archive_write_open(3)

1ARCHIVE_WRITE_OPEN(3)    BSD Library Functions Manual    ARCHIVE_WRITE_OPEN(3)
2

NAME

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

LIBRARY

9     Streaming Archive Library (libarchive, -larchive)
10

SYNOPSIS

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

DESCRIPTION

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
42             invoked by the compression layer to write the constructed ar‐
43             chive.  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
73             invoking 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
76             devices.
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
84             remains allocated until after the archive is closed.  This func‐
85             tion will disable padding unless you have specifically set the
86             block 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

CLIENT 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
105     error code and message and return ARCHIVE_FATAL.  Please note that if
106     open fails, close is not called and resources must be freed inside the
107     open 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

RETURN VALUES

144     These functions return ARCHIVE_OK on success, or ARCHIVE_FATAL.
145

ERRORS

147     Detailed error codes and textual descriptions are available from the
148     archive_errno() and archive_error_string() functions.
149