I had gave a big thought to the question, who should decide whether to try to
archive package. 

At first glance it looks like maintainer's responsibility. She/he/it creates a 
package without file conflicts intending possibility for multiple versions to 
be installed on a system. Yet this means boolean flag on packages in sync 
repository. Such flag will look really really ugly (at least to me).

Other option is no option at all. Pacman always checks file conflicts between
old and new versions and can try to archive any packages that has none. I guess
such approach wouldn't change a bit neither in speed of pacman operations, nor 
in
file system of users with current state of sync databases. It looks like every
package has at least one common file between versions. Yet at some point such
packages may appear and why would user want to keep multiple versions of package
neither she/he/it, nor maintainer intended to be `archived`?

And thus solution I have ended with - new config option. `MaxArchived` specifies
window of versions to `archive`, and `ArchivePkg` - patterns of packages' names.

In this patch `archived` packages are handled only in update and remove 
operations.
Of course additional changes are required to display `archived` packages in 
queries,
possibly package-level conflicts checking for `archived` packages is also 
required.

---
 lib/libalpm/add.c      | 177 +++++++++++++++++++++++++++++++++++++++++++++++--
 lib/libalpm/alpm.h     |  28 +++++++-
 lib/libalpm/be_local.c |  62 ++++++++++++++---
 lib/libalpm/conflict.c |  25 ++++++-
 lib/libalpm/db.c       |  22 ++++++
 lib/libalpm/db.h       |   3 +
 lib/libalpm/filelist.c |  54 +++++++++++++++
 lib/libalpm/filelist.h |   5 ++
 lib/libalpm/handle.c   |  38 +++++++++++
 lib/libalpm/handle.h   |   2 +
 lib/libalpm/package.c  |  13 ++++
 lib/libalpm/package.h  |   2 +
 lib/libalpm/pkghash.c  |  48 ++++++++++++++
 lib/libalpm/pkghash.h  |   8 +++
 lib/libalpm/remove.c   |  16 +++++
 src/pacman/callback.c  |  21 ++++++
 src/pacman/conf.c      |  20 ++++++
 src/pacman/conf.h      |   2 +
 18 files changed, 529 insertions(+), 17 deletions(-)

diff --git a/lib/libalpm/add.c b/lib/libalpm/add.c
index d132e52..eb035d7 100644
--- a/lib/libalpm/add.c
+++ b/lib/libalpm/add.c
@@ -46,6 +46,7 @@
 #include "db.h"
 #include "remove.h"
 #include "handle.h"
+#include "filelist.h"
 
 /** Add a package to the transaction. */
 int SYMEXPORT alpm_add_pkg(alpm_handle_t *handle, alpm_pkg_t *pkg)
@@ -393,6 +394,173 @@ static int extract_single_file(alpm_handle_t *handle, 
struct archive *archive,
        return errors;
 }
 
+static int should_archive_oldpkg(alpm_pkg_t *oldpkg, alpm_package_operation_t 
operation)
+{
+       return oldpkg->reason == ALPM_PKG_REASON_EXPLICIT &&
+                       oldpkg->handle->max_archived > 0 &&
+                       operation != ALPM_PACKAGE_REINSTALL &&
+                       alpm_list_find(oldpkg->handle->archivepkg, 
oldpkg->name, _alpm_fnmatch) != NULL;
+}
+
+static int should_remove_archivable_oldpkg(alpm_pkg_t *oldpkg, alpm_pkg_t 
*newpkg,
+               alpm_package_operation_t operation, int *files_overlap)
+{
+       if (operation == ALPM_PACKAGE_DOWNGRADE) {
+               return 1;
+       }
+       *files_overlap = _alpm_filelist_overlap(&oldpkg->files, &newpkg->files);
+       return *files_overlap;
+}
+
+static alpm_errno_t ask_to_remove_archived_pkgs(alpm_handle_t *handle,
+               alpm_pkg_t *newpkg, alpm_list_t *archived)
+{
+       alpm_errno_t ret = (alpm_errno_t)0;
+
+       if (archived) {
+               alpm_question_remove_from_archive_t question = {
+                       .type = ALPM_QUESTION_REMOVE_FROM_ARCHIVE,
+                       .remove = 0,
+                       .pkgs = archived
+               };
+
+               QUESTION(handle, &question);
+               if(question.remove) {
+                       alpm_list_t *itr;
+                       for (itr = archived; itr; itr = 
alpm_list_next(archived)) {
+                               alpm_pkg_t *archived_pkg = itr->data;
+
+                               _alpm_log(handle, ALPM_LOG_DEBUG, _("removing 
archived %s-%s\n"),
+                                               archived_pkg->name, 
archived_pkg->version);
+
+                               if(_alpm_remove_single_package(handle, 
archived_pkg, newpkg, 0, 0) == -1) {
+                                       ret = ALPM_ERR_TRANS_ABORT;
+                                       goto cleanup;
+                               }
+                       }
+               } else {
+                       ret = ALPM_ERR_TRANS_ABORT;
+                       goto cleanup;
+               }
+       }
+
+cleanup:
+       alpm_list_free(archived);
+       return ret;
+}
+
+static alpm_list_t *get_old_and_conficting_archived_pkgs(alpm_handle_t *handle,
+               alpm_pkg_t *newpkg, int oldpkg_files_overlap)
+{
+       alpm_list_t *archived = _alpm_db_get_archived_pkgs(handle->db_local, 
newpkg->name);
+       alpm_list_t *itr = NULL;
+       alpm_list_t *archived_descending = alpm_list_reverse(archived);
+       int max_archived_allowed = handle->max_archived;
+
+       alpm_list_free(archived);
+       archived = NULL;
+
+       if (!oldpkg_files_overlap) {
+               /* We need place for one new archived package. */
+               max_archived_allowed -= 1;
+       }
+
+       for (itr = archived_descending; itr && max_archived_allowed > 0; itr = 
alpm_list_next(itr)) {
+               alpm_list_t *tmp_itr;
+               alpm_pkg_t *archived_pkg = itr->data;
+
+               if (_alpm_filelist_overlap(&archived_pkg->files, 
&newpkg->files)) {
+                       continue;
+               }
+
+               tmp_itr = alpm_list_next(itr);
+               archived_descending = 
alpm_list_remove_item(archived_descending, itr);
+               max_archived_allowed -= 1;
+               free(itr);
+               itr = tmp_itr;
+       }
+
+       return archived_descending;
+}
+
+static alpm_errno_t archive_pkg(alpm_handle_t *handle, alpm_pkg_t *oldpkg)
+{
+       /* Removing package copy from pkgcache */
+       alpm_pkg_t *set_me_free;
+       _alpm_pkghash_remove(_alpm_db_get_pkgcache_hash(handle->db_local), 
oldpkg, &set_me_free);
+       _alpm_pkg_free(set_me_free);
+
+       _alpm_log(handle, ALPM_LOG_DEBUG, _("archiving %s-%s\n"),
+                       oldpkg->name, oldpkg->version);
+
+       oldpkg->archived = 1;
+       /* Writing new `archived` flag to db. */
+       if(_alpm_local_db_write(handle->db_local, oldpkg, INFRQ_DESC)) {
+               _alpm_log(handle, ALPM_LOG_ERROR, _("could not update database 
entry %s-%s\n"),
+                               oldpkg->name, oldpkg->version);
+               alpm_logaction(handle, ALPM_CALLER_PREFIX,
+                               "error: could not update database entry 
%s-%s\n",
+                               oldpkg->name, oldpkg->version);
+               return ALPM_ERR_DB_WRITE;
+       }
+
+       _alpm_pkghash_add_sorted(_alpm_db_get_pkgcache_hash(handle->db_local), 
oldpkg);
+
+       return (alpm_errno_t)0;
+}
+
+static alpm_errno_t archive_or_remove_oldpkg(alpm_handle_t *handle, alpm_pkg_t 
*oldpkg,
+               alpm_pkg_t *newpkg, alpm_package_operation_t operation)
+{
+       alpm_db_t *db = handle->db_local;
+       int oldpkg_files_overlap = 0;
+       int try_archive;
+       int can_archive = 0;
+
+       try_archive = should_archive_oldpkg(oldpkg, operation);
+       if (try_archive) {
+               can_archive = !should_remove_archivable_oldpkg(oldpkg, newpkg, 
operation,
+                               &oldpkg_files_overlap);
+       }
+       if (!can_archive) {
+               if (oldpkg_files_overlap) {
+                       _alpm_log(handle, ALPM_LOG_WARNING, _("Can not archive 
entry %s-%s, "
+                                       "files overlap with new package\n"),
+                                       oldpkg->name, oldpkg->version);
+               }
+               /* set up fake remove transaction */
+               if(_alpm_remove_single_package(handle, oldpkg, newpkg, 0, 0) == 
-1) {
+                       return ALPM_ERR_TRANS_ABORT;
+               }
+       }
+       if (!try_archive) {
+               return (alpm_errno_t)0;
+       }
+
+       if (operation == ALPM_PACKAGE_DOWNGRADE) {
+               return ask_to_remove_archived_pkgs(handle, newpkg,
+                               _alpm_db_get_archived_pkgs_newer(db, 
newpkg->name, newpkg->version));
+       } else if (operation == ALPM_PACKAGE_UPGRADE) {
+
+               alpm_list_t *archived = 
get_old_and_conficting_archived_pkgs(handle, newpkg,
+                       oldpkg_files_overlap);
+               alpm_errno_t result = ask_to_remove_archived_pkgs(handle, 
newpkg, archived);
+               if (result != (alpm_errno_t)0) {
+                       return result;
+               }
+
+               if (can_archive) {
+                       result = archive_pkg(handle, oldpkg);
+                       if (result != (alpm_errno_t)0) {
+                               return result;
+                       }
+                       newpkg->oldpkg = NULL;
+               }
+       }
+
+       return (alpm_errno_t)0;
+}
+
 static int commit_single_pkg(alpm_handle_t *handle, alpm_pkg_t *newpkg,
                size_t pkg_current, size_t pkg_count)
 {
@@ -457,10 +625,11 @@ static int commit_single_pkg(alpm_handle_t *handle, 
alpm_pkg_t *newpkg,
                newpkg->reason = ALPM_PKG_REASON_EXPLICIT;
        }
 
-       if(oldpkg) {
-               /* set up fake remove transaction */
-               if(_alpm_remove_single_package(handle, oldpkg, newpkg, 0, 0) == 
-1) {
-                       handle->pm_errno = ALPM_ERR_TRANS_ABORT;
+       if(oldpkg) {            
+               alpm_errno_t pm_errno = archive_or_remove_oldpkg(handle, 
oldpkg, newpkg,
+                               event.operation);
+               if(pm_errno != (alpm_errno_t)0) {
+                       handle->pm_errno = pm_errno;
                        ret = -1;
                        goto cleanup;
                }
diff --git a/lib/libalpm/alpm.h b/lib/libalpm/alpm.h
index 168d71b..8d3df03 100644
--- a/lib/libalpm/alpm.h
+++ b/lib/libalpm/alpm.h
@@ -612,7 +612,8 @@ typedef enum _alpm_question_type_t {
        ALPM_QUESTION_CORRUPTED_PKG = (1 << 3),
        ALPM_QUESTION_REMOVE_PKGS = (1 << 4),
        ALPM_QUESTION_SELECT_PROVIDER = (1 << 5),
-       ALPM_QUESTION_IMPORT_KEY = (1 << 6)
+       ALPM_QUESTION_IMPORT_KEY = (1 << 6),
+       ALPM_QUESTION_REMOVE_FROM_ARCHIVE = (1 << 7)
 } alpm_question_type_t;
 
 typedef struct _alpm_question_any_t {
@@ -693,6 +694,15 @@ typedef struct _alpm_question_import_key_t {
        alpm_pgpkey_t *key;
 } alpm_question_import_key_t;
 
+typedef struct _alpm_question_remove_from_archive_t {
+       /** Type of question. */
+       alpm_question_type_t type;
+       /** Answer: whether or not to remove archived versions. */
+       int remove;
+       /** List of archived alpm_pkg_t* which are to be removed. */
+       alpm_list_t *pkgs;
+} alpm_question_remove_from_archive_t;
+
 /**
  * Questions.
  * This is an union passed to the callback, that allows the frontend to know
@@ -709,6 +719,7 @@ typedef union _alpm_question_t {
        alpm_question_remove_pkgs_t remove_pkgs;
        alpm_question_select_provider_t select_provider;
        alpm_question_import_key_t import_key;
+       alpm_question_remove_from_archive_t remove_from_archive;
 } alpm_question_t;
 
 /** Question callback */
@@ -869,6 +880,18 @@ int alpm_option_remove_noextract(alpm_handle_t *handle, 
const char *path);
 int alpm_option_match_noextract(alpm_handle_t *handle, const char *path);
 /** @} */
 
+/** @name Accessors to the list of archived packages.
+ * These functions modify the list of packages several old
+ * versions of which should be preserved on filesystem when possible.
+ * @{
+ */
+alpm_list_t *alpm_option_get_archivepkgs(alpm_handle_t *handle);
+int alpm_option_add_archivepkg(alpm_handle_t *handle, const char *archivepkg);
+int alpm_option_set_archivepkgs(alpm_handle_t *handle, alpm_list_t 
*archivepkgs);
+int alpm_option_remove_archivepkg(alpm_handle_t *handle, const char 
*archivepkg);
+/** @} */
+
+
 /** @name Accessors to the list of ignored packages.
  * These functions modify the list of packages that
  * should be ignored by a sysupgrade.
@@ -910,6 +933,9 @@ int alpm_option_set_arch(alpm_handle_t *handle, const char 
*arch);
 double alpm_option_get_deltaratio(alpm_handle_t *handle);
 int alpm_option_set_deltaratio(alpm_handle_t *handle, double ratio);
 
+int alpm_option_get_maxarchived(alpm_handle_t *handle);
+int alpm_option_set_maxarchived(alpm_handle_t *handle, int max_archived);
+
 int alpm_option_get_checkspace(alpm_handle_t *handle);
 int alpm_option_set_checkspace(alpm_handle_t *handle, int checkspace);
 
diff --git a/lib/libalpm/be_local.c b/lib/libalpm/be_local.c
index cc2d8ba..e0d7761 100644
--- a/lib/libalpm/be_local.c
+++ b/lib/libalpm/be_local.c
@@ -556,7 +556,7 @@ static int local_db_populate(alpm_db_t *db)
        while((ent = readdir(dbdir)) != NULL) {
                const char *name = ent->d_name;
 
-               alpm_pkg_t *pkg;
+               alpm_pkg_t *pkg, *dbpkg;
 
                if(strcmp(name, ".") == 0 || strcmp(name, "..") == 0) {
                        continue;
@@ -579,18 +579,32 @@ static int local_db_populate(alpm_db_t *db)
                        continue;
                }
 
-               /* duplicated database entries are not allowed */
-               if(_alpm_pkghash_find(db->pkgcache, pkg->name)) {
-                       _alpm_log(db->handle, ALPM_LOG_ERROR, _("duplicated 
database entry '%s'\n"), pkg->name);
-                       _alpm_pkg_free(pkg);
-                       continue;
-               }
-
                pkg->origin = ALPM_PKG_FROM_LOCALDB;
                pkg->origin_data.db = db;
                pkg->ops = &local_pkg_ops;
                pkg->handle = db->handle;
 
+               dbpkg = _alpm_pkghash_find(db->pkgcache, pkg->name);
+               if (dbpkg != NULL) {
+                       /* Reading 'DESC' to distinquish which one is archived.
+                        * Actually, could be done with vercmp, but such 
approach
+                        * won't detect inconsistances in local db.
+                        */
+                       local_db_read(dbpkg, INFRQ_DESC);
+                       local_db_read(pkg, INFRQ_DESC);
+                       if (dbpkg->archived) {
+                               alpm_pkg_t tmp = *dbpkg;
+                               *dbpkg = *pkg;
+                               *pkg = tmp;
+                       } else if (!pkg->archived) {
+                               /* duplicated database entries without 
`archived` flag are not allowed */
+                               _alpm_log(db->handle, ALPM_LOG_ERROR, 
_("duplicated database entry '%s'\n"),
+                                               pkg->name);
+                               _alpm_pkg_free(pkg);
+                               continue;
+                       }
+               }
+
                /* explicitly read with only 'BASE' data, accessors will handle 
the rest */
                if(local_db_read(pkg, INFRQ_BASE) == -1) {
                        _alpm_log(db->handle, ALPM_LOG_ERROR, _("corrupted 
database entry '%s'\n"), name);
@@ -607,7 +621,10 @@ static int local_db_populate(alpm_db_t *db)
 
        closedir(dbdir);
        if(count > 0) {
-               db->pkgcache->list = alpm_list_msort(db->pkgcache->list, 
(size_t)count, _alpm_pkg_cmp);
+               size_t archived_count = alpm_list_count(db->pkgcache->archive);
+
+               db->pkgcache->list = alpm_list_msort(db->pkgcache->list, 
(size_t)db->pkgcache->entries, _alpm_pkg_cmp);
+               db->pkgcache->archive = alpm_list_msort(db->pkgcache->archive, 
archived_count, _alpm_pkg_cmp);
        }
        _alpm_log(db->handle, ALPM_LOG_DEBUG, "added %d packages to package 
cache for db '%s'\n",
                        count, db->treename);
@@ -689,6 +706,26 @@ static int local_db_read(alpm_pkg_t *info, alpm_dbinfrq_t 
inforeq)
        /* clear out 'line', to be certain - and to make valgrind happy */
        memset(line, 0, sizeof(line));
 
+       /* BASE */
+       if (inforeq & INFRQ_BASE) {
+               char *path = _alpm_local_db_pkgpath(db, info, "archived");
+               if(!path) {
+                       _alpm_log(db->handle, ALPM_LOG_ERROR, _("could not open 
file %s: %s\n"), path, strerror(errno));
+                       free(path);
+                       goto error;
+               }
+               if ((fp = fopen(path, "r")) != NULL){
+                       if (fscanf(fp, "%d", &info->archived) == EOF) {
+                               _alpm_log(db->handle, ALPM_LOG_ERROR, _("could 
not read archived flag from file %s: %s\n"), path, strerror(errno));
+                               free(path);
+                               goto error;
+                       }
+                       fclose(fp);
+                       fp = NULL;
+               }
+               free(path);
+       }
+
        /* DESC */
        if(inforeq & INFRQ_DESC && !(info->infolevel & INFRQ_DESC)) {
                char *path = _alpm_local_db_pkgpath(db, info, "desc");
@@ -741,6 +778,9 @@ static int local_db_read(alpm_pkg_t *info, alpm_dbinfrq_t 
inforeq)
                        } else if(strcmp(line, "%REASON%") == 0) {
                                READ_NEXT();
                                info->reason = (alpm_pkgreason_t)atoi(line);
+                       } else if(strcmp(line, "%ARCHIVED%") == 0) {
+                               READ_NEXT();
+                               info->archived = atoi(line);
                        } else if(strcmp(line, "%VALIDATION%") == 0) {
                                alpm_list_t *i, *v = NULL;
                                READ_AND_STORE_ALL(v);
@@ -978,6 +1018,10 @@ int _alpm_local_db_write(alpm_db_t *db, alpm_pkg_t *info, 
alpm_dbinfrq_t inforeq
                        fprintf(fp, "%%REASON%%\n"
                                                        "%u\n\n", info->reason);
                }
+               if(info->archived) {
+                       fprintf(fp, "%%ARCHIVED%%\n"
+                                                       "%u\n\n", 
info->archived);
+               }
                if(info->groups) {
                        fputs("%GROUPS%\n", fp);
                        for(lp = info->groups; lp; lp = lp->next) {
diff --git a/lib/libalpm/conflict.c b/lib/libalpm/conflict.c
index 092b019..0db59ad 100644
--- a/lib/libalpm/conflict.c
+++ b/lib/libalpm/conflict.c
@@ -385,6 +385,25 @@ static alpm_list_t *alpm_db_find_file_owners(alpm_db_t* 
db, const char *path)
        return owners;
 }
 
+static alpm_list_t *_alpm_filelist_difference_on_all_versions(
+               alpm_filelist_t *newpkg_filelist, alpm_db_t *db, alpm_pkg_t 
*oldpkg)
+{
+       alpm_list_t *archived, *itr;
+       alpm_list_t *tmpfiles = _alpm_filelist_difference(newpkg_filelist,
+                       alpm_pkg_get_files(oldpkg));
+
+       archived = _alpm_db_get_archived_pkgs(db, oldpkg->name);
+       for (itr = archived; itr; itr = alpm_list_next(itr)) {
+               alpm_pkg_t *archived_pkg = itr->data;
+
+               tmpfiles = _alpm_list_filelist_difference(tmpfiles,
+                               alpm_pkg_get_files(archived_pkg));
+       }
+       alpm_list_free(archived);
+
+       return tmpfiles;
+}
+
 /**
  * @brief Find file conflicts that may occur during the transaction.
  *
@@ -482,9 +501,9 @@ alpm_list_t *_alpm_db_find_fileconflicts(alpm_handle_t 
*handle,
                 * that the former list needs to be freed while the latter list 
should NOT
                 * be freed. */
                if(dbpkg) {
-                       /* older ver of package currently installed */
-                       tmpfiles = 
_alpm_filelist_difference(alpm_pkg_get_files(p1),
-                                       alpm_pkg_get_files(dbpkg));
+                       /* older verions (including archived) of package 
currently installed */
+                       tmpfiles = 
_alpm_filelist_difference_on_all_versions(alpm_pkg_get_files(p1),
+                                       handle->db_local, dbpkg);
                } else {
                        /* no version of package currently installed */
                        alpm_filelist_t *fl = alpm_pkg_get_files(p1);
diff --git a/lib/libalpm/db.c b/lib/libalpm/db.c
index f70f83c..85606a1 100644
--- a/lib/libalpm/db.c
+++ b/lib/libalpm/db.c
@@ -527,6 +527,8 @@ void _alpm_db_free_pkgcache(alpm_db_t *db)
        if(db->pkgcache) {
                alpm_list_free_inner(db->pkgcache->list,
                                (alpm_list_fn_free)_alpm_pkg_free);
+               alpm_list_free_inner(db->pkgcache->archive,
+                               (alpm_list_fn_free)_alpm_pkg_free);
                _alpm_pkghash_free(db->pkgcache);
        }
        db->status &= ~DB_STATUS_PKGCACHE;
@@ -636,6 +638,26 @@ alpm_pkg_t *_alpm_db_get_pkgfromcache(alpm_db_t *db, const 
char *target)
        return _alpm_pkghash_find(pkgcache, target);
 }
 
+alpm_list_t *_alpm_db_get_archived_pkgs(alpm_db_t *db, const char *name)
+{
+       return _alpm_db_get_archived_pkgs_newer(db, name, NULL);
+}
+
+alpm_list_t *_alpm_db_get_archived_pkgs_newer(alpm_db_t *db, const char *name,
+               const char *version)
+{
+       if (db == NULL) {
+               return NULL;
+       }
+
+       alpm_pkghash_t *pkgcache = _alpm_db_get_pkgcache_hash(db);
+       if(!pkgcache) {
+               return NULL;
+       }
+
+       return _alpm_pkghash_get_archived_pkgs_newer(pkgcache, name, version);
+}
+
 /* Returns a new group cache from db.
  */
 static int load_grpcache(alpm_db_t *db)
diff --git a/lib/libalpm/db.h b/lib/libalpm/db.h
index 05ef43e..eef2255 100644
--- a/lib/libalpm/db.h
+++ b/lib/libalpm/db.h
@@ -103,6 +103,9 @@ int _alpm_db_remove_pkgfromcache(alpm_db_t *db, alpm_pkg_t 
*pkg);
 alpm_pkghash_t *_alpm_db_get_pkgcache_hash(alpm_db_t *db);
 alpm_list_t *_alpm_db_get_pkgcache(alpm_db_t *db);
 alpm_pkg_t *_alpm_db_get_pkgfromcache(alpm_db_t *db, const char *target);
+alpm_list_t *_alpm_db_get_archived_pkgs(alpm_db_t *db, const char *name);
+alpm_list_t *_alpm_db_get_archived_pkgs_newer(alpm_db_t *db, const char *name,
+               const char *version);
 /* groups */
 alpm_list_t *_alpm_db_get_groupcache(alpm_db_t *db);
 alpm_group_t *_alpm_db_get_groupfromcache(alpm_db_t *db, const char *target);
diff --git a/lib/libalpm/filelist.c b/lib/libalpm/filelist.c
index 5783373..fd74e75 100644
--- a/lib/libalpm/filelist.c
+++ b/lib/libalpm/filelist.c
@@ -61,6 +61,35 @@ alpm_list_t *_alpm_filelist_difference(alpm_filelist_t 
*filesA,
        return ret;
 }
 
+alpm_list_t *_alpm_list_filelist_difference(alpm_list_t *tmpfiles,
+               alpm_filelist_t *filesB)
+{
+       alpm_list_t *itrA = tmpfiles;
+       size_t ctrB = 0;
+
+       while(itrA && ctrB < filesB->count) {
+               char *strA = itrA->data;
+               char *strB = filesB->files[ctrB].name;
+
+               int cmp = strcmp(strA, strB);
+               if(cmp < 0) {
+                       /* item only in filesA, qualifies as a difference */
+                       itrA = alpm_list_next(itrA);
+               } else if(cmp > 0) {
+                       ctrB++;
+               } else {
+                       alpm_list_t *tmp_itr = alpm_list_next(itrA);
+                       tmpfiles = alpm_list_remove_item(tmpfiles, itrA);
+                       free(itrA);
+                       itrA = tmp_itr;
+
+                       ctrB++;
+               }
+       }
+
+       return tmpfiles;
+}
+
 static int _alpm_filelist_pathcmp(const char *p1, const char *p2)
 {
        while(*p1 && *p1 == *p2) {
@@ -109,6 +138,31 @@ alpm_list_t *_alpm_filelist_intersection(alpm_filelist_t 
*filesA,
        return ret;
 }
 
+int _alpm_filelist_overlap(alpm_filelist_t *filesA, alpm_filelist_t *filesB)
+{
+       size_t ctrA = 0, ctrB = 0;
+       alpm_file_t *arrA = filesA->files, *arrB = filesB->files;
+
+       while(ctrA < filesA->count && ctrB < filesB->count) {
+               const char *strA = arrA[ctrA].name, *strB = arrB[ctrB].name;
+               int cmp = _alpm_filelist_pathcmp(strA, strB);
+               if(cmp < 0) {
+                       ctrA++;
+               } else if(cmp > 0) {
+                       ctrB++;
+               } else {
+                       /* when not directories, item in both qualifies as an 
intersect */
+                       if(strA[strlen(strA) - 1] != '/' || strB[strlen(strB) - 
1] != '/') {
+                               return 1;
+                       }
+                       ctrA++;
+                       ctrB++;
+               }
+       }
+
+       return 0;
+}
+
 /* Helper function for comparing files list entries
  */
 int _alpm_files_cmp(const void *f1, const void *f2)
diff --git a/lib/libalpm/filelist.h b/lib/libalpm/filelist.h
index 5560ea0..f1a7a5e 100644
--- a/lib/libalpm/filelist.h
+++ b/lib/libalpm/filelist.h
@@ -24,9 +24,14 @@
 alpm_list_t *_alpm_filelist_difference(alpm_filelist_t *filesA,
                alpm_filelist_t *filesB);
 
+alpm_list_t *_alpm_list_filelist_difference(alpm_list_t *tmpfiles,
+               alpm_filelist_t *filesB);
+
 alpm_list_t *_alpm_filelist_intersection(alpm_filelist_t *filesA,
                alpm_filelist_t *filesB);
 
+int _alpm_filelist_overlap(alpm_filelist_t *filesA, alpm_filelist_t *filesB);
+
 int _alpm_files_cmp(const void *f1, const void *f2);
 
 #endif /* _ALPM_FILELIST_H */
diff --git a/lib/libalpm/handle.c b/lib/libalpm/handle.c
index e9439a0..7e944f2 100644
--- a/lib/libalpm/handle.c
+++ b/lib/libalpm/handle.c
@@ -92,6 +92,7 @@ void _alpm_handle_free(alpm_handle_t *handle)
        FREELIST(handle->noextract);
        FREELIST(handle->ignorepkg);
        FREELIST(handle->ignoregroup);
+       FREELIST(handle->archivepkg);
 
        alpm_list_free_inner(handle->assumeinstalled, 
(alpm_list_fn_free)alpm_dep_free);
        alpm_list_free(handle->assumeinstalled);
@@ -271,6 +272,12 @@ alpm_list_t SYMEXPORT 
*alpm_option_get_noextracts(alpm_handle_t *handle)
        return handle->noextract;
 }
 
+alpm_list_t SYMEXPORT *alpm_option_get_archivepkgs(alpm_handle_t *handle)
+{
+       CHECK_HANDLE(handle, return NULL);
+       return handle->archivepkg;
+}
+
 alpm_list_t SYMEXPORT *alpm_option_get_ignorepkgs(alpm_handle_t *handle)
 {
        CHECK_HANDLE(handle, return NULL);
@@ -301,6 +308,12 @@ double SYMEXPORT alpm_option_get_deltaratio(alpm_handle_t 
*handle)
        return handle->deltaratio;
 }
 
+int SYMEXPORT alpm_option_get_maxarchived(alpm_handle_t *handle)
+{
+       CHECK_HANDLE(handle, return -1);
+       return handle->max_archived;
+}
+
 int SYMEXPORT alpm_option_get_checkspace(alpm_handle_t *handle)
 {
        CHECK_HANDLE(handle, return -1);
@@ -627,6 +640,21 @@ int SYMEXPORT alpm_option_match_noextract(alpm_handle_t 
*handle, const char *pat
        return _alpm_fnmatch_patterns(handle->noextract, path);
 }
 
+int SYMEXPORT alpm_option_add_archivepkg(alpm_handle_t *handle, const char 
*archivepkg)
+{
+       return _alpm_option_strlist_add(handle, &(handle->archivepkg), 
archivepkg);
+}
+
+int SYMEXPORT alpm_option_set_archivepkgs(alpm_handle_t *handle, alpm_list_t 
*archivepkg)
+{
+       return _alpm_option_strlist_set(handle, &(handle->archivepkg), 
archivepkg);
+}
+
+int SYMEXPORT alpm_option_remove_archivepkg(alpm_handle_t *handle, const char 
*archivepkg)
+{
+       return _alpm_option_strlist_rem(handle, &(handle->archivepkg), 
archivepkg);
+}
+
 int SYMEXPORT alpm_option_add_ignorepkg(alpm_handle_t *handle, const char *pkg)
 {
        return _alpm_option_strlist_add(handle, &(handle->ignorepkg), pkg);
@@ -742,6 +770,16 @@ int SYMEXPORT alpm_option_set_deltaratio(alpm_handle_t 
*handle, double ratio)
        return 0;
 }
 
+int SYMEXPORT alpm_option_set_maxarchived(alpm_handle_t *handle, int 
max_archived)
+{
+       CHECK_HANDLE(handle, return -1);
+       if(max_archived < 0) {
+               RET_ERR(handle, ALPM_ERR_WRONG_ARGS, -1);
+       }
+       handle->max_archived = max_archived;
+       return 0;
+}
+
 alpm_db_t SYMEXPORT *alpm_get_localdb(alpm_handle_t *handle)
 {
        CHECK_HANDLE(handle, return NULL);
diff --git a/lib/libalpm/handle.h b/lib/libalpm/handle.h
index a1d0f9a..31aeb02 100644
--- a/lib/libalpm/handle.h
+++ b/lib/libalpm/handle.h
@@ -90,10 +90,12 @@ struct __alpm_handle_t {
        alpm_list_t *ignorepkg;   /* List of packages to ignore */
        alpm_list_t *ignoregroup; /* List of groups to ignore */
        alpm_list_t *assumeinstalled;   /* List of virtual packages used to 
satisfy dependencies */
+       alpm_list_t *archivepkg;  /* List of packages to archive */
 
        /* options */
        char *arch;              /* Architecture of packages we should allow */
        double deltaratio;       /* Download deltas if possible; a ratio value 
*/
+       int max_archived;        /* Maximum number of package versions to 
archive */
        int usesyslog;           /* Use syslog instead of logfile? */ /* TODO 
move to frontend */
        int checkspace;          /* Check disk space before installing */
        char *dbext;             /* Sync DB extension */
diff --git a/lib/libalpm/package.c b/lib/libalpm/package.c
index f08df8b..c3cc9c8 100644
--- a/lib/libalpm/package.c
+++ b/lib/libalpm/package.c
@@ -591,6 +591,7 @@ int _alpm_pkg_dup(alpm_pkg_t *pkg, alpm_pkg_t **new_ptr)
        newpkg->scriptlet = pkg->scriptlet;
        newpkg->reason = pkg->reason;
        newpkg->validation = pkg->validation;
+       newpkg->archived = pkg->archived;
 
        newpkg->licenses   = alpm_list_strdup(pkg->licenses);
        newpkg->replaces   = list_depdup(pkg->replaces);
@@ -727,6 +728,18 @@ int _alpm_pkg_cmp(const void *p1, const void *p2)
        return strcmp(pkg1->name, pkg2->name);
 }
 
+int _alpm_pkg_version_cmp(const void *p1, const void *p2)
+{
+       const alpm_pkg_t *pkg1 = p1;
+       const alpm_pkg_t *pkg2 = p2;
+       int res = strcmp(pkg1->name, pkg2->name);
+       if (res == 0) {
+               return alpm_pkg_vercmp(pkg1->version, pkg2->version);
+       } else {
+               return res;
+       }
+}
+
 /* Test for existence of a package in a alpm_list_t*
  * of alpm_pkg_t*
  */
diff --git a/lib/libalpm/package.h b/lib/libalpm/package.h
index 31add9a..26a0b54 100644
--- a/lib/libalpm/package.h
+++ b/lib/libalpm/package.h
@@ -134,6 +134,7 @@ struct __alpm_pkg_t {
        alpm_pkgvalidation_t validation;
        alpm_pkgfrom_t origin;
        alpm_pkgreason_t reason;
+       int archived;
        int scriptlet;
 };
 
@@ -151,6 +152,7 @@ alpm_pkg_t *_alpm_pkg_load_internal(alpm_handle_t *handle,
                const char *pkgfile, int full);
 
 int _alpm_pkg_cmp(const void *p1, const void *p2);
+int _alpm_pkg_version_cmp(const void *p1, const void *p2);
 int _alpm_pkg_compare_versions(alpm_pkg_t *local_pkg, alpm_pkg_t *pkg);
 
 #endif /* _ALPM_PACKAGE_H */
diff --git a/lib/libalpm/pkghash.c b/lib/libalpm/pkghash.c
index 968218e..aaa298a 100644
--- a/lib/libalpm/pkghash.c
+++ b/lib/libalpm/pkghash.c
@@ -166,6 +166,15 @@ static alpm_pkghash_t *pkghash_add_pkg(alpm_pkghash_t 
*hash, alpm_pkg_t *pkg,
                return hash;
        }
 
+       if (pkg->archived) {
+               if (!sorted) {
+                       hash->archive = alpm_list_add(hash->archive, pkg);
+               } else {
+                       hash->archive = alpm_list_add_sorted(hash->archive, 
pkg, _alpm_pkg_version_cmp);
+               }
+               return hash;
+       }
+
        if(hash->entries >= hash->limit) {
                hash = rehash(hash);
        }
@@ -251,6 +260,12 @@ alpm_pkghash_t *_alpm_pkghash_remove(alpm_pkghash_t *hash, 
alpm_pkg_t *pkg,
                return hash;
        }
 
+       if (pkg->archived) {
+               hash->archive = alpm_list_remove(hash->archive, pkg, 
_alpm_pkg_version_cmp,
+                               (void**)data);
+               return hash;
+       }
+
        position = pkg->name_hash % hash->buckets;
        while((i = hash->hash_table[position]) != NULL) {
                alpm_pkg_t *info = i->data;
@@ -312,6 +327,7 @@ void _alpm_pkghash_free(alpm_pkghash_t *hash)
                }
                free(hash->hash_table);
        }
+       alpm_list_free(hash->archive);
        free(hash);
 }
 
@@ -345,4 +361,36 @@ alpm_pkg_t *_alpm_pkghash_find(alpm_pkghash_t *hash, const 
char *name)
        return NULL;
 }
 
+alpm_list_t *_alpm_pkghash_get_archived_pkgs(alpm_pkghash_t *hash, const char 
*name)
+{
+       return _alpm_pkghash_get_archived_pkgs_newer(hash, name, NULL);
+}
+
+alpm_list_t *_alpm_pkghash_get_archived_pkgs_newer(alpm_pkghash_t *hash,
+               const char *name, const char *version)
+{
+       alpm_list_t *result = NULL;
+       alpm_list_t *itr;
+
+       if(name == NULL || hash == NULL) {
+               return NULL;
+       }
+
+       for (itr = hash->archive; itr; itr = alpm_list_next(itr)) {
+               alpm_pkg_t *archived = itr->data;
+               int name_cmp = strcmp(archived->name, name);
+
+               if (name_cmp > 0) {
+                       break;
+               }
+
+               if (name_cmp == 0 && (version == NULL ||
+                               alpm_pkg_vercmp(archived->version, version) >= 
0)) {
+                       result = alpm_list_add(result, archived);
+               }
+       }
+
+       return result;
+}
+
 /* vim: set noet: */
diff --git a/lib/libalpm/pkghash.h b/lib/libalpm/pkghash.h
index c843a43..119edd1 100644
--- a/lib/libalpm/pkghash.h
+++ b/lib/libalpm/pkghash.h
@@ -37,6 +37,10 @@ struct __alpm_pkghash_t {
        alpm_list_t **hash_table;
        /** head node of the hash table data in normal list format */
        alpm_list_t *list;
+
+       /** sorted by name and version list of archived packages */
+       alpm_list_t *archive;
+
        /** number of buckets in hash table */
        unsigned int buckets;
        /** number of entries in hash table */
@@ -57,4 +61,8 @@ void _alpm_pkghash_free(alpm_pkghash_t *hash);
 
 alpm_pkg_t *_alpm_pkghash_find(alpm_pkghash_t *hash, const char *name);
 
+alpm_list_t *_alpm_pkghash_get_archived_pkgs(alpm_pkghash_t *hash, const char 
*name);
+alpm_list_t *_alpm_pkghash_get_archived_pkgs_newer(alpm_pkghash_t *hash,
+               const char *name, const char *version);
+
 #endif /* _ALPM_PKGHASH_H */
diff --git a/lib/libalpm/remove.c b/lib/libalpm/remove.c
index 45f7c2f..cda5e54 100644
--- a/lib/libalpm/remove.c
+++ b/lib/libalpm/remove.c
@@ -59,6 +59,7 @@ int SYMEXPORT alpm_remove_pkg(alpm_handle_t *handle, 
alpm_pkg_t *pkg)
        const char *pkgname;
        alpm_trans_t *trans;
        alpm_pkg_t *copy;
+       alpm_list_t *itr, *archived;
 
        /* Sanity checks */
        CHECK_HANDLE(handle, return -1);
@@ -83,6 +84,21 @@ int SYMEXPORT alpm_remove_pkg(alpm_handle_t *handle, 
alpm_pkg_t *pkg)
                return -1;
        }
        trans->remove = alpm_list_add(trans->remove, copy);
+
+       archived = _alpm_db_get_archived_pkgs(handle->db_local, pkgname);
+       for (itr = archived; itr; itr = alpm_list_next(itr)) {
+               alpm_pkg_t *archived_pkg = itr->data;
+
+               _alpm_log(handle, ALPM_LOG_DEBUG, "adding archived package 
%s-%s to the transaction remove list\n",
+                               pkgname, archived_pkg->version);
+               if(_alpm_pkg_dup(archived_pkg, &copy) == -1) {
+                       alpm_list_free(archived);
+                       return -1;
+               }
+               trans->remove = alpm_list_add(trans->remove, copy);
+       }
+       alpm_list_free(archived);
+
        return 0;
 }
 
diff --git a/src/pacman/callback.c b/src/pacman/callback.c
index 7f72b84..35a2c00 100644
--- a/src/pacman/callback.c
+++ b/src/pacman/callback.c
@@ -487,6 +487,27 @@ void cb_question(alpm_question_t *question)
                                }
                        }
                        break;
+               case ALPM_QUESTION_REMOVE_FROM_ARCHIVE:
+                       {
+                               alpm_question_remove_from_archive_t *q = 
&question->remove_from_archive;
+                               alpm_list_t *versionlist = NULL, *i;
+                               size_t count = 0;
+                               for(i = q->pkgs; i; i = i->next) {
+                                       versionlist = alpm_list_add(versionlist,
+                                                       (char 
*)alpm_pkg_get_version(i->data));
+                                       count++;
+                               }
+                               colon_printf(_n(
+                                                       "The following archived 
version of package %s have to be removed:\n",
+                                                       "The following archived 
versions of package %s have to be removed:\n",
+                                                       count), 
alpm_pkg_get_name(q->pkgs->data));
+                               list_display("     ", versionlist, getcols());
+                               printf("\n");
+                               q->remove = yesno(_("Proceed?"));
+                               alpm_list_free(versionlist);
+                       }
+                       break;
+
        }
        if(config->noask) {
                if(config->ask & question->type) {
diff --git a/src/pacman/conf.c b/src/pacman/conf.c
index 25de7af..1f2ffaa 100644
--- a/src/pacman/conf.c
+++ b/src/pacman/conf.c
@@ -150,6 +150,7 @@ int config_free(config_t *oldconfig)
        free(oldconfig->gpgdir);
        FREELIST(oldconfig->hookdirs);
        FREELIST(oldconfig->cachedirs);
+       FREELIST(oldconfig->archivepkg);
        free(oldconfig->xfercommand);
        free(oldconfig->print_format);
        free(oldconfig->arch);
@@ -524,6 +525,23 @@ static int _parse_options(const char *key, char *value,
                        if(!config->arch) {
                                config_set_arch(value);
                        }
+               } else if(strcmp(key, "ArchivePkg") == 0) {
+                       setrepeatingoption(value, "ArchivePkg", 
&(config->archivepkg));
+               } else if(strcmp(key, "MaxArchived") == 0) {
+                       long max_archived;
+                       char *endptr;
+
+                       max_archived = strtol(value, &endptr, 10);
+
+                       if(*endptr != '\0' || max_archived < 0 || max_archived 
> USHRT_MAX) {
+                               pm_printf(ALPM_LOG_ERROR,
+                                               _("config file %s, line %d: 
invalid value for '%s' : '%li'\n"),
+                                               file, linenum, "MaxArchived", 
max_archived);
+                               return 1;
+                       }
+
+                       config->max_archived = (unsigned short)max_archived;
+                       pm_printf(ALPM_LOG_DEBUG, "config: maxarchived: %li\n", 
max_archived);
                } else if(strcmp(key, "UseDelta") == 0) {
                        double ratio;
                        char *endptr;
@@ -810,11 +828,13 @@ static int setup_libalpm(void)
        alpm_option_set_checkspace(handle, config->checkspace);
        alpm_option_set_usesyslog(handle, config->usesyslog);
        alpm_option_set_deltaratio(handle, config->deltaratio);
+       alpm_option_set_maxarchived(handle, config->max_archived);
 
        alpm_option_set_ignorepkgs(handle, config->ignorepkg);
        alpm_option_set_ignoregroups(handle, config->ignoregrp);
        alpm_option_set_noupgrades(handle, config->noupgrade);
        alpm_option_set_noextracts(handle, config->noextract);
+       alpm_option_set_archivepkgs(handle, config->archivepkg);
 
        for(i = config->assumeinstalled; i; i = i->next) {
                char *entry = i->data;
diff --git a/src/pacman/conf.h b/src/pacman/conf.h
index 2aba8bf..19676c0 100644
--- a/src/pacman/conf.h
+++ b/src/pacman/conf.h
@@ -56,6 +56,7 @@ typedef struct __config_t {
        unsigned short usesyslog;
        unsigned short color;
        double deltaratio;
+       unsigned short max_archived;
        char *arch;
        char *print_format;
        /* unfortunately, we have to keep track of paths both here and in the 
library
@@ -120,6 +121,7 @@ typedef struct __config_t {
        alpm_list_t *assumeinstalled;
        alpm_list_t *noupgrade;
        alpm_list_t *noextract;
+       alpm_list_t *archivepkg;
        char *xfercommand;
 
        /* our connection to libalpm */
-- 
2.9.3

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