core/load-fragment: modify existing environment instead of copying strv over and over

2 files changed, 23 insertions, 0 deletions

diff --git a/src/basic/env-util.c b/src/basic/env-util.c
index b74290d6fd..7c69ccdaf9 100644
--- a/src/basic/env-util.c
+++ b/src/basic/env-util.c
@@ -384,6 +384,28 @@ char **strv_env_unset_many(char **l, ...) {
         return l;
 }
 
+int strv_env_replace(char ***l, char *p) {
+        char **f;
+
+        assert(p);
+
+        /* Replace first occurrence of the env var or add a new one in the
+         * string list. Drop other occurences. Edits in-place. Does not copy p.
+         */
+
+        for (f = *l; f && *f; f++)
+                if (env_match(*f, p)) {
+                        free_and_replace(*f, p);
+                        strv_env_unset(f + 1, p);
+                        return 0;
+                }
+
+        /* We didn't find a match, we need to append p or create a new strv */
+        if (strv_push(l, p) < 0)
+                return -ENOMEM;
+        return 1;
+}
+
 char **strv_env_set(char **x, const char *p) {
 
         char **k, **r;
diff --git a/src/basic/env-util.h b/src/basic/env-util.h
index b1fef704c2..8cb0fc2131 100644
--- a/src/basic/env-util.h
+++ b/src/basic/env-util.h
@@ -44,6 +44,7 @@ char **strv_env_delete(char **x, unsigned n_lists, ...); /* New copy */
 char **strv_env_set(char **x, const char *p); /* New copy ... */
 char **strv_env_unset(char **l, const char *p); /* In place ... */
 char **strv_env_unset_many(char **l, ...) _sentinel_;
+int strv_env_replace(char ***l, char *p); /* In place ... */
 
 char *strv_env_get_n(char **l, const char *name, size_t k) _pure_;
 char *strv_env_get(char **x, const char *n) _pure_;