basic: add new merge_env_file function

merge_env_file is a new function, that's like load_env_file, but takes a
pre-existing environment as an input argument. New environment entries are
merged. Variable expansion is performed.

Falling back to the process environment is supported (when a flag is set).
Alternatively this could be implemented as passing an additional fallback
environment array, but later on we're adding another flag to allow braceless
expansion, and the two flags can be combined in one arg, so there's less
stuff to pass around.

1 files changed, 28 insertions, 0 deletions

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;