From 12566e7f9b5e5c5d445bc4d36991d134b431dc6c Mon Sep 17 00:00:00 2001 From: Denys Vlasenko Date: Mon, 17 Jan 2022 03:02:40 +0100 Subject: 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 --- shell/ash.c | 39 +++++++++++++++++++++++++++-------- shell/hush.c | 67 ++++++++++++++++++++++++++++++++++++++++++------------------ 2 files changed, 77 insertions(+), 29 deletions(-) (limited to 'shell') 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()! -//This would cause a memory leak in interactive shell -//(repeated internal allocations in read_line_input): -// (while kill -INT $$; do :; done) & + /* For shell, LI_INTERRUPTIBLE is set: + * read_line_input will abort on either + * getting EINTR in poll(), or if it sees bb_got_signal != 0 + * (IOW: if signal arrives before poll() is reached). + * Interactive testcases: + * (while kill -INT $$; 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) + */ + 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); - raise(SIGINT); + write(STDOUT_FILENO, "^C\n", 3); + 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 . (^C works immediately) */ - r = read_line_input(G.line_input_state, prompt_str, + + bb_got_signal = 0; + 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 */ - if (r == 0) { - raise(SIGINT); + ); + /* read_line_input intercepts ^C, "convert" it to SIGINT */ + if (r == 0) + 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 */ - /* bash prints ^C even on real SIGINT (non-kbd generated) */ - write(STDOUT_FILENO, "^C\n", 3); - G.last_exitcode = 128 | SIGINT; - } - if (r < 0) { - /* EOF/error detected */ - /* ^D on interactive input goes to next line before exiting: */ - write(STDOUT_FILENO, "\n", 1); - i->p = NULL; - i->peek_buf[0] = r = EOF; - return r; + if (!bb_got_signal) { + /* r < 0: ^D/EOF/error detected (but not signal) */ + /* ^D on interactive input goes to next line before exiting: */ + write(STDOUT_FILENO, "\n", 1); + i->p = NULL; + i->peek_buf[0] = r = EOF; + return r; + } + /* it was a signal: go back, read another input line */ } i->p = G.user_input_buf; return (unsigned char)*i->p++; -- cgit v1.2.3-55-g6feb