diff options
| -rw-r--r-- | shell/hush.c | 139 |
1 files changed, 129 insertions, 10 deletions
diff --git a/shell/hush.c b/shell/hush.c index 5203f2eef..17673c0cb 100644 --- a/shell/hush.c +++ b/shell/hush.c @@ -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; |