libarchive/archive_write_open.3 - third_party/libarchive - Git at Google

 .\" Copyright (c) 2003-2011 Tim Kientzle
 .\" All rights reserved.
 .\"
 .\" Redistribution and use in source and binary forms, with or without
 .\" modification, are permitted provided that the following conditions
 .\" are met:
 .\" 1. Redistributions of source code must retain the above copyright
 .\"    notice, this list of conditions and the following disclaimer.
 .\" 2. Redistributions in binary form must reproduce the above copyright
 .\"    notice, this list of conditions and the following disclaimer in the
 .\"    documentation and/or other materials provided with the distribution.
 .\"
 .\" THIS SOFTWARE IS PROVIDED BY THE AUTHOR AND CONTRIBUTORS ``AS IS'' AND
 .\" ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
 .\" IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
 .\" ARE DISCLAIMED.  IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE
 .\" FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
 .\" DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
 .\" OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
 .\" HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
 .\" LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
 .\" OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
 .\" SUCH DAMAGE.
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 .\" $FreeBSD$
 .\"
 .Dd February 2, 2012
 .Dt ARCHIVE_WRITE_OPEN 3
 .Os
 .Sh NAME
 .Nm archive_write_open ,
 .Nm archive_write_open_fd ,
 .Nm archive_write_open_FILE ,
 .Nm archive_write_open_filename ,
 .Nm archive_write_open_memory
 .Nd functions for creating archives
 .Sh LIBRARY
 Streaming Archive Library (libarchive, -larchive)
 .Sh SYNOPSIS
 .In archive.h
 .Ft int
 .Fo archive_write_open
 .Fa "struct archive *"
 .Fa "void *client_data"
 .Fa "archive_open_callback *"
 .Fa "archive_write_callback *"
 .Fa "archive_close_callback *"
 .Fc
 .Ft int
 .Fn archive_write_open_fd "struct archive *" "int fd"
 .Ft int
 .Fn archive_write_open_FILE "struct archive *" "FILE *file"
 .Ft int
 .Fn archive_write_open_filename "struct archive *" "const char *filename"
 .Ft int
 .Fo archive_write_open_memory
 .Fa "struct archive *"
 .Fa "void *buffer"
 .Fa "size_t bufferSize"
 .Fa "size_t *outUsed"
 .Fc
 .Sh DESCRIPTION
 .Bl -tag -width indent
 .It Fn 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.
 This does not alter the default archive padding.
 .It Fn archive_write_open_fd
 A convenience form of
 .Fn archive_write_open
 that accepts a file descriptor.
 The
 .Fn archive_write_open_fd
 function is safe for use with tape drives or other
 block-oriented devices.
 .It Fn archive_write_open_FILE
 A convenience form of
 .Fn archive_write_open
 that accepts a
 .Ft "FILE *"
 pointer.
 Note that
 .Fn archive_write_open_FILE
 is not safe for writing to tape drives or other devices
 that require correct blocking.
 .It Fn archive_write_open_file
 A deprecated synonym for
 .Fn archive_write_open_filename .
 .It Fn archive_write_open_filename
 A convenience form of
 .Fn archive_write_open
 that accepts a filename.
 A NULL argument indicates that the output should be written to standard output;
 an argument of
 .Dq -
 will open a file with that name.
 If you have not invoked
 .Fn archive_write_set_bytes_in_last_block ,
 then
 .Fn 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
 .Fn archive_write_set_bytes_in_last_block
 before calling
 .Fn archive_write_open .
 The
 .Fn archive_write_open_filename
 function is safe for use with tape drives or other
 block-oriented devices.
 .It Fn archive_write_open_memory
 A convenience form of
 .Fn archive_write_open
 that accepts a pointer to a block of memory that will receive
 the archive.
 The final
 .Ft "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.
 This function will disable padding unless you
 have specifically set the block size.
 .El
 More information about the
 .Va struct archive
 object and the overall design of the library can be found in the
 .Xr libarchive 3
 overview.
 .Pp
 Note that the convenience forms above vary in how
 they block the output.
 See
 .Xr archive_write_blocksize 3
 if you need to control the block size used for writes
 or the end-of-file padding behavior.
 .\"
 .Sh 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
 .Fn archive_write_open :
 .Bl -item -offset indent
 .It
 .Ft typedef int
 .Fn archive_open_callback "struct archive *" "void *client_data"
 .El
 .Pp
 The open callback is invoked by
 .Fn archive_write_open .
 It should return
 .Cm ARCHIVE_OK
 if the underlying file or data source is successfully
 opened.
 If the open fails, it should call
 .Fn archive_set_error
 to register an error code and message and return
 .Cm ARCHIVE_FATAL .
 .Bl -item -offset indent
 .It
 .Ft typedef la_ssize_t
 .Fo archive_write_callback
 .Fa "struct archive *"
 .Fa "void *client_data"
 .Fa "const void *buffer"
 .Fa "size_t length"
 .Fc
 .El
 .Pp
 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
 .Xr 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
 .Fn archive_set_error
 to register an error code and message and return -1.
 .Bl -item -offset indent
 .It
 .Ft typedef int
 .Fn archive_close_callback "struct archive *" "void *client_data"
 .El
 .Pp
 The close callback is invoked by archive_close when
 the archive processing is complete.
 The callback should return
 .Cm ARCHIVE_OK
 on success.
 On failure, the callback should invoke
 .Fn archive_set_error
 to register an error code and message and
 return
 .Cm ARCHIVE_FATAL.
 .Pp
 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
 .Fn archive_write_header ,
 .Fn archive_write_data ,
 .Fn archive_write_close ,
 .Fn archive_write_finish ,
 or
 .Fn archive_write_free .
 The client callback can call
 .Fn archive_set_error
 to provide values that can then be retrieved by
 .Fn archive_errno
 and
 .Fn archive_error_string .
 .\" .Sh EXAMPLE
 .Sh RETURN VALUES
 These functions return
 .Cm ARCHIVE_OK
 on success, or
 .Cm ARCHIVE_FATAL .
 .\"
 .Sh ERRORS
 Detailed error codes and textual descriptions are available from the
 .Fn archive_errno
 and
 .Fn archive_error_string
 functions.
 .\"
 .Sh SEE ALSO
 .Xr tar 1 ,
 .Xr libarchive 3 ,
 .Xr archive_write 3 ,
 .Xr archive_write_blocksize 3 ,
 .Xr archive_write_filter 3 ,
 .Xr archive_write_format 3 ,
 .Xr archive_write_new 3 ,
 .Xr archive_write_set_options 3 ,
 .Xr cpio 5 ,
 .Xr mtree 5 ,
 .Xr tar 5
	.\" Copyright (c) 2003-2011 Tim Kientzle
	.\" All rights reserved.
	.\"
	.\" Redistribution and use in source and binary forms, with or without
	.\" modification, are permitted provided that the following conditions
	.\" are met:
	.\" 1. Redistributions of source code must retain the above copyright
	.\" notice, this list of conditions and the following disclaimer.
	.\" 2. Redistributions in binary form must reproduce the above copyright
	.\" notice, this list of conditions and the following disclaimer in the
	.\" documentation and/or other materials provided with the distribution.
	.\"
	.\" THIS SOFTWARE IS PROVIDED BY THE AUTHOR AND CONTRIBUTORS ``AS IS'' AND
	.\" ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
	.\" IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
	.\" ARE DISCLAIMED. IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE
	.\" FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
	.\" DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
	.\" OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
	.\" HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
	.\" LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
	.\" OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
	.\" SUCH DAMAGE.
	.\"
	.\" $FreeBSD$
	.\"
	.Dd February 2, 2012
	.Dt ARCHIVE_WRITE_OPEN 3
	.Os
	.Sh NAME
	.Nm archive_write_open ,
	.Nm archive_write_open_fd ,
	.Nm archive_write_open_FILE ,
	.Nm archive_write_open_filename ,
	.Nm archive_write_open_memory
	.Nd functions for creating archives
	.Sh LIBRARY
	Streaming Archive Library (libarchive, -larchive)
	.Sh SYNOPSIS
	.In archive.h
	.Ft int
	.Fo archive_write_open
	.Fa "struct archive *"
	.Fa "void *client_data"
	.Fa "archive_open_callback *"
	.Fa "archive_write_callback *"
	.Fa "archive_close_callback *"
	.Fc
	.Ft int
	.Fn archive_write_open_fd "struct archive *" "int fd"
	.Ft int
	.Fn archive_write_open_FILE "struct archive " "FILE file"
	.Ft int
	.Fn archive_write_open_filename "struct archive " "const char filename"
	.Ft int
	.Fo archive_write_open_memory
	.Fa "struct archive *"
	.Fa "void *buffer"
	.Fa "size_t bufferSize"
	.Fa "size_t *outUsed"
	.Fc
	.Sh DESCRIPTION
	.Bl -tag -width indent
	.It Fn 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.
	This does not alter the default archive padding.
	.It Fn archive_write_open_fd
	A convenience form of
	.Fn archive_write_open
	that accepts a file descriptor.
	The
	.Fn archive_write_open_fd
	function is safe for use with tape drives or other
	block-oriented devices.
	.It Fn archive_write_open_FILE
	A convenience form of
	.Fn archive_write_open
	that accepts a
	.Ft "FILE *"
	pointer.
	Note that
	.Fn archive_write_open_FILE
	is not safe for writing to tape drives or other devices
	that require correct blocking.
	.It Fn archive_write_open_file
	A deprecated synonym for
	.Fn archive_write_open_filename .
	.It Fn archive_write_open_filename
	A convenience form of
	.Fn archive_write_open
	that accepts a filename.
	A NULL argument indicates that the output should be written to standard output;
	an argument of
	.Dq -
	will open a file with that name.
	If you have not invoked
	.Fn archive_write_set_bytes_in_last_block ,
	then
	.Fn 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
	.Fn archive_write_set_bytes_in_last_block
	before calling
	.Fn archive_write_open .
	The
	.Fn archive_write_open_filename
	function is safe for use with tape drives or other
	block-oriented devices.
	.It Fn archive_write_open_memory
	A convenience form of
	.Fn archive_write_open
	that accepts a pointer to a block of memory that will receive
	the archive.
	The final
	.Ft "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.
	This function will disable padding unless you
	have specifically set the block size.
	.El
	More information about the
	.Va struct archive
	object and the overall design of the library can be found in the
	.Xr libarchive 3
	overview.
	.Pp
	Note that the convenience forms above vary in how
	they block the output.
	See
	.Xr archive_write_blocksize 3
	if you need to control the block size used for writes
	or the end-of-file padding behavior.
	.\"
	.Sh 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
	.Fn archive_write_open :
	.Bl -item -offset indent
	.It
	.Ft typedef int
	.Fn archive_open_callback "struct archive " "void client_data"
	.El
	.Pp
	The open callback is invoked by
	.Fn archive_write_open .
	It should return
	.Cm ARCHIVE_OK
	if the underlying file or data source is successfully
	opened.
	If the open fails, it should call
	.Fn archive_set_error
	to register an error code and message and return
	.Cm ARCHIVE_FATAL .
	.Bl -item -offset indent
	.It
	.Ft typedef la_ssize_t
	.Fo archive_write_callback
	.Fa "struct archive *"
	.Fa "void *client_data"
	.Fa "const void *buffer"
	.Fa "size_t length"
	.Fc
	.El
	.Pp
	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
	.Xr 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
	.Fn archive_set_error
	to register an error code and message and return -1.
	.Bl -item -offset indent
	.It
	.Ft typedef int
	.Fn archive_close_callback "struct archive " "void client_data"
	.El
	.Pp
	The close callback is invoked by archive_close when
	the archive processing is complete.
	The callback should return
	.Cm ARCHIVE_OK
	on success.
	On failure, the callback should invoke
	.Fn archive_set_error
	to register an error code and message and
	return
	.Cm ARCHIVE_FATAL.
	.Pp
	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
	.Fn archive_write_header ,
	.Fn archive_write_data ,
	.Fn archive_write_close ,
	.Fn archive_write_finish ,
	or
	.Fn archive_write_free .
	The client callback can call
	.Fn archive_set_error
	to provide values that can then be retrieved by
	.Fn archive_errno
	and
	.Fn archive_error_string .
	.\" .Sh EXAMPLE
	.Sh RETURN VALUES
	These functions return
	.Cm ARCHIVE_OK
	on success, or
	.Cm ARCHIVE_FATAL .
	.\"
	.Sh ERRORS
	Detailed error codes and textual descriptions are available from the
	.Fn archive_errno
	and
	.Fn archive_error_string
	functions.
	.\"
	.Sh SEE ALSO
	.Xr tar 1 ,
	.Xr libarchive 3 ,
	.Xr archive_write 3 ,
	.Xr archive_write_blocksize 3 ,
	.Xr archive_write_filter 3 ,
	.Xr archive_write_format 3 ,
	.Xr archive_write_new 3 ,
	.Xr archive_write_set_options 3 ,
	.Xr cpio 5 ,
	.Xr mtree 5 ,
	.Xr tar 5