From: Sami Kerola <kerolasa@iki.fi>
Date: Fri, 26 Dec 2014 17:43:49 +0000 (+0000)
Subject: script: remove io vs signal race
X-Git-Tag: v2.27-rc1~132^2~9^2~8
X-Git-Url: http://git.ipfire.org/?a=commitdiff_plain;h=89a859d433fbba81cd70ba5e42fc86e971233dce;p=thirdparty%2Futil-linux.git

script: remove io vs signal race

Make do_io() to run poll() until all streams are empty.  This should
remove the signal from child versus io handling race for good.

Addresses: https://github.com/karelzak/util-linux/pull/62
Addresses: https://bugs.launchpad.net/bugs/264967
Addresses: https://bugs.debian.org/305808
CC: Wolfgang Richter <wolf@cs.cmu.edu>
CC: Ruediger Meier <ruediger.meier@ga-group.nl>
Signed-off-by: Sami Kerola <kerolasa@iki.fi>
---

diff --git a/term-utils/script.c b/term-utils/script.c
index ea776cf72a..391aa9e5ec 100644
--- a/term-utils/script.c
+++ b/term-utils/script.c
@@ -92,6 +92,7 @@ struct script_control {
 	FILE *timingfp;		/* timing file pointer */
 	int master;		/* pseudoterminal master file descriptor */
 	int slave;		/* pseudoterminal slave file descriptor */
+	int poll_timeout;	/* poll() timeout, used in end of execution */
 	pid_t child;		/* child pid */
 	int childstatus;	/* child process exit value */
 	struct termios tt;	/* slave terminal runtime attributes */
@@ -205,16 +206,11 @@ static void finish(struct script_control *ctl, int wait)
 {
 	int status;
 	pid_t pid;
-	int errsv = errno;
 	int options = wait ? 0 : WNOHANG;
 
 	while ((pid = wait3(&status, options, 0)) > 0)
-		if (pid == ctl->child) {
+		if (pid == ctl->child)
 			ctl->childstatus = status;
-			ctl->die = 1;
-		}
-
-	errno = errsv;
 }
 
 static void write_output(struct script_control *ctl, char *obuf,
@@ -270,13 +266,15 @@ static void do_io(struct script_control *ctl)
 
 	while (!ctl->die) {
 		/* wait for input or signal */
-		ret = poll(pfd, POLLFDS, -1);
+		ret = poll(pfd, POLLFDS, ctl->poll_timeout);
 		if (ret < 0) {
 			if (errno == EAGAIN)
 				continue;
 			warn(_("poll failed"));
 			fail(ctl);
 		}
+		if (ret == 0)
+			ctl->die = 1;
 		for (i = 0; i < POLLFDS; i++) {
 			if (pfd[i].revents == 0)
 				continue;
@@ -315,6 +313,13 @@ static void do_io(struct script_control *ctl)
 				switch (info.ssi_signo) {
 				case SIGCHLD:
 					finish(ctl, 0);
+					ctl->poll_timeout = 10;
+					if (!ctl->isterm)
+						/* In situation such as 'date' in
+						* $ echo date | ./script
+						* ignore input when shell has
+						* exited.  */
+						pfd[0].fd = -1;
 					break;
 				case SIGWINCH:
 					if (ctl->isterm) {
@@ -496,6 +501,7 @@ int main(int argc, char **argv)
 		.line = "/dev/ptyXX",
 #endif
 		.master = -1,
+		.poll_timeout = -1,
 		0
 	};
 	int ch;
diff --git a/tests/ts/script/race b/tests/ts/script/race
index 02c8187d6a..65d48e29fd 100755
--- a/tests/ts/script/race
+++ b/tests/ts/script/race
@@ -27,10 +27,6 @@ ts_init "$*"
 
 ts_check_test_command "$TS_CMD_SCRIPT"
 
-# TODO see comments about script design
-# https://github.com/karelzak/util-linux/pull/62
-TS_KNOWN_FAIL="yes"
-
 bingofile="$TS_OUTDIR/${TS_TESTNAME}-bingo"
 
 count=1000