main: drop container/initrd env vars from inherited set

Leave the env vars used in the container/initrd logic set for PID1, but
don't inherit them to any children.

src/shared/strv.c

@@ -386,6 +386,31 @@ char **strv_remove(char **l, const char *s) {
         return l;
 }
 
+char **strv_remove_prefix(char **l, const char *s) {
+        char **f, **t;
+
+        if (!l)
+                return NULL;
+
+        assert(s);
+
+        /* Drops every occurrence of a string prefixed with s in the
+         * string list, edits in-place. */
+
+        for (f = t = l; *f; f++) {
+
+                if (startswith(*f, s)) {
+                        free(*f);
+                        continue;
+                }
+
+                *(t++) = *f;
+        }
+
+        *t = NULL;
+        return l;
+}
+
 static int env_append(char **r, char ***k, char **a) {
         assert(r);
         assert(k);

src/shared/strv.h

@@ -39,6 +39,7 @@ char **strv_merge_concat(char **a, char **b, const char *suffix);
 char **strv_append(char **l, const char *s);
 
 char **strv_remove(char **l, const char *s);
+char **strv_remove_prefix(char **l, const char *s);
 char **strv_uniq(char **l);
 
 #define strv_contains(l, s) (!!strv_find((l), (s)))

src/shared/util.c

@@ -4276,24 +4276,6 @@ char *fstab_node_to_udev_node(const char *p) {
         return strdup(p);
 }
 
-void filter_environ(const char *prefix) {
-        int i, j;
-        assert(prefix);
-
-        if (!environ)
-                return;
-
-        for (i = 0, j = 0; environ[i]; i++) {
-
-                if (startswith(environ[i], prefix))
-                        continue;
-
-                environ[j++] = environ[i];
-        }
-
-        environ[j] = NULL;
-}
-
 bool tty_is_vc(const char *tty) {
         assert(tty);
 

src/shared/util.h

@@ -409,8 +409,6 @@ void dual_timestamp_deserialize(const char *value, dual_timestamp *t);
 
 char *fstab_node_to_udev_node(const char *p);
 
-void filter_environ(const char *prefix);
-
 bool tty_is_vc(const char *tty);
 bool tty_is_vc_resolve(const char *tty);
 int vtnr_from_tty(const char *tty);