openpty(3) - change to use unix98 ptys

* Try, by default, to use unix98 ptys first. If they fail at any
  point, fall back to bsd ptys (/dev/[pt]ty*).

Partially-Obtained-From: FreeBSD

diff --git a/lib/libutil/pty.c b/lib/libutil/pty.c
index 0186354..3f3828d 100644 (file)
--- a/lib/libutil/pty.c
+++ b/lib/libutil/pty.c
@@ -45,6 +45,8 @@
 
 #include "libutil.h"
 
+#define UNIX98_PTYS    1
+
 int
 openpty(int *amaster, int *aslave, char *name, struct termios *termp,
        struct winsize *winp)
@@ -53,12 +55,55 @@ openpty(int *amaster, int *aslave, char *name, struct termios *termp,
        const char *cp1, *cp2;
        int master, slave, ttygid;
        struct group *gr;
+       const char *slave_name;
 
        if ((gr = getgrnam("tty")) != NULL)
                ttygid = gr->gr_gid;
        else
                ttygid = -1;
 
+#ifdef UNIX98_PTYS
+       master = posix_openpt(O_RDWR|O_NOCTTY);
+       if (master == -1)
+               goto fallback;
+
+       if (grantpt(master) != 0) {
+               close(master);
+               goto fallback;
+       }
+
+       if (unlockpt(master) != 0) {
+               close(master);
+               goto fallback;
+       }
+
+       slave_name = ptsname(master);
+       if (slave_name == NULL) {
+               close(master);
+               goto fallback;
+       }
+
+       slave = open(slave_name, O_RDWR);
+       if (slave == -1) {
+               close(master);
+               goto fallback;
+       }
+
+       *amaster = master;
+       *aslave = slave;
+
+       if (name)
+               strcpy(name, slave_name);
+       if (termp)
+               tcsetattr(slave, TCSAFLUSH, termp);
+       if (winp)
+               ioctl(slave, TIOCSWINSZ, (char *)winp);
+
+       return (0);
+
+fallback:
+#endif
+
        for (cp1 = "pqrsPQRS"; *cp1; cp1++) {
                line[8] = *cp1;
                for (cp2 = "0123456789abcdefghijklmnopqrstuv"; *cp2; cp2++) {