From f492fa9b676e95dbf317ec3b34d085909713da73 Mon Sep 17 00:00:00 2001
From: Kaz Kylheku <kaz@kylheku.com>
Date: Wed, 25 May 2016 19:43:09 -0700
Subject: New variable: txr-path.

* txr.c (dirname): New static function.
(sysroot_init): Register txr-path variable.

* txr.1: documented txr-path.
---
 txr.1 | 5 +++++
 txr.c | 7 +++++++
 2 files changed, 12 insertions(+)

diff --git a/txr.1 b/txr.1
index 91520a8e..4ad3ebbb 100644
--- a/txr.1
+++ b/txr.1
@@ -41444,6 +41444,11 @@ is restored.
 During the processing of the profile file (see Interactive Profile File),
 the variable is bound to the name of that file.
 
+.coNP Variable @ txr-path
+.desc
+This variable holds the absolute path name of the directory which
+holds the executable file of the current process.
+
 .SH* INTERACTIVE LISTENER
 
 .SS* Overview
diff --git a/txr.c b/txr.c
index aa1a5eaa..5243c941 100644
--- a/txr.c
+++ b/txr.c
@@ -267,6 +267,12 @@ static val maybe_sysroot(val exepart)
              sysroot_path = sub_str(prog_path, 0, neg(length(exepart))));
 }
 
+static val dirname(val path)
+{
+  val rslash = rpos(chr('/'), path, nil, nil);
+  return if3(rslash, sub_str(path, zero, succ(rslash)), path);
+}
+
 static val substitute_basename(val edited_path, val source_path)
 {
   val lslash = rpos(chr('/'), edited_path, nil, nil);
@@ -316,6 +322,7 @@ static void sysroot_init(void)
            toint(lit(TXR_VER), nil));
   reg_varl(intern(lit("txr-version"), user_package),
            toint(lit(TXR_VER), nil));
+  reg_varl(intern(lit("txr-path"), user_package), dirname(prog_path));
 }
 
 static int license(void)
-- 
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