1 files changed, 20 insertions, 13 deletions

diff --git a/lib/libc/stdlib/getenv.c b/lib/libc/stdlib/getenv.c
index 74595b2eae47f..2abf7fc7b01ee 100644
--- a/lib/libc/stdlib/getenv.c
+++ b/lib/libc/stdlib/getenv.c
@@ -1,5 +1,5 @@
 /*-
- * Copyright (c) 2007 Sean C. Farley <scf@FreeBSD.org>
+ * Copyright (c) 2007-2008 Sean C. Farley <scf@FreeBSD.org>
  * All rights reserved.
  *
  * Redistribution and use in source and binary forms, with or without
@@ -190,10 +190,6 @@ __findenv_environ(const char *name, size_t nameLen)
 {
 	int envNdx;
 
-	/* Check for non-existant environment. */
-	if (environ == NULL)
-		return (NULL);
-
 	/* Find variable within environ. */
 	for (envNdx = 0; environ[envNdx] != NULL; envNdx++)
 		if (strncmpeq(environ[envNdx], name, nameLen))
@@ -430,11 +426,17 @@ getenv(const char *name)
 	}
 
 	/*
-	 * Find environment variable via environ if no changes have been made
-	 * via a *env() call or environ has been replaced by a running program,
-	 * otherwise, use the rebuilt environment.
+	 * An empty environment (environ or its first value) regardless if
+	 * environ has been copied before will return a NULL.
+	 *
+	 * If the environment is not empty, find an environment variable via
+	 * environ if environ has not been copied via an *env() call or been
+	 * replaced by a running program, otherwise, use the rebuilt
+	 * environment.
 	 */
-	if (envVars == NULL || environ != intEnviron)
+	if (environ == NULL || environ[0] == NULL)
+		return (NULL);
+	else if (envVars == NULL || environ != intEnviron)
 		return (__findenv_environ(name, nameLen));
 	else {
 		envNdx = envVarsTotal - 1;
@@ -525,8 +527,8 @@ __setenv(const char *name, size_t nameLen, const char *value, int overwrite)
 
 /*
  * If the program attempts to replace the array of environment variables
- * (environ) environ, then deactivate all variables and merge in the new list
- * from environ.
+ * (environ) environ or sets the first varible to NULL, then deactivate all
+ * variables and merge in the new list from environ.
  */
 static int
 __merge_environ(void)
@@ -534,8 +536,13 @@ __merge_environ(void)
 	char **env;
 	char *equals;
 
-	/* environ has been replaced.  clean up everything. */
-	if (envVarsTotal > 0 && environ != intEnviron) {
+	/*
+	 * Internally-built environ has been replaced or cleared (detected by
+	 * using the count of active variables against a NULL as the first value
+	 * in environ).  Clean up everything.
+	 */
+	if (intEnviron != NULL && (environ != intEnviron || (envActive > 0 &&
+	    environ[0] == NULL))) {
 		/* Deactivate all environment variables. */
 		if (envActive > 0) {
 			origEnviron = NULL;