ARCHIVE_READ_OPEN
Section: C Library Functions (3)
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BSD mandoc
NAME
archive_read_open
archive_read_open2
archive_read_open_fd
archive_read_open_FILE
archive_read_open_filename
archive_read_open_memory
- functions for reading streaming archives
LIBRARY
Streaming Archive Library (libarchive, -larchive)
SYNOPSIS
In archive.h
Ft int
Fo archive_read_open
Fa struct archive *
Fa void *client_data
Fa archive_open_callback *
Fa archive_read_callback *
Fa archive_close_callback *
Fc Ft int
Fo archive_read_open2
Fa struct archive *
Fa void *client_data
Fa archive_open_callback *
Fa archive_read_callback *
Fa archive_skip_callback *
Fa archive_close_callback *
Fc Ft int
Fn archive_read_open_FILE struct archive * FILE *file
Ft int
Fn archive_read_open_fd struct archive * int fd size_t block_size
Ft int
Fo archive_read_open_filename
Fa struct archive *
Fa const char *filename
Fa size_t block_size
Fc Ft int
Fn archive_read_open_memory struct archive * const void *buff size_t size
DESCRIPTION
- Fn archive_read_open
-
The same as
Fn archive_read_open2 ,
except that the skip callback is assumed to be
NULL
- Fn archive_read_open2
-
Freeze the settings, open the archive, and prepare for reading entries.
This is the most generic version of this call, which accepts
four callback functions.
Most clients will want to use
Fn archive_read_open_filename ,
Fn archive_read_open_FILE ,
Fn archive_read_open_fd ,
or
Fn archive_read_open_memory
instead.
The library invokes the client-provided functions to obtain
raw bytes from the archive.
- Fn archive_read_open_FILE
-
Like
Fn archive_read_open ,
except that it accepts a
Ft FILE *
pointer.
This function should not be used with tape drives or other devices
that require strict I/O blocking.
- Fn archive_read_open_fd
-
Like
Fn archive_read_open ,
except that it accepts a file descriptor and block size rather than
a set of function pointers.
Note that the file descriptor will not be automatically closed at
end-of-archive.
This function is safe for use with tape drives or other blocked devices.
- Fn archive_read_open_file
-
This is a deprecated synonym for
Fn archive_read_open_filename .
- Fn archive_read_open_filename
-
Like
Fn archive_read_open ,
except that it accepts a simple filename and a block size.
A NULL filename represents standard input.
This function is safe for use with tape drives or other blocked devices.
- Fn archive_read_open_memory
-
Like
Fn archive_read_open ,
except that it accepts a pointer and size of a block of
memory containing the archive data.
A complete description of the
struct archive
and
struct archive_entry
objects can be found in the overview manual page for
libarchive(3).
CLIENT CALLBACKS
The callback functions must match the following prototypes:
- Ft typedef la_ssize_t
-
Fo archive_read_callback
Fa struct archive *
Fa void *client_data
Fa const void **buffer
Fc
- Ft typedef la_int64_t
-
Fo archive_skip_callback
Fa struct archive *
Fa void *client_data
Fa off_t request
Fc
- Ft typedef int
-
Fn archive_open_callback struct archive * void *client_data
- Ft typedef int
-
Fn archive_close_callback struct archive * void *client_data
The open callback is invoked by
Fn archive_open .
It should return
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
ARCHIVE_FATAL
The read callback is invoked whenever the library
requires raw bytes from the archive.
The read callback should read data into a buffer,
set the
const void **buffer
argument to point to the available data, and
return a count of the number of bytes available.
The library will invoke the read callback again
only after it has consumed this data.
The library imposes no constraints on the size
of the data blocks returned.
On end-of-file, the read callback should
return zero.
On error, the read callback should invoke
Fn archive_set_error
to register an error code and message and
return -1.
The skip callback is invoked when the
library wants to ignore a block of data.
The return value is the number of bytes actually
skipped, which may differ from the request.
If the callback cannot skip data, it should return
zero.
If the skip callback is not provided (the
function pointer is
NULL ),
the library will invoke the read function
instead and simply discard the result.
A skip callback can provide significant
performance gains when reading uncompressed
archives from slow disk drives or other media
that can skip quickly.
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
Fn archive_set_error
to register an error code and message and
return
ARCHIVE_FATAL.
RETURN VALUES
These functions return
ARCHIVE_OK
on success, or
ARCHIVE_FATAL
ERRORS
Detailed error codes and textual descriptions are available from the
Fn archive_errno
and
Fn archive_error_string
functions.
SEE ALSO
tar(1),
libarchive(3),
archive_read3,
archive_read_data3,
archive_read_filter3,
archive_read_format3,
archive_read_set_options3,
archive_util3,
tar(5)
Index
- NAME
-
- LIBRARY
-
- SYNOPSIS
-
- DESCRIPTION
-
- CLIENT CALLBACKS
-
- RETURN VALUES
-
- ERRORS
-
- SEE ALSO
-
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