ash: fix TMOUT not restoring tty attributes

function                                             old     new   delta
pgetc                                                420     500     +80
readtoken1                                          3202    3239     +37
read_line_input                                     3316    3337     +21
udhcpc_main                                         2610    2630     +20
file_get                                             266     272      +6
expandarg                                            958     963      +5
localcmd                                             257     259      +2
addLines                                              85      87      +2
read_line                                             94      95      +1
ed_main                                             2540    2541      +1
timed_out                                              1       -      -1
lineedit_read_key                                    256     255      -1
alrm_sighandler                                       44       -     -44
cmdloop                                              539     434    -105
------------------------------------------------------------------------------
(add/remove: 0/2 grow/shrink: 10/2 up/down: 175/-151)          Total: 24 bytes
   text    data     bss     dec     hex filename
 887379     936   17200  905515   dd12b busybox_old
 887411     936   17192  905539   dd143 busybox_unstripped

Signed-off-by: Denys Vlasenko <vda.linux@googlemail.com>

1 files changed, 27 insertions, 46 deletions

diff --git a/shell/ash.c b/shell/ash.c
index bdc64790c..aaf21cd6f 100644
--- a/shell/ash.c
+++ b/shell/ash.c
@@ -102,8 +102,7 @@
 //config:	default n
 //config:	depends on ASH
 //config:	help
-//config:	  Enables bash-like auto-logout after "$TMOUT" seconds
-//config:	  of idle time.
+//config:	  Enables bash-like auto-logout after $TMOUT seconds of idle time.
 //config:
 //config:config ASH_JOB_CONTROL
 //config:	bool "Job control"
@@ -408,6 +407,9 @@ static const char *var_end(const char *var)
 
 
 /* ============ Interrupts / exceptions */
+
+static void exitshell(void) NORETURN;
+
 /*
  * These macros allow the user to suspend the handling of interrupt signals
  * over a period of time.  This is similar to SIGHOLD or to sigblock, but
@@ -9573,10 +9575,21 @@ preadfd(void)
 	if (!iflag || g_parsefile->pf_fd != STDIN_FILENO)
 		nr = nonblock_safe_read(g_parsefile->pf_fd, buf, IBUFSIZ - 1);
 	else {
+		int timeout = -1;
+# if ENABLE_ASH_IDLE_TIMEOUT
+		if (iflag) {
+			const char *tmout_var = lookupvar("TMOUT");
+			if (tmout_var) {
+				timeout = atoi(tmout_var) * 1000;
+				if (timeout <= 0)
+					timeout = -1;
+			}
+		}
+# endif
 # if ENABLE_FEATURE_TAB_COMPLETION
 		line_input_state->path_lookup = pathval();
 # endif
-		nr = read_line_input(cmdedit_prompt, buf, IBUFSIZ, line_input_state);
+		nr = read_line_input(line_input_state, cmdedit_prompt, buf, IBUFSIZ, timeout);
 		if (nr == 0) {
 			/* Ctrl+C pressed */
 			if (trap[SIGINT]) {
@@ -9587,9 +9600,17 @@ preadfd(void)
 			}
 			goto retry;
 		}
-		if (nr < 0 && errno == 0) {
-			/* Ctrl+D pressed */
-			nr = 0;
+		if (nr < 0) {
+			if (errno == 0) {
+				/* Ctrl+D pressed */
+				nr = 0;
+			}
+# if ENABLE_ASH_IDLE_TIMEOUT
+			else if (errno == EAGAIN && timeout > 0) {
+				printf("\007timed out waiting for input: auto-logout\n");
+				exitshell();
+			}
+# endif
 		}
 	}
 #else
@@ -12056,23 +12077,6 @@ evalcmd(int argc UNUSED_PARAM, char **argv)
 	return exitstatus;
 }
 
-#if ENABLE_ASH_IDLE_TIMEOUT
-static smallint timed_out;
-
-static void alrm_sighandler(int sig UNUSED_PARAM)
-{
-	/* Close stdin, making interactive command reading stop.
-	 * Otherwise, timeout doesn't trigger until <Enter> is pressed.
-	 */
-	int sv = errno;
-	close(0);
-	open("/dev/null", O_RDONLY);
-	errno = sv;
-
-	timed_out = 1;
-}
-#endif
-
 /*
  * Read and execute commands.
  * "Top" is nonzero for the top level command loop;
@@ -12089,20 +12093,6 @@ cmdloop(int top)
 	TRACE(("cmdloop(%d) called\n", top));
 	for (;;) {
 		int skip;
-#if ENABLE_ASH_IDLE_TIMEOUT
-		int tmout_seconds = 0;
-
-		if (top && iflag) {
-			const char *tmout_var = lookupvar("TMOUT");
-			if (tmout_var) {
-				tmout_seconds = atoi(tmout_var);
-				if (tmout_seconds > 0) {
-					signal(SIGALRM, alrm_sighandler);
-					alarm(tmout_seconds);
-				}
-			}
-		}
-#endif
 
 		setstackmark(&smark);
 #if JOBS
@@ -12115,14 +12105,6 @@ cmdloop(int top)
 			chkmail();
 		}
 		n = parsecmd(inter);
-#if ENABLE_ASH_IDLE_TIMEOUT
-		if (timed_out) {
-			printf("\007timed out waiting for input: auto-logout\n");
-			break;
-		}
-		if (tmout_seconds > 0)
-			alarm(0);
-#endif
 #if DEBUG
 		if (DEBUG > 2 && debug && (n != NODE_EOF))
 			showtree(n);
@@ -12850,7 +12832,6 @@ ulimitcmd(int argc UNUSED_PARAM, char **argv)
 /*
  * Called to exit the shell.
  */
-static void exitshell(void) NORETURN;
 static void
 exitshell(void)
 {