svn commit: [25965] trunk/busybox/shell
vda at busybox.net
vda at busybox.net
Sun Apr 5 19:13:39 UTC 2009
Author: vda
Date: 2009-04-05 19:13:39 +0000 (Sun, 05 Apr 2009)
New Revision: 25965
Log:
hush: audit and fix "interactive shell" setup code.
function old new delta
block_signals - 139 +139
maybe_set_to_sigexit - 47 +47
run_list 2018 2030 +12
expand_variables 2155 2165 +10
maybe_set_sighandler 47 - -47
hush_main 992 918 -74
------------------------------------------------------------------------------
(add/remove: 2/1 grow/shrink: 2/1 up/down: 208/-121) Total: 87 bytes
Modified:
trunk/busybox/shell/hush.c
Changeset:
Modified: trunk/busybox/shell/hush.c
===================================================================
--- trunk/busybox/shell/hush.c 2009-04-05 10:39:03 UTC (rev 25964)
+++ trunk/busybox/shell/hush.c 2009-04-05 19:13:39 UTC (rev 25965)
@@ -850,8 +850,6 @@
* Note: as a result, we do not use signal handlers much. The only uses
* are to count SIGCHLDs [disabled - bug somewhere, + bloat]
* and to restore tty pgrp on signal-induced exit.
- *
- * TODO: check/fix wait builtin to be interruptible.
*/
//static void SIGCHLD_handler(int sig UNUSED_PARAM)
@@ -859,36 +857,6 @@
// G.count_SIGCHLD++;
//}
-/* called once at shell init */
-static void init_signal_mask(void)
-{
- unsigned sig;
- unsigned mask = (1 << SIGQUIT);
- if (G_interactive_fd) {
- mask = 0
- | (1 << SIGQUIT)
- | (1 << SIGTERM)
- | (1 << SIGHUP)
-#if ENABLE_HUSH_JOB
- | (1 << SIGTTIN) | (1 << SIGTTOU) | (1 << SIGTSTP)
-#endif
- | (1 << SIGINT)
- ;
- }
- G.non_DFL_mask = mask;
-
- sigprocmask(SIG_SETMASK, NULL, &G.blocked_set);
- sig = 0;
- while (mask) {
- if (mask & 1)
- sigaddset(&G.blocked_set, sig);
- mask >>= 1;
- sig++;
- }
- sigdelset(&G.blocked_set, SIGCHLD);
- sigprocmask(SIG_SETMASK, &G.blocked_set, &G.inherited_set);
-}
-
static int check_and_run_traps(int sig)
{
static const struct timespec zero_timespec = { 0, 0 };
@@ -934,7 +902,6 @@
}
#if ENABLE_HUSH_JOB
-
/* Restores tty foreground process group, and exits.
* May be called as signal handler for fatal signal
* (will faithfully resend signal to itself, producing correct exit state)
@@ -957,48 +924,6 @@
kill_myself_with_sig(sig); /* does not return */
}
-
-/* helper */
-static void maybe_set_sighandler(int sig)
-{
- void (*handler)(int);
- /* non_DFL_mask'ed signals are, well, masked,
- * no need to set handler for them.
- */
- if (!((G.non_DFL_mask >> sig) & 1)) {
- handler = signal(sig, sigexit);
- if (handler == SIG_IGN) /* oops... restore back to IGN! */
- signal(sig, handler);
- }
-}
-/* Used only to set handler to restore pgrp on exit */
-static void set_fatal_signals_to_sigexit(void)
-{
- if (HUSH_DEBUG) {
- maybe_set_sighandler(SIGILL );
- maybe_set_sighandler(SIGFPE );
- maybe_set_sighandler(SIGBUS );
- maybe_set_sighandler(SIGSEGV);
- maybe_set_sighandler(SIGTRAP);
- } /* else: hush is perfect. what SEGV? */
-
- maybe_set_sighandler(SIGABRT);
-
- /* bash 3.2 seems to handle these just like 'fatal' ones */
- maybe_set_sighandler(SIGPIPE);
- maybe_set_sighandler(SIGALRM);
- maybe_set_sighandler(SIGHUP );
-
- /* if we aren't interactive... but in this case
- * we never want to restore pgrp on exit, and this fn is not called */
- /*maybe_set_sighandler(SIGTERM);*/
- /*maybe_set_sighandler(SIGINT );*/
-}
-
-#else /* !JOB */
-
-#define set_fatal_signals_to_sigexit(handler) ((void)0)
-
#endif
/* Restores tty foreground process group, and exits. */
@@ -1007,6 +932,7 @@
{
if (G.traps && G.traps[0] && G.traps[0][0]) {
char *argv[] = { NULL, xstrdup(G.traps[0]), NULL };
+//TODO: do we need to prevent recursion?
builtin_eval(argv);
free(argv[1]);
}
@@ -2896,7 +2822,7 @@
command->pid = BB_MMU ? fork() : vfork();
if (!command->pid) { /* child */
#if ENABLE_HUSH_JOB
- die_sleep = 0; /* let nofork's xfuncs die */
+ die_sleep = 0; /* do not restore tty pgrp on xfunc death */
/* Every child adds itself to new process group
* with pgid == pid_of_first_child_in_pipe */
@@ -2930,7 +2856,10 @@
/* pseudo_exec() does not return */
}
- /* parent */
+ /* parent or error */
+#if ENABLE_HUSH_JOB
+ die_sleep = -1; /* restore tty pgrp on xfunc death */
+#endif
#if !BB_MMU
/* Clean up after vforked child */
clean_up_after_re_execute();
@@ -3900,6 +3829,9 @@
bb_perror_msg_and_die(BB_MMU ? "fork" : "vfork");
if (pid == 0) { /* child */
+#if ENABLE_HUSH_JOB
+ die_sleep = 0; /* do not restore tty pgrp on xfunc death */
+#endif
/* Process substitution is not considered to be usual
* 'command execution'.
* SUSv3 says ctrl-Z should be ignored, ctrl-C should not.
@@ -3909,8 +3841,6 @@
+ (1 << SIGTTIN)
+ (1 << SIGTTOU)
, SIG_IGN);
- if (ENABLE_HUSH_JOB)
- die_sleep = 0; /* let nofork's xfuncs die */
close(channel[0]); /* NB: close _first_, then move fd! */
xmove_fd(channel[1], 1);
/* Prevent it from trying to handle ctrl-z etc */
@@ -3920,8 +3850,8 @@
_exit(G.last_return_code);
#else
/* We re-execute after vfork on NOMMU. This makes this script safe:
- * yes "0123456789012345678901234567890" | dd bs=32 count=64k >TESTFILE
- * huge=`cat TESTFILE` # was blocking here forever
+ * yes "0123456789012345678901234567890" | dd bs=32 count=64k >BIG
+ * huge=`cat BIG` # was blocking here forever
* echo OK
*/
re_execute_shell(s);
@@ -3929,6 +3859,9 @@
}
/* parent */
+#if ENABLE_HUSH_JOB
+ die_sleep = -1; /* restore tty pgrp on xfunc death */
+#endif
clean_up_after_re_execute();
close(channel[1]);
pf = fdopen(channel[0], "r");
@@ -4945,32 +4878,82 @@
parse_and_run_stream(&input, ';');
}
-#if ENABLE_HUSH_JOB
-/* Make sure we have a controlling tty. If we get started under a job
- * aware app (like bash for example), make sure we are now in charge so
- * we don't fight over who gets the foreground */
-static void setup_job_control(void)
+/* Called a few times only (or even once if "sh -c") */
+static void block_signals(int second_time)
{
- pid_t shell_pgrp;
+ unsigned sig;
+ unsigned mask;
- shell_pgrp = getpgrp();
+ mask = (1 << SIGQUIT);
+ if (G_interactive_fd) {
+ mask = 0
+ | (1 << SIGQUIT)
+ | (1 << SIGTERM)
+ | (1 << SIGHUP)
+#if ENABLE_HUSH_JOB
+ | (1 << SIGTTIN) | (1 << SIGTTOU) | (1 << SIGTSTP)
+#endif
+ | (1 << SIGINT)
+ ;
+ }
+ G.non_DFL_mask = mask;
- /* If we were ran as 'hush &',
- * sleep until we are in the foreground. */
- while (tcgetpgrp(G_interactive_fd) != shell_pgrp) {
- /* Send TTIN to ourself (should stop us) */
- kill(- shell_pgrp, SIGTTIN);
- shell_pgrp = getpgrp();
+ if (!second_time)
+ sigprocmask(SIG_SETMASK, NULL, &G.blocked_set);
+ sig = 0;
+ while (mask) {
+ if (mask & 1)
+ sigaddset(&G.blocked_set, sig);
+ mask >>= 1;
+ sig++;
}
+ sigdelset(&G.blocked_set, SIGCHLD);
- /* We _must_ restore tty pgrp on fatal signals */
- set_fatal_signals_to_sigexit();
+ sigprocmask(SIG_SETMASK, &G.blocked_set,
+ second_time ? NULL : &G.inherited_set);
+ /* POSIX allows shell to re-enable SIGCHLD
+ * even if it was SIG_IGN on entry */
+// G.count_SIGCHLD++; /* ensure it is != G.handled_SIGCHLD */
+ if (!second_time)
+ signal(SIGCHLD, SIG_DFL); // SIGCHLD_handler);
+}
- /* Put ourselves in our own process group. */
- bb_setpgrp(); /* is the same as setpgid(our_pid, our_pid); */
- /* Grab control of the terminal. */
- tcsetpgrp(G_interactive_fd, getpid());
+#if ENABLE_HUSH_JOB
+/* helper */
+static void maybe_set_to_sigexit(int sig)
+{
+ void (*handler)(int);
+ /* non_DFL_mask'ed signals are, well, masked,
+ * no need to set handler for them.
+ */
+ if (!((G.non_DFL_mask >> sig) & 1)) {
+ handler = signal(sig, sigexit);
+ if (handler == SIG_IGN) /* oops... restore back to IGN! */
+ signal(sig, handler);
+ }
}
+/* Set handlers to restore tty pgrm and exit */
+static void set_fatal_handlers(void)
+{
+ /* We _must_ restore tty pgrp on fatal signals */
+ if (HUSH_DEBUG) {
+ maybe_set_to_sigexit(SIGILL );
+ maybe_set_to_sigexit(SIGFPE );
+ maybe_set_to_sigexit(SIGBUS );
+ maybe_set_to_sigexit(SIGSEGV);
+ maybe_set_to_sigexit(SIGTRAP);
+ } /* else: hush is perfect. what SEGV? */
+ maybe_set_to_sigexit(SIGABRT);
+ /* bash 3.2 seems to handle these just like 'fatal' ones */
+ maybe_set_to_sigexit(SIGPIPE);
+ maybe_set_to_sigexit(SIGALRM);
+ maybe_set_to_sigexit(SIGHUP );
+ /* if we are interactive, SIGTERM and SIGINT are masked.
+ * if we aren't interactive... but in this case
+ * we never want to restore pgrp on exit, and this fn is not called */
+ /*maybe_set_to_sigexit(SIGTERM);*/
+ /*maybe_set_to_sigexit(SIGINT );*/
+}
#endif
static int set_mode(const char cstate, const char mode)
@@ -4994,7 +4977,7 @@
.flg_export = 1,
.flg_read_only = 1,
};
-
+ int signal_mask_is_inited = 0;
int opt;
char **e;
struct variable *cur_var;
@@ -5060,6 +5043,7 @@
optind--;
} /* else -c 'script' PAR0 PAR1: $0 is PAR0 */
G.global_argc = argc - optind;
+ block_signals(0); /* 0: called 1st time */
parse_and_run_string(optarg);
goto final_return;
case 'i':
@@ -5104,10 +5088,12 @@
bb_show_usage();
#endif
}
- }
+ } /* option parsing loop */
if (!G.root_pid)
G.root_pid = getpid();
+
+ /* If we are login shell... */
if (argv[0] && argv[0][0] == '-') {
FILE *input;
/* XXX what should argv be while sourcing /etc/profile? */
@@ -5115,26 +5101,57 @@
input = fopen_for_read("/etc/profile");
if (input != NULL) {
close_on_exec_on(fileno(input));
+ block_signals(0); /* 0: called 1st time */
+ signal_mask_is_inited = 1;
parse_and_run_file(input);
fclose(input);
}
+ /* bash: after sourcing /etc/profile,
+ * tries to source (in the given order):
+ * ~/.bash_profile, ~/.bash_login, ~/.profile,
+ * stopping of first found. --noprofile turns this off.
+ * bash also sources ~/.bash_logout on exit.
+ * If called as sh, skips .bash_XXX files.
+ */
}
-#if ENABLE_HUSH_JOB
+ if (argv[optind]) {
+ FILE *input;
+ /*
+ * Non-interactive "bash <script>" sources $BASH_ENV here
+ * (without scanning $PATH).
+ * If called as sh, does the same but with $ENV.
+ */
+ debug_printf("running script '%s'\n", argv[optind]);
+ G.global_argv = argv + optind;
+ G.global_argc = argc - optind;
+ input = xfopen_for_read(argv[optind]);
+ close_on_exec_on(fileno(input));
+ if (!signal_mask_is_inited)
+ block_signals(0); /* 0: called 1st time */
+ parse_and_run_file(input);
+#if ENABLE_FEATURE_CLEAN_UP
+ fclose(input);
+#endif
+ goto final_return;
+ }
+
+ /* Up to here, shell was non-interactive. Now it may become one. */
+
/* A shell is interactive if the '-i' flag was given, or if all of
* the following conditions are met:
* no -c command
* no arguments remaining or the -s flag given
* standard input is a terminal
* standard output is a terminal
- * Refer to Posix.2, the description of the 'sh' utility. */
- if (argv[optind] == NULL
- && isatty(STDIN_FILENO) && isatty(STDOUT_FILENO)
- ) {
+ * Refer to Posix.2, the description of the 'sh' utility.
+ */
+#if ENABLE_HUSH_JOB
+ if (isatty(STDIN_FILENO) && isatty(STDOUT_FILENO)) {
G.saved_tty_pgrp = tcgetpgrp(STDIN_FILENO);
- debug_printf("saved_tty_pgrp=%d\n", G.saved_tty_pgrp);
+ debug_printf("saved_tty_pgrp:%d\n", G.saved_tty_pgrp);
if (G.saved_tty_pgrp >= 0) {
- /* try to dup to high fd#, >= 255 */
+ /* try to dup stdin to high fd#, >= 255 */
G_interactive_fd = fcntl(STDIN_FILENO, F_DUPFD, 255);
if (G_interactive_fd < 0) {
/* try to dup to any fd */
@@ -5147,12 +5164,35 @@
// to (inadvertently) close/redirect it
}
}
- init_signal_mask(); /* note: ensures SIGCHLD is not masked */
- debug_printf("interactive_fd=%d\n", G_interactive_fd);
+ debug_printf("interactive_fd:%d\n", G_interactive_fd);
if (G_interactive_fd) {
- fcntl(G_interactive_fd, F_SETFD, FD_CLOEXEC);
- /* Looks like they want an interactive shell */
- setup_job_control();
+ pid_t shell_pgrp;
+
+ /* We are indeed interactive shell, and we will perform
+ * job control. Setting up for that. */
+
+ close_on_exec_on(G_interactive_fd);
+ /* If we were run as 'hush &', sleep until we are
+ * in the foreground (tty pgrp == our pgrp).
+ * If we get started under a job aware app (like bash),
+ * make sure we are now in charge so we don't fight over
+ * who gets the foreground */
+ while (1) {
+ shell_pgrp = getpgrp();
+ G.saved_tty_pgrp = tcgetpgrp(G_interactive_fd);
+ if (G.saved_tty_pgrp == shell_pgrp)
+ break;
+ /* send TTIN to ourself (should stop us) */
+ kill(- shell_pgrp, SIGTTIN);
+ }
+ /* Block some signals */
+ block_signals(signal_mask_is_inited);
+ /* Set other signals to restore saved_tty_pgrp */
+ set_fatal_handlers();
+ /* Put ourselves in our own process group */
+ bb_setpgrp(); /* is the same as setpgid(our_pid, our_pid); */
+ /* Grab control of the terminal */
+ tcsetpgrp(G_interactive_fd, getpid());
/* -1 is special - makes xfuncs longjmp, not exit
* (we reset die_sleep = 0 whereever we [v]fork) */
die_sleep = -1;
@@ -5160,12 +5200,12 @@
/* xfunc has failed! die die die */
hush_exit(xfunc_error_retval);
}
- }
+ } else if (!signal_mask_is_inited) {
+ block_signals(0); /* 0: called 1st time */
+ } /* else: block_signals(0) was done before */
#elif ENABLE_HUSH_INTERACTIVE
-/* no job control compiled, only prompt/line editing */
- if (argv[optind] == NULL
- && isatty(STDIN_FILENO) && isatty(STDOUT_FILENO)
- ) {
+ /* No job control compiled in, only prompt/line editing */
+ if (isatty(STDIN_FILENO) && isatty(STDOUT_FILENO)) {
G_interactive_fd = fcntl(STDIN_FILENO, F_DUPFD, 255);
if (G_interactive_fd < 0) {
/* try to dup to any fd */
@@ -5174,45 +5214,32 @@
/* give up */
G_interactive_fd = 0;
}
- if (G_interactive_fd) {
- fcntl(G_interactive_fd, F_SETFD, FD_CLOEXEC);
- }
}
- init_signal_mask(); /* note: ensures SIGCHLD is not masked */
+ if (G_interactive_fd) {
+ close_on_exec_on(G_interactive_fd);
+ block_signals(signal_mask_is_inited);
+ } else if (!signal_mask_is_inited) {
+ block_signals(0);
+ }
#else
-//TODO: we didn't do it for -c or /etc/profile! Shouldn't we?
- init_signal_mask();
+ /* We have interactiveness code disabled */
+ if (!signal_mask_is_inited) {
+ block_signals(0);
+ }
#endif
- /* POSIX allows shell to re-enable SIGCHLD
- * even if it was SIG_IGN on entry */
-//TODO: we didn't do it for -c or /etc/profile! Shouldn't we?
-// G.count_SIGCHLD++; /* ensure it is != G.handled_SIGCHLD */
- signal(SIGCHLD, SIG_DFL); // SIGCHLD_handler);
+ /* bash:
+ * if interactive but not a login shell, sources ~/.bashrc
+ * (--norc turns this off, --rcfile <file> overrides)
+ */
-#if ENABLE_HUSH_INTERACTIVE && !ENABLE_FEATURE_SH_EXTRA_QUIET
- if (G_interactive_fd) {
+ if (!ENABLE_FEATURE_SH_EXTRA_QUIET && G_interactive_fd) {
printf("\n\n%s hush - the humble shell v"HUSH_VER_STR"\n", bb_banner);
printf("Enter 'help' for a list of built-in commands.\n\n");
}
-#endif
- if (argv[optind] == NULL) {
- parse_and_run_file(stdin);
- } else {
- FILE *input;
- debug_printf("\nrunning script '%s'\n", argv[optind]);
- G.global_argv = argv + optind;
- G.global_argc = argc - optind;
- input = xfopen_for_read(argv[optind]);
- fcntl(fileno(input), F_SETFD, FD_CLOEXEC);
- parse_and_run_file(input);
-#if ENABLE_FEATURE_CLEAN_UP
- fclose(input);
-#endif
- }
+ parse_and_run_file(stdin);
final_return:
-
#if ENABLE_FEATURE_CLEAN_UP
if (G.cwd != bb_msg_unknown)
free((char*)G.cwd);
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