From bc1444426b57c30af71af6a26fa1674984d414a4 Mon Sep 17 00:00:00 2001
From: hovercats <hovercatswithlasereyes@protonmail.com>
Date: Sat, 25 Apr 2026 16:54:31 +0200
Subject: [PATCH] keep $PATH and $path in sync

---
 exec.c | 12 ++++----
 fns.h  |  1 +
 rc.h   |  1 +
 var.c  | 93 ++++++++++++++++++++++++++++++++++++++++++++++++++++++++--
 4 files changed, 99 insertions(+), 8 deletions(-)

diff --git a/exec.c b/exec.c
index ce9872a..987960d 100644
--- a/exec.c
+++ b/exec.c
@@ -265,6 +265,7 @@ main(int argc, char *argv[])
 	Trapinit();
 	Vinit();
 	inttoascii(num, mypid = getpid());
+	pathinit();
 	setvar("pid", newword(num, (word *)0));
 	setvar("cflag", flag['c']?newword(flag['c'][0], (word *)0)
 				:(word *)0);
@@ -758,16 +759,15 @@ void
 Xassign(void)
 {
 	var *v;
+	word *w;
 
-	if(count(runq->argv->words)!=1){
+	w = Poplist();
+	if(count(w)!=1){
 		Xerror1("= variable name not singleton!");
 		return;
 	}
-	v = vlook(runq->argv->words->word);
-	poplist();
-	freewords(v->val);
-	v->val = Poplist();
-	v->changed = 1;
+	setvar(w->word, Poplist());
+	freewords(w);
 }
 
 /*
diff --git a/fns.h b/fns.h
index 1644d1e..a99f6fa 100644
--- a/fns.h
+++ b/fns.h
@@ -49,6 +49,7 @@ int	mapfd(int);
 int	match(char*, char*, int);
 char*	makepath(char*, char*);
 void	panic(char*, int);
+void	pathinit(void);
 void	pfln(io*, char*, int);
 void	poplist(void);
 void	popword(void);
diff --git a/rc.h b/rc.h
index a688663..3f48cce 100644
--- a/rc.h
+++ b/rc.h
@@ -117,6 +117,7 @@ struct var{
 	int	pc;		/* pc of start of function */
 	char	fnchanged;
 	char	changed;
+	void	(*changefn)(var*);
 	char	name[];
 };
 var *vlook(char*), *gvlook(char*), *newvar(char*, var*);
diff --git a/var.c b/var.c
index 73b01fa..e132a7b 100644
--- a/var.c
+++ b/var.c
@@ -70,6 +70,7 @@ newvar(char *name, var *next)
 	v->fn = 0;
 	v->changed = 0;
 	v->fnchanged = 0;
+	v->changefn = 0;
 	return v;
 }
 
@@ -92,13 +93,21 @@ vlook(char *name)
 	return gvlook(name);
 }
 
-void
-setvar(char *name, word *val)
+static void
+setvar_(char *name, word *val, int callfn)
 {
 	var *v = vlook(name);
 	freewords(v->val);
 	v->val = val;
 	v->changed = 1;
+	if(callfn && v->changefn)
+		v->changefn(v);
+}
+
+void
+setvar(char *name, word *val)
+{
+	setvar_(name, val, 1);
 }
 
 void
@@ -107,3 +116,83 @@ freevar(var *v)
 	freewords(v->val);
 	free(v);
 }
+
+static void
+bigpath(var *v)
+{
+	/* convert $PATH to $path */
+	char *p, *q;
+	word **l, *w;
+
+	if(v->val == 0){
+		setvar_("path", 0, 0);
+		return;
+	}
+	p = v->val->word;
+	w = 0;
+	l = &w;
+	/*
+	 * Doesn't handle escaped colon nonsense.
+	 */
+	if(p[0] == 0)
+		p = 0;
+	while(p){
+		q = strchr(p, ':');
+		if(q)
+			*q = 0;
+		*l = newword(p[0] ? p : ".", 0);
+		l = &(*l)->next;
+		if(q){
+			*q = ':';
+			p = q+1;
+		}else
+			p = 0;
+	}
+	setvar_("path", w, 0);
+}
+
+static char *
+list2strcolon(word *words)
+{
+	char *value, *s, *t;
+	int len = 0;
+	word *ap;
+	for(ap = words;ap;ap = ap->next)
+		len+=1+strlen(ap->word);
+	value = emalloc(len+1);
+	s = value;
+	for(ap = words;ap;ap = ap->next){
+		for(t = ap->word;*t;) *s++=*t++;
+		*s++=':';
+	}
+	if(s==value)
+		*s='\0';
+	else s[-1]='\0';
+	return value;
+}
+
+static void
+littlepath(var *v)
+{
+	/* convert $path to $PATH */
+	char *p;
+	word *w;
+
+	p = list2strcolon(v->val);
+	w = new(word);
+	w->word = p;
+	w->next = 0;
+	setvar_("PATH", w, 1);	/* 1: recompute $path to expose colon problems */
+}
+
+void
+pathinit(void)
+{
+	var *v;
+
+	v = gvlook("path");
+	v->changefn = littlepath;
+	v = gvlook("PATH");
+	v->changefn = bigpath;
+	bigpath(v);
+}
-- 
2.49.0