Allow setenv(3) and putenv(3) to operate on a NULL environ pointer.

The getenv(3) and unsetenv(3) functions already support this.
This will make it easier to emulate the glibc clearenv() function in ports.
Based on a diff from and OK jca@

1 files changed, 15 insertions, 11 deletions

diff --git a/src/lib/libc/stdlib/setenv.c b/src/lib/libc/stdlib/setenv.c
index 1182abdaa3..60c2cd46a6 100644
--- a/src/lib/libc/stdlib/setenv.c
+++ b/src/lib/libc/stdlib/setenv.c
@@ -1,4 +1,4 @@
-/*      $OpenBSD: setenv.c,v 1.17 2016/03/13 18:34:21 guenther Exp $ */
+/*      $OpenBSD: setenv.c,v 1.18 2016/04/25 21:36:04 millert Exp $ */
 /*
  * Copyright (c) 1987 Regents of the University of California.
  * All rights reserved.
@@ -43,7 +43,7 @@ int
 putenv(char *str)
 {
         char **P, *cp;
-        size_t cnt;
+        size_t cnt = 0;
         int offset = 0;
 
         for (cp = str; *cp && *cp != '='; ++cp)
@@ -65,13 +65,15 @@ putenv(char *str)
         }
 
         /* create new slot for string */
-        for (P = environ; *P != NULL; P++)
-                ;
-        cnt = P - environ;
+        if (environ != NULL) {
+                for (P = environ; *P != NULL; P++)
+                        ;
+                cnt = P - environ;
+        }
         P = reallocarray(lastenv, cnt + 2, sizeof(char *));
         if (!P)
                 return (-1);
-        if (lastenv != environ)
+        if (lastenv != environ && environ != NULL)
                 memcpy(P, environ, cnt * sizeof(char *));
         lastenv = environ = P;
         environ[cnt] = str;
@@ -122,15 +124,17 @@ setenv(const char *name, const char *value, int rewrite)
                                         break;
                 }
         } else {                                        /* create new slot */
-                size_t cnt;
+                size_t cnt = 0;
 
-                for (P = environ; *P != NULL; P++)
-                        ;
-                cnt = P - environ;
+                if (environ != NULL) {
+                        for (P = environ; *P != NULL; P++)
+                                ;
+                        cnt = P - environ;
+                }
                 P = reallocarray(lastenv, cnt + 2, sizeof(char *));
                 if (!P)
                         return (-1);
-                if (lastenv != environ)
+                if (lastenv != environ && environ != NULL)
                         memcpy(P, environ, cnt * sizeof(char *));
                 lastenv = environ = P;
                 offset = cnt;