NAME¶
archive_write_open
,
archive_write_open_fd
,
archive_write_open_FILE
,
archive_write_open_filename
,
archive_write_open_memory
—
functions for creating archives
LIBRARY¶
Streaming Archive Library (libarchive, -larchive)
SYNOPSIS¶
#include
<archive.h>
int
archive_write_open
(
struct
archive *,
void *client_data,
archive_open_callback *,
archive_write_callback *,
archive_close_callback *);
int
archive_write_open_fd
(
struct
archive *,
int
fd);
int
archive_write_open_FILE
(
struct
archive *,
FILE
*file);
int
archive_write_open_filename
(
struct
archive *,
const
char *filename);
int
archive_write_open_memory
(
struct
archive *,
void *buffer,
size_t bufferSize,
size_t *outUsed);
DESCRIPTION¶
archive_write_open
()
- Freeze the settings, open the archive, and prepare for writing entries.
This is the most generic form of this function, which accepts pointers to
three callback functions which will be invoked by the compression layer to
write the constructed archive.
archive_write_open_fd
()
- A convenience form of
archive_write_open
() that accepts a
file descriptor. The
archive_write_open_fd
() function is
safe for use with tape drives or other block-oriented devices.
archive_write_open_FILE
()
- A convenience form of
archive_write_open
() that accepts a
FILE * pointer. Note that
archive_write_open_FILE
() is not safe
for writing to tape drives or other devices that require correct
blocking.
archive_write_open_file
()
- A deprecated synonym for
archive_write_open_filename
().
archive_write_open_filename
()
- A convenience form of
archive_write_open
() that accepts a
filename. A NULL argument indicates that the output should be written to
standard output; an argument of “-” will open a file with
that name. If you have not invoked
archive_write_set_bytes_in_last_block
(),
then archive_write_open_filename
() will
adjust the last-block padding depending on the file: it will enable
padding when writing to standard output or to a character or block device
node, it will disable padding otherwise. You can override this by manually
invoking
archive_write_set_bytes_in_last_block
()
before calling archive_write_open
().
The archive_write_open_filename
()
function is safe for use with tape drives or other block-oriented
devices.
archive_write_open_memory
()
- A convenience form of
archive_write_open
() that accepts a
pointer to a block of memory that will receive the archive. The final
size_t * argument points to a variable
that will be updated after each write to reflect how much of the buffer is
currently in use. You should be careful to ensure that this variable
remains allocated until after the archive is closed.
More information about the
struct archive
object and the overall design of the library can be found in the
libarchive(3) overview.
CLIENT CALLBACKS¶
To use this library, you will need to define and register callback functions
that will be invoked to write data to the resulting archive. These functions
are registered by calling
archive_write_open
():
- typedef int
archive_open_callback
(struct
archive *, void *client_data)
The open callback is invoked by
archive_write_open
(). It should return
ARCHIVE_OK
if the underlying file or data
source is successfully opened. If the open fails, it should call
archive_set_error
() to register an error
code and message and return
ARCHIVE_FATAL
.
- typedef ssize_t
archive_write_callback
(struct
archive *, void *client_data,
const void *buffer,
size_t length);
The write callback is invoked whenever the library needs to write raw bytes to
the archive. For correct blocking, each call to the write callback function
should translate into a single
write(2) system
call. This is especially critical when writing archives to tape drives. On
success, the write callback should return the number of bytes actually
written. On error, the callback should invoke
archive_set_error
() to register an error
code and message and return -1.
- typedef int
archive_close_callback
(struct
archive *, void *client_data)
The close callback is invoked by archive_close when the archive processing is
complete. The callback should return
ARCHIVE_OK
on success. On failure, the
callback should invoke
archive_set_error
()
to register an error code and message and return
ARCHIVE_FATAL.
Note that if the client-provided write callback function returns a non-zero
value, that error will be propagated back to the caller through whatever API
function resulted in that call, which may include
archive_write_header
(),
archive_write_data
(),
archive_write_close
(),
archive_write_finish
(), or
archive_write_free
(). The client callback
can call
archive_set_error
() to provide
values that can then be retrieved by
archive_errno
() and
archive_error_string
().
RETURN VALUES¶
These functions return
ARCHIVE_OK
on success,
or
ARCHIVE_FATAL
.
ERRORS¶
Detailed error codes and textual descriptions are available from the
archive_errno
() and
archive_error_string
() functions.
SEE ALSO¶
tar(1),
libarchive(3),
archive_write(3),
archive_write_filter(3),
archive_write_format(3),
archive_write_new(3),
archive_write_set_options(3),
cpio(5),
mtree(5),
tar(5)