block pthread cancellation in openpty function

being a nonstandard function, this isn't strictly necessary, but it's
inexpensive and avoids unpleasant surprises. eventually I would like
all functions in libc to be safe against cancellation, either ignoring
it or acting on it cleanly.

diff --git a/src/misc/openpty.c b/src/misc/openpty.c
index b6962e131c8e6fe935d01b48a48f1d7fddf6d890..c10740606111778c16b1d6c3dd3adb5a791240b6 100644 (file)
--- a/src/misc/openpty.c
+++ b/src/misc/openpty.c
@@ -3,33 +3,38 @@
 #include <unistd.h>
 #include <pty.h>
 #include <stdio.h>
+#include <pthread.h>
 
 /* Nonstandard, but vastly superior to the standard functions */
 
 int openpty(int *pm, int *ps, char *name, const struct termios *tio, const struct winsize *ws)
 {
-       int m, s, n=0;
+       int m, s, n=0, cs;
        char buf[20];
 
        m = open("/dev/ptmx", O_RDWR|O_NOCTTY);
        if (m < 0) return -1;
 
-       if (ioctl(m, TIOCSPTLCK, &n) || ioctl (m, TIOCGPTN, &n)) {
-               close(m);
-               return -1;
-       }
+       pthread_setcancelstate(PTHREAD_CANCEL_DISABLE, &cs);
+
+       if (ioctl(m, TIOCSPTLCK, &n) || ioctl (m, TIOCGPTN, &n))
+               goto fail;
 
        if (!name) name = buf;
        snprintf(name, sizeof buf, "/dev/pts/%d", n);
-       if ((s = open(name, O_RDWR|O_NOCTTY)) < 0) {
-               close(m);
-               return -1;
-       }
+       if ((s = open(name, O_RDWR|O_NOCTTY)) < 0)
+               goto fail;
 
        if (tio) tcsetattr(s, TCSANOW, tio);
        if (ws) ioctl(s, TIOCSWINSZ, ws);
 
        *pm = m;
        *ps = s;
+
+       pthread_setcancelstate(cs, 0);
        return 0;
+fail:
+       close(m);
+       pthread_setcancelstate(cs, 0);
+       return -1;
 }