feat(vars): get_var_or_env

src/utils/vars/vars.c

@@ -2,7 +2,7 @@
 #include "vars.h"
 
 #include <stdbool.h>
-#include <stddef.h>
+#include <stdlib.h>
 #include <string.h>
 
 #include "../hash_map/hash_map.h"
@@ -19,6 +19,14 @@ char *get_var(const struct hash_map *vars, const char *key)
     return (char *)hash_map_get(vars, key);
 }
 
+char *get_var_or_env(const struct hash_map *vars, const char *key)
+{
+    char *value = (char *)hash_map_get(vars, key);
+    if (value == NULL)
+        value = getenv(key);
+    return value;
+}
+
 bool set_var(struct hash_map *vars, const char *key, const char *value)
 {
     if (key == NULL || value == NULL)

src/utils/vars/vars.h

@@ -15,6 +15,12 @@ struct hash_map *vars_init(void);
  */
 char *get_var(const struct hash_map *vars, const char *key);
 
+/**
+ * Get the value of a variable, from the environment if not found in vars,
+ * NULL if not found in either.
+ */
+char *get_var_or_env(const struct hash_map *vars, const char *key);
+
 /**
  * Set the value of a variable. Key and value ownership are transferred to
  * the hash_map and need to be on the heap. Returns true on success, false on