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9f8128f48

Mike Frysinger

2009-03-29

FAILED Duration: 29s

Subject

first pass at `trap` support in hush

Binary

No binary (build failed)

Architecture & Compiler Flags

Architecture: x86_64-linux-gnu Compiler: gcc (Ubuntu 11.4.0-1ubuntu1~22.04.3) 11.4.0

—

Build Log

(log yok)

Commit Diff GitHub →

shell/hush.c +129 -10

shell/hush.c+129 -10

@@ -489,6 +489,10 @@ struct globals {
	#endif
	unsigned char charmap[256];
	char user_input_buf[ENABLE_FEATURE_EDITING ? BUFSIZ : 2];
+	struct {
+	char *cmd;
+	struct sigaction oact;
+	} *traps;
	};

	#define G (*ptr_to_globals)
@@ -517,6 +521,8 @@ static int builtin_help(char **argv);
	static int builtin_pwd(char **argv);
	static int builtin_read(char **argv);
	static int builtin_test(char **argv);
+	static void handle_trap(int sig);
+	static int builtin_trap(char **argv);
	static int builtin_true(char **argv);
	static int builtin_set(char **argv);
	static int builtin_set_mode(const char, const char);
@@ -578,8 +584,8 @@ static const struct built_in_command bltins[] = {
	// BLTIN("return", builtin_not_written, "Return from a function"),
	BLTIN("set" , builtin_set, "Set/unset shell local variables"),
	BLTIN("shift" , builtin_shift, "Shift positional parameters"),
-	// BLTIN("trap" , builtin_not_written, "Trap signals"),
	BLTIN("test" , builtin_test, "Test condition"),
+	BLTIN("trap" , builtin_trap, "Trap signals"),
	// BLTIN("ulimit", builtin_not_written, "Control resource limits"),
	BLTIN("umask" , builtin_umask, "Set file creation mask"),
	BLTIN("unset" , builtin_unset, "Unset environment variable"),
@@ -857,22 +863,27 @@ static void sigexit(int sig)
	kill_myself_with_sig(sig); /* does not return */
	}

-	/* Restores tty foreground process group, and exits. */
-	static void hush_exit(int exitcode) NORETURN;
-	static void hush_exit(int exitcode)
-	{
-	fflush(NULL); /* flush all streams */
-	sigexit(- (exitcode & 0xff));
-	}
-
	#else /* !JOB */

	#define set_fatal_sighandler(handler) ((void)0)
	#define set_jobctrl_sighandler(handler) ((void)0)
-	#define hush_exit(e) exit(e)

	#endif /* JOB */

+	/* Restores tty foreground process group, and exits. */
+	static void hush_exit(int exitcode) NORETURN;
+	static void hush_exit(int exitcode)
+	{
+	if (G.traps && G.traps[0].cmd)
+	handle_trap(0);
+
+	if (ENABLE_HUSH_JOB) {
+	fflush(NULL); /* flush all streams */
+	sigexit(- (exitcode & 0xff));
+	} else
+	exit(exitcode);
+	}
+

	static const char *set_cwd(void)
	{
@@ -4516,6 +4527,114 @@ int lash_main(int argc, char **argv)
	/*
	* Built-ins
	*/
+	/* http://www.opengroup.org/onlinepubs/9699919799/utilities/V3_chap02.html#tag_18_28
+	*
+	* Traps are also evaluated immediately instead of being delayed properly:
+	* http://www.opengroup.org/onlinepubs/9699919799/utilities/V3_chap02.html#tag_18_11
+	* Example: hush -c 'trap "echo hi" 31; sleep 10; echo moo' & sleep 1; kill -31 $!
+	* "hi" should not be displayed until the sleep finishes
+	* This will have to get fixed ...
+	*/
+	static void handle_trap(int sig)
+	{
+	int save_errno, save_rcode;
+	char *argv[] = { NULL, G.traps[sig].cmd, NULL };
+	/* Race! We transitioned from handled to ignore/default, but
+	* the signal came in after updating .cmd but before we could
+	* register the new signal handler.
+	*/
+	if (!argv[1] \|\| argv[1][0] == '\0')
+	return;
+	/* need to save/restore errno/$? across traps */
+	save_errno = errno;
+	save_rcode = G.last_return_code;
+	builtin_eval(argv);
+	errno = save_errno;
+	G.last_return_code = save_rcode;
+	}
+	static int builtin_trap(char **argv)
+	{
+	size_t i;
+	int sig;
+	bool ign = false;
+	char *new_cmd = NULL;
+
+	if (!G.traps)
+	G.traps = xzalloc(sizeof(G.traps) NSIG);
+
+	if (!argv[1]) {
+	/* No args: print all trapped. This isn't 100% correct as we should
+	* be escaping the cmd so that it can be pasted back in ...
+	*/
+	for (i = 0; i < NSIG; ++i)
+	if (G.traps[i].cmd)
+	printf("trap -- '%s' %s\n", G.traps[i].cmd, get_signame(i));
+	return EXIT_SUCCESS;
+	}
+
+	/* first arg is decimal: reset all specified */
+	sig = bb_strtou(argv[1], NULL, 10);
+	if (errno == 0) {
+	int ret;
+	i = 0;
+	set_all:
+	ret = EXIT_SUCCESS;
+	while (argv[++i]) {
+	char *old_cmd;
+
+	sig = get_signum(argv[i]);
+	if (sig < 0 \|\| sig >= NSIG) {
+	ret = EXIT_FAILURE;
+	bb_perror_msg("trap: %s: invalid signal specification", argv[i]);
+	continue;
+	}
+
+	/* Make sure .cmd is always a valid command list since
+	* signals can occur at any time ...
+	*/
+	old_cmd = G.traps[sig].cmd;
+	G.traps[sig].cmd = xstrdup(new_cmd);
+	free(old_cmd);
+
+	debug_printf("trap: setting SIG%s (%i) to: %s",
+	get_signame(sig), sig, G.traps[sig].cmd);
+
+	/* There is no signal for 0 (EXIT) */
+	if (sig == 0)
+	continue;
+
+	if (new_cmd) {
+	/* add/update a handler */
+	struct sigaction act = {
+	.sa_handler = ign ? SIG_IGN : handle_trap,
+	.sa_flags = SA_RESTART,
+	};
+	sigemptyset(&act.sa_mask);
+	sigaction(sig, &act, old_cmd ? NULL : &G.traps[sig].oact);
+	} else if (old_cmd && !new_cmd)
+	/* there was a handler, and we are removing it */
+	sigaction_set(sig, &G.traps[sig].oact);
+	}
+	return ret;
+	}
+
+	/* first arg is "-": reset all specified to default */
+	/* first arg is "": ignore all specified */
+	/* everything else: execute first arg upon signal */
+	if (!argv[2]) {
+	bb_error_msg("trap: invalid arguments");
+	return EXIT_FAILURE;
+	}
+	if (LONE_DASH(argv[1]))
+	/* nothing! */;
+	else
+	new_cmd = argv[1];
+	if (argv[1][0] == '\0')
+	ign = true;
+	i = 1;
+	goto set_all;
+	}
+
	static int builtin_true(char **argv UNUSED_PARAM)
	{
	return 0;