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///////////////////////////////////////////////////////////////////////////////
//
/// \file file_io.h
/// \brief I/O types and functions
//
// Author: Lasse Collin
//
// This file has been put into the public domain.
// You can do whatever you want with this file.
//
///////////////////////////////////////////////////////////////////////////////
// Some systems have suboptimal BUFSIZ. Use a bit bigger value on them.
// We also need that IO_BUFFER_SIZE is a multiple of 8 (sizeof(uint64_t))
#if BUFSIZ <= 1024
# define IO_BUFFER_SIZE 8192
#else
# define IO_BUFFER_SIZE (BUFSIZ & ~7U)
#endif
/// is_sparse() accesses the buffer as uint64_t for maximum speed.
/// Use an union to make sure that the buffer is properly aligned.
typedef union {
uint8_t u8[IO_BUFFER_SIZE];
uint32_t u32[IO_BUFFER_SIZE / sizeof(uint32_t)];
uint64_t u64[IO_BUFFER_SIZE / sizeof(uint64_t)];
} io_buf;
typedef struct {
/// Name of the source filename (as given on the command line) or
/// pointer to static "(stdin)" when reading from standard input.
const char *src_name;
/// Destination filename converted from src_name or pointer to static
/// "(stdout)" when writing to standard output.
char *dest_name;
/// File descriptor of the source file
int src_fd;
/// File descriptor of the target file
int dest_fd;
/// True once end of the source file has been detected.
bool src_eof;
/// If true, we look for long chunks of zeros and try to create
/// a sparse file.
bool dest_try_sparse;
/// This is used only if dest_try_sparse is true. This holds the
/// number of zero bytes we haven't written out, because we plan
/// to make that byte range a sparse chunk.
off_t dest_pending_sparse;
/// Stat of the source file.
struct stat src_st;
/// Stat of the destination file.
struct stat dest_st;
} file_pair;
/// \brief Initialize the I/O module
extern void io_init(void);
/// \brief Disable creation of sparse files when decompressing
extern void io_no_sparse(void);
/// \brief Opens a file pair
extern file_pair *io_open(const char *src_name);
/// \brief Closes the file descriptors and frees possible allocated memory
///
/// The success argument determines if source or destination file gets
/// unlinked:
/// - false: The destination file is unlinked.
/// - true: The source file is unlinked unless writing to stdout or --keep
/// was used.
extern void io_close(file_pair *pair, bool success);
/// \brief Reads from the source file to a buffer
///
/// \param pair File pair having the source file open for reading
/// \param buf Destination buffer to hold the read data
/// \param size Size of the buffer; assumed be smaller than SSIZE_MAX
///
/// \return On success, number of bytes read is returned. On end of
/// file zero is returned and pair->src_eof set to true.
/// On error, SIZE_MAX is returned and error message printed.
extern size_t io_read(file_pair *pair, io_buf *buf, size_t size);
/// \brief Read from source file from given offset to a buffer
///
/// This is remotely similar to standard pread(). This uses lseek() though,
/// so the read offset is changed on each call.
///
/// \param pair Seekable source file
/// \param buf Destination buffer
/// \param size Amount of data to read
/// \param pos Offset relative to the beginning of the file,
/// from which the data should be read.
///
/// \return On success, false is returned. On error, error message
/// is printed and true is returned.
extern bool io_pread(file_pair *pair, io_buf *buf, size_t size, off_t pos);
/// \brief Writes a buffer to the destination file
///
/// \param pair File pair having the destination file open for writing
/// \param buf Buffer containing the data to be written
/// \param size Size of the buffer; assumed be smaller than SSIZE_MAX
///
/// \return On success, zero is returned. On error, -1 is returned
/// and error message printed.
extern bool io_write(file_pair *pair, const io_buf *buf, size_t size);
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