From e6ac257f362f8b879b62225bedca9e8aafef4f3b Mon Sep 17 00:00:00 2001
From: bakkeby <bakkeby@gmail.com>
Date: Mon, 12 Jul 2021 09:35:04 +0200
Subject: [PATCH] Add shortcut to spawn new terminal in the current dir

Ctrl-Shift-Return now creates a new ST terminal, whose CWD is the same
as the parent st's CWD.

This version of the patch does a double fork, a technique commonly used
by daemons to spawn orphan processes.

This solution is specific to the swallow patch for dwm which traverses
the process tree to determine if the new window is a decendant of a
terminal window, in which case the new window should take the place of
the terminal window.

The way the original newterm patch worked the new st terminal would be
a direct decendant of the parent st terminal process, which could lead
to the wrong terminal window being swallowed.

The double fork method avoids this by leaving all new st terminals as
orphans, i.e. they will have no parent process.
---
 config.def.h |  1 +
 st.c         | 32 ++++++++++++++++++++++++++++++++
 st.h         |  1 +
 3 files changed, 34 insertions(+)

diff --git a/config.def.h b/config.def.h
index 6f05dce..9029e8d 100644
--- a/config.def.h
+++ b/config.def.h
@@ -199,6 +199,7 @@ static Shortcut shortcuts[] = {
 	{ TERMMOD,              XK_Y,           selpaste,       {.i =  0} },
 	{ ShiftMask,            XK_Insert,      selpaste,       {.i =  0} },
 	{ TERMMOD,              XK_Num_Lock,    numlock,        {.i =  0} },
+	{ TERMMOD,              XK_Return,      newterm,        {.i =  0} },
 };
 
 /*
diff --git a/st.c b/st.c
index ebdf360..cb79bc0 100644
--- a/st.c
+++ b/st.c
@@ -153,6 +153,7 @@ typedef struct {
 } STREscape;
 
 static void execsh(char *, char **);
+static char *getcwd_by_pid(pid_t pid);
 static void stty(char **);
 static void sigchld(int);
 static void ttywriteraw(const char *, size_t);
@@ -1060,6 +1061,37 @@ tswapscreen(void)
 	tfulldirt();
 }
 
+void
+newterm(const Arg* a)
+{
+	int res;
+	switch (fork()) {
+	case -1:
+		die("fork failed: %s\n", strerror(errno));
+		break;
+	case 0:
+		switch (fork()) {
+		case -1:
+			die("fork failed: %s\n", strerror(errno));
+			break;
+		case 0:
+			res = chdir(getcwd_by_pid(pid));
+			execlp("st", "./st", NULL);
+			break;
+		default:
+			exit(0);
+		}
+	default:
+		wait(NULL);
+	}
+}
+
+static char *getcwd_by_pid(pid_t pid) {
+	char buf[32];
+	snprintf(buf, sizeof buf, "/proc/%d/cwd", pid);
+	return realpath(buf, NULL);
+}
+
 void
 tscrolldown(int orig, int n)
 {
diff --git a/st.h b/st.h
index fa2eddf..b13399b 100644
--- a/st.h
+++ b/st.h
@@ -81,6 +81,7 @@ void die(const char *, ...);
 void redraw(void);
 void draw(void);
 
+void newterm(const Arg *);
 void printscreen(const Arg *);
 void printsel(const Arg *);
 void sendbreak(const Arg *);
-- 
2.32.0