by timeout.
+# (operating systems might add more messages, like "killed").
+sed -n '1,2p' err6t > err6 || framework_failure_
+
+compare exp-err6 err6 || fail=1
+
+
+# env test - ignore signal handler (2)
+# ------------------------------------
+# Repeat the previous test with "--ignore-signals" and no signal names,
+# i.e., all signals.
+
+env timeout --verbose --kill-after=1 --signal=INT 1 \
+ env --ignore-signal \
+ seq inf > /dev/null 2>err7t
+
+# check only the first two lines from stderr, which are printed by timeout.
+# (operating systems might add more messages, like "killed").
+sed -n '1,2p' err7t > err7 || framework_failure_
+
+compare exp-err6 err7 || fail=1
+
+
+
+Exit $fail
--
2.11.0
>From deb0d5a64eef13bdffe9a84f98fc6a5b18805262 Mon Sep 17 00:00:00 2001
From: Assaf Gordon <assafgor...@gmail.com>
Date: Mon, 25 Feb 2019 15:37:47 -0700
Subject: [PATCH 2/3] env: add --{block,unblock,setmask}-signal=SIG options
Suggested by Paul Eggert in http://bugs.gnu.org/34488#71 .
* NEWS: Mention new options.
* doc/coreutils.texi (env invocation): Document new options.
* src/env.c (block_signals, unblock_signals): New global variables.
(longopts, usage): Add new options.
(parse_block_signal_params): Parse command-line options.
(set_signal_proc_mask): Call sigprocmask to block/unblock signals.
(main): Handle new command-line options, call set_signal_proc_mask.
* man/env.x (SEE ALSO): Mention sigprocmask.
---
NEWS | 3 ++
doc/coreutils.texi | 10 +++++
man/env.x | 2 +-
src/env.c | 112 ++++++++++++++++++++++++++++++++++++++++++++++++++++-
4 files changed, 125 insertions(+), 2 deletions(-)
diff --git a/NEWS b/NEWS
index ddbbaf138..cb8aa107f 100644
--- a/NEWS
+++ b/NEWS
@@ -84,6 +84,9 @@ GNU coreutils NEWS -*- outline -*-
env now supports '--default-singal[=SIG]' and '--ignore-signal[=SIG]'
options to set signal handlers before executing a program.
+ env now supports '--{block,unblock,setmask}-singal[=SIG]' to block/unblock
+ signal delivery before executing a program.
+
** New commands
basenc is added to complement existing base64,base32 commands,
diff --git a/doc/coreutils.texi b/doc/coreutils.texi
index c2c202b28..8f5212a72 100644
--- a/doc/coreutils.texi
+++ b/doc/coreutils.texi
@@ -17299,6 +17299,16 @@ set to default while @samp{SIGINT} is ignored:
env --default-signal=INT,PIPE --ignore-signal=INT
@end example
+@item --block-signal[=@var{sig}]
+Block signal @var{sig} from being delivered.
+
+@item --unblock-signal[=@var{sig}]
+Unblock signal @var{sig}.
+
+@item --setmask-signal[=@var{sig}]
+Set list of blocked signals to @var{sig}. All other signals will be unblocked.
+
+
@item -p
Equivalent to @option{--default-signal=PIPE} - sets SIGPIPE to its default
diff --git a/man/env.x b/man/env.x
index 09c7f0f3a..b787fe3a7 100644
--- a/man/env.x
+++ b/man/env.x
@@ -105,4 +105,4 @@ cooperating) programs."
.RE
[SEE ALSO]
-sigaction(2), signal(7)
+sigaction(2), sigprocmask(2), signal(7)
diff --git a/src/env.c b/src/env.c
index bd9b68560..4cae7d47f 100644
--- a/src/env.c
+++ b/src/env.c
@@ -61,6 +61,11 @@ enum SIGNAL_MODE {
};
static enum SIGNAL_MODE signals[SIGNUM_BOUND];
+/* Set of signals to block. */
+static sigset_t block_signals;
+
+/* Set of signals to unblock. */
+static sigset_t unblock_signals;
static char const shortopts[] = "+C:ipS:u:v0 \t";
@@ -70,7 +75,10 @@ static char const shortopts[] = "+C:ipS:u:v0 \t";
enum
{
DEFAULT_SIGNAL_OPTION = CHAR_MAX + 1,
- IGNORE_SIGNAL_OPTION
+ IGNORE_SIGNAL_OPTION,
+ BLOCK_SIGNAL_OPTION,
+ UNBLOCK_SIGNAL_OPTION,
+ SETMASK_SIGNAL_OPTION
};
static struct option const longopts[] =
@@ -81,6 +89,9 @@ static struct option const longopts[] =
{"chdir", required_argument, NULL, 'C'},
{"default-signal", optional_argument, NULL, DEFAULT_SIGNAL_OPTION},
{"ignore-signal", optional_argument, NULL, IGNORE_SIGNAL_OPTION},
+ {"block-signal", optional_argument, NULL, BLOCK_SIGNAL_OPTION},
+ {"unblock-signal", optional_argument, NULL, UNBLOCK_SIGNAL_OPTION},
+ {"setmask-signal", optional_argument, NULL, SETMASK_SIGNAL_OPTION},
{"debug", no_argument, NULL, 'v'},
{"split-string", required_argument, NULL, 'S'},
{GETOPT_HELP_OPTION_DECL},
@@ -110,6 +121,15 @@ Set each NAME to VALUE in the environment and run COMMAND.\n\
-u, --unset=NAME remove variable from the environment\n\
"), stdout);
fputs (_("\
+ --block-signal[=SIG] block signal SIG.\n\
+"), stdout);
+ fputs (_("\
+ --unblock-signal[=SIG] unblock signal SIG.\n\
+"), stdout);
+ fputs (_("\
+ --setmask-signal[=SIG] set blocked signal(s) mask to SIG.\n\
+"), stdout);
+ fputs (_("\
-C, --chdir=DIR change working directory to DIR\n\
"), stdout);
fputs (_("\
@@ -649,6 +669,84 @@ reset_signal_handlers (void)
}
}
+static void
+parse_block_signal_params (const char* optarg, bool block)
+{
+ char signame[SIG2STR_MAX];
+ char *opt_sig;
+ char *optarg_writable;
+
+ if (! optarg)
+ {
+ /* without an argument, reset all signals. */
+ sigfillset (block ? &block_signals : &unblock_signals);
+ sigemptyset (block ? &unblock_signals : &block_signals);
+ return;
+ }
+
+ optarg_writable = xstrdup (optarg);
+
+ opt_sig = strtok (optarg_writable, ",");
+ while (opt_sig)
+ {
+ int signum = operand2sig (opt_sig, signame);
+ /* operand2sig accepts signal 0 (EXIT) - but we reject it. */
+ if (signum == 0)
+ error (0, 0, _("%s: invalid signal"), quote (opt_sig));
+ if (signum <= 0)
+ usage (exit_failure);
+
+ sigaddset (block ? &block_signals : &unblock_signals, signum);
+ sigdelset (block ? &unblock_signals : &block_signals, signum);
+
+ opt_sig = strtok (NULL, ",");
+ }
+
+ free (optarg_writable);
+}
+
+static void
+set_signal_proc_mask (void)
+{
+ /* Get the existing signal mask */
+ sigset_t set;
+ const char *debug_act;
+
+ sigemptyset (&set);
+
+ if (sigprocmask (0, NULL, &set))
+ die (EXIT_CANCELED, errno, _("failed to get signal process mask"));
+
+ for (int i = 1; i < SIGNUM_BOUND; i++)
+ {
+ if (sigismember (&block_signals, i))
+ {
+ sigaddset (&set, i);
+ debug_act = "BLOCK";
+ }
+ else if (sigismember (&unblock_signals, i))
+ {
+ sigdelset (&set, i);
+ debug_act = "UNBLOCK";
+ }
+ else
+ {
+ debug_act = NULL;
+ }
+
+ if (dev_debug && debug_act)
+ {
+ char signame[SIG2STR_MAX];
+ sig2str (i, signame);
+ devmsg ("signal %s (%d) procmask set to %s\n",
+ signame, i, debug_act);
+ }
+ }
+
+ if (sigprocmask (SIG_SETMASK, &set, NULL))
+ die (EXIT_CANCELED, errno, _("failed to set signal process mask"));
+}
+
int
main (int argc, char **argv)
{
@@ -692,6 +790,17 @@ main (int argc, char **argv)
case IGNORE_SIGNAL_OPTION:
parse_signal_action_params (optarg, false);
break;
+ case BLOCK_SIGNAL_OPTION:
+ parse_block_signal_params (optarg, true);
+ break;
+ case UNBLOCK_SIGNAL_OPTION:
+ parse_block_signal_params (optarg, false);
+ break;
+ case SETMASK_SIGNAL_OPTION:
+ sigfillset (&unblock_signals);
+ sigemptyset (&block_signals);
+ parse_block_signal_params (optarg, true);
+ break;
case 'C':
newdir = optarg;
break;
@@ -768,6 +877,7 @@ main (int argc, char **argv)
}
reset_signal_handlers ();
+ set_signal_proc_mask ();
if (newdir)
{
--
2.11.0
>From 150c30aec340d6ce00afa1251e6962c012449407 Mon Sep 17 00:00:00 2001
From: Assaf Gordon <assafgor...@gmail.com>
Date: Mon, 25 Feb 2019 18:03:19 -0700
Subject: [PATCH 3/3] env: add --list-blocked-signals/--list-signal-actions
options
Example:
$ ( trap '' PIPE && env --list-signal-actions )
PIPE (13): ignore
* NEWS: Mention new options.
* doc/coreutils.texi (env invocation): Mention new options.
* src/env.c (longopts,usage): Add new options.
(list_signal_actions, list_blocked_signals): New functions.
(main): Handle new options.
---
NEWS | 3 +++
doc/coreutils.texi | 8 ++++++
src/env.c | 73 +++++++++++++++++++++++++++++++++++++++++++++++++++++-
3 files changed, 83 insertions(+), 1 deletion(-)
diff --git a/NEWS b/NEWS
index cb8aa107f..3cef6066e 100644
--- a/NEWS
+++ b/NEWS
@@ -87,6 +87,9 @@ GNU coreutils NEWS -*- outline -*-
env now supports '--{block,unblock,setmask}-singal[=SIG]' to block/unblock
signal delivery before executing a program.
+ env now supports '--list-signal-actions' and '--list-blocked-signals'
+ options.
+
** New commands
basenc is added to complement existing base64,base32 commands,
diff --git a/doc/coreutils.texi b/doc/coreutils.texi
index 8f5212a72..b63161803 100644
--- a/doc/coreutils.texi
+++ b/doc/coreutils.texi
@@ -17309,6 +17309,14 @@ Unblock signal @var{sig}.
Set list of blocked signals to @var{sig}. All other signals will be unblocked.
+@item --list-signal-actions
+List non-default actions for all signals and exit.
+If all signals are set to their default action, nothing is printed.
+
+@item --list-blocked-signals
+List blocked (masked) signals and exit.
+If no signals are blocked, nothing is printed.
+
@item -p
Equivalent to @option{--default-signal=PIPE} - sets SIGPIPE to its default
diff --git a/src/env.c b/src/env.c
index 4cae7d47f..43856200f 100644
--- a/src/env.c
+++ b/src/env.c
@@ -78,7 +78,9 @@ enum
IGNORE_SIGNAL_OPTION,
BLOCK_SIGNAL_OPTION,
UNBLOCK_SIGNAL_OPTION,
- SETMASK_SIGNAL_OPTION
+ SETMASK_SIGNAL_OPTION,
+ LIST_SIGNAL_ACTIONS_OPTION,
+ LIST_BLOCKED_SIGNALS_OPTION,
};
static struct option const longopts[] =
@@ -89,9 +91,11 @@ static struct option const longopts[] =
{"chdir", required_argument, NULL, 'C'},
{"default-signal", optional_argument, NULL, DEFAULT_SIGNAL_OPTION},
{"ignore-signal", optional_argument, NULL, IGNORE_SIGNAL_OPTION},
+ {"list-signal-actions", no_argument, NULL, LIST_SIGNAL_ACTIONS_OPTION},
{"block-signal", optional_argument, NULL, BLOCK_SIGNAL_OPTION},
{"unblock-signal", optional_argument, NULL, UNBLOCK_SIGNAL_OPTION},
{"setmask-signal", optional_argument, NULL, SETMASK_SIGNAL_OPTION},
+ {"list-blocked-signals", no_argument, NULL, LIST_BLOCKED_SIGNALS_OPTION},
{"debug", no_argument, NULL, 'v'},
{"split-string", required_argument, NULL, 'S'},
{GETOPT_HELP_OPTION_DECL},
@@ -143,6 +147,15 @@ Set each NAME to VALUE in the environment and run COMMAND.\n\
used to pass multiple arguments on shebang lines\n\
"), stdout);
fputs (_("\
+ --list-signal-actions list non-default actions for signals and exit.\n\
+ if all signals use their default actions,\n\
+ nothing is printed.\n\
+"), stdout);
+ fputs (_("\
+ --list-blocked-signals list blocked (masked) signals and exit.\n\
+ if no signals are blocked, nothing is printed.\n\
+"), stdout);
+ fputs (_("\
-p same as --default-signal=PIPE\n\
"), stdout);
fputs (_("\
@@ -670,6 +683,35 @@ reset_signal_handlers (void)
}
static void
+list_signal_actions (void)
+{
+ char signame[SIG2STR_MAX];
+ const char* action;
+
+ for (int i = 1; i < SIGNUM_BOUND; i++)
+ {
+ struct sigaction act;
+ if (sigaction (i, NULL, &act))
+ continue;
+
+ if (act.sa_flags & SA_SIGINFO)
+ action = "sig-action";
+ else if (act.sa_handler == SIG_DFL)
+ continue; /* no need to print defaults. */
+ else if (act.sa_handler == SIG_IGN)
+ action = "ignore";
+ else
+ action = "sig-handler";
+
+ sig2str (i, signame);
+ printf ("%-10s (%2d): %s\n", signame, i, action);
+ }
+
+ exit (EXIT_SUCCESS);
+}
+
+
+static void
parse_block_signal_params (const char* optarg, bool block)
{
char signame[SIG2STR_MAX];
@@ -747,6 +789,29 @@ set_signal_proc_mask (void)
die (EXIT_CANCELED, errno, _("failed to set signal process mask"));
}
+static void
+list_blocked_signals (void)
+{
+ sigset_t set;
+ char signame[SIG2STR_MAX];
+
+ sigemptyset (&set);
+ if (sigprocmask (0, NULL, &set))
+ die (EXIT_CANCELED, errno, _("failed to get signal process mask"));
+
+ for (int i = 1; i < SIGNUM_BOUND; i++)
+ {
+ if (!sigismember (&set, i))
+ continue;
+
+ sig2str (i, signame);
+ printf ("%-10s (%2d)\n", signame, i);
+ }
+
+ exit (EXIT_SUCCESS);
+}
+
+
int
main (int argc, char **argv)
{
@@ -790,6 +855,9 @@ main (int argc, char **argv)
case IGNORE_SIGNAL_OPTION:
parse_signal_action_params (optarg, false);
break;
+ case LIST_SIGNAL_ACTIONS_OPTION:
+ list_signal_actions ();
+ break;
case BLOCK_SIGNAL_OPTION:
parse_block_signal_params (optarg, true);
break;
@@ -801,6 +869,9 @@ main (int argc, char **argv)
sigemptyset (&block_signals);
parse_block_signal_params (optarg, true);
break;
+ case LIST_BLOCKED_SIGNALS_OPTION:
+ list_blocked_signals ();
+ break;
case 'C':
newdir = optarg;
break;
--
2.11.0
