diff options
| -rw-r--r-- | include/libbb.h | 2 | ||||
| -rw-r--r-- | libbb/read_printf.c | 9 | ||||
| -rw-r--r-- | shell/ash.c | 6 | ||||
| -rw-r--r-- | shell/hush.c | 98 | ||||
| -rw-r--r-- | shell/shell_common.c | 17 |
5 files changed, 120 insertions, 12 deletions
diff --git a/include/libbb.h b/include/libbb.h index 4ea94e77f..56dfa61b7 100644 --- a/include/libbb.h +++ b/include/libbb.h @@ -672,7 +672,7 @@ void* xrealloc_vector_helper(void *vector, unsigned sizeof_and_shift, int idx) F extern ssize_t safe_read(int fd, void *buf, size_t count) FAST_FUNC; -extern ssize_t nonblock_immune_read(int fd, void *buf, size_t count) FAST_FUNC; +extern ssize_t nonblock_immune_read(int fd, void *buf, size_t count, int loop_on_EINTR) FAST_FUNC; // NB: will return short read on error, not -1, // if some data was read before error occurred extern ssize_t full_read(int fd, void *buf, size_t count) FAST_FUNC; diff --git a/libbb/read_printf.c b/libbb/read_printf.c index 0e6fbf662..192f83d6e 100644 --- a/libbb/read_printf.c +++ b/libbb/read_printf.c @@ -55,19 +55,20 @@ * which detects EAGAIN and uses poll() to wait on the fd. * Thankfully, poll() doesn't care about O_NONBLOCK flag. */ -ssize_t FAST_FUNC nonblock_immune_read(int fd, void *buf, size_t count) +ssize_t FAST_FUNC nonblock_immune_read(int fd, void *buf, size_t count, int loop_on_EINTR) { struct pollfd pfd[1]; ssize_t n; while (1) { - n = safe_read(fd, buf, count); + n = loop_on_EINTR ? safe_read(fd, buf, count) : read(fd, buf, count); if (n >= 0 || errno != EAGAIN) return n; /* fd is in O_NONBLOCK mode. Wait using poll and repeat */ pfd[0].fd = fd; pfd[0].events = POLLIN; - safe_poll(pfd, 1, -1); /* note: this pulls in printf */ + /* note: safe_poll pulls in printf */ + loop_on_EINTR ? safe_poll(pfd, 1, -1) : poll(pfd, 1, -1); } } @@ -90,7 +91,7 @@ char* FAST_FUNC xmalloc_reads(int fd, size_t *maxsz_p) p = buf + sz; sz += 128; } - if (nonblock_immune_read(fd, p, 1) != 1) { + if (nonblock_immune_read(fd, p, 1, /*loop_on_EINTR:*/ 1) != 1) { /* EOF/error */ if (p == buf) { /* we read nothing */ free(buf); diff --git a/shell/ash.c b/shell/ash.c index b1b11bd1b..d48cd016f 100644 --- a/shell/ash.c +++ b/shell/ash.c @@ -5918,7 +5918,7 @@ expbackq(union node *cmd, int quoted, int quotes) read: if (in.fd < 0) break; - i = nonblock_immune_read(in.fd, buf, sizeof(buf)); + i = nonblock_immune_read(in.fd, buf, sizeof(buf), /*loop_on_EINTR:*/ 1); TRACE(("expbackq: read returns %d\n", i)); if (i <= 0) break; @@ -9617,7 +9617,7 @@ preadfd(void) #if ENABLE_FEATURE_EDITING retry: if (!iflag || g_parsefile->pf_fd != STDIN_FILENO) - nr = nonblock_immune_read(g_parsefile->pf_fd, buf, IBUFSIZ - 1); + nr = nonblock_immune_read(g_parsefile->pf_fd, buf, IBUFSIZ - 1, /*loop_on_EINTR:*/ 1); else { int timeout = -1; # if ENABLE_ASH_IDLE_TIMEOUT @@ -9663,7 +9663,7 @@ preadfd(void) } } #else - nr = nonblock_immune_read(g_parsefile->pf_fd, buf, IBUFSIZ - 1); + nr = nonblock_immune_read(g_parsefile->pf_fd, buf, IBUFSIZ - 1, /*loop_on_EINTR:*/ 1); #endif #if 0 /* disabled: nonblock_immune_read() handles this problem */ diff --git a/shell/hush.c b/shell/hush.c index bcd458427..0b17b222d 100644 --- a/shell/hush.c +++ b/shell/hush.c @@ -795,8 +795,15 @@ struct globals { /* which signals have non-DFL handler (even with no traps set)? */ unsigned non_DFL_mask; char **traps; /* char *traps[NSIG] */ - sigset_t blocked_set; + /* Signal mask on the entry to the (top-level) shell. Never modified. */ sigset_t inherited_set; + /* Starts equal to inherited_set, + * but shell-special signals are added and SIGCHLD is removed. + * When a trap is set/cleared, signal is added to/removed from it: + */ + sigset_t blocked_set; + /* Used by read() */ + sigset_t detected_set; #if HUSH_DEBUG unsigned long memleak_value; int debug_indent; @@ -1476,6 +1483,17 @@ static int check_and_run_traps(int sig) goto got_sig; while (1) { + if (!sigisemptyset(&G.detected_set)) { + sig = 0; + do { + sig++; + if (sigismember(&G.detected_set, sig)) { + sigdelset(&G.detected_set, sig); + goto got_sig; + } + } while (sig < NSIG); + } + sig = sigtimedwait(&G.blocked_set, NULL, &zero_timespec); if (sig <= 0) break; @@ -8484,6 +8502,32 @@ static int FAST_FUNC builtin_pwd(char **argv UNUSED_PARAM) return EXIT_SUCCESS; } +/* Interruptibility of read builtin in bash + * (tested on bash-4.2.8 by sending signals (not by ^C)): + * + * Empty trap makes read ignore corresponding signal, for any signal. + * + * SIGINT: + * - terminates non-interactive shell; + * - interrupts read in interactive shell; + * if it has non-empty trap: + * - executes trap and returns to command prompt in interactive shell; + * - executes trap and returns to read in non-interactive shell; + * SIGTERM: + * - is ignored (does not interrupt) read in interactive shell; + * - terminates non-interactive shell; + * if it has non-empty trap: + * - executes trap and returns to read; + * SIGHUP: + * - terminates shell (regardless of interactivity); + * if it has non-empty trap: + * - executes trap and returns to read; + */ +/* helper */ +static void record_signal(int sig) +{ + sigaddset(&G.detected_set, sig); +} static int FAST_FUNC builtin_read(char **argv) { const char *r; @@ -8491,7 +8535,9 @@ static int FAST_FUNC builtin_read(char **argv) char *opt_p = NULL; char *opt_t = NULL; char *opt_u = NULL; + const char *ifs; int read_flags; + sigset_t saved_blkd_set; /* "!": do not abort on errors. * Option string must start with "sr" to match BUILTIN_READ_xxx @@ -8500,10 +8546,47 @@ static int FAST_FUNC builtin_read(char **argv) if (read_flags == (uint32_t)-1) return EXIT_FAILURE; argv += optind; + ifs = get_local_var_value("IFS"); /* can be NULL */ + + again: + /* We need to temporarily unblock and record signals around read */ + + saved_blkd_set = G.blocked_set; + { + unsigned sig; + struct sigaction sa, old_sa; + + memset(&sa, 0, sizeof(sa)); + sigfillset(&sa.sa_mask); + /*sa.sa_flags = 0;*/ + sa.sa_handler = record_signal; + + sig = 0; + do { + sig++; + if (sigismember(&G.blocked_set, sig)) { + char *sig_trap = (G.traps && G.traps[sig]) ? G.traps[sig] : NULL; + /* If has a nonempty trap... */ + if ((sig_trap && sig_trap[0]) + /* ...or has no trap and is SIGINT or SIGHUP */ + || (!sig_trap && (sig == SIGINT || sig == SIGHUP)) + ) { + sigaction(sig, &sa, &old_sa); + if (old_sa.sa_handler == SIG_IGN) /* oops... restore back to IGN! */ + sigaction_set(sig, &old_sa); + else + sigdelset(&G.blocked_set, sig); + } + } + } while (sig < NSIG-1); + } + + if (memcmp(&saved_blkd_set, &G.blocked_set, sizeof(saved_blkd_set)) != 0) + sigprocmask_set(&G.blocked_set); r = shell_builtin_read(set_local_var_from_halves, argv, - get_local_var_value("IFS"), /* can be NULL */ + ifs, read_flags, opt_n, opt_p, @@ -8511,6 +8594,17 @@ static int FAST_FUNC builtin_read(char **argv) opt_u ); + if (memcmp(&saved_blkd_set, &G.blocked_set, sizeof(saved_blkd_set)) != 0) { + G.blocked_set = saved_blkd_set; + sigprocmask_set(&G.blocked_set); + } + + if ((uintptr_t)r == 1 && errno == EINTR) { + unsigned sig = check_and_run_traps(0); + if (sig && sig != SIGINT) + goto again; + } + if ((uintptr_t)r > 1) { bb_error_msg("%s", r); r = (char*)(uintptr_t)1; diff --git a/shell/shell_common.c b/shell/shell_common.c index 86a6493ed..a5c455c8e 100644 --- a/shell/shell_common.c +++ b/shell/shell_common.c @@ -36,6 +36,10 @@ int FAST_FUNC is_well_formed_var_name(const char *s, char terminator) /* read builtin */ +/* Needs to be interruptible: shell mush handle traps and shell-special signals + * while inside read. To implement this, be sure to not loop on EINTR + * and return errno == EINTR reliably. + */ //TODO: use more efficient setvar() which takes a pointer to malloced "VAR=VAL" //string. hush naturally has it, and ash has setvareq(). //Here we can simply store "VAR=" at buffer start and store read data directly @@ -51,6 +55,7 @@ shell_builtin_read(void FAST_FUNC (*setvar)(const char *name, const char *val), const char *opt_u ) { + unsigned err; unsigned end_ms; /* -t TIMEOUT */ int fd; /* -u FD */ int nchars; /* -n NUM */ @@ -62,6 +67,8 @@ shell_builtin_read(void FAST_FUNC (*setvar)(const char *name, const char *val), int startword; smallint backslash; + errno = err = 0; + pp = argv; while (*pp) { if (!is_well_formed_var_name(*pp, '\0')) { @@ -153,6 +160,8 @@ shell_builtin_read(void FAST_FUNC (*setvar)(const char *name, const char *val), do { char c; + errno = 0; + if (end_ms) { int timeout; struct pollfd pfd[1]; @@ -161,8 +170,9 @@ shell_builtin_read(void FAST_FUNC (*setvar)(const char *name, const char *val), pfd[0].events = POLLIN; timeout = end_ms - (unsigned)monotonic_ms(); if (timeout <= 0 /* already late? */ - || safe_poll(pfd, 1, timeout) != 1 /* no? wait... */ + || poll(pfd, 1, timeout) != 1 /* no? wait... */ ) { /* timed out! */ + err = errno; retval = (const char *)(uintptr_t)1; goto ret; } @@ -170,7 +180,8 @@ shell_builtin_read(void FAST_FUNC (*setvar)(const char *name, const char *val), if ((bufpos & 0xff) == 0) buffer = xrealloc(buffer, bufpos + 0x100); - if (nonblock_immune_read(fd, &buffer[bufpos], 1) != 1) { + if (nonblock_immune_read(fd, &buffer[bufpos], 1, /*loop_on_EINTR:*/ 0) != 1) { + err = errno; retval = (const char *)(uintptr_t)1; break; } @@ -240,6 +251,8 @@ shell_builtin_read(void FAST_FUNC (*setvar)(const char *name, const char *val), free(buffer); if (read_flags & BUILTIN_READ_SILENT) tcsetattr(fd, TCSANOW, &old_tty); + + errno = err; return retval; } |