#ifndef BREAD_H #define BREAD_H // A BREAD reads a file backwards using buffered I/O. BREAD stands for Buffered Read or Backwards Read. // Conceivably, we could read forward too. // The buffered I/O is buffered using a large buffer (e.g., something like a megabyte). // Furthermore, data is compressed into blocks. Each block is a 4-byte compressed length (in network order), followed by compressed data, followed by a 4-byte uncompressed-length (in network order), followed by a 4-byte compressed length // The compressed-length appears twice so that the file can be read backward or forward. // If not for the large-buffer requirement, as well as compression, as well as reading backward, we could have used a FILE. #include typedef struct bread *BREAD; BREAD create_bread_from_fd_initialize_at(int fd); // Effect: Given a file descriptor, fd, create a BREAD. // Requires: The fd must be an open fd. int close_bread_without_closing_fd(BREAD); // Effect: Close the BREAD, but don't close the underlying fd. ssize_t bread_backwards(BREAD, void *buf, size_t nbytes); // Read nbytes into buf, reading backwards. int bread_has_more(BREAD); // Is there more to read? #endif