1ARCHIVE_WRITE_OPEN(3)	 BSD Library Functions Manual	 ARCHIVE_WRITE_OPEN(3)
2
3NAME
4     archive_write_open, archive_write_open2, archive_write_open_fd,
5     archive_write_open_FILE, archive_write_open_filename,
6     archive_write_open_memory — functions for creating archives
7
8LIBRARY
9     Streaming Archive Library (libarchive, -larchive)
10
11SYNOPSIS
12     #include <archive.h>
13
14     int
15     archive_write_open(struct archive *, void *client_data,
16	 archive_open_callback *, archive_write_callback *,
17	 archive_close_callback *);
18
19     int
20     archive_write_open2(struct archive *, void *client_data,
21	 archive_open_callback *, archive_write_callback *,
22	 archive_close_callback *, archive_free_callback *);
23
24     int
25     archive_write_open_fd(struct archive *, int fd);
26
27     int
28     archive_write_open_FILE(struct archive *, FILE *file);
29
30     int
31     archive_write_open_filename(struct archive *, const char *filename);
32
33     int
34     archive_write_open_memory(struct archive *, void *buffer,
35	 size_t bufferSize, size_t *outUsed);
36
37DESCRIPTION
38     archive_write_open()
39	     Freeze the settings, open the archive, and prepare for writing
40	     entries.  This is the most generic form of this function, which
41	     accepts pointers to three callback functions which will be in‐
42	     voked by the compression layer to write the constructed archive.
43	     This does not alter the default archive padding.
44
45     archive_write_open2()
46	     Same as archive_write_open() with an additional fourth free call‐
47	     back. This function should be preferred to archive_write_open().
48
49     archive_write_open_fd()
50	     A convenience form of archive_write_open() that accepts a file
51	     descriptor.  The archive_write_open_fd() function is safe for use
52	     with tape drives or other block-oriented devices.
53
54     archive_write_open_FILE()
55	     A convenience form of archive_write_open() that accepts a FILE *
56	     pointer.  Note that archive_write_open_FILE() is not safe for
57	     writing to tape drives or other devices that require correct
58	     blocking.
59
60     archive_write_open_file()
61	     A deprecated synonym for archive_write_open_filename().
62
63     archive_write_open_filename()
64	     A convenience form of archive_write_open() that accepts a file‐
65	     name.  A NULL argument indicates that the output should be writ‐
66	     ten to standard output; an argument of “-” will open a file with
67	     that name.  If you have not invoked
68	     archive_write_set_bytes_in_last_block(), then
69	     archive_write_open_filename() will adjust the last-block padding
70	     depending on the file: it will enable padding when writing to
71	     standard output or to a character or block device node, it will
72	     disable padding otherwise.  You can override this by manually in‐
73	     voking archive_write_set_bytes_in_last_block() before calling
74	     archive_write_open2().  The archive_write_open_filename() func‐
75	     tion is safe for use with tape drives or other block-oriented de‐
76	     vices.
77
78     archive_write_open_memory()
79	     A convenience form of archive_write_open2() that accepts a
80	     pointer to a block of memory that will receive the archive.  The
81	     final size_t * argument points to a variable that will be updated
82	     after each write to reflect how much of the buffer is currently
83	     in use.  You should be careful to ensure that this variable re‐
84	     mains allocated until after the archive is closed.  This function
85	     will disable padding unless you have specifically set the block
86	     size.
87     More information about the struct archive object and the overall design
88     of the library can be found in the libarchive(3) overview.
89
90     Note that the convenience forms above vary in how they block the output.
91     See archive_write_blocksize(3) if you need to control the block size used
92     for writes or the end-of-file padding behavior.
93
94CLIENT CALLBACKS
95     To use this library, you will need to define and register callback func‐
96     tions that will be invoked to write data to the resulting archive.  These
97     functions are registered by calling archive_write_open2():
98
99	   typedef int archive_open_callback(struct archive *, void
100	   *client_data)
101
102     The open callback is invoked by archive_write_open().  It should return
103     ARCHIVE_OK if the underlying file or data source is successfully opened.
104     If the open fails, it should call archive_set_error() to register an er‐
105     ror code and message and return ARCHIVE_FATAL.  Please note that if open
106     fails, close is not called and resources must be freed inside the open
107     callback or with the free callback.
108
109	   typedef la_ssize_t archive_write_callback(struct archive *,
110	   void *client_data, const void *buffer, size_t length)
111
112     The write callback is invoked whenever the library needs to write raw
113     bytes to the archive.  For correct blocking, each call to the write call‐
114     back function should translate into a single write(2) system call.  This
115     is especially critical when writing archives to tape drives.  On success,
116     the write callback should return the number of bytes actually written.
117     On error, the callback should invoke archive_set_error() to register an
118     error code and message and return -1.
119
120	   typedef int archive_close_callback(struct archive *, void
121	   *client_data)
122
123     The close callback is invoked by archive_close when the archive process‐
124     ing is complete. If the open callback fails, the close callback is not
125     invoked.  The callback should return ARCHIVE_OK on success.  On failure,
126     the callback should invoke archive_set_error() to register an error code
127     and message and return
128
129	   typedef int archive_free_callback(struct archive *, void
130	   *client_data)
131
132     The free callback is always invoked on archive_free.  The return code of
133     this callback is not processed.
134
135     Note that if the client-provided write callback function returns a non-
136     zero value, that error will be propagated back to the caller through
137     whatever API function resulted in that call, which may include
138     archive_write_header(), archive_write_data(), archive_write_close(),
139     archive_write_finish(), or archive_write_free().  The client callback can
140     call archive_set_error() to provide values that can then be retrieved by
141     archive_errno() and archive_error_string().
142
143RETURN VALUES
144     These functions return ARCHIVE_OK on success, or ARCHIVE_FATAL.
145
146ERRORS
147     Detailed error codes and textual descriptions are available from the
148     archive_errno() and archive_error_string() functions.
149
150SEE ALSO
151     tar(1), archive_write(3), archive_write_blocksize(3),
152     archive_write_filter(3), archive_write_format(3), archive_write_new(3),
153     archive_write_set_options(3), libarchive(3), cpio(5), mtree(5), tar(5)
154
155BSD			       November 12, 2020			   BSD
156