Adding upstream version 1.20.13.upstream/1.20.13upstream

Signed-off-by: Daniel Baumann <daniel.baumann@progress-linux.org>

1 files changed, 1674 insertions, 0 deletions

diff --git a/src/archives.c b/src/archives.c
new file mode 100644
index 0000000..aa56e9e
--- /dev/null
+++ b/src/archives.c
@@ -0,0 +1,1674 @@
+/*
+ * dpkg - main program for package management
+ * archives.c - actions that process archive files, mainly unpack
+ *
+ * Copyright © 1994,1995 Ian Jackson <ijackson@chiark.greenend.org.uk>
+ * Copyright © 2000 Wichert Akkerman <wakkerma@debian.org>
+ * Copyright © 2007-2015 Guillem Jover <guillem@debian.org>
+ * Copyright © 2011 Linaro Limited
+ * Copyright © 2011 Raphaël Hertzog <hertzog@debian.org>
+ *
+ * This is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation; either version 2 of the License, or
+ * (at your option) any later version.
+ *
+ * This is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program.  If not, see <https://www.gnu.org/licenses/>.
+ */
+
+#include <config.h>
+#include <compat.h>
+
+#include <sys/types.h>
+#include <sys/time.h>
+#include <sys/stat.h>
+
+#include <errno.h>
+#include <string.h>
+#include <time.h>
+#include <fcntl.h>
+#include <unistd.h>
+#include <stdint.h>
+#include <stdlib.h>
+#include <stdio.h>
+#include <obstack.h>
+#define obstack_chunk_alloc m_malloc
+#define obstack_chunk_free free
+
+#include <dpkg/i18n.h>
+#include <dpkg/dpkg.h>
+#include <dpkg/dpkg-db.h>
+#include <dpkg/pkg.h>
+#include <dpkg/path.h>
+#include <dpkg/fdio.h>
+#include <dpkg/buffer.h>
+#include <dpkg/subproc.h>
+#include <dpkg/command.h>
+#include <dpkg/file.h>
+#include <dpkg/treewalk.h>
+#include <dpkg/tarfn.h>
+#include <dpkg/options.h>
+#include <dpkg/triglib.h>
+#include <dpkg/db-ctrl.h>
+#include <dpkg/db-fsys.h>
+
+#include "main.h"
+#include "archives.h"
+#include "filters.h"
+
+static inline void
+fd_writeback_init(int fd)
+{
+  /* Ignore the return code as it should be considered equivalent to an
+   * asynchronous hint for the kernel, we are doing an fsync() later on
+   * anyway. */
+#if defined(SYNC_FILE_RANGE_WRITE)
+  sync_file_range(fd, 0, 0, SYNC_FILE_RANGE_WRITE);
+#elif defined(HAVE_POSIX_FADVISE)
+  posix_fadvise(fd, 0, 0, POSIX_FADV_DONTNEED);
+#endif
+}
+
+static struct obstack tar_pool;
+static bool tar_pool_init = false;
+
+/**
+ * Allocate memory from the tar memory pool.
+ */
+static void *
+tar_pool_alloc(size_t size)
+{
+  if (!tar_pool_init) {
+    obstack_init(&tar_pool);
+    tar_pool_init = true;
+  }
+
+  return obstack_alloc(&tar_pool, size);
+}
+
+/**
+ * Free memory from the tar memory pool.
+ */
+static void
+tar_pool_free(void *ptr)
+{
+  obstack_free(&tar_pool, ptr);
+}
+
+/**
+ * Release the tar memory pool.
+ */
+static void
+tar_pool_release(void)
+{
+  if (tar_pool_init) {
+    obstack_free(&tar_pool, NULL);
+    tar_pool_init = false;
+  }
+}
+
+struct fsys_namenode_list *
+tar_fsys_namenode_queue_push(struct fsys_namenode_queue *queue,
+                            struct fsys_namenode *namenode)
+{
+  struct fsys_namenode_list *node;
+
+  node = tar_pool_alloc(sizeof(*node));
+  node->namenode = namenode;
+  node->next = NULL;
+
+  *queue->tail = node;
+  queue->tail = &node->next;
+
+  return node;
+}
+
+static void
+tar_fsys_namenode_queue_pop(struct fsys_namenode_queue *queue,
+                           struct fsys_namenode_list **tail_prev,
+                           struct fsys_namenode_list *node)
+{
+  tar_pool_free(node);
+  queue->tail = tail_prev;
+  *tail_prev = NULL;
+}
+
+/**
+ * Check if a file or directory will save a package from disappearance.
+ *
+ * A package can only be saved by a file or directory which is part
+ * only of itself - it must be neither part of the new package being
+ * installed nor part of any 3rd package (this is important so that
+ * shared directories don't stop packages from disappearing).
+ */
+bool
+filesavespackage(struct fsys_namenode_list *file,
+                 struct pkginfo *pkgtobesaved,
+                 struct pkginfo *pkgbeinginstalled)
+{
+  struct fsys_node_pkgs_iter *iter;
+  struct pkgset *divpkgset;
+  struct pkginfo *thirdpkg;
+
+  debug(dbg_eachfiledetail, "filesavespackage file '%s' package %s",
+        file->namenode->name, pkg_name(pkgtobesaved, pnaw_always));
+
+  /* If the file is a contended one and it's overridden by either
+   * the package we're considering disappearing or the package
+   * we're installing then they're not actually the same file, so
+   * we can't disappear the package - it is saved by this file. */
+  if (file->namenode->divert && file->namenode->divert->useinstead) {
+    divpkgset = file->namenode->divert->pkgset;
+    if (divpkgset == pkgtobesaved->set || divpkgset == pkgbeinginstalled->set) {
+      debug(dbg_eachfiledetail,"filesavespackage ... diverted -- save!");
+      return true;
+    }
+  }
+  /* Is the file in the package being installed? If so then it can't save. */
+  if (file->namenode->flags & FNNF_NEW_INARCHIVE) {
+    debug(dbg_eachfiledetail,"filesavespackage ... in new archive -- no save");
+    return false;
+  }
+  /* Look for a 3rd package which can take over the file (in case
+   * it's a directory which is shared by many packages. */
+  iter = fsys_node_pkgs_iter_new(file->namenode);
+  while ((thirdpkg = fsys_node_pkgs_iter_next(iter))) {
+    debug(dbg_eachfiledetail, "filesavespackage ... also in %s",
+          pkg_name(thirdpkg, pnaw_always));
+
+    /* Is this not the package being installed or the one being
+     * checked for disappearance? */
+    if (thirdpkg == pkgbeinginstalled || thirdpkg == pkgtobesaved)
+      continue;
+
+    /* A Multi-Arch: same package can share files and their presence in a
+     * third package of the same set is not a sign that we can get rid of
+     * it. */
+    if (pkgtobesaved->installed.multiarch == PKG_MULTIARCH_SAME &&
+        thirdpkg->set == pkgtobesaved->set)
+      continue;
+
+    /* If !fileslistvalid then we've already disappeared this one, so
+     * we shouldn't try to make it take over this shared directory. */
+    debug(dbg_eachfiledetail,"filesavespackage ...  is 3rd package");
+
+    if (!thirdpkg->files_list_valid) {
+      debug(dbg_eachfiledetail, "process_archive ... already disappeared!");
+      continue;
+    }
+
+    /* We've found a package that can take this file. */
+    debug(dbg_eachfiledetail, "filesavespackage ...  taken -- no save");
+    fsys_node_pkgs_iter_free(iter);
+    return false;
+  }
+  fsys_node_pkgs_iter_free(iter);
+
+  debug(dbg_eachfiledetail, "filesavespackage ... not taken -- save !");
+  return true;
+}
+
+static void
+md5hash_prev_conffile(struct pkginfo *pkg, char *oldhash, const char *oldname,
+                      struct fsys_namenode *namenode)
+{
+  struct pkginfo *otherpkg;
+  struct conffile *conff;
+
+  debug(dbg_conffdetail, "tarobject looking for shared conffile %s",
+        namenode->name);
+
+  for (otherpkg = &pkg->set->pkg; otherpkg; otherpkg = otherpkg->arch_next) {
+    if (otherpkg == pkg)
+      continue;
+    /* If we are reinstalling, even if the other package is only unpacked,
+     * we can always make use of the Conffiles hash value from an initial
+     * installation, if that happened at all. */
+    if (otherpkg->status <= PKG_STAT_UNPACKED &&
+        dpkg_version_compare(&otherpkg->installed.version,
+                             &otherpkg->configversion) != 0)
+      continue;
+    for (conff = otherpkg->installed.conffiles; conff; conff = conff->next) {
+      if (conff->obsolete || conff->remove_on_upgrade)
+        continue;
+      if (strcmp(conff->name, namenode->name) == 0)
+        break;
+    }
+    if (conff) {
+      strcpy(oldhash, conff->hash);
+      debug(dbg_conffdetail,
+            "tarobject found shared conffile, from pkg %s (%s); hash=%s",
+            pkg_name(otherpkg, pnaw_always),
+            pkg_status_name(otherpkg), oldhash);
+      break;
+    }
+  }
+
+  /* If no package was found with a valid Conffiles field, we make the
+   * risky assumption that the hash of the current .dpkg-new file is
+   * the one of the previously unpacked package. */
+  if (otherpkg == NULL) {
+    md5hash(pkg, oldhash, oldname);
+    debug(dbg_conffdetail,
+          "tarobject found shared conffile, from disk; hash=%s", oldhash);
+  }
+}
+
+void cu_pathname(int argc, void **argv) {
+  path_remove_tree((char*)(argv[0]));
+}
+
+int
+tarfileread(struct tar_archive *tar, char *buf, int len)
+{
+  struct tarcontext *tc = (struct tarcontext *)tar->ctx;
+  int r;
+
+  r = fd_read(tc->backendpipe, buf, len);
+  if (r < 0)
+    ohshite(_("error reading from dpkg-deb pipe"));
+  return r;
+}
+
+static void
+tarobject_skip_padding(struct tarcontext *tc, struct tar_entry *te)
+{
+  struct dpkg_error err;
+  size_t r;
+
+  r = te->size % TARBLKSZ;
+  if (r == 0)
+    return;
+
+  if (fd_skip(tc->backendpipe, TARBLKSZ - r, &err) < 0)
+    ohshit(_("cannot skip padding for file '%.255s': %s"), te->name, err.str);
+}
+
+static void
+tarobject_skip_entry(struct tarcontext *tc, struct tar_entry *ti)
+{
+  /* We need to advance the tar file to the next object, so read the
+   * file data and set it to oblivion. */
+  if (ti->type == TAR_FILETYPE_FILE) {
+    struct dpkg_error err;
+    char fnamebuf[256];
+
+    if (fd_skip(tc->backendpipe, ti->size, &err) < 0)
+      ohshit(_("cannot skip file '%.255s' (replaced or excluded?) from pipe: %s"),
+             path_quote_filename(fnamebuf, ti->name, 256), err.str);
+    tarobject_skip_padding(tc, ti);
+  }
+}
+
+struct varbuf_state fname_state;
+struct varbuf fnamevb;
+struct varbuf fnametmpvb;
+struct varbuf fnamenewvb;
+struct pkg_deconf_list *deconfigure = NULL;
+
+static time_t currenttime;
+
+static int
+does_replace(struct pkginfo *new_pkg, struct pkgbin *new_pkgbin,
+             struct pkginfo *old_pkg, struct pkgbin *old_pkgbin)
+{
+  struct dependency *dep;
+
+  debug(dbg_depcon,"does_replace new=%s old=%s (%s)",
+        pkgbin_name(new_pkg, new_pkgbin, pnaw_always),
+        pkgbin_name(old_pkg, old_pkgbin, pnaw_always),
+        versiondescribe_c(&old_pkgbin->version, vdew_always));
+  for (dep = new_pkgbin->depends; dep; dep = dep->next) {
+    if (dep->type != dep_replaces || dep->list->ed != old_pkg->set)
+      continue;
+    debug(dbg_depcondetail,"does_replace ... found old, version %s",
+          versiondescribe_c(&dep->list->version,vdew_always));
+    if (!versionsatisfied(old_pkgbin, dep->list))
+      continue;
+    /* The test below can only trigger if dep_replaces start having
+     * arch qualifiers different from “any”. */
+    if (!archsatisfied(old_pkgbin, dep->list))
+      continue;
+    debug(dbg_depcon,"does_replace ... yes");
+    return true;
+  }
+  debug(dbg_depcon,"does_replace ... no");
+  return false;
+}
+
+static void
+tarobject_extract(struct tarcontext *tc, struct tar_entry *te,
+                  const char *path, struct file_stat *st,
+                  struct fsys_namenode *namenode)
+{
+  static struct varbuf hardlinkfn;
+  static int fd;
+
+  struct dpkg_error err;
+  struct fsys_namenode *linknode;
+  char fnamebuf[256];
+  char fnamenewbuf[256];
+  char *newhash;
+  int rc;
+
+  switch (te->type) {
+  case TAR_FILETYPE_FILE:
+    /* We create the file with mode 0 to make sure nobody can do anything with
+     * it until we apply the proper mode, which might be a statoverride. */
+    fd = open(path, O_CREAT | O_EXCL | O_WRONLY, 0);
+    if (fd < 0)
+      ohshite(_("unable to create '%.255s' (while processing '%.255s')"),
+              path, te->name);
+    push_cleanup(cu_closefd, ehflag_bombout, 1, &fd);
+    debug(dbg_eachfiledetail, "tarobject file open size=%jd",
+          (intmax_t)te->size);
+
+    /* We try to tell the filesystem how much disk space we are going to
+     * need to let it reduce fragmentation and possibly improve performance,
+     * as we do know the size beforehand. */
+    fd_allocate_size(fd, 0, te->size);
+
+    newhash = nfmalloc(MD5HASHLEN + 1);
+    if (fd_fd_copy_and_md5(tc->backendpipe, fd, newhash, te->size, &err) < 0)
+      ohshit(_("cannot copy extracted data for '%.255s' to '%.255s': %s"),
+             path_quote_filename(fnamebuf, te->name, 256),
+             path_quote_filename(fnamenewbuf, fnamenewvb.buf, 256), err.str);
+    namenode->newhash = newhash;
+    debug(dbg_eachfiledetail, "tarobject file hash=%s", namenode->newhash);
+
+    tarobject_skip_padding(tc, te);
+
+    fd_writeback_init(fd);
+
+    if (namenode->statoverride)
+      debug(dbg_eachfile, "tarobject ... stat override, uid=%d, gid=%d, mode=%04o",
+            namenode->statoverride->uid,
+            namenode->statoverride->gid,
+            namenode->statoverride->mode);
+    rc = fchown(fd, st->uid, st->gid);
+    if (forcible_nonroot_error(rc))
+      ohshite(_("error setting ownership of '%.255s'"), te->name);
+    rc = fchmod(fd, st->mode & ~S_IFMT);
+    if (forcible_nonroot_error(rc))
+      ohshite(_("error setting permissions of '%.255s'"), te->name);
+
+    /* Postpone the fsync, to try to avoid massive I/O degradation. */
+    if (!in_force(FORCE_UNSAFE_IO))
+      namenode->flags |= FNNF_DEFERRED_FSYNC;
+
+    pop_cleanup(ehflag_normaltidy); /* fd = open(path) */
+    if (close(fd))
+      ohshite(_("error closing/writing '%.255s'"), te->name);
+    break;
+  case TAR_FILETYPE_FIFO:
+    if (mkfifo(path, 0))
+      ohshite(_("error creating pipe '%.255s'"), te->name);
+    debug(dbg_eachfiledetail, "tarobject fifo");
+    break;
+  case TAR_FILETYPE_CHARDEV:
+    if (mknod(path, S_IFCHR, te->dev))
+      ohshite(_("error creating device '%.255s'"), te->name);
+    debug(dbg_eachfiledetail, "tarobject chardev");
+    break;
+  case TAR_FILETYPE_BLOCKDEV:
+    if (mknod(path, S_IFBLK, te->dev))
+      ohshite(_("error creating device '%.255s'"), te->name);
+    debug(dbg_eachfiledetail, "tarobject blockdev");
+    break;
+  case TAR_FILETYPE_HARDLINK:
+    varbuf_reset(&hardlinkfn);
+    varbuf_add_str(&hardlinkfn, instdir);
+    linknode = fsys_hash_find_node(te->linkname, 0);
+    varbuf_add_str(&hardlinkfn,
+                   namenodetouse(linknode, tc->pkg, &tc->pkg->available)->name);
+    if (linknode->flags & (FNNF_DEFERRED_RENAME | FNNF_NEW_CONFF))
+      varbuf_add_str(&hardlinkfn, DPKGNEWEXT);
+    varbuf_end_str(&hardlinkfn);
+    if (link(hardlinkfn.buf, path))
+      ohshite(_("error creating hard link '%.255s'"), te->name);
+    namenode->newhash = linknode->newhash;
+    debug(dbg_eachfiledetail, "tarobject hardlink hash=%s", namenode->newhash);
+    break;
+  case TAR_FILETYPE_SYMLINK:
+    /* We've already checked for an existing directory. */
+    if (symlink(te->linkname, path))
+      ohshite(_("error creating symbolic link '%.255s'"), te->name);
+    debug(dbg_eachfiledetail, "tarobject symlink creating");
+    break;
+  case TAR_FILETYPE_DIR:
+    /* We've already checked for an existing directory. */
+    if (mkdir(path, 0))
+      ohshite(_("error creating directory '%.255s'"), te->name);
+    debug(dbg_eachfiledetail, "tarobject directory creating");
+    break;
+  default:
+    internerr("unknown tar type '%d', but already checked", te->type);
+  }
+}
+
+static void
+tarobject_hash(struct tarcontext *tc, struct tar_entry *te,
+               struct fsys_namenode *namenode)
+{
+  if (te->type == TAR_FILETYPE_FILE) {
+    struct dpkg_error err;
+    char fnamebuf[256];
+    char *newhash;
+
+    newhash = nfmalloc(MD5HASHLEN + 1);
+    if (fd_md5(tc->backendpipe, newhash, te->size, &err) < 0)
+      ohshit(_("cannot compute MD5 hash for tar file '%.255s': %s"),
+             path_quote_filename(fnamebuf, te->name, 256), err.str);
+    tarobject_skip_padding(tc, te);
+
+    namenode->newhash = newhash;
+    debug(dbg_eachfiledetail, "tarobject file hash=%s", namenode->newhash);
+  } else if (te->type == TAR_FILETYPE_HARDLINK) {
+    struct fsys_namenode *linknode;
+
+    linknode = fsys_hash_find_node(te->linkname, 0);
+    namenode->newhash = linknode->newhash;
+    debug(dbg_eachfiledetail, "tarobject hardlink hash=%s", namenode->newhash);
+  }
+}
+
+static void
+tarobject_set_mtime(struct tar_entry *te, const char *path)
+{
+  struct timeval tv[2];
+
+  tv[0].tv_sec = currenttime;
+  tv[0].tv_usec = 0;
+  tv[1].tv_sec = te->mtime;
+  tv[1].tv_usec = 0;
+
+  if (te->type == TAR_FILETYPE_SYMLINK) {
+#ifdef HAVE_LUTIMES
+    if (lutimes(path, tv) && errno != ENOSYS)
+      ohshite(_("error setting timestamps of '%.255s'"), path);
+#endif
+  } else {
+    if (utimes(path, tv))
+      ohshite(_("error setting timestamps of '%.255s'"), path);
+  }
+}
+
+static void
+tarobject_set_perms(struct tar_entry *te, const char *path, struct file_stat *st)
+{
+  int rc;
+
+  if (te->type == TAR_FILETYPE_FILE)
+    return; /* Already handled using the file descriptor. */
+
+  if (te->type == TAR_FILETYPE_SYMLINK) {
+    rc = lchown(path, st->uid, st->gid);
+    if (forcible_nonroot_error(rc))
+      ohshite(_("error setting ownership of symlink '%.255s'"), path);
+  } else {
+    rc = chown(path, st->uid, st->gid);
+    if (forcible_nonroot_error(rc))
+      ohshite(_("error setting ownership of '%.255s'"), path);
+    rc = chmod(path, st->mode & ~S_IFMT);
+    if (forcible_nonroot_error(rc))
+      ohshite(_("error setting permissions of '%.255s'"), path);
+  }
+}
+
+static void
+tarobject_set_se_context(const char *matchpath, const char *path, mode_t mode)
+{
+  dpkg_selabel_set_context(matchpath, path, mode);
+}
+
+static void
+tarobject_matches(struct tarcontext *tc,
+                  const char *fn_old, struct stat *stab, char *oldhash,
+                  const char *fn_new, struct tar_entry *te,
+                  struct fsys_namenode *namenode)
+{
+  char *linkname;
+  ssize_t linksize;
+
+  debug(dbg_eachfiledetail, "tarobject matches on-disk object?");
+
+  switch (te->type) {
+  case TAR_FILETYPE_DIR:
+    /* Nothing to check for a new directory. */
+    return;
+  case TAR_FILETYPE_SYMLINK:
+    /* Symlinks to existing dirs have already been dealt with, only
+     * remain real symlinks where we can compare the target. */
+    if (!S_ISLNK(stab->st_mode))
+      break;
+    linkname = m_malloc(stab->st_size + 1);
+    linksize = readlink(fn_old, linkname, stab->st_size + 1);
+    if (linksize < 0)
+      ohshite(_("unable to read link '%.255s'"), fn_old);
+    else if (linksize > stab->st_size)
+      ohshit(_("symbolic link '%.250s' size has changed from %jd to %zd"),
+             fn_old, (intmax_t)stab->st_size, linksize);
+    else if (linksize < stab->st_size)
+      warning(_("symbolic link '%.250s' size has changed from %jd to %zd"),
+             fn_old, (intmax_t)stab->st_size, linksize);
+    linkname[linksize] = '\0';
+    if (strcmp(linkname, te->linkname) == 0) {
+      free(linkname);
+      return;
+    } else {
+      free(linkname);
+    }
+    break;
+  case TAR_FILETYPE_CHARDEV:
+    if (S_ISCHR(stab->st_mode) && stab->st_rdev == te->dev)
+      return;
+    break;
+  case TAR_FILETYPE_BLOCKDEV:
+    if (S_ISBLK(stab->st_mode) && stab->st_rdev == te->dev)
+      return;
+    break;
+  case TAR_FILETYPE_FIFO:
+    if (S_ISFIFO(stab->st_mode))
+      return;
+    break;
+  case TAR_FILETYPE_HARDLINK:
+    /* Fall through. */
+  case TAR_FILETYPE_FILE:
+    /* Only check metadata for non-conffiles. */
+    if (!(namenode->flags & FNNF_NEW_CONFF) &&
+        !(S_ISREG(stab->st_mode) && te->size == stab->st_size))
+      break;
+    if (strcmp(oldhash, namenode->newhash) == 0)
+      return;
+    break;
+  default:
+    internerr("unknown tar type '%d', but already checked", te->type);
+  }
+
+  forcibleerr(FORCE_OVERWRITE,
+              _("trying to overwrite shared '%.250s', which is different "
+                "from other instances of package %.250s"),
+              namenode->name, pkg_name(tc->pkg, pnaw_nonambig));
+}
+
+void setupfnamevbs(const char *filename) {
+  varbuf_rollback(&fnamevb, &fname_state);
+  varbuf_add_str(&fnamevb, filename);
+  varbuf_end_str(&fnamevb);
+
+  varbuf_rollback(&fnametmpvb, &fname_state);
+  varbuf_add_str(&fnametmpvb, filename);
+  varbuf_add_str(&fnametmpvb, DPKGTEMPEXT);
+  varbuf_end_str(&fnametmpvb);
+
+  varbuf_rollback(&fnamenewvb, &fname_state);
+  varbuf_add_str(&fnamenewvb, filename);
+  varbuf_add_str(&fnamenewvb, DPKGNEWEXT);
+  varbuf_end_str(&fnamenewvb);
+
+  debug(dbg_eachfiledetail, "setupvnamevbs main='%s' tmp='%s' new='%s'",
+        fnamevb.buf, fnametmpvb.buf, fnamenewvb.buf);
+}
+
+static bool
+linktosameexistingdir(const struct tar_entry *ti, const char *fname,
+                      struct varbuf *symlinkfn)
+{
+  struct stat oldstab, newstab;
+  int statr;
+  const char *lastslash;
+
+  statr= stat(fname, &oldstab);
+  if (statr) {
+    if (!(errno == ENOENT || errno == ELOOP || errno == ENOTDIR))
+      ohshite(_("failed to stat (dereference) existing symlink '%.250s'"),
+              fname);
+    return false;
+  }
+  if (!S_ISDIR(oldstab.st_mode))
+    return false;
+
+  /* But is it to the same dir? */
+  varbuf_reset(symlinkfn);
+  if (ti->linkname[0] == '/') {
+    varbuf_add_str(symlinkfn, instdir);
+  } else {
+    lastslash= strrchr(fname, '/');
+    if (lastslash == NULL)
+      internerr("tar entry filename '%s' does not contain '/'", fname);
+    varbuf_add_buf(symlinkfn, fname, (lastslash - fname) + 1);
+  }
+  varbuf_add_str(symlinkfn, ti->linkname);
+  varbuf_end_str(symlinkfn);
+
+  statr= stat(symlinkfn->buf, &newstab);
+  if (statr) {
+    if (!(errno == ENOENT || errno == ELOOP || errno == ENOTDIR))
+      ohshite(_("failed to stat (dereference) proposed new symlink target"
+                " '%.250s' for symlink '%.250s'"), symlinkfn->buf, fname);
+    return false;
+  }
+  if (!S_ISDIR(newstab.st_mode))
+    return false;
+  if (newstab.st_dev != oldstab.st_dev ||
+      newstab.st_ino != oldstab.st_ino)
+    return false;
+  return true;
+}
+
+int
+tarobject(struct tar_archive *tar, struct tar_entry *ti)
+{
+  static struct varbuf conffderefn, symlinkfn;
+  const char *usename;
+  struct fsys_namenode *namenode, *usenode;
+
+  struct conffile *conff;
+  struct tarcontext *tc = tar->ctx;
+  bool existingdir, keepexisting;
+  bool refcounting;
+  char oldhash[MD5HASHLEN + 1];
+  int statr;
+  ssize_t r;
+  struct stat stab, stabtmp;
+  struct file_stat nodestat;
+  struct fsys_namenode_list *nifd, **oldnifd;
+  struct pkgset *divpkgset;
+  struct pkginfo *otherpkg;
+
+  tar_entry_update_from_system(ti);
+
+  /* Perform some sanity checks on the tar entry. */
+  if (strchr(ti->name, '\n'))
+    ohshit(_("newline not allowed in archive object name '%.255s'"), ti->name);
+
+  namenode = fsys_hash_find_node(ti->name, 0);
+
+  if (namenode->flags & FNNF_RM_CONFF_ON_UPGRADE)
+    ohshit(_("conffile '%s' marked for removal on upgrade, shipped in package"),
+           ti->name);
+
+  /* Append to list of files.
+   * The trailing ‘/’ put on the end of names in tarfiles has already
+   * been stripped by tar_extractor(). */
+  oldnifd = tc->newfiles_queue->tail;
+  nifd = tar_fsys_namenode_queue_push(tc->newfiles_queue, namenode);
+  nifd->namenode->flags |= FNNF_NEW_INARCHIVE;
+
+  debug(dbg_eachfile,
+        "tarobject ti->name='%s' mode=%lo owner=%u:%u type=%d(%c)"
+        " ti->linkname='%s' namenode='%s' flags=%o instead='%s'",
+        ti->name, (long)ti->stat.mode,
+        (unsigned)ti->stat.uid, (unsigned)ti->stat.gid,
+        ti->type,
+        ti->type >= '0' && ti->type <= '6' ? "-hlcbdp"[ti->type - '0'] : '?',
+        ti->linkname,
+        nifd->namenode->name, nifd->namenode->flags,
+        nifd->namenode->divert && nifd->namenode->divert->useinstead
+        ? nifd->namenode->divert->useinstead->name : "<none>");
+
+  if (nifd->namenode->divert && nifd->namenode->divert->camefrom) {
+    divpkgset = nifd->namenode->divert->pkgset;
+
+    if (divpkgset) {
+      forcibleerr(FORCE_OVERWRITE_DIVERTED,
+                  _("trying to overwrite '%.250s', which is the "
+                    "diverted version of '%.250s' (package: %.100s)"),
+                  nifd->namenode->name, nifd->namenode->divert->camefrom->name,
+                  divpkgset->name);
+    } else {
+      forcibleerr(FORCE_OVERWRITE_DIVERTED,
+                  _("trying to overwrite '%.250s', which is the "
+                    "diverted version of '%.250s'"),
+                  nifd->namenode->name, nifd->namenode->divert->camefrom->name);
+    }
+  }
+
+  if (nifd->namenode->statoverride) {
+    nodestat = *nifd->namenode->statoverride;
+    nodestat.mode |= ti->stat.mode & S_IFMT;
+  } else {
+    nodestat = ti->stat;
+  }
+
+  usenode = namenodetouse(nifd->namenode, tc->pkg, &tc->pkg->available);
+  usename = usenode->name;
+
+  trig_file_activate(usenode, tc->pkg);
+
+  if (nifd->namenode->flags & FNNF_NEW_CONFF) {
+    /* If it's a conffile we have to extract it next to the installed
+     * version (i.e. we do the usual link-following). */
+    if (conffderef(tc->pkg, &conffderefn, usename))
+      usename= conffderefn.buf;
+    debug(dbg_conff, "tarobject FNNF_NEW_CONFF deref='%s'", usename);
+  }
+
+  setupfnamevbs(usename);
+
+  statr= lstat(fnamevb.buf,&stab);
+  if (statr) {
+    /* The lstat failed. */
+    if (errno != ENOENT && errno != ENOTDIR)
+      ohshite(_("unable to stat '%.255s' (which was about to be installed)"),
+              ti->name);
+    /* OK, so it doesn't exist.
+     * However, it's possible that we were in the middle of some other
+     * backup/restore operation and were rudely interrupted.
+     * So, we see if we have .dpkg-tmp, and if so we restore it. */
+    if (rename(fnametmpvb.buf,fnamevb.buf)) {
+      if (errno != ENOENT && errno != ENOTDIR)
+        ohshite(_("unable to clean up mess surrounding '%.255s' before "
+                  "installing another version"), ti->name);
+      debug(dbg_eachfiledetail,"tarobject nonexistent");
+    } else {
+      debug(dbg_eachfiledetail,"tarobject restored tmp to main");
+      statr= lstat(fnamevb.buf,&stab);
+      if (statr)
+        ohshite(_("unable to stat restored '%.255s' before installing"
+                  " another version"), ti->name);
+    }
+  } else {
+    debug(dbg_eachfiledetail,"tarobject already exists");
+  }
+
+  /* Check to see if it's a directory or link to one and we don't need to
+   * do anything. This has to be done now so that we don't die due to
+   * a file overwriting conflict. */
+  existingdir = false;
+  switch (ti->type) {
+  case TAR_FILETYPE_SYMLINK:
+    /* If it's already an existing directory, do nothing. */
+    if (!statr && S_ISDIR(stab.st_mode)) {
+      debug(dbg_eachfiledetail, "tarobject symlink exists as directory");
+      existingdir = true;
+    } else if (!statr && S_ISLNK(stab.st_mode)) {
+      if (linktosameexistingdir(ti, fnamevb.buf, &symlinkfn))
+        existingdir = true;
+    }
+    break;
+  case TAR_FILETYPE_DIR:
+    /* If it's already an existing directory, do nothing. */
+    if (!stat(fnamevb.buf,&stabtmp) && S_ISDIR(stabtmp.st_mode)) {
+      debug(dbg_eachfiledetail, "tarobject directory exists");
+      existingdir = true;
+    }
+    break;
+  case TAR_FILETYPE_FILE:
+  case TAR_FILETYPE_CHARDEV:
+  case TAR_FILETYPE_BLOCKDEV:
+  case TAR_FILETYPE_FIFO:
+  case TAR_FILETYPE_HARDLINK:
+    break;
+  default:
+    ohshit(_("archive contained object '%.255s' of unknown type 0x%x"),
+           ti->name, ti->type);
+  }
+
+  keepexisting = false;
+  refcounting = false;
+  if (!existingdir) {
+    struct fsys_node_pkgs_iter *iter;
+
+    iter = fsys_node_pkgs_iter_new(nifd->namenode);
+    while ((otherpkg = fsys_node_pkgs_iter_next(iter))) {
+      if (otherpkg == tc->pkg)
+        continue;
+      debug(dbg_eachfile, "tarobject ... found in %s",
+            pkg_name(otherpkg, pnaw_always));
+
+      /* A pkgset can share files between its instances. Overwriting
+       * is allowed when they are not getting in sync, otherwise the
+       * file content must match the installed file. */
+      if (otherpkg->set == tc->pkg->set &&
+          otherpkg->installed.multiarch == PKG_MULTIARCH_SAME &&
+          tc->pkg->available.multiarch == PKG_MULTIARCH_SAME) {
+        if (statr == 0 && tc->pkgset_getting_in_sync)
+          refcounting = true;
+        debug(dbg_eachfiledetail, "tarobject ... shared with %s %s (syncing=%d)",
+              pkg_name(otherpkg, pnaw_always),
+              versiondescribe_c(&otherpkg->installed.version, vdew_nonambig),
+              tc->pkgset_getting_in_sync);
+        continue;
+      }
+
+      if (nifd->namenode->divert && nifd->namenode->divert->useinstead) {
+        /* Right, so we may be diverting this file. This makes the conflict
+         * OK iff one of us is the diverting package (we don't need to
+         * check for both being the diverting package, obviously). */
+        divpkgset = nifd->namenode->divert->pkgset;
+        debug(dbg_eachfile, "tarobject ... diverted, divpkgset=%s",
+              divpkgset ? divpkgset->name : "<none>");
+        if (otherpkg->set == divpkgset || tc->pkg->set == divpkgset)
+          continue;
+      }
+
+      /* If the new object is a directory and the previous object does
+       * not exist assume it's also a directory and skip further checks.
+       * XXX: Ideally with more information about the installed files we
+       * could perform more clever checks. */
+      if (statr != 0 && ti->type == TAR_FILETYPE_DIR) {
+        debug(dbg_eachfile, "tarobject ... assuming shared directory");
+        continue;
+      }
+
+      ensure_package_clientdata(otherpkg);
+
+      /* Nope? Hmm, file conflict, perhaps. Check Replaces. */
+      switch (otherpkg->clientdata->replacingfilesandsaid) {
+      case 2:
+        keepexisting = true;
+        /* Fall through. */
+      case 1:
+        continue;
+      }
+
+      /* Is the package with the conflicting file in the “config files only”
+       * state? If so it must be a config file and we can silently take it
+       * over. */
+      if (otherpkg->status == PKG_STAT_CONFIGFILES)
+        continue;
+
+      /* Perhaps we're removing a conflicting package? */
+      if (otherpkg->clientdata->istobe == PKG_ISTOBE_REMOVE)
+        continue;
+
+      /* Is the file an obsolete conffile in the other package
+       * and a conffile in the new package? */
+      if ((nifd->namenode->flags & FNNF_NEW_CONFF) &&
+          !statr && S_ISREG(stab.st_mode)) {
+        for (conff = otherpkg->installed.conffiles;
+             conff;
+             conff = conff->next) {
+          if (!conff->obsolete)
+            continue;
+          if (strcmp(conff->name, nifd->namenode->name) == 0)
+            break;
+        }
+        if (conff) {
+          debug(dbg_eachfiledetail, "tarobject other's obsolete conffile");
+          /* process_archive() will have copied its hash already. */
+          continue;
+        }
+      }
+
+      if (does_replace(tc->pkg, &tc->pkg->available,
+                       otherpkg, &otherpkg->installed)) {
+        printf(_("Replacing files in old package %s (%s) ...\n"),
+               pkg_name(otherpkg, pnaw_nonambig),
+               versiondescribe(&otherpkg->installed.version, vdew_nonambig));
+        otherpkg->clientdata->replacingfilesandsaid = 1;
+      } else if (does_replace(otherpkg, &otherpkg->installed,
+                              tc->pkg, &tc->pkg->available)) {
+        printf(_("Replaced by files in installed package %s (%s) ...\n"),
+               pkg_name(otherpkg, pnaw_nonambig),
+               versiondescribe(&otherpkg->installed.version, vdew_nonambig));
+        otherpkg->clientdata->replacingfilesandsaid = 2;
+        nifd->namenode->flags &= ~FNNF_NEW_INARCHIVE;
+        keepexisting = true;
+      } else {
+        /* At this point we are replacing something without a Replaces. */
+        if (!statr && S_ISDIR(stab.st_mode)) {
+          forcibleerr(FORCE_OVERWRITE_DIR,
+                      _("trying to overwrite directory '%.250s' "
+                        "in package %.250s %.250s with nondirectory"),
+                      nifd->namenode->name, pkg_name(otherpkg, pnaw_nonambig),
+                      versiondescribe(&otherpkg->installed.version,
+                                      vdew_nonambig));
+        } else {
+          forcibleerr(FORCE_OVERWRITE,
+                      _("trying to overwrite '%.250s', "
+                        "which is also in package %.250s %.250s"),
+                      nifd->namenode->name, pkg_name(otherpkg, pnaw_nonambig),
+                      versiondescribe(&otherpkg->installed.version,
+                                      vdew_nonambig));
+        }
+      }
+    }
+    fsys_node_pkgs_iter_free(iter);
+  }
+
+  if (keepexisting) {
+    if (nifd->namenode->flags & FNNF_NEW_CONFF)
+      nifd->namenode->flags |= FNNF_OBS_CONFF;
+    tar_fsys_namenode_queue_pop(tc->newfiles_queue, oldnifd, nifd);
+    tarobject_skip_entry(tc, ti);
+    return 0;
+  }
+
+  if (filter_should_skip(ti)) {
+    nifd->namenode->flags &= ~FNNF_NEW_INARCHIVE;
+    nifd->namenode->flags |= FNNF_FILTERED;
+    tarobject_skip_entry(tc, ti);
+
+    return 0;
+  }
+
+  if (existingdir)
+    return 0;
+
+  /* Compute the hash of the previous object, before we might replace it
+   * with the new version on forced overwrites. */
+  if (refcounting) {
+    debug(dbg_eachfiledetail, "tarobject hashing on-disk file '%s', refcounting",
+          fnamevb.buf);
+    if (nifd->namenode->flags & FNNF_NEW_CONFF) {
+      md5hash_prev_conffile(tc->pkg, oldhash, fnamenewvb.buf, nifd->namenode);
+    } else if (S_ISREG(stab.st_mode)) {
+      md5hash(tc->pkg, oldhash, fnamevb.buf);
+    } else {
+      strcpy(oldhash, EMPTYHASHFLAG);
+    }
+  }
+
+  if (refcounting && !in_force(FORCE_OVERWRITE)) {
+    /* If we are not forced to overwrite the path and are refcounting,
+     * just compute the hash w/o extracting the object. */
+    tarobject_hash(tc, ti, nifd->namenode);
+  } else {
+    /* Now, at this stage we want to make sure neither of .dpkg-new and
+     * .dpkg-tmp are hanging around. */
+    path_remove_tree(fnamenewvb.buf);
+    path_remove_tree(fnametmpvb.buf);
+
+    /* Now we start to do things that we need to be able to undo
+     * if something goes wrong. Watch out for the CLEANUP comments to
+     * keep an eye on what's installed on the disk at each point. */
+    push_cleanup(cu_installnew, ~ehflag_normaltidy, 1, nifd->namenode);
+
+    /*
+     * CLEANUP: Now we either have the old file on the disk, or not, in
+     * its original filename.
+     */
+
+    /* Extract whatever it is as .dpkg-new ... */
+    tarobject_extract(tc, ti, fnamenewvb.buf, &nodestat, nifd->namenode);
+  }
+
+  /* For shared files, check now if the object matches. */
+  if (refcounting)
+    tarobject_matches(tc, fnamevb.buf, &stab, oldhash,
+                          fnamenewvb.buf, ti, nifd->namenode);
+
+  /* If we didn't extract anything, there's nothing else to do. */
+  if (refcounting && !in_force(FORCE_OVERWRITE))
+    return 0;
+
+  tarobject_set_perms(ti, fnamenewvb.buf, &nodestat);
+  tarobject_set_mtime(ti, fnamenewvb.buf);
+  tarobject_set_se_context(fnamevb.buf, fnamenewvb.buf, nodestat.mode);
+
+  /*
+   * CLEANUP: Now we have extracted the new object in .dpkg-new (or,
+   * if the file already exists as a directory and we were trying to
+   * extract a directory or symlink, we returned earlier, so we don't
+   * need to worry about that here).
+   *
+   * The old file is still in the original filename,
+   */
+
+  /* First, check to see if it's a conffile. If so we don't install
+   * it now - we leave it in .dpkg-new for --configure to take care of. */
+  if (nifd->namenode->flags & FNNF_NEW_CONFF) {
+    debug(dbg_conffdetail,"tarobject conffile extracted");
+    nifd->namenode->flags |= FNNF_ELIDE_OTHER_LISTS;
+    return 0;
+  }
+
+  /* Now we move the old file out of the way, the backup file will
+   * be deleted later. */
+  if (statr) {
+    /* Don't try to back it up if it didn't exist. */
+    debug(dbg_eachfiledetail,"tarobject new - no backup");
+  } else {
+    if (ti->type == TAR_FILETYPE_DIR || S_ISDIR(stab.st_mode)) {
+      /* One of the two is a directory - can't do atomic install. */
+      debug(dbg_eachfiledetail,"tarobject directory, nonatomic");
+      nifd->namenode->flags |= FNNF_NO_ATOMIC_OVERWRITE;
+      if (rename(fnamevb.buf,fnametmpvb.buf))
+        ohshite(_("unable to move aside '%.255s' to install new version"),
+                ti->name);
+    } else if (S_ISLNK(stab.st_mode)) {
+      int rc;
+
+      /* We can't make a symlink with two hardlinks, so we'll have to
+       * copy it. (Pretend that making a copy of a symlink is the same
+       * as linking to it.) */
+      varbuf_reset(&symlinkfn);
+      varbuf_grow(&symlinkfn, stab.st_size + 1);
+      r = readlink(fnamevb.buf, symlinkfn.buf, symlinkfn.size);
+      if (r < 0)
+        ohshite(_("unable to read link '%.255s'"), ti->name);
+      else if (r > stab.st_size)
+        ohshit(_("symbolic link '%.250s' size has changed from %jd to %zd"),
+               fnamevb.buf, (intmax_t)stab.st_size, r);
+      else if (r < stab.st_size)
+        warning(_("symbolic link '%.250s' size has changed from %jd to %zd"),
+               fnamevb.buf, (intmax_t)stab.st_size, r);
+      varbuf_trunc(&symlinkfn, r);
+      varbuf_end_str(&symlinkfn);
+      if (symlink(symlinkfn.buf,fnametmpvb.buf))
+        ohshite(_("unable to make backup symlink for '%.255s'"), ti->name);
+      rc = lchown(fnametmpvb.buf, stab.st_uid, stab.st_gid);
+      if (forcible_nonroot_error(rc))
+        ohshite(_("unable to chown backup symlink for '%.255s'"), ti->name);
+      tarobject_set_se_context(fnamevb.buf, fnametmpvb.buf, stab.st_mode);
+    } else {
+      debug(dbg_eachfiledetail, "tarobject nondirectory, 'link' backup");
+      if (link(fnamevb.buf,fnametmpvb.buf))
+        ohshite(_("unable to make backup link of '%.255s' before installing new version"),
+                ti->name);
+    }
+  }
+
+  /*
+   * CLEANUP: Now the old file is in .dpkg-tmp, and the new file is still
+   * in .dpkg-new.
+   */
+
+  if (ti->type == TAR_FILETYPE_FILE || ti->type == TAR_FILETYPE_HARDLINK ||
+      ti->type == TAR_FILETYPE_SYMLINK) {
+    nifd->namenode->flags |= FNNF_DEFERRED_RENAME;
+
+    debug(dbg_eachfiledetail, "tarobject done and installation deferred");
+  } else {
+    if (rename(fnamenewvb.buf, fnamevb.buf))
+      ohshite(_("unable to install new version of '%.255s'"), ti->name);
+
+    /*
+     * CLEANUP: Now the new file is in the destination file, and the
+     * old file is in .dpkg-tmp to be cleaned up later. We now need
+     * to take a different attitude to cleanup, because we need to
+     * remove the new file.
+     */
+
+    nifd->namenode->flags |= FNNF_PLACED_ON_DISK;
+    nifd->namenode->flags |= FNNF_ELIDE_OTHER_LISTS;
+
+    debug(dbg_eachfiledetail, "tarobject done and installed");
+  }
+
+  return 0;
+}
+
+#if defined(SYNC_FILE_RANGE_WAIT_BEFORE)
+static void
+tar_writeback_barrier(struct fsys_namenode_list *files, struct pkginfo *pkg)
+{
+  struct fsys_namenode_list *cfile;
+
+  for (cfile = files; cfile; cfile = cfile->next) {
+    struct fsys_namenode *usenode;
+    int fd;
+
+    if (!(cfile->namenode->flags & FNNF_DEFERRED_FSYNC))
+      continue;
+
+    usenode = namenodetouse(cfile->namenode, pkg, &pkg->available);
+
+    setupfnamevbs(usenode->name);
+
+    fd = open(fnamenewvb.buf, O_WRONLY);
+    if (fd < 0)
+      ohshite(_("unable to open '%.255s'"), fnamenewvb.buf);
+    /* Ignore the return code as it should be considered equivalent to an
+     * asynchronous hint for the kernel, we are doing an fsync() later on
+     * anyway. */
+    sync_file_range(fd, 0, 0, SYNC_FILE_RANGE_WAIT_BEFORE);
+    if (close(fd))
+      ohshite(_("error closing/writing '%.255s'"), fnamenewvb.buf);
+  }
+}
+#else
+static void
+tar_writeback_barrier(struct fsys_namenode_list *files, struct pkginfo *pkg)
+{
+}
+#endif
+
+void
+tar_deferred_extract(struct fsys_namenode_list *files, struct pkginfo *pkg)
+{
+  struct fsys_namenode_list *cfile;
+  struct fsys_namenode *usenode;
+
+  tar_writeback_barrier(files, pkg);
+
+  for (cfile = files; cfile; cfile = cfile->next) {
+    debug(dbg_eachfile, "deferred extract of '%.255s'", cfile->namenode->name);
+
+    if (!(cfile->namenode->flags & FNNF_DEFERRED_RENAME))
+      continue;
+
+    usenode = namenodetouse(cfile->namenode, pkg, &pkg->available);
+
+    setupfnamevbs(usenode->name);
+
+    if (cfile->namenode->flags & FNNF_DEFERRED_FSYNC) {
+      int fd;
+
+      debug(dbg_eachfiledetail, "deferred extract needs fsync");
+
+      fd = open(fnamenewvb.buf, O_WRONLY);
+      if (fd < 0)
+        ohshite(_("unable to open '%.255s'"), fnamenewvb.buf);
+      if (fsync(fd))
+        ohshite(_("unable to sync file '%.255s'"), fnamenewvb.buf);
+      if (close(fd))
+        ohshite(_("error closing/writing '%.255s'"), fnamenewvb.buf);
+
+      cfile->namenode->flags &= ~FNNF_DEFERRED_FSYNC;
+    }
+
+    debug(dbg_eachfiledetail, "deferred extract needs rename");
+
+    if (rename(fnamenewvb.buf, fnamevb.buf))
+      ohshite(_("unable to install new version of '%.255s'"),
+              cfile->namenode->name);
+
+    cfile->namenode->flags &= ~FNNF_DEFERRED_RENAME;
+
+    /*
+     * CLEANUP: Now the new file is in the destination file, and the
+     * old file is in .dpkg-tmp to be cleaned up later. We now need
+     * to take a different attitude to cleanup, because we need to
+     * remove the new file.
+     */
+
+    cfile->namenode->flags |= FNNF_PLACED_ON_DISK;
+    cfile->namenode->flags |= FNNF_ELIDE_OTHER_LISTS;
+
+    debug(dbg_eachfiledetail, "deferred extract done and installed");
+  }
+}
+
+void
+enqueue_deconfigure(struct pkginfo *pkg, struct pkginfo *pkg_removal)
+{
+  struct pkg_deconf_list *newdeconf;
+
+  ensure_package_clientdata(pkg);
+  pkg->clientdata->istobe = PKG_ISTOBE_DECONFIGURE;
+  newdeconf = m_malloc(sizeof(*newdeconf));
+  newdeconf->next = deconfigure;
+  newdeconf->pkg = pkg;
+  newdeconf->pkg_removal = pkg_removal;
+  deconfigure = newdeconf;
+}
+
+void
+clear_deconfigure_queue(void)
+{
+  struct pkg_deconf_list *deconf, *deconf_next;
+
+  for (deconf = deconfigure; deconf; deconf = deconf_next) {
+    deconf_next = deconf->next;
+    free(deconf);
+  }
+  deconfigure = NULL;
+}
+
+/**
+ * Try if we can deconfigure the package and queue it if so.
+ *
+ * Also checks whether the pdep is forced, first, according to force_p.
+ * force_p may be NULL in which case nothing is considered forced.
+ *
+ * Action is a string describing the action which causes the
+ * deconfiguration:
+ *
+ *   "removal of <package>"       (due to Conflicts+Depends; removal != NULL)
+ *   "installation of <package>"  (due to Breaks;            removal == NULL)
+ *
+ * @retval 0 Not possible (why is printed).
+ * @retval 1 Deconfiguration queued ok (no message printed).
+ * @retval 2 Forced (no deconfiguration needed, why is printed).
+ */
+static int
+try_deconfigure_can(bool (*force_p)(struct deppossi *), struct pkginfo *pkg,
+                    struct deppossi *pdep, const char *action,
+                    struct pkginfo *removal, const char *why)
+{
+  if (force_p && force_p(pdep)) {
+    warning(_("ignoring dependency problem with %s:\n%s"), action, why);
+    return 2;
+  } else if (f_autodeconf) {
+    if (removal && pkg->installed.essential) {
+      if (in_force(FORCE_REMOVE_ESSENTIAL)) {
+        warning(_("considering deconfiguration of essential\n"
+                  " package %s, to enable %s"),
+                pkg_name(pkg, pnaw_nonambig), action);
+      } else {
+        notice(_("no, %s is essential, will not deconfigure\n"
+                 " it in order to enable %s"),
+               pkg_name(pkg, pnaw_nonambig), action);
+        return 0;
+      }
+    }
+    if (removal && pkg->installed.is_protected) {
+      if (in_force(FORCE_REMOVE_PROTECTED)) {
+        warning(_("considering deconfiguration of protected\n"
+                  " package %s, to enable %s"),
+                pkg_name(pkg, pnaw_nonambig), action);
+      } else {
+        notice(_("no, %s is protected, will not deconfigure\n"
+                 " it in order to enable %s"),
+               pkg_name(pkg, pnaw_nonambig), action);
+        return 0;
+      }
+    }
+
+    enqueue_deconfigure(pkg, removal);
+    return 1;
+  } else {
+    notice(_("no, cannot proceed with %s (--auto-deconfigure will help):\n%s"),
+           action, why);
+    return 0;
+  }
+}
+
+static int try_remove_can(struct deppossi *pdep,
+                          struct pkginfo *fixbyrm,
+                          const char *why) {
+  char action[512];
+  sprintf(action, _("removal of %.250s"), pkg_name(fixbyrm, pnaw_nonambig));
+  return try_deconfigure_can(force_depends, pdep->up->up, pdep,
+                             action, fixbyrm, why);
+}
+
+void check_breaks(struct dependency *dep, struct pkginfo *pkg,
+                  const char *pfilename) {
+  struct pkginfo *fixbydeconf;
+  struct varbuf why = VARBUF_INIT;
+  int ok;
+
+  fixbydeconf = NULL;
+  if (depisok(dep, &why, &fixbydeconf, NULL, false)) {
+    varbuf_destroy(&why);
+    return;
+  }
+
+  varbuf_end_str(&why);
+
+  if (fixbydeconf && f_autodeconf) {
+    char action[512];
+
+    ensure_package_clientdata(fixbydeconf);
+
+    if (fixbydeconf->clientdata->istobe != PKG_ISTOBE_NORMAL)
+      internerr("package %s being fixed by deconf is not to be normal, "
+                "is to be %d",
+                pkg_name(pkg, pnaw_always), fixbydeconf->clientdata->istobe);
+
+    sprintf(action, _("installation of %.250s"),
+            pkgbin_name(pkg, &pkg->available, pnaw_nonambig));
+    notice(_("considering deconfiguration of %s, which would be broken by %s ..."),
+           pkg_name(fixbydeconf, pnaw_nonambig), action);
+
+    ok= try_deconfigure_can(force_breaks, fixbydeconf, dep->list,
+                            action, NULL, why.buf);
+    if (ok == 1) {
+      notice(_("yes, will deconfigure %s (broken by %s)"),
+             pkg_name(fixbydeconf, pnaw_nonambig),
+             pkgbin_name(pkg, &pkg->available, pnaw_nonambig));
+    }
+  } else {
+    notice(_("regarding %s containing %s:\n%s"), pfilename,
+           pkgbin_name(pkg, &pkg->available, pnaw_nonambig), why.buf);
+    ok= 0;
+  }
+  varbuf_destroy(&why);
+  if (ok > 0) return;
+
+  if (force_breaks(dep->list)) {
+    warning(_("ignoring breakage, may proceed anyway!"));
+    return;
+  }
+
+  if (fixbydeconf && !f_autodeconf) {
+    ohshit(_("installing %.250s would break %.250s, and\n"
+             " deconfiguration is not permitted (--auto-deconfigure might help)"),
+           pkgbin_name(pkg, &pkg->available, pnaw_nonambig),
+           pkg_name(fixbydeconf, pnaw_nonambig));
+  } else {
+    ohshit(_("installing %.250s would break existing software"),
+           pkgbin_name(pkg, &pkg->available, pnaw_nonambig));
+  }
+}
+
+void check_conflict(struct dependency *dep, struct pkginfo *pkg,
+                    const char *pfilename) {
+  struct pkginfo *fixbyrm;
+  struct deppossi *pdep, flagdeppossi = { 0 };
+  struct varbuf conflictwhy = VARBUF_INIT, removalwhy = VARBUF_INIT;
+  struct dependency *providecheck;
+
+  fixbyrm = NULL;
+  if (depisok(dep, &conflictwhy, &fixbyrm, NULL, false)) {
+    varbuf_destroy(&conflictwhy);
+    varbuf_destroy(&removalwhy);
+    return;
+  }
+  if (fixbyrm) {
+    ensure_package_clientdata(fixbyrm);
+    if (fixbyrm->clientdata->istobe == PKG_ISTOBE_INSTALLNEW) {
+      fixbyrm= dep->up;
+      ensure_package_clientdata(fixbyrm);
+    }
+    if (((pkg->available.essential || pkg->available.is_protected) &&
+         (fixbyrm->installed.essential || fixbyrm->installed.is_protected)) ||
+        (((fixbyrm->want != PKG_WANT_INSTALL &&
+           fixbyrm->want != PKG_WANT_HOLD) ||
+          does_replace(pkg, &pkg->available, fixbyrm, &fixbyrm->installed)) &&
+         ((!fixbyrm->installed.essential || in_force(FORCE_REMOVE_ESSENTIAL)) ||
+          (!fixbyrm->installed.is_protected || in_force(FORCE_REMOVE_PROTECTED))))) {
+      if (fixbyrm->clientdata->istobe != PKG_ISTOBE_NORMAL &&
+          fixbyrm->clientdata->istobe != PKG_ISTOBE_DECONFIGURE)
+        internerr("package %s to be fixed by removal is not to be normal "
+                  "nor deconfigure, is to be %d",
+                  pkg_name(pkg, pnaw_always), fixbyrm->clientdata->istobe);
+      fixbyrm->clientdata->istobe = PKG_ISTOBE_REMOVE;
+      notice(_("considering removing %s in favour of %s ..."),
+             pkg_name(fixbyrm, pnaw_nonambig),
+             pkgbin_name(pkg, &pkg->available, pnaw_nonambig));
+      if (!(fixbyrm->status == PKG_STAT_INSTALLED ||
+            fixbyrm->status == PKG_STAT_TRIGGERSPENDING ||
+            fixbyrm->status == PKG_STAT_TRIGGERSAWAITED)) {
+        notice(_("%s is not properly installed; ignoring any dependencies on it"),
+               pkg_name(fixbyrm, pnaw_nonambig));
+        pdep = NULL;
+      } else {
+        for (pdep = fixbyrm->set->depended.installed;
+             pdep;
+             pdep = pdep->rev_next) {
+          if (pdep->up->type != dep_depends && pdep->up->type != dep_predepends)
+            continue;
+          if (depisok(pdep->up, &removalwhy, NULL, NULL, false))
+            continue;
+          varbuf_end_str(&removalwhy);
+          if (!try_remove_can(pdep,fixbyrm,removalwhy.buf))
+            break;
+        }
+        if (!pdep) {
+          /* If we haven't found a reason not to yet, let's look some more. */
+          for (providecheck= fixbyrm->installed.depends;
+               providecheck;
+               providecheck= providecheck->next) {
+            if (providecheck->type != dep_provides) continue;
+            for (pdep = providecheck->list->ed->depended.installed;
+                 pdep;
+                 pdep = pdep->rev_next) {
+              if (pdep->up->type != dep_depends && pdep->up->type != dep_predepends)
+                continue;
+              if (depisok(pdep->up, &removalwhy, NULL, NULL, false))
+                continue;
+              varbuf_end_str(&removalwhy);
+              notice(_("may have trouble removing %s, as it provides %s ..."),
+                     pkg_name(fixbyrm, pnaw_nonambig),
+                     providecheck->list->ed->name);
+              if (!try_remove_can(pdep,fixbyrm,removalwhy.buf))
+                goto break_from_both_loops_at_once;
+            }
+          }
+        break_from_both_loops_at_once:;
+        }
+      }
+      if (!pdep && skip_due_to_hold(fixbyrm)) {
+        pdep= &flagdeppossi;
+      }
+      if (!pdep && (fixbyrm->eflag & PKG_EFLAG_REINSTREQ)) {
+        if (in_force(FORCE_REMOVE_REINSTREQ)) {
+          notice(_("package %s requires reinstallation, but will "
+                   "remove anyway as you requested"),
+                 pkg_name(fixbyrm, pnaw_nonambig));
+        } else {
+          notice(_("package %s requires reinstallation, will not remove"),
+                 pkg_name(fixbyrm, pnaw_nonambig));
+          pdep= &flagdeppossi;
+        }
+      }
+      if (!pdep) {
+        /* This conflict is OK - we'll remove the conflictor. */
+        enqueue_conflictor(fixbyrm);
+        varbuf_destroy(&conflictwhy); varbuf_destroy(&removalwhy);
+        notice(_("yes, will remove %s in favour of %s"),
+               pkg_name(fixbyrm, pnaw_nonambig),
+               pkgbin_name(pkg, &pkg->available, pnaw_nonambig));
+        return;
+      }
+      /* Put it back. */
+      fixbyrm->clientdata->istobe = PKG_ISTOBE_NORMAL;
+    }
+  }
+  varbuf_end_str(&conflictwhy);
+  notice(_("regarding %s containing %s:\n%s"), pfilename,
+         pkgbin_name(pkg, &pkg->available, pnaw_nonambig), conflictwhy.buf);
+  if (!force_conflicts(dep->list))
+    ohshit(_("conflicting packages - not installing %.250s"),
+           pkgbin_name(pkg, &pkg->available, pnaw_nonambig));
+  warning(_("ignoring conflict, may proceed anyway!"));
+  varbuf_destroy(&conflictwhy);
+
+  return;
+}
+
+void cu_cidir(int argc, void **argv) {
+  char *cidir= (char*)argv[0];
+  char *cidirrest= (char*)argv[1];
+  cidirrest[-1] = '\0';
+  path_remove_tree(cidir);
+  free(cidir);
+}
+
+void cu_fileslist(int argc, void **argv) {
+  tar_pool_release();
+}
+
+int
+archivefiles(const char *const *argv)
+{
+  const char *const *volatile argp;
+  const char **volatile arglist = NULL;
+  int i;
+  jmp_buf ejbuf;
+  enum modstatdb_rw msdbflags;
+
+  trigproc_install_hooks();
+
+  if (f_noact)
+    msdbflags = msdbrw_readonly;
+  else if (cipaction->arg_int == act_avail)
+    msdbflags = msdbrw_readonly | msdbrw_available_write;
+  else if (in_force(FORCE_NON_ROOT))
+    msdbflags = msdbrw_write;
+  else
+    msdbflags = msdbrw_needsuperuser;
+
+  modstatdb_open(msdbflags);
+
+  checkpath();
+  pkg_infodb_upgrade();
+
+  log_message("startup archives %s", cipaction->olong);
+
+  if (f_recursive) {
+    const char *const *ap;
+    int nfiles = 0;
+
+    if (!*argv)
+      badusage(_("--%s --recursive needs at least one path argument"),cipaction->olong);
+
+    for (ap = argv; *ap; ap++) {
+      struct treeroot *tree;
+      struct treenode *node;
+
+      tree = treewalk_open((const char *)*ap, TREEWALK_FOLLOW_LINKS, NULL);
+
+      while ((node = treewalk_next(tree))) {
+        const char *nodename;
+
+        if (!S_ISREG(treenode_get_mode(node)))
+          continue;
+
+        /* Check if it looks like a .deb file. */
+        nodename = treenode_get_pathname(node);
+        if (strcmp(nodename + strlen(nodename) - 4, ".deb") != 0)
+          continue;
+
+        arglist = m_realloc(arglist, sizeof(char *) * (nfiles + 2));
+        arglist[nfiles++] = m_strdup(nodename);
+      }
+
+      treewalk_close(tree);
+    }
+
+    if (!nfiles)
+      ohshit(_("searched, but found no packages (files matching *.deb)"));
+
+    arglist[nfiles] = NULL;
+    argp= arglist;
+  } else {
+    if (!*argv) badusage(_("--%s needs at least one package archive file argument"),
+                         cipaction->olong);
+    argp= argv;
+  }
+
+  /* Perform some sanity checks on the passed archives. */
+  for (i = 0; argp[i]; i++) {
+    struct stat st;
+
+    /* We need the filename to exist. */
+    if (stat(argp[i], &st) < 0)
+      ohshite(_("cannot access archive '%s'"), argp[i]);
+
+    /* We cannot work with anything that is not a regular file. */
+    if (!S_ISREG(st.st_mode))
+      ohshit(_("archive '%s' is not a regular file"), argp[i]);
+  }
+
+  currenttime = time(NULL);
+
+  /* Initialize fname variables contents. */
+
+  varbuf_reset(&fnamevb);
+  varbuf_reset(&fnametmpvb);
+  varbuf_reset(&fnamenewvb);
+
+  varbuf_add_str(&fnamevb, instdir);
+  varbuf_add_str(&fnametmpvb, instdir);
+  varbuf_add_str(&fnamenewvb, instdir);
+
+  varbuf_snapshot(&fnamevb, &fname_state);
+
+  ensure_diversions();
+  ensure_statoverrides(STATDB_PARSE_NORMAL);
+
+  for (i = 0; argp[i]; i++) {
+    if (setjmp(ejbuf)) {
+      pop_error_context(ehflag_bombout);
+      if (abort_processing)
+        break;
+      continue;
+    }
+    push_error_context_jump(&ejbuf, print_error_perarchive, argp[i]);
+
+    dpkg_selabel_load();
+
+    process_archive(argp[i]);
+    onerr_abort++;
+    m_output(stdout, _("<standard output>"));
+    m_output(stderr, _("<standard error>"));
+    onerr_abort--;
+
+    pop_error_context(ehflag_normaltidy);
+  }
+
+  dpkg_selabel_close();
+
+  free(arglist);
+
+  switch (cipaction->arg_int) {
+  case act_install:
+  case act_configure:
+  case act_triggers:
+  case act_remove:
+  case act_purge:
+    process_queue();
+  case act_unpack:
+  case act_avail:
+    break;
+  default:
+    internerr("unknown action '%d'", cipaction->arg_int);
+  }
+
+  trigproc_run_deferred();
+  modstatdb_shutdown();
+
+  return 0;
+}
+
+/**
+ * Decide whether we want to install a new version of the package.
+ *
+ * @param pkg The package with the version we might want to install
+ *
+ * @retval true  If the package should be skipped.
+ * @retval false If the package should be installed.
+ */
+bool
+wanttoinstall(struct pkginfo *pkg)
+{
+  int rc;
+
+  if (pkg->want != PKG_WANT_INSTALL && pkg->want != PKG_WANT_HOLD) {
+    if (f_alsoselect) {
+      printf(_("Selecting previously unselected package %s.\n"),
+             pkgbin_name(pkg, &pkg->available, pnaw_nonambig));
+      return true;
+    } else {
+      printf(_("Skipping unselected package %s.\n"),
+             pkgbin_name(pkg, &pkg->available, pnaw_nonambig));
+      return false;
+    }
+  }
+
+  if (pkg->eflag & PKG_EFLAG_REINSTREQ)
+    return true;
+  if (pkg->status < PKG_STAT_UNPACKED)
+    return true;
+
+  rc = dpkg_version_compare(&pkg->available.version, &pkg->installed.version);
+  if (rc > 0) {
+    return true;
+  } else if (rc == 0) {
+    /* Same version fully installed. */
+    if (f_skipsame) {
+      notice(_("version %.250s of %.250s already installed, skipping"),
+             versiondescribe(&pkg->installed.version, vdew_nonambig),
+             pkg_name(pkg, pnaw_nonambig));
+      return false;
+    } else {
+      return true;
+    }
+  } else {
+    if (in_force(FORCE_DOWNGRADE)) {
+      warning(_("downgrading %.250s from %.250s to %.250s"),
+              pkg_name(pkg, pnaw_nonambig),
+              versiondescribe(&pkg->installed.version, vdew_nonambig),
+              versiondescribe(&pkg->available.version, vdew_nonambig));
+      return true;
+    } else {
+      notice(_("will not downgrade %.250s from %.250s to %.250s, skipping"),
+             pkg_name(pkg, pnaw_nonambig),
+             versiondescribe(&pkg->installed.version, vdew_nonambig),
+             versiondescribe(&pkg->available.version, vdew_nonambig));
+      return false;
+    }
+  }
+}