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authorMartin Matuska <mm@FreeBSD.org>2011-12-20 22:47:56 +0000
committerMartin Matuska <mm@FreeBSD.org>2011-12-20 22:47:56 +0000
commit35fa5e2f58abd428bff0de1238364880447ef095 (patch)
tree07565a115ca59ea7230cd38e88901b0290750cde /libarchive/archive_entry.h
downloadsrc-35fa5e2f58abd428bff0de1238364880447ef095.tar.gz
src-35fa5e2f58abd428bff0de1238364880447ef095.zip
Vendor import of libarchive (release/2.8, r3824)
Notes
Notes: svn path=/vendor/libarchive/dist/; revision=228753
Diffstat (limited to 'libarchive/archive_entry.h')
-rw-r--r--libarchive/archive_entry.h524
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diff --git a/libarchive/archive_entry.h b/libarchive/archive_entry.h
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+/*-
+ * Copyright (c) 2003-2008 Tim Kientzle
+ * All rights reserved.
+ *
+ * Redistribution and use in source and binary forms, with or without
+ * modification, are permitted provided that the following conditions
+ * are met:
+ * 1. Redistributions of source code must retain the above copyright
+ * notice, this list of conditions and the following disclaimer.
+ * 2. Redistributions in binary form must reproduce the above copyright
+ * notice, this list of conditions and the following disclaimer in the
+ * documentation and/or other materials provided with the distribution.
+ *
+ * THIS SOFTWARE IS PROVIDED BY THE AUTHOR(S) ``AS IS'' AND ANY EXPRESS OR
+ * IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
+ * OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED.
+ * IN NO EVENT SHALL THE AUTHOR(S) BE LIABLE FOR ANY DIRECT, INDIRECT,
+ * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT
+ * NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
+ * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
+ * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
+ * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF
+ * THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
+ *
+ * $FreeBSD: head/lib/libarchive/archive_entry.h 201096 2009-12-28 02:41:27Z kientzle $
+ */
+
+#ifndef ARCHIVE_ENTRY_H_INCLUDED
+#define ARCHIVE_ENTRY_H_INCLUDED
+
+/*
+ * Note: archive_entry.h is for use outside of libarchive; the
+ * configuration headers (config.h, archive_platform.h, etc.) are
+ * purely internal. Do NOT use HAVE_XXX configuration macros to
+ * control the behavior of this header! If you must conditionalize,
+ * use predefined compiler and/or platform macros.
+ */
+
+#include <sys/types.h>
+#include <stddef.h> /* for wchar_t */
+#include <time.h>
+
+#if defined(_WIN32) && !defined(__CYGWIN__)
+#include <windows.h>
+#endif
+
+/* Get appropriate definitions of standard POSIX-style types. */
+/* These should match the types used in 'struct stat' */
+#if defined(_WIN32) && !defined(__CYGWIN__)
+#define __LA_INT64_T __int64
+# if defined(__BORLANDC__)
+# define __LA_UID_T uid_t
+# define __LA_GID_T gid_t
+# define __LA_DEV_T dev_t
+# define __LA_MODE_T mode_t
+# else
+# define __LA_UID_T short
+# define __LA_GID_T short
+# define __LA_DEV_T unsigned int
+# define __LA_MODE_T unsigned short
+# endif
+#else
+#include <unistd.h>
+#define __LA_INT64_T int64_t
+#define __LA_UID_T uid_t
+#define __LA_GID_T gid_t
+#define __LA_DEV_T dev_t
+#define __LA_MODE_T mode_t
+#endif
+
+/*
+ * XXX Is this defined for all Windows compilers? If so, in what
+ * header? It would be nice to remove the __LA_INO_T indirection and
+ * just use plain ino_t everywhere. Likewise for the other types just
+ * above.
+ */
+#define __LA_INO_T ino_t
+
+
+/*
+ * On Windows, define LIBARCHIVE_STATIC if you're building or using a
+ * .lib. The default here assumes you're building a DLL. Only
+ * libarchive source should ever define __LIBARCHIVE_BUILD.
+ */
+#if ((defined __WIN32__) || (defined _WIN32) || defined(__CYGWIN__)) && (!defined LIBARCHIVE_STATIC)
+# ifdef __LIBARCHIVE_BUILD
+# ifdef __GNUC__
+# define __LA_DECL __attribute__((dllexport)) extern
+# else
+# define __LA_DECL __declspec(dllexport)
+# endif
+# else
+# ifdef __GNUC__
+# define __LA_DECL __attribute__((dllimport)) extern
+# else
+# define __LA_DECL __declspec(dllimport)
+# endif
+# endif
+#else
+/* Static libraries on all platforms and shared libraries on non-Windows. */
+# define __LA_DECL
+#endif
+
+#ifdef __cplusplus
+extern "C" {
+#endif
+
+/*
+ * Description of an archive entry.
+ *
+ * You can think of this as "struct stat" with some text fields added in.
+ *
+ * TODO: Add "comment", "charset", and possibly other entries that are
+ * supported by "pax interchange" format. However, GNU, ustar, cpio,
+ * and other variants don't support these features, so they're not an
+ * excruciatingly high priority right now.
+ *
+ * TODO: "pax interchange" format allows essentially arbitrary
+ * key/value attributes to be attached to any entry. Supporting
+ * such extensions may make this library useful for special
+ * applications (e.g., a package manager could attach special
+ * package-management attributes to each entry).
+ */
+struct archive_entry;
+
+/*
+ * File-type constants. These are returned from archive_entry_filetype()
+ * and passed to archive_entry_set_filetype().
+ *
+ * These values match S_XXX defines on every platform I've checked,
+ * including Windows, AIX, Linux, Solaris, and BSD. They're
+ * (re)defined here because platforms generally don't define the ones
+ * they don't support. For example, Windows doesn't define S_IFLNK or
+ * S_IFBLK. Instead of having a mass of conditional logic and system
+ * checks to define any S_XXX values that aren't supported locally,
+ * I've just defined a new set of such constants so that
+ * libarchive-based applications can manipulate and identify archive
+ * entries properly even if the hosting platform can't store them on
+ * disk.
+ *
+ * These values are also used directly within some portable formats,
+ * such as cpio. If you find a platform that varies from these, the
+ * correct solution is to leave these alone and translate from these
+ * portable values to platform-native values when entries are read from
+ * or written to disk.
+ */
+#define AE_IFMT 0170000
+#define AE_IFREG 0100000
+#define AE_IFLNK 0120000
+#define AE_IFSOCK 0140000
+#define AE_IFCHR 0020000
+#define AE_IFBLK 0060000
+#define AE_IFDIR 0040000
+#define AE_IFIFO 0010000
+
+/*
+ * Basic object manipulation
+ */
+
+__LA_DECL struct archive_entry *archive_entry_clear(struct archive_entry *);
+/* The 'clone' function does a deep copy; all of the strings are copied too. */
+__LA_DECL struct archive_entry *archive_entry_clone(struct archive_entry *);
+__LA_DECL void archive_entry_free(struct archive_entry *);
+__LA_DECL struct archive_entry *archive_entry_new(void);
+
+/*
+ * Retrieve fields from an archive_entry.
+ *
+ * There are a number of implicit conversions among these fields. For
+ * example, if a regular string field is set and you read the _w wide
+ * character field, the entry will implicitly convert narrow-to-wide
+ * using the current locale. Similarly, dev values are automatically
+ * updated when you write devmajor or devminor and vice versa.
+ *
+ * In addition, fields can be "set" or "unset." Unset string fields
+ * return NULL, non-string fields have _is_set() functions to test
+ * whether they've been set. You can "unset" a string field by
+ * assigning NULL; non-string fields have _unset() functions to
+ * unset them.
+ *
+ * Note: There is one ambiguity in the above; string fields will
+ * also return NULL when implicit character set conversions fail.
+ * This is usually what you want.
+ */
+__LA_DECL time_t archive_entry_atime(struct archive_entry *);
+__LA_DECL long archive_entry_atime_nsec(struct archive_entry *);
+__LA_DECL int archive_entry_atime_is_set(struct archive_entry *);
+__LA_DECL time_t archive_entry_birthtime(struct archive_entry *);
+__LA_DECL long archive_entry_birthtime_nsec(struct archive_entry *);
+__LA_DECL int archive_entry_birthtime_is_set(struct archive_entry *);
+__LA_DECL time_t archive_entry_ctime(struct archive_entry *);
+__LA_DECL long archive_entry_ctime_nsec(struct archive_entry *);
+__LA_DECL int archive_entry_ctime_is_set(struct archive_entry *);
+__LA_DECL dev_t archive_entry_dev(struct archive_entry *);
+__LA_DECL dev_t archive_entry_devmajor(struct archive_entry *);
+__LA_DECL dev_t archive_entry_devminor(struct archive_entry *);
+__LA_DECL __LA_MODE_T archive_entry_filetype(struct archive_entry *);
+__LA_DECL void archive_entry_fflags(struct archive_entry *,
+ unsigned long * /* set */,
+ unsigned long * /* clear */);
+__LA_DECL const char *archive_entry_fflags_text(struct archive_entry *);
+__LA_DECL __LA_GID_T archive_entry_gid(struct archive_entry *);
+__LA_DECL const char *archive_entry_gname(struct archive_entry *);
+__LA_DECL const wchar_t *archive_entry_gname_w(struct archive_entry *);
+__LA_DECL const char *archive_entry_hardlink(struct archive_entry *);
+__LA_DECL const wchar_t *archive_entry_hardlink_w(struct archive_entry *);
+__LA_DECL __LA_INO_T archive_entry_ino(struct archive_entry *);
+__LA_DECL __LA_INT64_T archive_entry_ino64(struct archive_entry *);
+__LA_DECL __LA_MODE_T archive_entry_mode(struct archive_entry *);
+__LA_DECL time_t archive_entry_mtime(struct archive_entry *);
+__LA_DECL long archive_entry_mtime_nsec(struct archive_entry *);
+__LA_DECL int archive_entry_mtime_is_set(struct archive_entry *);
+__LA_DECL unsigned int archive_entry_nlink(struct archive_entry *);
+__LA_DECL const char *archive_entry_pathname(struct archive_entry *);
+__LA_DECL const wchar_t *archive_entry_pathname_w(struct archive_entry *);
+__LA_DECL dev_t archive_entry_rdev(struct archive_entry *);
+__LA_DECL dev_t archive_entry_rdevmajor(struct archive_entry *);
+__LA_DECL dev_t archive_entry_rdevminor(struct archive_entry *);
+__LA_DECL const char *archive_entry_sourcepath(struct archive_entry *);
+__LA_DECL __LA_INT64_T archive_entry_size(struct archive_entry *);
+__LA_DECL int archive_entry_size_is_set(struct archive_entry *);
+__LA_DECL const char *archive_entry_strmode(struct archive_entry *);
+__LA_DECL const char *archive_entry_symlink(struct archive_entry *);
+__LA_DECL const wchar_t *archive_entry_symlink_w(struct archive_entry *);
+__LA_DECL __LA_UID_T archive_entry_uid(struct archive_entry *);
+__LA_DECL const char *archive_entry_uname(struct archive_entry *);
+__LA_DECL const wchar_t *archive_entry_uname_w(struct archive_entry *);
+
+/*
+ * Set fields in an archive_entry.
+ *
+ * Note that string 'set' functions do not copy the string, only the pointer.
+ * In contrast, 'copy' functions do copy the object pointed to.
+ *
+ * Note: As of libarchive 2.4, 'set' functions do copy the string and
+ * are therefore exact synonyms for the 'copy' versions. The 'copy'
+ * names will be retired in libarchive 3.0.
+ */
+
+__LA_DECL void archive_entry_set_atime(struct archive_entry *, time_t, long);
+__LA_DECL void archive_entry_unset_atime(struct archive_entry *);
+#if defined(_WIN32) && !defined(__CYGWIN__)
+__LA_DECL void archive_entry_copy_bhfi(struct archive_entry *,
+ BY_HANDLE_FILE_INFORMATION *);
+#endif
+__LA_DECL void archive_entry_set_birthtime(struct archive_entry *, time_t, long);
+__LA_DECL void archive_entry_unset_birthtime(struct archive_entry *);
+__LA_DECL void archive_entry_set_ctime(struct archive_entry *, time_t, long);
+__LA_DECL void archive_entry_unset_ctime(struct archive_entry *);
+__LA_DECL void archive_entry_set_dev(struct archive_entry *, dev_t);
+__LA_DECL void archive_entry_set_devmajor(struct archive_entry *, dev_t);
+__LA_DECL void archive_entry_set_devminor(struct archive_entry *, dev_t);
+__LA_DECL void archive_entry_set_filetype(struct archive_entry *, unsigned int);
+__LA_DECL void archive_entry_set_fflags(struct archive_entry *,
+ unsigned long /* set */, unsigned long /* clear */);
+/* Returns pointer to start of first invalid token, or NULL if none. */
+/* Note that all recognized tokens are processed, regardless. */
+__LA_DECL const char *archive_entry_copy_fflags_text(struct archive_entry *,
+ const char *);
+__LA_DECL const wchar_t *archive_entry_copy_fflags_text_w(struct archive_entry *,
+ const wchar_t *);
+__LA_DECL void archive_entry_set_gid(struct archive_entry *, __LA_GID_T);
+__LA_DECL void archive_entry_set_gname(struct archive_entry *, const char *);
+__LA_DECL void archive_entry_copy_gname(struct archive_entry *, const char *);
+__LA_DECL void archive_entry_copy_gname_w(struct archive_entry *, const wchar_t *);
+__LA_DECL int archive_entry_update_gname_utf8(struct archive_entry *, const char *);
+__LA_DECL void archive_entry_set_hardlink(struct archive_entry *, const char *);
+__LA_DECL void archive_entry_copy_hardlink(struct archive_entry *, const char *);
+__LA_DECL void archive_entry_copy_hardlink_w(struct archive_entry *, const wchar_t *);
+__LA_DECL int archive_entry_update_hardlink_utf8(struct archive_entry *, const char *);
+#if ARCHIVE_VERSION_NUMBER >= 3000000
+/* Starting with libarchive 3.0, this will be synonym for ino64. */
+__LA_DECL void archive_entry_set_ino(struct archive_entry *, __LA_INT64_T);
+#else
+__LA_DECL void archive_entry_set_ino(struct archive_entry *, unsigned long);
+#endif
+__LA_DECL void archive_entry_set_ino64(struct archive_entry *, __LA_INT64_T);
+__LA_DECL void archive_entry_set_link(struct archive_entry *, const char *);
+__LA_DECL void archive_entry_copy_link(struct archive_entry *, const char *);
+__LA_DECL void archive_entry_copy_link_w(struct archive_entry *, const wchar_t *);
+__LA_DECL int archive_entry_update_link_utf8(struct archive_entry *, const char *);
+__LA_DECL void archive_entry_set_mode(struct archive_entry *, __LA_MODE_T);
+__LA_DECL void archive_entry_set_mtime(struct archive_entry *, time_t, long);
+__LA_DECL void archive_entry_unset_mtime(struct archive_entry *);
+__LA_DECL void archive_entry_set_nlink(struct archive_entry *, unsigned int);
+__LA_DECL void archive_entry_set_pathname(struct archive_entry *, const char *);
+__LA_DECL void archive_entry_copy_pathname(struct archive_entry *, const char *);
+__LA_DECL void archive_entry_copy_pathname_w(struct archive_entry *, const wchar_t *);
+__LA_DECL int archive_entry_update_pathname_utf8(struct archive_entry *, const char *);
+__LA_DECL void archive_entry_set_perm(struct archive_entry *, __LA_MODE_T);
+__LA_DECL void archive_entry_set_rdev(struct archive_entry *, dev_t);
+__LA_DECL void archive_entry_set_rdevmajor(struct archive_entry *, dev_t);
+__LA_DECL void archive_entry_set_rdevminor(struct archive_entry *, dev_t);
+__LA_DECL void archive_entry_set_size(struct archive_entry *, __LA_INT64_T);
+__LA_DECL void archive_entry_unset_size(struct archive_entry *);
+__LA_DECL void archive_entry_copy_sourcepath(struct archive_entry *, const char *);
+__LA_DECL void archive_entry_set_symlink(struct archive_entry *, const char *);
+__LA_DECL void archive_entry_copy_symlink(struct archive_entry *, const char *);
+__LA_DECL void archive_entry_copy_symlink_w(struct archive_entry *, const wchar_t *);
+__LA_DECL int archive_entry_update_symlink_utf8(struct archive_entry *, const char *);
+__LA_DECL void archive_entry_set_uid(struct archive_entry *, __LA_UID_T);
+__LA_DECL void archive_entry_set_uname(struct archive_entry *, const char *);
+__LA_DECL void archive_entry_copy_uname(struct archive_entry *, const char *);
+__LA_DECL void archive_entry_copy_uname_w(struct archive_entry *, const wchar_t *);
+__LA_DECL int archive_entry_update_uname_utf8(struct archive_entry *, const char *);
+/*
+ * Routines to bulk copy fields to/from a platform-native "struct
+ * stat." Libarchive used to just store a struct stat inside of each
+ * archive_entry object, but this created issues when trying to
+ * manipulate archives on systems different than the ones they were
+ * created on.
+ *
+ * TODO: On Linux, provide both stat32 and stat64 versions of these functions.
+ */
+__LA_DECL const struct stat *archive_entry_stat(struct archive_entry *);
+__LA_DECL void archive_entry_copy_stat(struct archive_entry *, const struct stat *);
+
+
+/*
+ * ACL routines. This used to simply store and return text-format ACL
+ * strings, but that proved insufficient for a number of reasons:
+ * = clients need control over uname/uid and gname/gid mappings
+ * = there are many different ACL text formats
+ * = would like to be able to read/convert archives containing ACLs
+ * on platforms that lack ACL libraries
+ *
+ * This last point, in particular, forces me to implement a reasonably
+ * complete set of ACL support routines.
+ *
+ * TODO: Extend this to support NFSv4/NTFS permissions. That should
+ * allow full ACL support on Mac OS, in particular, which uses
+ * POSIX.1e-style interfaces to manipulate NFSv4/NTFS permissions.
+ */
+
+/*
+ * Permission bits mimic POSIX.1e. Note that I've not followed POSIX.1e's
+ * "permset"/"perm" abstract type nonsense. A permset is just a simple
+ * bitmap, following long-standing Unix tradition.
+ */
+#define ARCHIVE_ENTRY_ACL_EXECUTE 1
+#define ARCHIVE_ENTRY_ACL_WRITE 2
+#define ARCHIVE_ENTRY_ACL_READ 4
+
+/* We need to be able to specify either or both of these. */
+#define ARCHIVE_ENTRY_ACL_TYPE_ACCESS 256
+#define ARCHIVE_ENTRY_ACL_TYPE_DEFAULT 512
+
+/* Tag values mimic POSIX.1e */
+#define ARCHIVE_ENTRY_ACL_USER 10001 /* Specified user. */
+#define ARCHIVE_ENTRY_ACL_USER_OBJ 10002 /* User who owns the file. */
+#define ARCHIVE_ENTRY_ACL_GROUP 10003 /* Specified group. */
+#define ARCHIVE_ENTRY_ACL_GROUP_OBJ 10004 /* Group who owns the file. */
+#define ARCHIVE_ENTRY_ACL_MASK 10005 /* Modify group access. */
+#define ARCHIVE_ENTRY_ACL_OTHER 10006 /* Public. */
+
+/*
+ * Set the ACL by clearing it and adding entries one at a time.
+ * Unlike the POSIX.1e ACL routines, you must specify the type
+ * (access/default) for each entry. Internally, the ACL data is just
+ * a soup of entries. API calls here allow you to retrieve just the
+ * entries of interest. This design (which goes against the spirit of
+ * POSIX.1e) is useful for handling archive formats that combine
+ * default and access information in a single ACL list.
+ */
+__LA_DECL void archive_entry_acl_clear(struct archive_entry *);
+__LA_DECL void archive_entry_acl_add_entry(struct archive_entry *,
+ int /* type */, int /* permset */, int /* tag */,
+ int /* qual */, const char * /* name */);
+__LA_DECL void archive_entry_acl_add_entry_w(struct archive_entry *,
+ int /* type */, int /* permset */, int /* tag */,
+ int /* qual */, const wchar_t * /* name */);
+
+/*
+ * To retrieve the ACL, first "reset", then repeatedly ask for the
+ * "next" entry. The want_type parameter allows you to request only
+ * access entries or only default entries.
+ */
+__LA_DECL int archive_entry_acl_reset(struct archive_entry *, int /* want_type */);
+__LA_DECL int archive_entry_acl_next(struct archive_entry *, int /* want_type */,
+ int * /* type */, int * /* permset */, int * /* tag */,
+ int * /* qual */, const char ** /* name */);
+__LA_DECL int archive_entry_acl_next_w(struct archive_entry *, int /* want_type */,
+ int * /* type */, int * /* permset */, int * /* tag */,
+ int * /* qual */, const wchar_t ** /* name */);
+
+/*
+ * Construct a text-format ACL. The flags argument is a bitmask that
+ * can include any of the following:
+ *
+ * ARCHIVE_ENTRY_ACL_TYPE_ACCESS - Include access entries.
+ * ARCHIVE_ENTRY_ACL_TYPE_DEFAULT - Include default entries.
+ * ARCHIVE_ENTRY_ACL_STYLE_EXTRA_ID - Include extra numeric ID field in
+ * each ACL entry. (As used by 'star'.)
+ * ARCHIVE_ENTRY_ACL_STYLE_MARK_DEFAULT - Include "default:" before each
+ * default ACL entry.
+ */
+#define ARCHIVE_ENTRY_ACL_STYLE_EXTRA_ID 1024
+#define ARCHIVE_ENTRY_ACL_STYLE_MARK_DEFAULT 2048
+__LA_DECL const wchar_t *archive_entry_acl_text_w(struct archive_entry *,
+ int /* flags */);
+
+/* Return a count of entries matching 'want_type' */
+__LA_DECL int archive_entry_acl_count(struct archive_entry *, int /* want_type */);
+
+/*
+ * Private ACL parser. This is private because it handles some
+ * very weird formats that clients should not be messing with.
+ * Clients should only deal with their platform-native formats.
+ * Because of the need to support many formats cleanly, new arguments
+ * are likely to get added on a regular basis. Clients who try to use
+ * this interface are likely to be surprised when it changes.
+ *
+ * You were warned!
+ *
+ * TODO: Move this declaration out of the public header and into
+ * a private header. Warnings above are silly.
+ */
+__LA_DECL int __archive_entry_acl_parse_w(struct archive_entry *,
+ const wchar_t *, int /* type */);
+
+/*
+ * extended attributes
+ */
+
+__LA_DECL void archive_entry_xattr_clear(struct archive_entry *);
+__LA_DECL void archive_entry_xattr_add_entry(struct archive_entry *,
+ const char * /* name */, const void * /* value */,
+ size_t /* size */);
+
+/*
+ * To retrieve the xattr list, first "reset", then repeatedly ask for the
+ * "next" entry.
+ */
+
+__LA_DECL int archive_entry_xattr_count(struct archive_entry *);
+__LA_DECL int archive_entry_xattr_reset(struct archive_entry *);
+__LA_DECL int archive_entry_xattr_next(struct archive_entry *,
+ const char ** /* name */, const void ** /* value */, size_t *);
+
+/*
+ * Utility to match up hardlinks.
+ *
+ * The 'struct archive_entry_linkresolver' is a cache of archive entries
+ * for files with multiple links. Here's how to use it:
+ * 1. Create a lookup object with archive_entry_linkresolver_new()
+ * 2. Tell it the archive format you're using.
+ * 3. Hand each archive_entry to archive_entry_linkify().
+ * That function will return 0, 1, or 2 entries that should
+ * be written.
+ * 4. Call archive_entry_linkify(resolver, NULL) until
+ * no more entries are returned.
+ * 5. Call archive_entry_link_resolver_free(resolver) to free resources.
+ *
+ * The entries returned have their hardlink and size fields updated
+ * appropriately. If an entry is passed in that does not refer to
+ * a file with multiple links, it is returned unchanged. The intention
+ * is that you should be able to simply filter all entries through
+ * this machine.
+ *
+ * To make things more efficient, be sure that each entry has a valid
+ * nlinks value. The hardlink cache uses this to track when all links
+ * have been found. If the nlinks value is zero, it will keep every
+ * name in the cache indefinitely, which can use a lot of memory.
+ *
+ * Note that archive_entry_size() is reset to zero if the file
+ * body should not be written to the archive. Pay attention!
+ */
+struct archive_entry_linkresolver;
+
+/*
+ * There are three different strategies for marking hardlinks.
+ * The descriptions below name them after the best-known
+ * formats that rely on each strategy:
+ *
+ * "Old cpio" is the simplest, it always returns any entry unmodified.
+ * As far as I know, only cpio formats use this. Old cpio archives
+ * store every link with the full body; the onus is on the dearchiver
+ * to detect and properly link the files as they are restored.
+ * "tar" is also pretty simple; it caches a copy the first time it sees
+ * any link. Subsequent appearances are modified to be hardlink
+ * references to the first one without any body. Used by all tar
+ * formats, although the newest tar formats permit the "old cpio" strategy
+ * as well. This strategy is very simple for the dearchiver,
+ * and reasonably straightforward for the archiver.
+ * "new cpio" is trickier. It stores the body only with the last
+ * occurrence. The complication is that we might not
+ * see every link to a particular file in a single session, so
+ * there's no easy way to know when we've seen the last occurrence.
+ * The solution here is to queue one link until we see the next.
+ * At the end of the session, you can enumerate any remaining
+ * entries by calling archive_entry_linkify(NULL) and store those
+ * bodies. If you have a file with three links l1, l2, and l3,
+ * you'll get the following behavior if you see all three links:
+ * linkify(l1) => NULL (the resolver stores l1 internally)
+ * linkify(l2) => l1 (resolver stores l2, you write l1)
+ * linkify(l3) => l2, l3 (all links seen, you can write both).
+ * If you only see l1 and l2, you'll get this behavior:
+ * linkify(l1) => NULL
+ * linkify(l2) => l1
+ * linkify(NULL) => l2 (at end, you retrieve remaining links)
+ * As the name suggests, this strategy is used by newer cpio variants.
+ * It's noticably more complex for the archiver, slightly more complex
+ * for the dearchiver than the tar strategy, but makes it straightforward
+ * to restore a file using any link by simply continuing to scan until
+ * you see a link that is stored with a body. In contrast, the tar
+ * strategy requires you to rescan the archive from the beginning to
+ * correctly extract an arbitrary link.
+ */
+
+__LA_DECL struct archive_entry_linkresolver *archive_entry_linkresolver_new(void);
+__LA_DECL void archive_entry_linkresolver_set_strategy(
+ struct archive_entry_linkresolver *, int /* format_code */);
+__LA_DECL void archive_entry_linkresolver_free(struct archive_entry_linkresolver *);
+__LA_DECL void archive_entry_linkify(struct archive_entry_linkresolver *,
+ struct archive_entry **, struct archive_entry **);
+
+#ifdef __cplusplus
+}
+#endif
+
+/* This is meaningless outside of this header. */
+#undef __LA_DECL
+
+#endif /* !ARCHIVE_ENTRY_H_INCLUDED */