Re: script input redirection / eof handling

Karel Zak
2013-12-02T17:02:13Z

On Mon, Dec 02, 2013 at 09:45:19AM -0500, Phillip Susi wrote:
> -----BEGIN PGP SIGNED MESSAGE-----
> Hash: SHA1
>
> On 12/2/2013 7:54 AM, Karel Zak wrote:
> > Note, that if you want to support this scenario (stdin is not a
> > terminal) then send a patch ;-)
>
> It seems to work fine up until it hits eof, which can also happen on a

well, it's nasty that the code ignores return codes and it call's tty
ioctls/functions for non-tty file descriptors.

> tty and you'll get the same bad behavior, so I think refusing to run
> on a non tty isn't a proper fix.
>
> >> Yep, I think it would be enough to add
> >>
> >> kill(0, SIGTERM);
> >>
> >> before done() in doinput() to avoid orphans.
>
> You don't want to just make sure the children die, you want to make
> sure that the child sees the eof and capture any final output it may have.

never ending orphans suck...

The possible solution (hack) to emulate end-of-file is by write "exit\n" to
the master tty. For example patch below works for me (it also make it
more robust for non-ttys).

Karel

diff --git a/term-utils/script.c b/term-utils/script.c
index c18274c..8437ec8 100644
--- a/term-utils/script.c
+++ b/term-utils/script.c
@@ -107,6 +107,7 @@ int fflg = 0;
int qflg = 0;
int tflg = 0;
int forceflg = 0;
+int isterm;

int die;
int resized;
@@ -230,9 +231,6 @@ main(int argc, char **argv) {
die_if_link(fname);
}

- if (!isatty(STDIN_FILENO))
- errx(EXIT_FAILURE, _("The stdin is not a terminal."));
-
if ((fscript = fopen(fname, aflg ? "a" : "w")) == NULL) {
warn(_("cannot open %s"), fname);
fail();
@@ -314,11 +312,21 @@ doinput(void) {
else if (cc < 0 && errno == EINTR && resized)
{
/* transmit window change information to the child */
- ioctl(STDIN_FILENO, TIOCGWINSZ, (char *)&win);
- ioctl(slave, TIOCSWINSZ, (char *)&win);
+ if (isterm) {
+ ioctl(STDIN_FILENO, TIOCGWINSZ, (char *)&win);
+ ioctl(slave, TIOCSWINSZ, (char *)&win);
+ }
resized = 0;
- }
- else
+ } else if (cc == 0 && errno == 0) {
+ /* end-of-file, probably "foo | script" */
+ strcpy(ibuf, "exit\n");
+ if (write(master, ibuf, 5) < 0) {
+ warn (_("write failed"));
+ fail();
+ }
+ pause(); /* wait for SIGCHLD */
+ break;
+ } else
break;
}

@@ -473,6 +481,9 @@ void
fixtty(void) {
struct termios rtt;

+ if (!isterm)
+ return;
+
rtt = tt;
cfmakeraw(&rtt);
rtt.c_lflag &= ~ECHO;
@@ -503,7 +514,8 @@ done(void) {

master = -1;
} else {
- tcsetattr(STDIN_FILENO, TCSADRAIN, &tt);
+ if (isterm)
+ tcsetattr(STDIN_FILENO, TCSADRAIN, &tt);
if (!qflg)
printf(_("Script done, file is %s\n"), fname);
#ifdef HAVE_LIBUTEMPTER
@@ -524,9 +536,19 @@ done(void) {
void
getmaster(void) {
#if defined(HAVE_LIBUTIL) && defined(HAVE_PTY_H)
- tcgetattr(STDIN_FILENO, &tt);
- ioctl(STDIN_FILENO, TIOCGWINSZ, (char *)&win);
- if (openpty(&master, &slave, NULL, &tt, &win) < 0) {
+ int rc;
+
+ isterm = isatty(STDIN_FILENO);
+
+ if (isterm) {
+ if (tcgetattr(STDIN_FILENO, &tt) != 0)
+ err(EXIT_FAILURE, _("failed to get terminal attributes"));
+ ioctl(STDIN_FILENO, TIOCGWINSZ, (char *) &win);
+ rc = openpty(&master, &slave, NULL, &tt, &win);
+ } else
+ rc = openpty(&master, &slave, NULL, NULL, NULL);
+
+ if (rc < 0) {
warn(_("openpty failed"));
fail();
}
@@ -534,6 +556,8 @@ getmaster(void) {
char *pty, *bank, *cp;
struct stat stb;

+ isterm = isatty(STDIN_FILENO);
+
pty = &line[strlen("/dev/ptyp")];
for (bank = "pqrs"; *bank; bank++) {
line[strlen("/dev/pty")] = *bank;
@@ -552,9 +576,11 @@ getmaster(void) {
ok = access(line, R_OK|W_OK) == 0;
*tp = 'p';
if (ok) {
- tcgetattr(STDIN_FILENO, &tt);
- ioctl(STDIN_FILENO, TIOCGWINSZ,
- (char *)&win);
+ if (isterm) {
+ tcgetattr(STDIN_FILENO, &tt);
+ ioctl(STDIN_FILENO, TIOCGWINSZ,
+ (char *)&win);
+ }
return;
}
close(master);
@@ -577,8 +603,10 @@ getslave(void) {
warn(_("cannot open %s"), line);
fail();
}
- tcsetattr(slave, TCSANOW, &tt);
- ioctl(slave, TIOCSWINSZ, (char *)&win);
+ if (isterm) {
+ tcsetattr(slave, TCSANOW, &tt);
+ ioctl(slave, TIOCSWINSZ, (char *)&win);
+ }
#endif
setsid();
ioctl(slave, TIOCSCTTY, 0);