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