+/* 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);
+
+/* 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);
+
+/* Wrapper to successive call of fclose() from function called "f" on "file",
+ * then unlink() on file at "p2" if it exists, then rename() on "p1" to "p2".
+ * Used for handling atomic saving of files via temp files.
+ */
+extern void try_fclose_unlink_rename(FILE * file, char * p1, char * p2,
+ char * f);
+
+/* Wrapper: Call textfile_sizes() from function called "f" to get max line
+ * length of "file", exit via exit_err() with trouble_msg()-generated error
+ * message on failure.
+ */
+extern uint16_t get_linemax(FILE * file, char * f);
+