Fix setsid with vfork, redo command line arguments.

Switch -t to -c (like man page says), add -w (wait) and -d (detach from tty)

1 files changed, 29 insertions, 7 deletions

diff --git a/toys/other/setsid.c b/toys/other/setsid.c
index 95698260..57a926ef 100644
--- a/toys/other/setsid.c
+++ b/toys/other/setsid.c
@@ -2,27 +2,49 @@
  *
  * Copyright 2006 Rob Landley <rob@landley.net>
 
-USE_SETSID(NEWTOY(setsid, "^<1t", TOYFLAG_USR|TOYFLAG_BIN))
+USE_SETSID(NEWTOY(setsid, "^<1wcd[!dc]", TOYFLAG_USR|TOYFLAG_BIN))
 
 config SETSID
   bool "setsid"
   default y
   help
-    usage: setsid [-t] command [args...]
+    usage: setsid [-cdw] command [args...]
 
     Run process in a new session.
 
-    -t	Grab tty (become foreground process, receiving keyboard signals)
+    -d	Detach from tty
+    -c	Control tty (become foreground process & receive keyboard signals)
 */
 
+#define FOR_setsid
 #include "toys.h"
 
 void setsid_main(void)
 {
-  while (setsid()<0) if (XVFORK()) _exit(0);
-  if (toys.optflags) {
-    setpgid(0, 0);
-    tcsetpgrp(0, getpid());
+  int i;
+
+  // This must be before vfork() or tcsetpgrp() will hang waiting for parent.
+  setpgid(0, 0);
+
+  // setsid() fails if we're already session leader, ala "exec setsid" from sh.
+  // Second call can't fail, so loop won't continue endlessly.
+  while (setsid()<0) {
+    pid_t pid = XVFORK();
+
+    if (pid) {
+      i = 0;
+      if (FLAG(w)) {
+        i = 127;
+        if (pid>0) i = xwaitpid(pid);
+      }
+      _exit(i);
+    }
+  }
+
+  if (FLAG(c)) tcsetpgrp(0, getpid());
+  if (FLAG(d) && (i = open("/dev/tty", O_RDONLY)) != -1) {
+    ioctl(i, TIOCNOTTY);
+    close(i);
   }
   xexec(toys.optargs);
 }