Add the '-t timeout' option to the 'read' builtin. This allows the

'read' command to return an error if the user fails to supply any
input withink a given time period.  The behaviour of this option is
similar to that of the like-named option in ksh93.

Reviewed by:	joerg

2 files changed, 72 insertions, 6 deletions

diff --git a/bin/sh/miscbltin.c b/bin/sh/miscbltin.c
index c05e017..7fbb339 100644
--- a/bin/sh/miscbltin.c
+++ b/bin/sh/miscbltin.c
@@ -33,7 +33,7 @@
  * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
  * SUCH DAMAGE.
  *
- *	$Id: miscbltin.c,v 1.12 1997/04/28 03:06:36 steve Exp $
+ *	$Id: miscbltin.c,v 1.13 1997/05/19 00:18:43 steve Exp $
  */
 
 #ifndef lint
@@ -52,6 +52,7 @@ static char const sccsid[] = "@(#)miscbltin.c	8.4 (Berkeley) 5/4/95";
 #include <ctype.h>
 #include <errno.h>
 #include <stdio.h>
+#include <termios.h>
 
 #include "shell.h"
 #include "options.h"
@@ -88,14 +89,43 @@ readcmd(argc, argv)
 	int startword;
 	int status;
 	int i;
+	struct timeval tv;
+	char *tvptr;
+	fd_set ifds;
+	struct termios told, tnew;
+	int tsaved;
 
 	eflag = 0;
 	prompt = NULL;
-	while ((i = nextopt("ep:")) != '\0') {
-		if (i == 'p')
+	tv.tv_sec = -1;
+	tv.tv_usec = 0;
+	while ((i = nextopt("ep:t:")) != '\0') {
+		switch(i) {
+		case 'p':
 			prompt = optarg;
-		else
+			break;
+		case 'e':
 			eflag = 1;
+			break;
+		case 't':
+			tv.tv_sec = strtol(optarg, &tvptr, 0);
+			if (tvptr == optarg)
+				error("timeout value");
+			switch(*tvptr) {
+			case 0:
+			case 's':
+				break;
+			case 'h':
+				tv.tv_sec *= 60;
+				/* FALLTHROUGH */
+			case 'm':
+				tv.tv_sec *= 60;
+				break;
+			default:
+				error("timeout unit");
+			}
+			break;
+		}
 	}
 	if (prompt && isatty(0)) {
 		out2str(prompt);
@@ -105,6 +135,35 @@ readcmd(argc, argv)
 		error("arg count");
 	if ((ifs = bltinlookup("IFS", 1)) == NULL)
 		ifs = nullstr;
+
+	if (tv.tv_sec >= 0) {
+		/*
+		 * See if we can disable input processing; this will
+		 * not give the desired result if we are in a pipeline
+		 * and someone upstream is still in line-by-line mode.
+		 */
+		tsaved = 0;
+		if (tcgetattr(0, &told) == 0) {
+			memcpy(&tnew, &told, sizeof(told));
+			cfmakeraw(&tnew);
+			tcsetattr(0, TCSANOW, &tnew);
+			tsaved = 1;
+		}
+		/*
+		 * Wait for something to become available.
+		 */
+		FD_ZERO(&ifds);
+		FD_SET(0, &ifds);
+		status = select(1, &ifds, NULL, NULL, &tv);
+		if (tsaved)
+			tcsetattr(0, TCSANOW, &told);
+		/*
+		 * If there's nothing ready, return an error.
+		 */
+		if (status <= 0)
+			return(1);
+	}
+
 	status = 0;
 	startword = 1;
 	backslash = 0;
diff --git a/bin/sh/sh.1 b/bin/sh/sh.1
index 3144390..4ac5ea2 100644
--- a/bin/sh/sh.1
+++ b/bin/sh/sh.1
@@ -33,7 +33,7 @@
 .\" SUCH DAMAGE.
 .\"
 .\"	from: @(#)sh.1	8.6 (Berkeley) 5/4/95
-.\"	$Id: sh.1,v 1.14 1997/05/07 11:42:00 steve Exp $
+.\"	$Id: sh.1,v 1.15 1997/09/13 17:40:00 wosch Exp $
 .\"
 .Dd May 5, 1995
 .Dt SH 1
@@ -1123,7 +1123,7 @@ is rather than recomputing it each time.  This makes
 it faster.  However, if the current directory is
 renamed, the builtin version of pwd will continue to
 print the old name for the directory.
-.It read [ -p prompt ] [ -e ] variable ...
+.It Li "read [ -p prompt ] [ -t timeout ] [ -e ] variable ...
 The prompt is printed if the -p option is specified
 and the standard input is a terminal.  Then a line is
 read from the standard input.  The trailing newline
@@ -1136,6 +1136,13 @@ separated them) are assigned to the last variable.
 If there are more variables than pieces, the remaining
 variables are assigned the null string.
 .Pp
+If the -t option is specified the timeout elapses
+before any input is supplied, the read command will
+return without assigning any values.  The timeout value
+may optionally be followed by one of 's', 'm' or 'h' to
+explicitly specify seconds, minutes or or hours.  If none
+is supplied, 's' is assumed.
+.Pp
 The -e option causes any backslashes in the input to
 be treated specially.  If a backslash is followed by
 a newline, the backslash and the newline will be