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authorGravatar Denys Vlasenko <vda.linux@googlemail.com>2017-08-02 16:37:39 +0200
committerGravatar Denys Vlasenko <vda.linux@googlemail.com>2017-08-02 16:37:39 +0200
commit7c40ddd9500907925041131374cb43eb87ef5494 (patch)
tree415676f7439a3c42e2137f357c8e8904a93007cc
parent95f7953f2c46c7b9c799250aa8dc6eb10cc5c726 (diff)
downloadbusybox-7c40ddd9500907925041131374cb43eb87ef5494.tar.gz
busybox-7c40ddd9500907925041131374cb43eb87ef5494.tar.bz2
NOFORK fixes
"rm -i FILE" and "yes" can now be interrupted by ^C in hush. This also now works: $ usleep 19999999 ^C $ echo $? 130 function old new delta run_pipe 1668 1711 +43 pseudo_exec_argv 312 321 +9 ------------------------------------------------------------------------------ (add/remove: 0/0 grow/shrink: 2/0 up/down: 52/0) Total: 52 bytes Signed-off-by: Denys Vlasenko <vda.linux@googlemail.com>
-rw-r--r--coreutils/rm.c5
-rw-r--r--coreutils/seq.c5
-rw-r--r--coreutils/usleep.c7
-rw-r--r--coreutils/yes.c3
-rw-r--r--docs/nofork_noexec.txt3
-rw-r--r--shell/hush.c31
6 files changed, 48 insertions, 6 deletions
diff --git a/coreutils/rm.c b/coreutils/rm.c
index f91c94570..5e4acab8c 100644
--- a/coreutils/rm.c
+++ b/coreutils/rm.c
@@ -16,7 +16,8 @@
//config: help
//config: rm is used to remove files or directories.
-//applet:IF_RM(APPLET_NOFORK(rm, rm, BB_DIR_BIN, BB_SUID_DROP, rm))
+//applet:IF_RM(APPLET_NOEXEC(rm, rm, BB_DIR_BIN, BB_SUID_DROP, rm))
+/* was NOFORK, but then "rm -i FILE" can't be ^C'ed if run by hush */
//kbuild:lib-$(CONFIG_RM) += rm.o
@@ -36,7 +37,7 @@
#include "libbb.h"
-/* This is a NOFORK applet. Be very careful! */
+/* This is a NOEXEC applet. Be very careful! */
int rm_main(int argc, char **argv) MAIN_EXTERNALLY_VISIBLE;
int rm_main(int argc UNUSED_PARAM, char **argv)
diff --git a/coreutils/seq.c b/coreutils/seq.c
index f36dbb4ec..c26ff06b9 100644
--- a/coreutils/seq.c
+++ b/coreutils/seq.c
@@ -12,7 +12,8 @@
//config: help
//config: print a sequence of numbers
-//applet:IF_SEQ(APPLET_NOFORK(seq, seq, BB_DIR_USR_BIN, BB_SUID_DROP, seq))
+//applet:IF_SEQ(APPLET_NOEXEC(seq, seq, BB_DIR_USR_BIN, BB_SUID_DROP, seq))
+/* was NOFORK, but then "seq 1 999999999" can't be ^C'ed if run by hush */
//kbuild:lib-$(CONFIG_SEQ) += seq.o
@@ -26,7 +27,7 @@
#include "libbb.h"
-/* This is a NOFORK applet. Be very careful! */
+/* This is a NOEXEC applet. Be very careful! */
int seq_main(int argc, char **argv) MAIN_EXTERNALLY_VISIBLE;
int seq_main(int argc, char **argv)
diff --git a/coreutils/usleep.c b/coreutils/usleep.c
index 7c25aada1..684ab781b 100644
--- a/coreutils/usleep.c
+++ b/coreutils/usleep.c
@@ -38,6 +38,13 @@ int usleep_main(int argc UNUSED_PARAM, char **argv)
bb_show_usage();
}
+ /* Safe wrt NOFORK? (noforks are not allowed to run for
+ * a long time). Try "usleep 99999999" + ^C + "echo $?"
+ * in hush with FEATURE_SH_NOFORK=y.
+ * At least on uclibc, usleep() thanslates to nanosleep()
+ * which returns early on any signal (even caught one),
+ * and uclibc does not loop back on EINTR.
+ */
usleep(xatou(argv[1]));
return EXIT_SUCCESS;
diff --git a/coreutils/yes.c b/coreutils/yes.c
index ea35d146c..c244bfe10 100644
--- a/coreutils/yes.c
+++ b/coreutils/yes.c
@@ -17,7 +17,8 @@
//config: yes is used to repeatedly output a specific string, or
//config: the default string 'y'.
-//applet:IF_YES(APPLET_NOFORK(yes, yes, BB_DIR_USR_BIN, BB_SUID_DROP, yes))
+//applet:IF_YES(APPLET_NOEXEC(yes, yes, BB_DIR_USR_BIN, BB_SUID_DROP, yes))
+/* was NOFORK, but then yes can't be ^C'ed if run by hush */
//kbuild:lib-$(CONFIG_YES) += yes.o
diff --git a/docs/nofork_noexec.txt b/docs/nofork_noexec.txt
index a24dd9c27..0ad4e6e60 100644
--- a/docs/nofork_noexec.txt
+++ b/docs/nofork_noexec.txt
@@ -52,6 +52,9 @@ xargs, find, shells do it (grep for "spawn_and_wait" and
This poses much more serious limitations on what applet can do:
* all NOEXEC limitations apply.
+* do not run for a long time or wait for user input:
+ hush shell only handles signals (like ^C) after you return
+ from APPLET_main().
* do not ever exit() or exec().
- xfuncs are okay. They are using special trick to return
to the caller applet instead of dying when they detect "x" condition.
diff --git a/shell/hush.c b/shell/hush.c
index 9f946d82f..cfefb7324 100644
--- a/shell/hush.c
+++ b/shell/hush.c
@@ -7363,6 +7363,8 @@ static NOINLINE void pseudo_exec_argv(nommu_save_t *nommu_save,
*/
close_saved_fds_and_FILE_fds();
//FIXME: should also close saved redir fds
+ /* Without this, "rm -i FILE" can't be ^C'ed: */
+ switch_off_special_sigs(G.special_sig_mask);
debug_printf_exec("running applet '%s'\n", argv[0]);
run_applet_no_and_exit(a, argv[0], argv);
}
@@ -8045,6 +8047,24 @@ static NOINLINE int run_pipe(struct pipe *pi)
add_vars(old_vars);
/* clean_up_and_ret0: */
restore_redirects(squirrel);
+ /*
+ * Try "usleep 99999999" + ^C + "echo $?"
+ * with FEATURE_SH_NOFORK=y.
+ */
+ if (!funcp) {
+ /* It was builtin or nofork.
+ * if this would be a real fork/execed program,
+ * it should have died if a fatal sig was received.
+ * But OTOH, there was no separate process,
+ * the sig was sent to _shell_, not to non-existing
+ * child.
+ * Let's just handle ^C only, this one is obvious:
+ * we aren't ok with exitcode 0 when ^C was pressed
+ * during builtin/nofork.
+ */
+ if (sigismember(&G.pending_set, SIGINT))
+ rcode = 128 + SIGINT;
+ }
clean_up_and_ret1:
free(argv_expanded);
IF_HAS_KEYWORDS(if (pi->pi_inverted) rcode = !rcode;)
@@ -8060,6 +8080,14 @@ static NOINLINE int run_pipe(struct pipe *pi)
if (rcode == 0) {
debug_printf_exec(": run_nofork_applet '%s' '%s'...\n",
argv_expanded[0], argv_expanded[1]);
+ /*
+ * Note: signals (^C) can't interrupt here.
+ * We remember them and they will be acted upon
+ * after applet returns.
+ * This makes applets which can run for a long time
+ * and/or wait for user input ineligible for NOFORK:
+ * for example, "yes" or "rm" (rm -i waits for input).
+ */
rcode = run_nofork_applet(n, argv_expanded);
}
goto clean_up_and_ret;
@@ -8491,7 +8519,7 @@ static int run_list(struct pipe *pi)
G.last_bg_pid = pi->cmds[pi->num_cmds - 1].pid;
G.last_bg_pid_exitcode = 0;
debug_printf_exec(": cmd&: exitcode EXIT_SUCCESS\n");
-/* Check pi->pi_inverted? "! sleep 1 & echo $?": bash says 1. dash and ash says 0 */
+/* Check pi->pi_inverted? "! sleep 1 & echo $?": bash says 1. dash and ash say 0 */
rcode = EXIT_SUCCESS;
goto check_traps;
} else {
@@ -10178,6 +10206,7 @@ static int wait_for_child_or_signal(struct pipe *waitfor_pipe, pid_t waitfor_pid
/* So, did we get a signal? */
sig = check_and_run_traps();
if (sig /*&& sig != SIGCHLD - always true */) {
+ /* Do this for any (non-ignored) signal, not only for ^C */
ret = 128 + sig;
break;
}