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NAMElibarchive —
functions for reading and writing streaming archives
OVERVIEWThelibarchive library provides a flexible interface for
reading and writing archives in various formats such as tar and cpio.
libarchive also supports reading and writing archives
compressed using various compression filters such as gzip and bzip2. The
library is inherently stream-oriented; readers serially iterate through the
archive, writers serially add things to the archive. In particular, note that
there is currently no built-in support for random access nor for in-place
modification.
When reading an archive, the library automatically detects the format and the compression. The library currently has read support for:
When writing an archive, you can specify the compression to be used and the format to use. The library can write
The read and write APIs are accessed through the
The rest of this manual page provides an overview of the library operation. More detailed information can be found in the individual manual pages for each API or utility function. READING AN ARCHIVESee archive_read(3).WRITING AN ARCHIVESee archive_write(3).WRITING ENTRIES TO DISKThe archive_write_disk(3) API allows you to write archive_entry(3) objects to disk using the same API used by archive_write(3). The archive_write_disk(3) API is used internally byarchive_read_extract ();
using it directly can provide greater control over how entries get written to
disk. This API also makes it possible to share code between archive-to-archive
copy and archive-to-disk extraction operations.
READING ENTRIES FROM DISKThe archive_read_disk(3) supports for populating archive_entry(3) objects from information in the filesystem. This includes the information accessible from the stat(2) system call as well as ACLs, extended attributes, and other metadata. The archive_read_disk(3) API also supports iterating over directory trees, which allows directories of files to be read using an API compatible with the archive_read(3) API.DESCRIPTIONDetailed descriptions of each function are provided by the corresponding manual pages.All of the functions utilize an opaque struct archive datatype that provides access to the archive contents. The struct archive_entry structure contains a complete description of a single archive entry. It uses an opaque interface that is fully documented in archive_entry(3). Users familiar with historic formats should be aware that the newer variants have eliminated most restrictions on the length of textual fields. Clients should not assume that filenames, link names, user names, or group names are limited in length. In particular, pax interchange format can easily accommodate pathnames in arbitrary character sets that exceed PATH_MAX. RETURN VALUESMost functions returnARCHIVE_OK (zero) on success,
non-zero on error. The return value indicates the general severity of the
error, ranging from ARCHIVE_WARN , which indicates a
minor problem that should probably be reported to the user, to
ARCHIVE_FATAL , which indicates a serious problem that
will prevent any further operations on this archive. On error, the
archive_errno () function can be used to retrieve a
numeric error code (see
errno(2)).
The archive_error_string () returns a textual error
message suitable for display.
ENVIRONMENTThere are character set conversions within the archive_entry(3) functions that are impacted by the currently-selected locale.SEE ALSOtar(1), archive_entry(3), archive_read(3), archive_util(3), archive_write(3), tar(5)HISTORYThelibarchive library first appeared in
FreeBSD 5.3.
AUTHORSThelibarchive library was originally written by
Tim Kientzle ⟨kientzle@acm.org⟩.
BUGSSome archive formats support information that is not supported by struct archive_entry. Such information cannot be fully archived or restored using this library. This includes, for example, comments, character sets, or the arbitrary key/value pairs that can appear in pax interchange format archives.Conversely, of course, not all of the information that can be stored in an struct archive_entry is supported by all formats. For example, cpio formats do not support nanosecond timestamps; old tar formats do not support large device numbers. The ISO9660 reader cannot yet read all ISO9660 images; it should learn how to seek. The AR writer requires the client program to use two passes, unlike all other libarchive writers.
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