From 6c17f630901eec2a4b54b70748d7fbc9b47eecd8 Mon Sep 17 00:00:00 2001
From: Russ Cox <rsc@swtch.com>
Date: Mon, 13 Jan 2020 19:20:34 -0500
Subject: mk: treat X= as empty list in rc shell

This brings mk's behavior when using rc in line with Plan 9's.
The existing code is for Unix environment data structures but
also was assuming Unix shell semantics where empty and missing
variables are mostly equivalent.

The Plan 9 code (/sys/src/cmd/mk/plan9.c in the distribution)
explicitly removes /env/name (creating an empty list) when the
value is missing or an empty string.

Fixes #255.
---
 src/cmd/mk/unix.c | 18 ++++++++++++------
 1 file changed, 12 insertions(+), 6 deletions(-)

(limited to 'src')

diff --git a/src/cmd/mk/unix.c b/src/cmd/mk/unix.c
index 37f05b71..66bdb1ff 100644
--- a/src/cmd/mk/unix.c
+++ b/src/cmd/mk/unix.c
@@ -53,20 +53,26 @@ readenv(void)
 void
 exportenv(Envy *e, Shell *sh)
 {
-	int i;
+	int w, n;
 	char **p;
+	Envy *e1;
 	static char buf[16384];
 
-	p = 0;
-	for(i = 0; e->name; e++, i++) {
-		p = (char**) Realloc(p, (i+2)*sizeof(char*));
+	n = 0;
+	for(e1 = e; e1->name; e1++)
+		n++;
+	p = Malloc((n+1)*sizeof(char*));
+	w = 0;
+	for(; e->name; e++) {
+		if(sh == &rcshell && (e->values == 0 || e->values->s == 0 || e->values->s[0] == 0))
+			continue; /* do not write empty string for empty list */
 		if(e->values)
 			snprint(buf, sizeof buf, "%s=%s", e->name,  wtos(e->values, sh->iws));
 		else
 			snprint(buf, sizeof buf, "%s=", e->name);
-		p[i] = strdup(buf);
+		p[w++] = strdup(buf);
 	}
-	p[i] = 0;
+	p[w] = 0;
 	environ = p;
 }
 
-- 
cgit v1.2.3