ARCHIVE_READ_OPEN(3) | Library Functions Manual | ARCHIVE_READ_OPEN(3) |
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
Streaming Archive Library (libarchive, -larchive)
#include
<archive.h>
int
archive_read_open
(struct archive
*, void *client_data,
archive_open_callback *,
archive_read_callback *,
archive_close_callback *);
int
archive_read_open2
(struct archive
*, void *client_data,
archive_open_callback *,
archive_read_callback *,
archive_skip_callback *,
archive_close_callback *);
int
archive_read_open_FILE
(struct
archive *, FILE
*file);
int
archive_read_open_fd
(struct
archive *, int fd,
size_t block_size);
int
archive_read_open_filename
(struct
archive *, const char *filename,
size_t block_size);
int
archive_read_open_memory
(struct
archive *, const void
*buff, size_t
size);
archive_read_open
()archive_read_open2
(),
except that the skip callback is assumed to be
NULL
.archive_read_open2
()archive_read_open_filename
(),
archive_read_open_FILE
(),
archive_read_open_fd
(),
or
archive_read_open_memory
()
instead. The library invokes the client-provided functions to obtain raw
bytes from the archive.archive_read_open_FILE
()archive_read_open
(), except that it accepts a
FILE * pointer. This function should not be used
with tape drives or other devices that require strict I/O blocking.archive_read_open_fd
()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.archive_read_open_file
()archive_read_open_filename
().archive_read_open_filename
()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.archive_read_open_memory
()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).
The callback functions must match the following prototypes:
archive_read_callback
(struct
archive *, void *client_data,
const void **buffer);archive_skip_callback
(struct
archive *, void *client_data,
off_t request);archive_open_callback
(struct
archive *, void *client_data)archive_close_callback
(struct
archive *, void *client_data)The open callback is invoked by
archive_open
().
It should return ARCHIVE_OK
if the underlying file
or data source is successfully opened. If the open fails, it should call
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
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
archive_set_error
()
to register an error code and message and return
ARCHIVE_FATAL
.
These functions return ARCHIVE_OK
on
success, or ARCHIVE_FATAL
.
Detailed error codes and textual descriptions are available from
the archive_errno
() and
archive_error_string
() functions.
tar(1), archive_read(3), archive_read_data(3), archive_read_filter(3), archive_read_format(3), archive_read_set_options(3), archive_util(3), libarchive(3), tar(5)
February 2, 2012 | macOS 14.6 |