From b5930a30ceffba7e8dfc1f34ea8f3c8eee781fc8 Mon Sep 17 00:00:00 2001 From: Koichi Murase Date: Mon, 8 Feb 2021 18:10:23 +0900 Subject: [PATCH] Use select(2) for the read timeout --- bashline.c | 10 +-- builtins/common.h | 8 ++- builtins/read.def | 179 +++++++++++++++++++++++++++++++++++++++++----- config-bot.h | 4 ++ lib/sh/zread.c | 4 +- quit.h | 6 -- trap.c | 2 +- 7 files changed, 180 insertions(+), 33 deletions(-) diff --git a/bashline.c b/bashline.c index c69c0c5e..89ef83e0 100644 --- a/bashline.c +++ b/bashline.c @@ -4625,16 +4625,18 @@ bash_event_hook () sig = terminating_signal; else if (interrupt_state) sig = SIGINT; - else if (sigalrm_seen) +#if !defined (USE_SELECT_FOR_READ_TIMEOUT) + else if (is_timeout_reached ()) sig = SIGALRM; +#endif else sig = first_pending_trap (); /* If we're going to longjmp to top_level, make sure we clean up readline. check_signals will call QUIT, which will eventually longjmp to top_level, - calling run_interrupt_trap along the way. The check for sigalrm_seen is - to clean up the read builtin's state. */ - if (terminating_signal || interrupt_state || sigalrm_seen) + calling run_interrupt_trap along the way. The check for + is_timeout_reached is to clean up the read builtin's state. */ + if (terminating_signal || interrupt_state || is_timeout_reached ()) rl_cleanup_after_signal (); bashline_reset_event_hook (); diff --git a/builtins/common.h b/builtins/common.h index a4f9275d..f4265b00 100644 --- a/builtins/common.h +++ b/builtins/common.h @@ -218,6 +218,11 @@ extern int force_execute_file PARAMS((const char *, int)); extern int source_file PARAMS((const char *, int)); extern int fc_execute_file PARAMS((const char *)); +/* Functions from read.def */ +extern int is_timeout_reached PARAMS((void)); +extern int do_timeout PARAMS((int)); +extern void check_timeout PARAMS((void)); + /* variables from common.c */ extern sh_builtin_func_t *this_shell_builtin; extern sh_builtin_func_t *last_shell_builtin; @@ -236,9 +241,6 @@ extern int breaking; extern int continuing; extern int loop_level; -/* variables from read.def */ -extern int sigalrm_seen; - /* variables from shift.def */ extern int print_shift_error; diff --git a/builtins/read.def b/builtins/read.def index 39828f3f..cdfa0f51 100644 --- a/builtins/read.def +++ b/builtins/read.def @@ -89,6 +89,10 @@ $END # include #endif +#if defined (USE_SELECT_FOR_READ_TIMEOUT) +# include +#endif + #include "../bashintl.h" #include "../shell.h" @@ -132,25 +136,127 @@ static int read_mbchar PARAMS((int, char *, int, int, int)); #endif static void ttyrestore PARAMS((struct ttsave *)); +#if !defined (USE_SELECT_FOR_READ_TIMEOUT) static sighandler sigalrm PARAMS((int)); -static void reset_alarm PARAMS((void)); +#endif +static void set_timeout PARAMS((unsigned int, unsigned int)); +static void reset_timeout PARAMS((void)); +static void cleanup_timeout PARAMS((void)); +int is_timeout_reached PARAMS((void)); +int do_timeout PARAMS((int)); +void check_timeout PARAMS((void)); /* Try this to see what the rest of the shell can do with the information. */ procenv_t alrmbuf; -int sigalrm_seen; +#if defined (USE_SELECT_FOR_READ_TIMEOUT) +static struct timeval tmout_time; +#else +static int sigalrm_seen; +static SigHandler *old_alrm; +#endif static int reading, tty_modified; -static SigHandler *old_alrm; static unsigned char delim; static struct ttsave termsave; +#if defined (USE_SELECT_FOR_READ_TIMEOUT) +static void +set_timeout (unsigned int tmsec, unsigned int tmusec) +{ + if (gettimeofday(&tmout_time, 0) != 0) + { + tmout_time.tv_sec = 0; + tmout_time.tv_usec = 0; + } + tmout_time.tv_sec += tmsec; + tmout_time.tv_usec += tmusec; + if (tmout_time.tv_usec >= 1000000) + { + tmout_time.tv_sec++; + tmout_time.tv_usec -= 1000000; + } + return 0; +} + +static void +reset_timeout () +{ + cleanup_timeout(); +} + +static void +cleanup_timeout () +{ + tmout_time.tv_sec = 0; + tmout_time.tv_usec = 0; +} + +int +is_timeout_reached () +{ + struct timeval current_time; + + /* timeout is not set */ + if (tmout_time.tv_sec == 0 && tmout_time.tv_usec == 0) + return 0; + + /* timeout has been reached */ + if (gettimeofday(¤t_time, 0) != 0 || + current_time.tv_sec > tmout_time.tv_sec || + (current_time.tv_sec == tmout_time.tv_sec && + current_time.tv_usec >= tmout_time.tv_usec)) + return 1; + + return 0; +} + +int +do_timeout (int fd) +{ + int r; + struct timeval current_time, timeout; + fd_set readfds; + + /* If timeout is not set, return 0. */ + if (tmout_time.tv_sec == 0 && tmout_time.tv_usec == 0) + return 0; + + /* If timeout has been reached, do longjmp. */ + if (gettimeofday(¤t_time, 0) != 0 || + current_time.tv_sec > tmout_time.tv_sec || + (current_time.tv_sec == tmout_time.tv_sec && + current_time.tv_usec >= tmout_time.tv_usec)) + sh_longjmp (alrmbuf, 1); + + /* Call select with timeout */ + FD_ZERO (&readfds); + FD_SET (fd, &readfds); + timeout.tv_sec = tmout_time.tv_sec - current_time.tv_sec; + timeout.tv_usec = tmout_time.tv_usec - current_time.tv_usec; + if (current_time.tv_usec > tmout_time.tv_usec) + { + timeout.tv_sec--; + timeout.tv_usec += 1000000; + } + r = select (fd + 1, &readfds, NULL, NULL, &timeout); + + if (r < 0) + return r; /* Error: select sets errno. */ + else if (r == 0) + sh_longjmp (alrmbuf, 1); + else + return 0; +} + +#else /* In all cases, SIGALRM just sets a flag that we check periodically. This avoids problems with the semi-tricky stuff we do with the xfree of input_string at the top of the unwind-protect list (see below). */ -/* Set a flag that CHECK_ALRM can check. This relies on zread or read_builtin - calling trap.c:check_signals(), which knows about sigalrm_seen and alrmbuf. */ +/* Set a flag that check_timeout() can check. This relies on zread or + read_builtin calling trap.c:check_signals(), which knows about + sigalrm_seen and alrmbuf. */ static sighandler sigalrm (s) int s; @@ -159,13 +265,50 @@ sigalrm (s) } static void -reset_alarm () +set_timeout (unsigned int tmsec, unsigned int tmusec) +{ + old_alrm = set_signal_handler (SIGALRM, sigalrm); + add_unwind_protect (reset_timeout, (char *)NULL); + falarm (tmsec, tmusec); +} + +static void +reset_timeout () { /* Cancel alarm before restoring signal handler. */ falarm (0, 0); set_signal_handler (SIGALRM, old_alrm); } +static void +cleanup_timeout () +{ + sigalrm_seen = 0; +} + +int +is_timeout_reached () +{ + return sigalrm_seen; +} + +int +do_timeout (int fd) +{ + /* Nothing needed here. The timeout would be instead processed by + SIGALRM while executing read(2). */ + (void) fd; + return 0; +} +#endif + +void +check_timeout () +{ + if (is_timeout_reached()) + sh_longjmp (alrmbuf, 1); +} + /* Read the value of the shell variables whose names follow. The reading is done from the current input stream, whatever that may be. Successive words of the input line are assigned @@ -226,7 +369,8 @@ read_builtin (list) USE_VAR(ps2); USE_VAR(lastsig); - sigalrm_seen = reading = tty_modified = 0; + cleanup_timeout (); + reading = tty_modified = 0; i = 0; /* Index into the string that we are reading. */ raw = edit = 0; /* Not reading raw input by default. */ @@ -439,7 +583,8 @@ read_builtin (list) code = setjmp_nosigs (alrmbuf); if (code) { - sigalrm_seen = 0; + cleanup_timeout (); + /* Tricky. The top of the unwind-protect stack is the free of input_string. We want to run all the rest and use input_string, so we have to save input_string temporarily, run the unwind- @@ -461,8 +606,6 @@ read_builtin (list) } if (interactive_shell == 0) initialize_terminating_signals (); - old_alrm = set_signal_handler (SIGALRM, sigalrm); - add_unwind_protect (reset_alarm, (char *)NULL); #if defined (READLINE) if (edit) { @@ -470,7 +613,7 @@ read_builtin (list) add_unwind_protect (bashline_reset_event_hook, (char *)NULL); } #endif - falarm (tmsec, tmusec); + set_timeout (tmsec, tmusec); } /* If we've been asked to read only NCHARS chars, or we're using some @@ -546,7 +689,7 @@ read_builtin (list) of the unwind-protect stack after the realloc() works right. */ add_unwind_protect (xfree, input_string); - CHECK_ALRM; + check_timeout (); if ((nchars > 0) && (input_is_tty == 0) && ignore_delim) /* read -N */ unbuffered_read = 2; else if ((nchars > 0) || (delim != '\n') || input_is_pipe) @@ -565,7 +708,7 @@ read_builtin (list) ps2 = 0; for (print_ps2 = eof = retval = 0;;) { - CHECK_ALRM; + check_timeout (); #if defined (READLINE) if (edit) @@ -604,7 +747,7 @@ read_builtin (list) } reading = 1; - CHECK_ALRM; + check_timeout (); errno = 0; if (unbuffered_read == 2) retval = posixly_correct ? zreadintr (fd, &c, 1) : zreadn (fd, &c, nchars - nr); @@ -645,7 +788,7 @@ read_builtin (list) #endif if (retval <= 0) /* XXX shouldn't happen */ - CHECK_ALRM; + check_timeout (); /* XXX -- use i + mb_cur_max (at least 4) for multibyte/read_mbchar */ if (i + (mb_cur_max > 4 ? mb_cur_max : 4) >= size) @@ -705,7 +848,7 @@ read_builtin (list) add_char: input_string[i++] = c; - CHECK_ALRM; + check_timeout (); #if defined (HANDLE_MULTIBYTE) /* XXX - what if C == 127? Can DEL introduce a multibyte sequence? */ @@ -742,7 +885,7 @@ add_char: break; } input_string[i] = '\0'; - CHECK_ALRM; + check_timeout (); #if defined (READLINE) if (edit) @@ -759,7 +902,7 @@ add_char: } if (tmsec > 0 || tmusec > 0) - reset_alarm (); + reset_timeout (); if (nchars > 0 || delim != '\n') { diff --git a/config-bot.h b/config-bot.h index b075c778..75e67018 100644 --- a/config-bot.h +++ b/config-bot.h @@ -60,6 +60,10 @@ # define SYS_SIGLIST_DECLARED #endif +#if defined (HAVE_SELECT) && defined (HAVE_GETTIMEOFDAY) +# define USE_SELECT_FOR_READ_TIMEOUT +#endif + /***********************************************************************/ /* Unset defines based on what configure reports as missing or broken. */ /***********************************************************************/ diff --git a/lib/sh/zread.c b/lib/sh/zread.c index 71a06a76..06620661 100644 --- a/lib/sh/zread.c +++ b/lib/sh/zread.c @@ -46,6 +46,7 @@ extern int executing_builtin; extern void check_signals_and_traps (void); extern void check_signals (void); extern int signal_is_trapped (int); +extern int do_timeout (int); /* Read LEN bytes from FD into BUF. Retry the read on EINTR. Any other error causes the loop to break. */ @@ -58,7 +59,8 @@ zread (fd, buf, len) ssize_t r; check_signals (); /* check for signals before a blocking read */ - while ((r = read (fd, buf, len)) < 0 && errno == EINTR) + while (((r = do_timeout (fd)) < 0 + || (r = read (fd, buf, len)) < 0) && errno == EINTR) { int t; t = errno; diff --git a/quit.h b/quit.h index db8a776b..887d2b91 100644 --- a/quit.h +++ b/quit.h @@ -38,12 +38,6 @@ extern volatile sig_atomic_t terminating_signal; if (interrupt_state) throw_to_top_level (); \ } while (0) -#define CHECK_ALRM \ - do { \ - if (sigalrm_seen) \ - sh_longjmp (alrmbuf, 1); \ - } while (0) - #define SETINTERRUPT interrupt_state = 1 #define CLRINTERRUPT interrupt_state = 0 diff --git a/trap.c b/trap.c index 1b27fb3a..9c3db84a 100644 --- a/trap.c +++ b/trap.c @@ -587,7 +587,7 @@ clear_pending_traps () void check_signals () { - CHECK_ALRM; /* set by the read builtin */ + check_timeout (); /* check timeout set by the read builtin */ QUIT; } -- 2.21.3