feat: add environment variable passing

include/executor.h

@@ -1,7 +1,9 @@
 #ifndef SCI_EXECUTOR_H
 #define SCI_EXECUTOR_H
+#include "strlist.h"
 
 void executor(void* pipeline_event);
 void set_logdir(const char* logdir);
+void set_shared_environment(const strlist_node* root);
 
 #endif

include/util.h

@@ -40,6 +40,7 @@ typedef void(*line_handler)(const char*);
 void per_line(const char* file, line_handler handler);
 
 char* join(const char* a, const char* b);
+char* join3(const char* a, const char* b, const char* c);
 
 const char* skip_arg(const char* cp);
 char* skip_spaces(const char* str);