From eb50973552a62e49274cfeeddf31245739c8f47e Mon Sep 17 00:00:00 2001
From: Simon Tatham <anakin@pobox.com>
Date: Sat, 7 May 2016 16:58:07 +0100
Subject: [PATCH] Add -f option, to fork after a successful locking.

This permits a chain of commands of the form 'xtrlock -f && suspend',
where 'suspend' is whatever CLI command suspends your particular
laptop environment, so that when you unsuspend you then have to unlock
the xtrlock.

Without this option, you have to run xtrlock in the background, and
then either include a bodgy sleep to try to avoid the suspend command
winning the race, or else find a way to test by some X-related means
that the locking has happened.

Signed-off-by: Simon Tatham <anakin@pobox.com>
---
 xtrlock.c   | 33 ++++++++++++++++++++++++++-------
 xtrlock.man |  6 +++++-
 2 files changed, 31 insertions(+), 8 deletions(-)

diff --git a/xtrlock.c b/xtrlock.c
index 7598560..6117c6f 100644
--- a/xtrlock.c
+++ b/xtrlock.c
@@ -81,19 +81,27 @@ int main(int argc, char **argv){
   Cursor cursor;
   Pixmap csr_source,csr_mask;
   XColor csr_fg, csr_bg, dummy, black;
-  int ret, screen, blank = 0;
+  int ret, screen, blank = 0, fork_after = 0;
 #ifdef SHADOW_PWD
   struct spwd *sp;
 #endif
   struct timeval tv;
   int tvt, gs;
 
-  if ((argc == 2) && (strcmp(argv[1], "-b") == 0)) {
-    blank = 1;
-  } else if (argc > 1) {
-    fprintf(stderr,"xtrlock (version %s); usage: xtrlock [-b]\n",
-            program_version);
-    exit(1);
+  while (argc > 1) {
+    if ((strcmp(argv[1], "-b") == 0)) {
+      blank = 1;
+      argc--;
+      argv++;
+    } else if ((strcmp(argv[1], "-f") == 0)) {
+      fork_after = 1;
+      argc--;
+      argv++;
+    } else {
+      fprintf(stderr,"xtrlock (version %s); usage: xtrlock [-b] [-f]\n",
+              program_version);
+      exit(1);
+    }
   }
   
   errno=0;  pw= getpwuid(getuid());
@@ -208,6 +216,17 @@ int main(int argc, char **argv){
     exit(1);
   }
 
+  if (fork_after) {
+    pid_t pid = fork();
+    if (pid < 0) {
+      fprintf(stderr,"xtrlock (version %s): cannot fork: %s\n",
+              program_version, strerror(errno));
+      exit(1);
+    } else if (pid > 0) {
+      exit(0);
+    }
+  }
+
   for (;;) {
     XNextEvent(display,&ev);
     switch (ev.type) {
diff --git a/xtrlock.man b/xtrlock.man
index 7a869a6..e211bd5 100644
--- a/xtrlock.man
+++ b/xtrlock.man
@@ -2,7 +2,7 @@
 .SH NAME
 xtrlock \- Lock X display until password supplied, leaving windows visible
 .SH SYNOPSIS
-.B xtrlock [-b]
+.B xtrlock [-b] [-f]
 .SH DESCRIPTION
 .B xtrlock
 locks the X server till the user enters their password at the keyboard.
@@ -30,6 +30,10 @@ touching a key (Shift, for example) or the mouse.
 .TP
 \fB\-b\fR
 blank the screen as well as displaying the padlock
+.TP
+\fB\-f\fR
+fork after locking is complete, and return success from the parent
+process
 .SH X RESOURCES, CONFIGURATION
 None.
 .SH BUGS
-- 
2.30.2