+#include <stdio.h> /* for FILE typedef */
+#include <stdint.h> /* for uint8_t, uint16_t, uint32_t */
+
+
+
+/* Wrappers to calling from function called "f" of fopen(), fclose(), fgets()
+ * and fwrite() and calling exit_err() with appropriate error messages.
+ */
+extern FILE * try_fopen(char * path, char * mode, char * f);
+extern void try_fclose(FILE * file, char * f);
+extern void try_fwrite(void * ptr, size_t size, size_t nmemb, FILE * stream,
+ char * f);
+extern void try_fputc(uint8_t c, FILE * file, char * f);
+
+/* Wrapper to calling fgets() from function called "f". The return code of
+ * fgets() is returned unless it is NULL *and* ferror() indicates that an error
+ * occured; otherwise end of file is assumed and NULL is returned properly.
+ */
+extern char * try_fgets(char * line, int size, FILE * file, char * f);
+
+/* Wrappers to calling fgetc() and (try_fgetc_noeof()) treating all EOFs returns
+ * as errors to call exit_trouble(), or (try_fgetc()) only if ferror() says so.
+ */
+extern int try_fgetc(FILE * file, char * f);
+extern uint8_t try_fgetc_noeof(FILE * file, char * f);