file_io.h File Reference

I/O types and functions. More...

Go to the source code of this file.

Data Structures
union	io_buf
struct	file_pair

Macros
#define	IO_BUFFER_SIZE   8192

Functions
void	io_init (void)
	Initialize the I/O module.
void	io_write_to_user_abort_pipe (void)
	Write a byte to user_abort_pipe[1].
void	io_no_sparse (void)
	Disable creation of sparse files when decompressing.
file_pair *	io_open_src (const char *src_name)
	Open the source file.
bool	io_open_dest (file_pair *pair)
	Open the destination file.
void	io_close (file_pair *pair, bool success)
	Closes the file descriptors and frees possible allocated memory.
size_t	io_read (file_pair *pair, io_buf *buf, size_t size)
	Reads from the source file to a buffer.
void	io_fix_src_pos (file_pair *pair, size_t rewind_size)
	Fix the position in src_fd.
bool	io_seek_src (file_pair *pair, uint64_t pos)
	Seek to the given absolute position in the source file.
bool	io_pread (file_pair *pair, io_buf *buf, size_t size, uint64_t pos)
	Read from source file from given offset to a buffer.
bool	io_write (file_pair *pair, const io_buf *buf, size_t size)
	Writes a buffer to the destination file.

Detailed Description

I/O types and functions.

Macro Definition Documentation

IO_BUFFER_SIZE

#define IO_BUFFER_SIZE   8192

Function Documentation

io_close()

void io_close ( file_pair * pair, bool success )

extern

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.

io_fix_src_pos()

void io_fix_src_pos ( file_pair * pair, size_t rewind_size )

extern

Fix the position in src_fd.

This is used when –single-thream has been specified and decompression is successful. If the input file descriptor supports seeking, this function fixes the input position to point to the next byte after the decompressed stream.

Parameters

pair	File pair having the source file open for reading
rewind_size	How many bytes of extra have been read i.e. how much to seek backwards.

io_init()

void io_init ( void )

extern

Initialize the I/O module.

io_no_sparse()

void io_no_sparse ( void )

extern

Disable creation of sparse files when decompressing.

io_open_dest()

bool io_open_dest ( file_pair * pair )

extern

Open the destination file.

io_open_src()

file_pair * io_open_src ( const char * src_name )

extern

Open the source file.

io_pread()

bool io_pread ( file_pair * pair, io_buf * buf, size_t size, uint64_t pos )

extern

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.

Parameters

pair	Seekable source file
buf	Destination buffer
size	Amount of data to read
pos	Offset relative to the beginning of the file, from which the data should be read.

Returns

On success, false is returned. On error, error message is printed and true is returned.

io_read()

size_t io_read ( file_pair * pair, io_buf * buf, size_t size )

extern

Reads from the source file to a buffer.

Parameters

pair	File pair having the source file open for reading
buf	Destination buffer to hold the read data
size	Size of the buffer; must be at most IO_BUFFER_SIZE

Returns

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.

Parameters

pair	File pair having the source file open for reading
buf	Destination buffer to hold the read data
size	Size of the buffer; assumed be smaller than SSIZE_MAX

Returns

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.

io_seek_src()

bool io_seek_src ( file_pair * pair, uint64_t pos )

extern

Seek to the given absolute position in the source file.

This calls lseek() and also clears pair->src_eof.

Parameters

pair	Seekable source file
pos	Offset relative to the beginning of the file, from which the data should be read.

Returns

On success, false is returned. On error, error message is printed and true is returned.

io_write()

bool io_write ( file_pair * pair, const io_buf * buf, size_t size )

extern

Writes a buffer to the destination file.

Parameters

pair	File pair having the destination file open for writing
buf	Buffer containing the data to be written
size	Size of the buffer; must be at most IO_BUFFER_SIZE

Returns

On success, zero is returned. On error, -1 is returned and error message printed.

Parameters

pair	File pair having the destination file open for writing
buf	Buffer containing the data to be written
size	Size of the buffer; assumed be smaller than SSIZE_MAX

Returns

On success, zero is returned. On error, -1 is returned and error message printed.

io_write_to_user_abort_pipe()

void io_write_to_user_abort_pipe ( void )

extern

Write a byte to user_abort_pipe[1].

This is called from a signal handler.