+extern void carefully_write(int fd, const void *buf, size_t sz);
+extern void open_file_on_demand(const char *file, FILE **fp_inout,
+ const char *what);
+extern void check_write(FILE *fp, const char *what);
+extern void carefully_fclose(FILE *fp, const char *what);
+extern off_t device_size(int fd, const char *file, int *blksz_out);
+