ash,hush: fix handling of SIGINT while waiting for interactive input

function old new delta lineedit_read_key 160 237 +77 __pgetc 522 589 +67 fgetc_interactive 244 309 +65 safe_read_key - 39 +39 read_key 588 607 +19 record_pending_signo 23 32 +9 signal_handler 75 81 +6 .rodata 104312 104309 -3 ------------------------------------------------------------------------------ (add/remove: 1/0 grow/shrink: 6/1 up/down: 282/-3) Total: 279 bytes Signed-off-by: Denys Vlasenko <vda.linux@googlemail.com>
author: Denys Vlasenko <vda.linux@googlemail.com> 2022-01-17 03:02:40 +0100
committer: Denys Vlasenko <vda.linux@googlemail.com> 2022-01-17 11:46:23 +0100
commit: 12566e7f9b5e5c5d445bc4d36991d134b431dc6c (patch)
tree: 2571356a77f7d421da368e9b31dad182e83b2408 /shell
parent: a277506a64404e6c4472ff89c944c4f353db1c33 (diff)
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2 files changed, 77 insertions, 29 deletions
diff --git a/shell/ash.c b/shell/ash.c
index 086773dd7..55df54bd0 100644
--- a/shell/ash.c
+++ b/shell/ash.c
@@ -3679,7 +3679,9 @@ signal_handler(int signo)
                if (!trap[SIGCHLD])
                        return;
        }
+#if ENABLE_FEATURE_EDITING
+        bb_got_signal = signo; /* for read_line_input: "we got a signal" */
+#endif
        gotsig[signo - 1] = 1;
        pending_sig = signo;
@@ -10784,33 +10786,52 @@ preadfd(void)
 # endif
                reinit_unicode_for_ash();
 again:
-//BUG: not in INT_OFF/INT_ON section - SIGINT et al would longjmp out of read_line_input()!
+                /* For shell, LI_INTERRUPTIBLE is set:
-//This would cause a memory leak in interactive shell
+                 * read_line_input will abort on either
-//(repeated internal allocations in read_line_input):
+                 * getting EINTR in poll(), or if it sees bb_got_signal != 0
-// (while kill -INT $$; do :; done) &
+                 * (IOW: if signal arrives before poll() is reached).
+                 * Interactive testcases:
+                 * (while kill -INT $$; do sleep 1; done) &
+                 * #^^^ prints ^C, prints prompt, repeats
+                 * trap 'echo I' int; (while kill -INT $$; do sleep 1; done) &
+                 * #^^^ prints ^C, prints "I", prints prompt, repeats
+                 * trap 'echo T' term; (while kill $$; do sleep 1; done) &
+                 * #^^^ prints "T", prints prompt, repeats
+                 * #(bash 5.0.17 exits after first "T", looks like a bug)
+                 */
+                bb_got_signal = 0;
+                INT_OFF; /* no longjmp'ing out of read_line_input please */
                nr = read_line_input(line_input_state, cmdedit_prompt, buf, IBUFSIZ);
+                if (bb_got_signal == SIGINT)
+                        write(STDOUT_FILENO, "^C\n", 3);
+                INT_ON; /* here non-blocked SIGINT will longjmp */
                if (nr == 0) {
                        /* ^C pressed, "convert" to SIGINT */
-                        write(STDOUT_FILENO, "^C", 2);
+                        write(STDOUT_FILENO, "^C\n", 3);
-                        raise(SIGINT);
+                        raise(SIGINT); /* here non-blocked SIGINT will longjmp */
                        /* raise(SIGINT) did not work! (e.g. if SIGINT
                         * is SIG_IGNed on startup, it stays SIG_IGNed)
                         */
                        if (trap[SIGINT]) {
+ empty_line_input:
                                buf[0] = '\n';
                                buf[1] = '\0';
                                return 1;
                        }
                        exitstatus = 128 + SIGINT;
                        /* bash behavior on ^C + ignored SIGINT: */
-                        write(STDOUT_FILENO, "\n", 1);
                        goto again;
                }
                if (nr < 0) {
                        if (errno == 0) {
-                                /* Ctrl+D pressed */
+                                /* ^D pressed */
                                nr = 0;
                        }
+                        else if (errno == EINTR) { /* got signal? */
+                                if (bb_got_signal != SIGINT)
+                                        write(STDOUT_FILENO, "\n", 1);
+                                goto empty_line_input;
+                        }
 # if ENABLE_ASH_IDLE_TIMEOUT
                        else if (errno == EAGAIN && timeout > 0) {
                                puts("\007timed out waiting for input: auto-logout");
diff --git a/shell/hush.c b/shell/hush.c
index 7d0dc67e4..6dc2ecaac 100644
--- a/shell/hush.c
+++ b/shell/hush.c
@@ -918,6 +918,7 @@ struct globals {
 #if ENABLE_HUSH_INTERACTIVE
        smallint promptmode; /* 0: PS1, 1: PS2 */
 #endif
+        /* set by signal handler if SIGINT is received _and_ its trap is not set */
        smallint flag_SIGINT;
 #if ENABLE_HUSH_LOOPS
        smallint flag_break_continue;
@@ -1944,6 +1945,9 @@ enum {
 static void record_pending_signo(int sig)
 {
        sigaddset(&G.pending_set, sig);
+#if ENABLE_FEATURE_EDITING
+        bb_got_signal = sig; /* for read_line_input: "we got a signal" */
+#endif
 #if ENABLE_HUSH_FAST
        if (sig == SIGCHLD) {
                G.count_SIGCHLD++;
@@ -2652,30 +2656,53 @@ static int get_user_input(struct in_str *i)
        for (;;) {
                reinit_unicode_for_hush();
                G.flag_SIGINT = 0;
-                /* buglet: SIGINT will not make new prompt to appear _at once_,
-                 * only after <Enter>. (^C works immediately) */
+                bb_got_signal = 0;
-                r = read_line_input(G.line_input_state, prompt_str,
+                if (!sigisemptyset(&G.pending_set)) {
+                        /* Whoops, already got a signal, do not call read_line_input */
+                        bb_got_signal = r = -1;
+                } else {
+                        /* For shell, LI_INTERRUPTIBLE is set:
+                         * read_line_input will abort on either
+                         * getting EINTR in poll(), or if it sees bb_got_signal != 0
+                         * (IOW: if signal arrives before poll() is reached).
+                         * Interactive testcases:
+                         * (while kill -INT $$; do sleep 1; done) &
+                         * #^^^ prints ^C, prints prompt, repeats
+                         * trap 'echo I' int; (while kill -INT $$; do sleep 1; done) &
+                         * #^^^ prints ^C, prints "I", prints prompt, repeats
+                         * trap 'echo T' term; (while kill $$; do sleep 1; done) &
+                         * #^^^ prints "T", prints prompt, repeats
+                         * #(bash 5.0.17 exits after first "T", looks like a bug)
+                         */
+                        r = read_line_input(G.line_input_state, prompt_str,
                                G.user_input_buf, CONFIG_FEATURE_EDITING_MAX_LEN-1
-                );
+                        );
-                /* read_line_input intercepts ^C, "convert" it to SIGINT */
+                        /* read_line_input intercepts ^C, "convert" it to SIGINT */
-                if (r == 0) {
+                        if (r == 0)
-                        raise(SIGINT);
+                                raise(SIGINT);
+                }
+                /* bash prints ^C (before running a trap, if any)
+                 * both on keyboard ^C and on real SIGINT (non-kbd generated).
+                 */
+                if (sigismember(&G.pending_set, SIGINT)) {
+                        write(STDOUT_FILENO, "^C\n", 3);
+                        G.last_exitcode = 128 | SIGINT;
                }
                check_and_run_traps();
-                if (r != 0 && !G.flag_SIGINT)
+                if (r == 0) /* keyboard ^C? */
+                        continue; /* go back, read another input line */
+                if (r > 0) /* normal input? (no ^C, no ^D, no signals) */
                        break;
-                /* ^C or SIGINT: repeat */
+                if (!bb_got_signal) {
-                /* bash prints ^C even on real SIGINT (non-kbd generated) */
+                        /* r < 0: ^D/EOF/error detected (but not signal) */
-                write(STDOUT_FILENO, "^C\n", 3);
+                        /* ^D on interactive input goes to next line before exiting: */
-                G.last_exitcode = 128 | SIGINT;
+                        write(STDOUT_FILENO, "\n", 1);
-        }
+                        i->p = NULL;
-        if (r < 0) {
+                        i->peek_buf[0] = r = EOF;
-                /* EOF/error detected */
+                        return r;
-                /* ^D on interactive input goes to next line before exiting: */
+                }
-                write(STDOUT_FILENO, "\n", 1);
+                /* it was a signal: go back, read another input line */
-                i->p = NULL;
-                i->peek_buf[0] = r = EOF;
-                return r;
        }
        i->p = G.user_input_buf;
        return (unsigned char)*i->p++;
author	Denys Vlasenko <vda.linux@googlemail.com>	2022-01-17 03:02:40 +0100
committer	Denys Vlasenko <vda.linux@googlemail.com>	2022-01-17 11:46:23 +0100
commit	12566e7f9b5e5c5d445bc4d36991d134b431dc6c (patch)
tree	2571356a77f7d421da368e9b31dad182e83b2408 /shell
parent	a277506a64404e6c4472ff89c944c4f353db1c33 (diff)
download	busybox-w32-12566e7f9b5e5c5d445bc4d36991d134b431dc6c.tar.gz busybox-w32-12566e7f9b5e5c5d445bc4d36991d134b431dc6c.tar.bz2 busybox-w32-12566e7f9b5e5c5d445bc4d36991d134b431dc6c.zip

diff --git a/shell/ash.c b/shell/ash.c index 086773dd7..55df54bd0 100644 --- a/shell/ash.c +++ b/shell/ash.c
@@ -3679,7 +3679,9 @@ signal_handler(int signo)
3679	if (!trap[SIGCHLD])	3679	if (!trap[SIGCHLD])
3680	return;	3680	return;
3681	}	3681	}
3682		3682	#if ENABLE_FEATURE_EDITING
		3683	bb_got_signal = signo; /* for read_line_input: "we got a signal" */
		3684	#endif
3683	gotsig[signo - 1] = 1;	3685	gotsig[signo - 1] = 1;
3684	pending_sig = signo;	3686	pending_sig = signo;
3685		3687
@@ -10784,33 +10786,52 @@ preadfd(void)
10784	# endif	10786	# endif
10785	reinit_unicode_for_ash();	10787	reinit_unicode_for_ash();
10786	again:	10788	again:
10787	//BUG: not in INT_OFF/INT_ON section - SIGINT et al would longjmp out of read_line_input()!	10789	/* For shell, LI_INTERRUPTIBLE is set:
10788	//This would cause a memory leak in interactive shell	10790	* read_line_input will abort on either
10789	//(repeated internal allocations in read_line_input):	10791	* getting EINTR in poll(), or if it sees bb_got_signal != 0
10790	// (while kill -INT $$; do :; done) &	10792	* (IOW: if signal arrives before poll() is reached).
		10793	* Interactive testcases:
		10794	* (while kill -INT $$; do sleep 1; done) &
		10795	* #^^^ prints ^C, prints prompt, repeats
		10796	* trap 'echo I' int; (while kill -INT $$; do sleep 1; done) &
		10797	* #^^^ prints ^C, prints "I", prints prompt, repeats
		10798	* trap 'echo T' term; (while kill $$; do sleep 1; done) &
		10799	* #^^^ prints "T", prints prompt, repeats
		10800	* #(bash 5.0.17 exits after first "T", looks like a bug)
		10801	*/
		10802	bb_got_signal = 0;
		10803	INT_OFF; /* no longjmp'ing out of read_line_input please */
10791	nr = read_line_input(line_input_state, cmdedit_prompt, buf, IBUFSIZ);	10804	nr = read_line_input(line_input_state, cmdedit_prompt, buf, IBUFSIZ);
		10805	if (bb_got_signal == SIGINT)
		10806	write(STDOUT_FILENO, "^C\n", 3);
		10807	INT_ON; /* here non-blocked SIGINT will longjmp */
10792	if (nr == 0) {	10808	if (nr == 0) {
10793	/* ^C pressed, "convert" to SIGINT */	10809	/* ^C pressed, "convert" to SIGINT */
10794	write(STDOUT_FILENO, "^C", 2);	10810	write(STDOUT_FILENO, "^C\n", 3);
10795	raise(SIGINT);	10811	raise(SIGINT); /* here non-blocked SIGINT will longjmp */
10796	/* raise(SIGINT) did not work! (e.g. if SIGINT	10812	/* raise(SIGINT) did not work! (e.g. if SIGINT
10797	* is SIG_IGNed on startup, it stays SIG_IGNed)	10813	* is SIG_IGNed on startup, it stays SIG_IGNed)
10798	*/	10814	*/
10799	if (trap[SIGINT]) {	10815	if (trap[SIGINT]) {
		10816	empty_line_input:
10800	buf[0] = '\n';	10817	buf[0] = '\n';
10801	buf[1] = '\0';	10818	buf[1] = '\0';
10802	return 1;	10819	return 1;
10803	}	10820	}
10804	exitstatus = 128 + SIGINT;	10821	exitstatus = 128 + SIGINT;
10805	/* bash behavior on ^C + ignored SIGINT: */	10822	/* bash behavior on ^C + ignored SIGINT: */
10806	write(STDOUT_FILENO, "\n", 1);
10807	goto again;	10823	goto again;
10808	}	10824	}
10809	if (nr < 0) {	10825	if (nr < 0) {
10810	if (errno == 0) {	10826	if (errno == 0) {
10811	/* Ctrl+D pressed */	10827	/* ^D pressed */
10812	nr = 0;	10828	nr = 0;
10813	}	10829	}
		10830	else if (errno == EINTR) { /* got signal? */
		10831	if (bb_got_signal != SIGINT)
		10832	write(STDOUT_FILENO, "\n", 1);
		10833	goto empty_line_input;
		10834	}
10814	# if ENABLE_ASH_IDLE_TIMEOUT	10835	# if ENABLE_ASH_IDLE_TIMEOUT
10815	else if (errno == EAGAIN && timeout > 0) {	10836	else if (errno == EAGAIN && timeout > 0) {
10816	puts("\007timed out waiting for input: auto-logout");	10837	puts("\007timed out waiting for input: auto-logout");


diff --git a/shell/hush.c b/shell/hush.c index 7d0dc67e4..6dc2ecaac 100644 --- a/shell/hush.c +++ b/shell/hush.c
@@ -918,6 +918,7 @@ struct globals {
918	#if ENABLE_HUSH_INTERACTIVE	918	#if ENABLE_HUSH_INTERACTIVE
919	smallint promptmode; /* 0: PS1, 1: PS2 */	919	smallint promptmode; /* 0: PS1, 1: PS2 */
920	#endif	920	#endif
		921	/* set by signal handler if SIGINT is received _and_ its trap is not set */
921	smallint flag_SIGINT;	922	smallint flag_SIGINT;
922	#if ENABLE_HUSH_LOOPS	923	#if ENABLE_HUSH_LOOPS
923	smallint flag_break_continue;	924	smallint flag_break_continue;
@@ -1944,6 +1945,9 @@ enum {
1944	static void record_pending_signo(int sig)	1945	static void record_pending_signo(int sig)
1945	{	1946	{
1946	sigaddset(&G.pending_set, sig);	1947	sigaddset(&G.pending_set, sig);
		1948	#if ENABLE_FEATURE_EDITING
		1949	bb_got_signal = sig; /* for read_line_input: "we got a signal" */
		1950	#endif
1947	#if ENABLE_HUSH_FAST	1951	#if ENABLE_HUSH_FAST
1948	if (sig == SIGCHLD) {	1952	if (sig == SIGCHLD) {
1949	G.count_SIGCHLD++;	1953	G.count_SIGCHLD++;
@@ -2652,30 +2656,53 @@ static int get_user_input(struct in_str *i)
2652	for (;;) {	2656	for (;;) {
2653	reinit_unicode_for_hush();	2657	reinit_unicode_for_hush();
2654	G.flag_SIGINT = 0;	2658	G.flag_SIGINT = 0;
2655	/* buglet: SIGINT will not make new prompt to appear _at once_,	2659
2656	* only after <Enter>. (^C works immediately) */	2660	bb_got_signal = 0;
2657	r = read_line_input(G.line_input_state, prompt_str,	2661	if (!sigisemptyset(&G.pending_set)) {
		2662	/* Whoops, already got a signal, do not call read_line_input */
		2663	bb_got_signal = r = -1;
		2664	} else {
		2665	/* For shell, LI_INTERRUPTIBLE is set:
		2666	* read_line_input will abort on either
		2667	* getting EINTR in poll(), or if it sees bb_got_signal != 0
		2668	* (IOW: if signal arrives before poll() is reached).
		2669	* Interactive testcases:
		2670	* (while kill -INT $$; do sleep 1; done) &
		2671	* #^^^ prints ^C, prints prompt, repeats
		2672	* trap 'echo I' int; (while kill -INT $$; do sleep 1; done) &
		2673	* #^^^ prints ^C, prints "I", prints prompt, repeats
		2674	* trap 'echo T' term; (while kill $$; do sleep 1; done) &
		2675	* #^^^ prints "T", prints prompt, repeats
		2676	* #(bash 5.0.17 exits after first "T", looks like a bug)
		2677	*/
		2678	r = read_line_input(G.line_input_state, prompt_str,
2658	G.user_input_buf, CONFIG_FEATURE_EDITING_MAX_LEN-1	2679	G.user_input_buf, CONFIG_FEATURE_EDITING_MAX_LEN-1
2659	);	2680	);
2660	/* read_line_input intercepts ^C, "convert" it to SIGINT */	2681	/* read_line_input intercepts ^C, "convert" it to SIGINT */
2661	if (r == 0) {	2682	if (r == 0)
2662	raise(SIGINT);	2683	raise(SIGINT);
		2684	}
		2685	/* bash prints ^C (before running a trap, if any)
		2686	* both on keyboard ^C and on real SIGINT (non-kbd generated).
		2687	*/
		2688	if (sigismember(&G.pending_set, SIGINT)) {
		2689	write(STDOUT_FILENO, "^C\n", 3);
		2690	G.last_exitcode = 128 \| SIGINT;
2663	}	2691	}
2664	check_and_run_traps();	2692	check_and_run_traps();
2665	if (r != 0 && !G.flag_SIGINT)	2693	if (r == 0) /* keyboard ^C? */
		2694	continue; /* go back, read another input line */
		2695	if (r > 0) /* normal input? (no ^C, no ^D, no signals) */
2666	break;	2696	break;
2667	/* ^C or SIGINT: repeat */	2697	if (!bb_got_signal) {
2668	/* bash prints ^C even on real SIGINT (non-kbd generated) */	2698	/* r < 0: ^D/EOF/error detected (but not signal) */
2669	write(STDOUT_FILENO, "^C\n", 3);	2699	/* ^D on interactive input goes to next line before exiting: */
2670	G.last_exitcode = 128 \| SIGINT;	2700	write(STDOUT_FILENO, "\n", 1);
2671	}	2701	i->p = NULL;
2672	if (r < 0) {	2702	i->peek_buf[0] = r = EOF;
2673	/* EOF/error detected */	2703	return r;
2674	/* ^D on interactive input goes to next line before exiting: */	2704	}
2675	write(STDOUT_FILENO, "\n", 1);	2705	/* it was a signal: go back, read another input line */
2676	i->p = NULL;
2677	i->peek_buf[0] = r = EOF;
2678	return r;
2679	}	2706	}
2680	i->p = G.user_input_buf;	2707	i->p = G.user_input_buf;
2681	return (unsigned char)*i->p++;	2708	return (unsigned char)*i->p++;