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222 lines
6.3 KiB
Groff
222 lines
6.3 KiB
Groff
.TH ARCHIVE_WRITE_OPEN 3 "February 2, 2012" ""
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.SH NAME
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.ad l
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\fB\%archive_write_open\fP,
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\fB\%archive_write_open_fd\fP,
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\fB\%archive_write_open_FILE\fP,
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\fB\%archive_write_open_filename\fP,
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\fB\%archive_write_open_memory\fP
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\- functions for creating archives
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.SH LIBRARY
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.ad l
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Streaming Archive Library (libarchive, -larchive)
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.SH SYNOPSIS
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.ad l
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\fB#include <archive.h>\fP
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.br
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\fIint\fP
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.br
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\fB\%archive_write_open\fP(\fI\%struct\ archive\ *\fP, \fI\%void\ *client_data\fP, \fI\%archive_open_callback\ *\fP, \fI\%archive_write_callback\ *\fP, \fI\%archive_close_callback\ *\fP);
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.br
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\fIint\fP
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.br
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\fB\%archive_write_open_fd\fP(\fI\%struct\ archive\ *\fP, \fI\%int\ fd\fP);
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.br
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\fIint\fP
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.br
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\fB\%archive_write_open_FILE\fP(\fI\%struct\ archive\ *\fP, \fI\%FILE\ *file\fP);
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.br
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\fIint\fP
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.br
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\fB\%archive_write_open_filename\fP(\fI\%struct\ archive\ *\fP, \fI\%const\ char\ *filename\fP);
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.br
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\fIint\fP
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.br
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\fB\%archive_write_open_memory\fP(\fI\%struct\ archive\ *\fP, \fI\%void\ *buffer\fP, \fI\%size_t\ bufferSize\fP, \fI\%size_t\ *outUsed\fP);
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.SH DESCRIPTION
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.ad l
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.RS 5
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.TP
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\fB\%archive_write_open\fP()
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Freeze the settings, open the archive, and prepare for writing entries.
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This is the most generic form of this function, which accepts
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pointers to three callback functions which will be invoked by
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the compression layer to write the constructed archive.
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This does not alter the default archive padding.
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.TP
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\fB\%archive_write_open_fd\fP()
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A convenience form of
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\fB\%archive_write_open\fP()
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that accepts a file descriptor.
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The
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\fB\%archive_write_open_fd\fP()
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function is safe for use with tape drives or other
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block-oriented devices.
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.TP
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\fB\%archive_write_open_FILE\fP()
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A convenience form of
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\fB\%archive_write_open\fP()
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that accepts a
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\fIFILE *\fP
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pointer.
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Note that
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\fB\%archive_write_open_FILE\fP()
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is not safe for writing to tape drives or other devices
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that require correct blocking.
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.TP
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\fB\%archive_write_open_file\fP()
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A deprecated synonym for
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\fB\%archive_write_open_filename\fP().
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.TP
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\fB\%archive_write_open_filename\fP()
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A convenience form of
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\fB\%archive_write_open\fP()
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that accepts a filename.
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A NULL argument indicates that the output should be written to standard output;
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an argument of
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``-''
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will open a file with that name.
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If you have not invoked
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\fB\%archive_write_set_bytes_in_last_block\fP(),
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then
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\fB\%archive_write_open_filename\fP()
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will adjust the last-block padding depending on the file:
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it will enable padding when writing to standard output or
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to a character or block device node, it will disable padding otherwise.
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You can override this by manually invoking
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\fB\%archive_write_set_bytes_in_last_block\fP()
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before calling
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\fB\%archive_write_open\fP().
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The
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\fB\%archive_write_open_filename\fP()
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function is safe for use with tape drives or other
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block-oriented devices.
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.TP
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\fB\%archive_write_open_memory\fP()
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A convenience form of
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\fB\%archive_write_open\fP()
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that accepts a pointer to a block of memory that will receive
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the archive.
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The final
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\fIsize_t *\fP
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argument points to a variable that will be updated
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after each write to reflect how much of the buffer
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is currently in use.
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You should be careful to ensure that this variable
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remains allocated until after the archive is
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closed.
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This function will disable padding unless you
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have specifically set the block size.
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.RE
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More information about the
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\fIstruct\fP archive
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object and the overall design of the library can be found in the
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\fBlibarchive\fP(3)
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overview.
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.PP
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Note that the convenience forms above vary in how
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they block the output.
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See
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\fBarchive_write_blocksize\fP(3)
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if you need to control the block size used for writes
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or the end-of-file padding behavior.
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.SH CLIENT CALLBACKS
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.ad l
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To use this library, you will need to define and register
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callback functions that will be invoked to write data to the
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resulting archive.
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These functions are registered by calling
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\fB\%archive_write_open\fP():
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.RS 5
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.IP
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\fItypedef int\fP
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\fB\%archive_open_callback\fP(\fI\%struct\ archive\ *\fP, \fI\%void\ *client_data\fP)
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.RE
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.PP
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The open callback is invoked by
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\fB\%archive_write_open\fP().
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It should return
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\fBARCHIVE_OK\fP
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if the underlying file or data source is successfully
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opened.
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If the open fails, it should call
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\fB\%archive_set_error\fP()
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to register an error code and message and return
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\fBARCHIVE_FATAL\fP.
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.RS 5
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.IP
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\fItypedef la_ssize_t\fP
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\fB\%archive_write_callback\fP(\fI\%struct\ archive\ *\fP, \fI\%void\ *client_data\fP, \fI\%const\ void\ *buffer\fP, \fI\%size_t\ length\fP)
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.RE
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.PP
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The write callback is invoked whenever the library
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needs to write raw bytes to the archive.
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For correct blocking, each call to the write callback function
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should translate into a single
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\fBwrite\fP(2)
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system call.
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This is especially critical when writing archives to tape drives.
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On success, the write callback should return the
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number of bytes actually written.
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On error, the callback should invoke
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\fB\%archive_set_error\fP()
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to register an error code and message and return -1.
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.RS 5
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.IP
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\fItypedef int\fP
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\fB\%archive_close_callback\fP(\fI\%struct\ archive\ *\fP, \fI\%void\ *client_data\fP)
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.RE
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.PP
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The close callback is invoked by archive_close when
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the archive processing is complete.
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The callback should return
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\fBARCHIVE_OK\fP
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on success.
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On failure, the callback should invoke
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\fB\%archive_set_error\fP()
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to register an error code and message and
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return
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\fBARCHIVE_FATAL\fP.
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.PP
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Note that if the client-provided write callback function
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returns a non-zero value, that error will be propagated back to the caller
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through whatever API function resulted in that call, which
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may include
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\fB\%archive_write_header\fP(),
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\fB\%archive_write_data\fP(),
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\fB\%archive_write_close\fP(),
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\fB\%archive_write_finish\fP(),
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or
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\fB\%archive_write_free\fP().
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The client callback can call
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\fB\%archive_set_error\fP()
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to provide values that can then be retrieved by
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\fB\%archive_errno\fP()
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and
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\fB\%archive_error_string\fP().
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.SH RETURN VALUES
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.ad l
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These functions return
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\fBARCHIVE_OK\fP
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on success, or
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\fBARCHIVE_FATAL\fP.
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.SH ERRORS
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.ad l
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Detailed error codes and textual descriptions are available from the
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\fB\%archive_errno\fP()
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and
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\fB\%archive_error_string\fP()
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functions.
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.SH SEE ALSO
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.ad l
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\fBtar\fP(1),
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\fBarchive_write\fP(3),
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\fBarchive_write_blocksize\fP(3),
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\fBarchive_write_filter\fP(3),
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\fBarchive_write_format\fP(3),
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\fBarchive_write_new\fP(3),
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\fBarchive_write_set_options\fP(3),
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\fBlibarchive\fP(3),
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\fBcpio\fP(5),
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\fBmtree\fP(5),
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\fBtar\fP(5)
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