PATCH: Run builtins, functions, etc. under zpty

["Bart Schaefer" <schaefer@xxxxxxxxxxxxxxxxxxxxxxx>]

This patch copies code from the clone module into newptycmd(), so that the
forked process set up on the pty is initially a clone of the current shell.
Then instead of calling execve(), the command can be parsed and executed
with execode().  This is thus roughly equivalent to a shell function:

	clone /dev/ttyxx
	[[ $TTY == /dev/ttyxx ]] && {
	    eval $*
	    exit
	}

where zpty takes care of allocating the pty for /dev/ttyxx.

I initially wanted to avoid the "eval", e.g. do the equivalent of executing
$* directly; but there isn't any simple function for converting a char** to
the wordcode for a simple command without re-parsing it, and anyway without
the eval you can't do conditionals, loops or pipelines.

This does mean that zpty can't test the goodness of the command until after
it is executed in the forked process (no more findcmd() call).  Does anyone
think this is a serious drawback?

Included is correction of a couple of inconsequential typos in utils.c.

Index: Doc/Zsh/mod_zpty.yo
===================================================================
@@ -5,12 +5,13 @@
 
 startitem()
 findex(zpty)
-item(tt(zpty) [ tt(-e) ] [ tt(-b) ] var(name) var(command) [ var(args ...) ])(
-In the first form, the var(command) is started with the var(args) as
-arguments.  The command runs under a newly assigned pseudo-terminal; this
-is useful for running commands non-interactively which expect an
-interactive environment.  The var(name) is used to refer to this command
-in later calls to tt(zpty).
+item(tt(zpty) [ tt(-e) ] [ tt(-b) ] var(name) [ var(arg ...) ])(
+The arguments following var(name) are concatenated with spaces between,
+then executed as a command, as if passed to the tt(eval) builtin.  The
+command runs under a newly assigned pseudo-terminal; this is useful for
+running commands non-interactively which expect an interactive
+environment.  The var(name) is not part of the command, but is used to
+refer to this command in later calls to tt(zpty).
 
 With the tt(-e) option, the pseudo-terminal is set up so that input
 characters are echoed.
Index: Src/utils.c
===================================================================
@@ -2548,7 +2548,7 @@
  *   META_NOALLOC:  buf points to a memory area which is long enough to hold *
  *                  the quoted form, just quote it and return buf.           *
  *   META_STATIC:   store the quoted string in a static area.  The original  *
- *                  sting should be at most PATH_MAX long.                   *
+ *                  string should be at most PATH_MAX long.                   *
  *   META_ALLOC:    allocate memory for the new string with zalloc().        *
  *   META_DUP:      leave buf unchanged and allocate space for the return    *
  *                  value even if buf does not contains special characters   *
@@ -2600,7 +2600,7 @@
 	case META_NOALLOC:
 	    break;
 	default:
-	    fprintf(stderr, "BUG: metafy called with invaild heap value\n");
+	    fprintf(stderr, "BUG: metafy called with invalid heap value\n");
 	    fflush(stderr);
 	    break;
 #endif
Index: Src/Modules/zpty.c
===================================================================
@@ -171,7 +171,7 @@
     int ret;
 
     if (master) {
-	if ((mfd = open("/dev/ptmx", O_RDWR)) < 0)
+	if ((mfd = open("/dev/ptmx", O_RDWR|O_NOCTTY)) < 0)
 	    return 1;
 
 	if (grantpt(mfd) || unlockpt(mfd) || !(name = ptsname(mfd))) {
@@ -182,7 +182,7 @@
 
 	return 0;
     }
-    if ((sfd = open(name, O_RDWR)) < 0) {
+    if ((sfd = open(name, O_RDWR|O_NOCTTY)) < 0) {
 	close(mfd);
 	return 1;
     }
@@ -242,7 +242,7 @@
 	    name[8] = *p1;
 	    for (p2 = char2; *p2; p2++) {
 		name[9] = *p2;
-		if ((mfd = open(name, O_RDWR)) >= 0) {
+		if ((mfd = open(name, O_RDWR|O_NOCTTY)) >= 0) {
 		    *retfd = mfd;
 
 		    return 0;
@@ -251,7 +251,7 @@
 	}
     }
     name[5] = 't';
-    if ((sfd = open(name, O_RDWR)) >= 0) {
+    if ((sfd = open(name, O_RDWR|O_NOCTTY)) >= 0) {
 	*retfd = sfd;
 
 	return 0;
@@ -268,12 +268,14 @@
 {
     Ptycmd p;
     int master, slave, pid;
-    char *cmd;
+    Eprog prog;
 
-    if (!(cmd = findcmd(*args, 1))) {
-	zwarnnam(nam, "unknown command: %s", *args, 0);
+    prog = parse_string(zjoin(args, ' ', 1), 0);
+    if (!prog) {
+	errflag = 0;
 	return 1;
     }
+
     if (get_pty(1, &master)) {
 	zwarnnam(nam, "can't open pseudo terminal: %e", NULL, errno);
 	return 1;
@@ -283,41 +285,40 @@
 	close(master);
 	return 1;
     } else if (!pid) {
-
-	pid = getpid();
+	/* This code copied from the clone module, except for getting *
+	 * the descriptor from get_pty() and duplicating it to 0/1/2. */
 
+	clearjobtab();
+	ppid = getppid();
+	mypid = getpid();
 #ifdef HAVE_SETSID
-	setsid();
-#else
+	if (setsid() != mypid) {
+	    zwarnnam(nam, "failed to create new session: %e", NULL, errno);
+#endif
 #ifdef TIOCNOTTY
-	{
-	    int t = open("/dev/tty", O_RDWR);
-
-	    ioctl(t, TIOCNOTTY, 0);
-	    close(t);
-	}
+	    if (ioctl(SHTTY, TIOCNOTTY, 0))
+		zwarnnam(nam, "%e", NULL, errno);
+	    setpgrp(0L, mypid);
 #endif
+#ifdef HAVE_SETSID
+	}
 #endif
 
 	if (get_pty(0, &slave))
 	    exit(1);
-
-#ifdef TIOCSCTTY
-	ioctl(slave, TIOCSCTTY, 0);
-#endif
-
-	/* This is taken from attachtty(). Should we exit in case of
-	 * failure? */
+#ifdef TIOCGWINSZ
+	/* Set the window size before associating with the terminal *
+	 * so that we don't get hit with a SIGWINCH.  I'm paranoid. */
+	if (interact) {
+	    struct ttyinfo info;
 
-#ifdef HAVE_TCSETPGRP
-	tcsetpgrp(slave, pid);
-#else
-# if ardent
-	setpgrp();
-# else
-	ioctl(slave, TIOCSPGRP, &pid);
-# endif
-#endif
+	    if (ioctl(slave, TIOCGWINSZ, (char *) &info.winsize) == 0) {
+		info.winsize.ws_row = lines;
+		info.winsize.ws_col = columns;
+		ioctl(slave, TIOCSWINSZ, (char *) &info.winsize);
+	    }
+	}
+#endif /* TIOCGWINSZ */
 
 	if (!echo) {
 	    struct ttyinfo info;
@@ -336,21 +337,9 @@
 	    }
 	}
 
-#ifdef TIOCGWINSZ
-	if (interact) {
-	    struct ttyinfo info;
-
-	    if (ioctl(slave, TIOCGWINSZ, (char *) &info.winsize) == 0) {
-		info.winsize.ws_row = lines;
-		info.winsize.ws_col = columns;
-		ioctl(slave, TIOCSWINSZ, (char *) &info.winsize);
-	    }
-	}
-#endif /* TIOCGWINSZ */
-
-	signal_default(SIGTERM);
-	signal_default(SIGINT);
-	signal_default(SIGQUIT);
+#ifdef TIOCSCTTY
+	ioctl(slave, TIOCSCTTY, 0);
+#endif
 
 	close(0);
 	close(1);
@@ -360,16 +349,16 @@
 	dup2(slave, 1);
 	dup2(slave, 2);
 
+	closem(0);
 	close(slave);
 	close(master);
-
-	if (SHTTY != -1)
-	    close(SHTTY);
-
-	closedumps();
+	close(coprocin);
+	close(coprocout);
+	init_io();
+	setsparam("TTY", ztrdup(ttystrname));
 
-	execve(cmd, args, environ);
-	exit(0);
+	execode(prog, 1, 0);
+	zexit(lastval, 0);
     }
     master = movefd(master);
 

-- 
Bart Schaefer                                 Brass Lantern Enterprises
http://www.well.com/user/barts              http://www.brasslantern.com

Zsh: http://www.zsh.org | PHPerl Project: http://phperl.sourceforge.net