4 files changed, 48 insertions, 7 deletions
diff --git a/src/basic/env-util.c b/src/basic/env-util.c
index 86ac07e1b6..99a130008b 100644
--- a/src/basic/env-util.c
+++ b/src/basic/env-util.c
@@ -454,7 +454,7 @@ fail:
         return NULL;
 }
 
-char *strv_env_get_n(char **l, const char *name, size_t k) {
+char *strv_env_get_n(char **l, const char *name, size_t k, unsigned flags) {
         char **i;
 
         assert(name);
@@ -467,13 +467,20 @@ char *strv_env_get_n(char **l, const char *name, size_t k) {
                     (*i)[k] == '=')
                         return *i + k + 1;
 
+        if (flags & REPLACE_ENV_USE_ENVIRONMENT) {
+                const char *t;
+
+                t = strndupa(name, k);
+                return getenv(t);
+        };
+
         return NULL;
 }
 
 char *strv_env_get(char **l, const char *name) {
         assert(name);
 
-        return strv_env_get_n(l, name, strlen(name));
+        return strv_env_get_n(l, name, strlen(name), 0);
 }
 
 char **strv_env_clean_with_callback(char **e, void (*invalid_callback)(const char *p, void *userdata), void *userdata) {
@@ -512,7 +519,7 @@ char **strv_env_clean_with_callback(char **e, void (*invalid_callback)(const cha
         return e;
 }
 
-char *replace_env(const char *format, char **env) {
+char *replace_env(const char *format, char **env, unsigned flags) {
         enum {
                 WORD,
                 CURLY,
@@ -563,7 +570,7 @@ char *replace_env(const char *format, char **env) {
                         if (*e == '}') {
                                 const char *t;
 
-                                t = strv_env_get_n(env, word+2, e-word-2);
+                                t = strv_env_get_n(env, word+2, e-word-2, flags);
 
                                 k = strappend(r, t);
                                 if (!k)
@@ -643,7 +650,7 @@ char **replace_env_argv(char **argv, char **env) {
                 }
 
                 /* If ${FOO} appears as part of a word, replace it by the variable as-is */
-                ret[k] = replace_env(*i, env);
+                ret[k] = replace_env(*i, env, 0);
                 if (!ret[k]) {
                         strv_free(ret);
                         return NULL;
diff --git a/src/basic/env-util.h b/src/basic/env-util.h
index 90df5b1cd9..4e83dcb43a 100644
--- a/src/basic/env-util.h
+++ b/src/basic/env-util.h
@@ -29,7 +29,11 @@ bool env_name_is_valid(const char *e);
 bool env_value_is_valid(const char *e);
 bool env_assignment_is_valid(const char *e);
 
-char *replace_env(const char *format, char **env);
+enum {
+        REPLACE_ENV_USE_ENVIRONMENT = 1u,
+};
+
+char *replace_env(const char *format, char **env, unsigned flags);
 char **replace_env_argv(char **argv, char **env);
 
 bool strv_env_is_valid(char **e);
@@ -47,7 +51,7 @@ 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_n(char **l, const char *name, size_t k, unsigned flags) _pure_;
 char *strv_env_get(char **x, const char *n) _pure_;
 
 int getenv_bool(const char *p);
diff --git a/src/basic/fileio.c b/src/basic/fileio.c
index a1e4978125..49dd52bfd9 100644
--- a/src/basic/fileio.c
+++ b/src/basic/fileio.c
@@ -762,6 +762,34 @@ int load_env_file_pairs(FILE *f, const char *fname, const char *newline, char **
         return 0;
 }
 
+static int merge_env_file_push(
+                const char *filename, unsigned line,
+                const char *key, char *value,
+                void *userdata,
+                int *n_pushed) {
+
+        char ***env = userdata;
+        char *expanded_value;
+
+        assert(env);
+
+        expanded_value = replace_env(value, *env, REPLACE_ENV_USE_ENVIRONMENT);
+        if (!expanded_value)
+                return -ENOMEM;
+
+        free_and_replace(value, expanded_value);
+
+        return load_env_file_push(filename, line, key, value, env, n_pushed);
+}
+
+int merge_env_file(
+                char ***env,
+                FILE *f,
+                const char *fname) {
+
+        return parse_env_file_internal(f, fname, NEWLINE, merge_env_file_push, env, NULL);
+}
+
 static void write_env_var(FILE *f, const char *v) {
         const char *p;
 
diff --git a/src/basic/fileio.h b/src/basic/fileio.h
index 64852b15a8..e547614cc4 100644
--- a/src/basic/fileio.h
+++ b/src/basic/fileio.h
@@ -48,6 +48,8 @@ int parse_env_file(const char *fname, const char *separator, ...) _sentinel_;
 int load_env_file(FILE *f, const char *fname, const char *separator, char ***l);
 int load_env_file_pairs(FILE *f, const char *fname, const char *separator, char ***l);
 
+int merge_env_file(char ***env, FILE *f, const char *fname);
+
 int write_env_file(const char *fname, char **l);
 
 int executable_is_script(const char *path, char **interpreter);