Stash the environment pointer we get from realloc() instead of just

setting a flag.  That way when we are called again we can be sure
to realloc() the right thing, regardless of the current value of
environ.  When the stashed value != environ (or when we are called
for the first time), copy the existing entries from environ and set
environ to the new value.  OK deraadt@, beck@, djm@

src/lib/libc/stdlib/setenv.c

@@ -28,7 +28,7 @@
  */
 
 #if defined(LIBC_SCCS) && !defined(lint)
-static char *rcsid = "$OpenBSD: setenv.c,v 1.6 2003/06/02 20:18:38 millert Exp $";
+static char *rcsid = "$OpenBSD: setenv.c,v 1.7 2005/02/16 21:20:22 millert Exp $";
 #endif /* LIBC_SCCS and not lint */
 
 #include <stdlib.h>
@@ -36,6 +36,8 @@ static char *rcsid = "$OpenBSD: setenv.c,v 1.6 2003/06/02 20:18:38 millert Exp $
 
 char *__findenv(const char *name, int *offset);
 
+extern char **environ;
+
 /*
  * setenv --
  *	Set the value of the environmental variable "name" to be
@@ -43,13 +45,12 @@ char *__findenv(const char *name, int *offset);
  */
 int
 setenv(name, value, rewrite)
-	register const char *name;
-	register const char *value;
+	const char *name;
+	const char *value;
 	int rewrite;
 {
-	extern char **environ;
-	static int alloced;			/* if allocated space before */
-	register char *C;
+	static char **lastenv;			/* last value of environ */
+	char *C;
 	int l_value, offset;
 
 	if (*value == '=')			/* no `=' in value */
@@ -64,30 +65,23 @@ setenv(name, value, rewrite)
 			return (0);
 		}
 	} else {					/* create new slot */
-		register int	cnt;
-		register char	**P;
+		size_t cnt;
+		char **P;
 
-		for (P = environ, cnt = 0; *P; ++P, ++cnt);
-		if (alloced) {			/* just increase size */
-			P = (char **)realloc((void *)environ,
-			    (size_t)(sizeof(char *) * (cnt + 2)));
-			if (!P)
-				return (-1);
-			environ = P;
-		}
-		else {				/* get new space */
-			alloced = 1;		/* copy old entries into it */
-			P = (char **)malloc((size_t)(sizeof(char *) *
-			    (cnt + 2)));
-			if (!P)
-				return (-1);
-			bcopy(environ, P, cnt * sizeof(char *));
-			environ = P;
-		}
-		environ[cnt + 1] = NULL;
+		for (P = environ; *P != NULL; P++)
+			;
+		cnt = P - environ;
+		P = (char **)realloc(lastenv, sizeof(char *) * (cnt + 2));
+		if (!P)
+			return (-1);
+		if (lastenv != environ)
+			memcpy(P, environ, cnt * sizeof(char *));
+		lastenv = environ = P;
 		offset = cnt;
+		environ[cnt + 1] = NULL;
 	}
-	for (C = (char *)name; *C && *C != '='; ++C);	/* no `=' in name */
+	for (C = (char *)name; *C && *C != '='; ++C)
+		;				/* no `=' in name */
 	if (!(environ[offset] =			/* name + `=' + value */
 	    malloc((size_t)((int)(C - name) + l_value + 2))))
 		return (-1);
@@ -104,14 +98,12 @@ setenv(name, value, rewrite)
  */
 void
 unsetenv(name)
-	const char	*name;
+	const char *name;
 {
-	extern char **environ;
-	register char **P;
+	char **P;
 	int offset;
-	char *__findenv();
 
-	while (__findenv(name, &offset))		/* if set multiple times */
+	while (__findenv(name, &offset))	/* if set multiple times */
 		for (P = &environ[offset];; ++P)
 			if (!(*P = *(P + 1)))
 				break;