Adding upstream version 1.19.8.upstream/1.19.8upstream

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

1 files changed, 699 insertions, 0 deletions

diff --git a/src/depcon.c b/src/depcon.c
new file mode 100644
index 0000000..593edfb
--- /dev/null
+++ b/src/depcon.c
@@ -0,0 +1,699 @@
+/*
+ * dpkg - main program for package management
+ * depcon.c - dependency and conflict checking
+ *
+ * Copyright © 1994,1995 Ian Jackson <ijackson@chiark.greenend.org.uk>
+ * Copyright © 2006-2014 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/stat.h>
+
+#include <errno.h>
+#include <stdlib.h>
+#include <unistd.h>
+
+#include <dpkg/i18n.h>
+#include <dpkg/dpkg.h>
+#include <dpkg/dpkg-db.h>
+#include <dpkg/db-ctrl.h>
+#include <dpkg/db-fsys.h>
+
+#include "main.h"
+
+struct deppossi_pkg_iterator {
+  struct deppossi *possi;
+  struct pkginfo *pkg_next;
+  enum which_pkgbin which_pkgbin;
+};
+
+struct deppossi_pkg_iterator *
+deppossi_pkg_iter_new(struct deppossi *possi, enum which_pkgbin wpb)
+{
+  struct deppossi_pkg_iterator *iter;
+
+  iter = m_malloc(sizeof(*iter));
+  iter->possi = possi;
+  iter->pkg_next = &possi->ed->pkg;
+  iter->which_pkgbin = wpb;
+
+  return iter;
+}
+
+struct pkginfo *
+deppossi_pkg_iter_next(struct deppossi_pkg_iterator *iter)
+{
+  struct pkginfo *pkg_cur;
+  struct pkgbin *pkgbin;
+
+  while ((pkg_cur = iter->pkg_next)) {
+    iter->pkg_next = pkg_cur->arch_next;
+
+    switch (iter->which_pkgbin) {
+    case wpb_installed:
+      pkgbin = &pkg_cur->installed;
+      break;
+    case wpb_available:
+      pkgbin = &pkg_cur->available;
+      break;
+    case wpb_by_istobe:
+      if (pkg_cur->clientdata &&
+          pkg_cur->clientdata->istobe == PKG_ISTOBE_INSTALLNEW)
+        pkgbin = &pkg_cur->available;
+      else
+        pkgbin = &pkg_cur->installed;
+      break;
+    default:
+      internerr("unknown which_pkgbin %d", iter->which_pkgbin);
+    }
+
+    if (archsatisfied(pkgbin, iter->possi))
+      return pkg_cur;
+  }
+
+  return NULL;
+}
+
+void
+deppossi_pkg_iter_free(struct deppossi_pkg_iterator *iter)
+{
+  free(iter);
+}
+
+struct cyclesofarlink {
+  struct cyclesofarlink *prev;
+  struct pkginfo *pkg;
+  struct deppossi *possi;
+};
+
+static bool findbreakcyclerecursive(struct pkginfo *pkg,
+                                    struct cyclesofarlink *sofar);
+
+static bool
+foundcyclebroken(struct cyclesofarlink *thislink, struct cyclesofarlink *sofar,
+                 struct pkginfo *dependedon, struct deppossi *possi)
+{
+  struct cyclesofarlink *sol;
+
+  if(!possi)
+    return false;
+
+  /* We're investigating the dependency ‘possi’ to see if it
+   * is part of a loop. To this end we look to see whether the
+   * depended-on package is already one of the packages whose
+   * dependencies we're searching. */
+  for (sol = sofar; sol && sol->pkg != dependedon; sol = sol->prev);
+
+  /* If not, we do a recursive search on it to see what we find. */
+  if (!sol)
+    return findbreakcyclerecursive(dependedon, thislink);
+
+  debug(dbg_depcon,"found cycle");
+  /* Right, we now break one of the links. We prefer to break
+   * a dependency of a package without a postinst script, as
+   * this is a null operation. If this is not possible we break
+   * the other link in the recursive calling tree which mentions
+   * this package (this being the first package involved in the
+   * cycle). It doesn't particularly matter which we pick, but if
+   * we break the earliest dependency we came across we may be
+   * able to do something straight away when findbreakcycle returns. */
+  sofar= thislink;
+  for (sol = sofar; !(sol != sofar && sol->pkg == dependedon); sol = sol->prev) {
+    if (!pkg_infodb_has_file(sol->pkg, &sol->pkg->installed, POSTINSTFILE))
+      break;
+  }
+
+  /* Now we have either a package with no postinst, or the other
+   * occurrence of the current package in the list. */
+  sol->possi->cyclebreak = true;
+
+  debug(dbg_depcon, "cycle broken at %s -> %s",
+        pkg_name(sol->possi->up->up, pnaw_always), sol->possi->ed->name);
+
+  return true;
+}
+
+/**
+ * Cycle breaking works recursively down the package dependency tree.
+ *
+ * ‘sofar’ is the list of packages we've descended down already - if we
+ * encounter any of its packages again in a dependency we have found a cycle.
+ */
+static bool
+findbreakcyclerecursive(struct pkginfo *pkg, struct cyclesofarlink *sofar)
+{
+  struct cyclesofarlink thislink, *sol;
+  struct dependency *dep;
+  struct deppossi *possi, *providelink;
+  struct pkginfo *provider, *pkg_pos;
+
+  if (pkg->clientdata->color == PKG_CYCLE_BLACK)
+    return false;
+  pkg->clientdata->color = PKG_CYCLE_GRAY;
+
+  if (debug_has_flag(dbg_depcondetail)) {
+    struct varbuf str_pkgs = VARBUF_INIT;
+
+    for (sol = sofar; sol; sol = sol->prev) {
+      varbuf_add_str(&str_pkgs, " <- ");
+      varbuf_add_pkgbin_name(&str_pkgs, sol->pkg, &sol->pkg->installed, pnaw_nonambig);
+    }
+    varbuf_end_str(&str_pkgs);
+    debug(dbg_depcondetail, "findbreakcyclerecursive %s %s",
+          pkg_name(pkg, pnaw_always), str_pkgs.buf);
+    varbuf_destroy(&str_pkgs);
+  }
+  thislink.pkg= pkg;
+  thislink.prev = sofar;
+  thislink.possi = NULL;
+  for (dep= pkg->installed.depends; dep; dep= dep->next) {
+    if (dep->type != dep_depends && dep->type != dep_predepends) continue;
+    for (possi= dep->list; possi; possi= possi->next) {
+      struct deppossi_pkg_iterator *possi_iter;
+
+      /* Don't find the same cycles again. */
+      if (possi->cyclebreak) continue;
+      thislink.possi= possi;
+
+      possi_iter = deppossi_pkg_iter_new(possi, wpb_installed);
+      while ((pkg_pos = deppossi_pkg_iter_next(possi_iter)))
+        if (foundcyclebroken(&thislink, sofar, pkg_pos, possi)) {
+          deppossi_pkg_iter_free(possi_iter);
+          return true;
+        }
+      deppossi_pkg_iter_free(possi_iter);
+
+      /* Right, now we try all the providers ... */
+      for (providelink = possi->ed->depended.installed;
+           providelink;
+           providelink = providelink->rev_next) {
+        if (providelink->up->type != dep_provides) continue;
+        provider= providelink->up->up;
+        if (provider->clientdata->istobe == PKG_ISTOBE_NORMAL)
+          continue;
+        /* We don't break things at ‘provides’ links, so ‘possi’ is
+         * still the one we use. */
+        if (foundcyclebroken(&thislink, sofar, provider, possi))
+          return true;
+      }
+    }
+  }
+  /* Nope, we didn't find a cycle to break. */
+  pkg->clientdata->color = PKG_CYCLE_BLACK;
+  return false;
+}
+
+bool
+findbreakcycle(struct pkginfo *pkg)
+{
+  struct pkg_hash_iter *iter;
+  struct pkginfo *tpkg;
+
+  /* Clear the visited flag of all packages before we traverse them. */
+  iter = pkg_hash_iter_new();
+  while ((tpkg = pkg_hash_iter_next_pkg(iter))) {
+    ensure_package_clientdata(tpkg);
+    tpkg->clientdata->color = PKG_CYCLE_WHITE;
+  }
+  pkg_hash_iter_free(iter);
+
+  return findbreakcyclerecursive(pkg, NULL);
+}
+
+void describedepcon(struct varbuf *addto, struct dependency *dep) {
+  const char *fmt;
+  struct varbuf depstr = VARBUF_INIT;
+
+  switch (dep->type) {
+  case dep_depends:
+    fmt = _("%s depends on %s");
+    break;
+  case dep_predepends:
+    fmt = _("%s pre-depends on %s");
+    break;
+  case dep_recommends:
+    fmt = _("%s recommends %s");
+    break;
+  case dep_suggests:
+    fmt = _("%s suggests %s");
+    break;
+  case dep_breaks:
+    fmt = _("%s breaks %s");
+    break;
+  case dep_conflicts:
+    fmt = _("%s conflicts with %s");
+    break;
+  case dep_enhances:
+    fmt = _("%s enhances %s");
+    break;
+  default:
+    internerr("unknown deptype '%d'", dep->type);
+  }
+
+  varbufdependency(&depstr, dep);
+  varbuf_end_str(&depstr);
+
+  varbuf_printf(addto, fmt, pkg_name(dep->up, pnaw_nonambig), depstr.buf);
+  varbuf_destroy(&depstr);
+}
+
+/*
+ * *whynot must already have been initialized; it need not be
+ * empty though - it will be reset before use.
+ *
+ * If depisok returns false for ‘not OK’ it will contain a description,
+ * newline-terminated BUT NOT NUL-TERMINATED, of the reason.
+ *
+ * If depisok returns true it will contain garbage.
+ * allowunconfigd should be non-zero during the ‘Pre-Depends’ checking
+ * before a package is unpacked, when it is sufficient for the package
+ * to be unpacked provided that both the unpacked and previously-configured
+ * versions are acceptable.
+ *
+ * On false return (‘not OK’), *canfixbyremove refers to a package which
+ * if removed (dep_conflicts) or deconfigured (dep_breaks) will fix
+ * the problem. Caller may pass NULL for canfixbyremove and need not
+ * initialize *canfixbyremove.
+ *
+ * On false return (‘not OK’), *canfixbytrigaw refers to a package which
+ * can fix the problem if all the packages listed in Triggers-Awaited have
+ * their triggers processed. Caller may pass NULL for canfixbytrigaw and
+ * need not initialize *canfixbytrigaw.
+ */
+bool
+depisok(struct dependency *dep, struct varbuf *whynot,
+        struct pkginfo **canfixbyremove, struct pkginfo **canfixbytrigaw,
+        bool allowunconfigd)
+{
+  struct deppossi *possi;
+  struct deppossi *provider;
+  struct pkginfo *pkg_pos;
+  int nconflicts;
+
+  /* Use this buffer so that when internationalisation comes along we
+   * don't have to rewrite the code completely, only redo the sprintf strings
+   * (assuming we have the fancy argument-number-specifiers).
+   * Allow 250x3 for package names, versions, &c, + 250 for ourselves. */
+  char linebuf[1024];
+
+  if (dep->type != dep_depends &&
+      dep->type != dep_predepends &&
+      dep->type != dep_breaks &&
+      dep->type != dep_conflicts &&
+      dep->type != dep_recommends &&
+      dep->type != dep_suggests &&
+      dep->type != dep_enhances)
+    internerr("unknown dependency type %d", dep->type);
+
+  if (canfixbyremove)
+    *canfixbyremove = NULL;
+  if (canfixbytrigaw)
+    *canfixbytrigaw = NULL;
+
+  /* The dependency is always OK if we're trying to remove the depend*ing*
+   * package. */
+  switch (dep->up->clientdata->istobe) {
+  case PKG_ISTOBE_REMOVE:
+  case PKG_ISTOBE_DECONFIGURE:
+    return true;
+  case PKG_ISTOBE_NORMAL:
+    /* Only installed packages can be made dependency problems. */
+    switch (dep->up->status) {
+    case PKG_STAT_INSTALLED:
+    case PKG_STAT_TRIGGERSPENDING:
+    case PKG_STAT_TRIGGERSAWAITED:
+      break;
+    case PKG_STAT_HALFCONFIGURED:
+    case PKG_STAT_UNPACKED:
+    case PKG_STAT_HALFINSTALLED:
+      if (dep->type == dep_predepends ||
+          dep->type == dep_conflicts ||
+          dep->type == dep_breaks)
+        break;
+      /* Fall through. */
+    case PKG_STAT_CONFIGFILES:
+    case PKG_STAT_NOTINSTALLED:
+      return true;
+    default:
+      internerr("unknown status depending '%d'", dep->up->status);
+    }
+    break;
+  case PKG_ISTOBE_INSTALLNEW:
+  case PKG_ISTOBE_PREINSTALL:
+    break;
+  default:
+    internerr("unknown istobe depending '%d'", dep->up->clientdata->istobe);
+  }
+
+  /* Describe the dependency, in case we have to moan about it. */
+  varbuf_reset(whynot);
+  varbuf_add_char(whynot, ' ');
+  describedepcon(whynot, dep);
+  varbuf_add_char(whynot, '\n');
+
+  /* TODO: Check dep_enhances as well. */
+  if (dep->type == dep_depends || dep->type == dep_predepends ||
+      dep->type == dep_recommends || dep->type == dep_suggests ) {
+    /* Go through the alternatives. As soon as we find one that
+     * we like, we return ‘true’ straight away. Otherwise, when we get to
+     * the end we'll have accumulated all the reasons in whynot and
+     * can return ‘false’. */
+
+    for (possi= dep->list; possi; possi= possi->next) {
+      struct deppossi_pkg_iterator *possi_iter;
+
+      possi_iter = deppossi_pkg_iter_new(possi, wpb_by_istobe);
+      while ((pkg_pos = deppossi_pkg_iter_next(possi_iter))) {
+        switch (pkg_pos->clientdata->istobe) {
+        case PKG_ISTOBE_REMOVE:
+          sprintf(linebuf, _("  %.250s is to be removed.\n"),
+                  pkg_name(pkg_pos, pnaw_nonambig));
+          break;
+        case PKG_ISTOBE_DECONFIGURE:
+          sprintf(linebuf, _("  %.250s is to be deconfigured.\n"),
+                  pkg_name(pkg_pos, pnaw_nonambig));
+          break;
+        case PKG_ISTOBE_INSTALLNEW:
+          if (versionsatisfied(&pkg_pos->available, possi)) {
+            deppossi_pkg_iter_free(possi_iter);
+            return true;
+          }
+          sprintf(linebuf, _("  %.250s is to be installed, but is version "
+                             "%.250s.\n"),
+                  pkgbin_name(pkg_pos, &pkg_pos->available, pnaw_nonambig),
+                  versiondescribe(&pkg_pos->available.version, vdew_nonambig));
+          break;
+        case PKG_ISTOBE_NORMAL:
+        case PKG_ISTOBE_PREINSTALL:
+          switch (pkg_pos->status) {
+          case PKG_STAT_INSTALLED:
+          case PKG_STAT_TRIGGERSPENDING:
+            if (versionsatisfied(&pkg_pos->installed, possi)) {
+              deppossi_pkg_iter_free(possi_iter);
+              return true;
+            }
+            sprintf(linebuf, _("  %.250s is installed, but is version "
+                               "%.250s.\n"),
+                    pkg_name(pkg_pos, pnaw_nonambig),
+                    versiondescribe(&pkg_pos->installed.version, vdew_nonambig));
+            break;
+          case PKG_STAT_NOTINSTALLED:
+            /* Don't say anything about this yet - it might be a virtual package.
+             * Later on, if nothing has put anything in linebuf, we know that it
+             * isn't and issue a diagnostic then. */
+            *linebuf = '\0';
+            break;
+          case PKG_STAT_TRIGGERSAWAITED:
+              if (canfixbytrigaw && versionsatisfied(&pkg_pos->installed, possi))
+                *canfixbytrigaw = pkg_pos;
+              /* Fall through. */
+          case PKG_STAT_UNPACKED:
+          case PKG_STAT_HALFCONFIGURED:
+            if (allowunconfigd) {
+              if (!dpkg_version_is_informative(&pkg_pos->configversion)) {
+                sprintf(linebuf, _("  %.250s is unpacked, but has never been "
+                                   "configured.\n"),
+                        pkg_name(pkg_pos, pnaw_nonambig));
+                break;
+              } else if (!versionsatisfied(&pkg_pos->installed, possi)) {
+                sprintf(linebuf, _("  %.250s is unpacked, but is version "
+                                   "%.250s.\n"),
+                        pkg_name(pkg_pos, pnaw_nonambig),
+                        versiondescribe(&pkg_pos->installed.version,
+                                        vdew_nonambig));
+                break;
+              } else if (!dpkg_version_relate(&pkg_pos->configversion,
+                                              possi->verrel,
+                                              &possi->version)) {
+                sprintf(linebuf, _("  %.250s latest configured version is "
+                                   "%.250s.\n"),
+                        pkg_name(pkg_pos, pnaw_nonambig),
+                        versiondescribe(&pkg_pos->configversion, vdew_nonambig));
+                break;
+              } else {
+                deppossi_pkg_iter_free(possi_iter);
+                return true;
+              }
+            }
+            /* Fall through. */
+          default:
+            sprintf(linebuf, _("  %.250s is %s.\n"),
+                    pkg_name(pkg_pos, pnaw_nonambig),
+                    gettext(statusstrings[pkg_pos->status]));
+            break;
+          }
+          break;
+        default:
+          internerr("unknown istobe depended '%d'", pkg_pos->clientdata->istobe);
+        }
+        varbuf_add_str(whynot, linebuf);
+      }
+      deppossi_pkg_iter_free(possi_iter);
+
+        /* See if the package we're about to install Provides it. */
+        for (provider = possi->ed->depended.available;
+             provider;
+             provider = provider->rev_next) {
+          if (provider->up->type != dep_provides) continue;
+          if (!pkg_virtual_deppossi_satisfied(possi, provider))
+            continue;
+          if (provider->up->up->clientdata->istobe == PKG_ISTOBE_INSTALLNEW)
+            return true;
+        }
+
+        /* Now look at the packages already on the system. */
+        for (provider = possi->ed->depended.installed;
+             provider;
+             provider = provider->rev_next) {
+          if (provider->up->type != dep_provides) continue;
+          if (!pkg_virtual_deppossi_satisfied(possi, provider))
+            continue;
+
+          switch (provider->up->up->clientdata->istobe) {
+          case PKG_ISTOBE_INSTALLNEW:
+            /* Don't pay any attention to the Provides field of the
+             * currently-installed version of the package we're trying
+             * to install. We dealt with that by using the available
+             * information above. */
+            continue;
+          case PKG_ISTOBE_REMOVE:
+            sprintf(linebuf, _("  %.250s provides %.250s but is to be removed.\n"),
+                    pkg_name(provider->up->up, pnaw_nonambig),
+                    possi->ed->name);
+            break;
+          case PKG_ISTOBE_DECONFIGURE:
+            sprintf(linebuf, _("  %.250s provides %.250s but is to be deconfigured.\n"),
+                    pkg_name(provider->up->up, pnaw_nonambig),
+                    possi->ed->name);
+            break;
+          case PKG_ISTOBE_NORMAL:
+          case PKG_ISTOBE_PREINSTALL:
+            if (provider->up->up->status == PKG_STAT_INSTALLED ||
+                provider->up->up->status == PKG_STAT_TRIGGERSPENDING)
+              return true;
+            if (provider->up->up->status == PKG_STAT_TRIGGERSAWAITED)
+              *canfixbytrigaw = provider->up->up;
+            sprintf(linebuf, _("  %.250s provides %.250s but is %s.\n"),
+                    pkg_name(provider->up->up, pnaw_nonambig),
+                    possi->ed->name,
+                    gettext(statusstrings[provider->up->up->status]));
+            break;
+          default:
+            internerr("unknown istobe provider '%d'",
+                      provider->up->up->clientdata->istobe);
+          }
+          varbuf_add_str(whynot, linebuf);
+        }
+
+        if (!*linebuf) {
+          /* If the package wasn't installed at all, and we haven't said
+           * yet why this isn't satisfied, we should say so now. */
+          sprintf(linebuf, _("  %.250s is not installed.\n"), possi->ed->name);
+          varbuf_add_str(whynot, linebuf);
+        }
+    }
+
+    return false;
+  } else {
+    /* It's conflicts or breaks. There's only one main alternative,
+     * but we also have to consider Providers. We return ‘false’ as soon
+     * as we find something that matches the conflict, and only describe
+     * it then. If we get to the end without finding anything we return
+     * ‘true’. */
+
+    possi= dep->list;
+    nconflicts= 0;
+
+    if (possi->ed != possi->up->up->set) {
+      struct deppossi_pkg_iterator *possi_iter;
+
+      /* If the package conflicts with or breaks itself it must mean
+       * other packages which provide the same virtual name. We
+       * therefore don't look at the real package and go on to the
+       * virtual ones. */
+
+      possi_iter = deppossi_pkg_iter_new(possi, wpb_by_istobe);
+      while ((pkg_pos = deppossi_pkg_iter_next(possi_iter))) {
+        switch (pkg_pos->clientdata->istobe) {
+        case PKG_ISTOBE_REMOVE:
+          break;
+        case PKG_ISTOBE_INSTALLNEW:
+          if (!versionsatisfied(&pkg_pos->available, possi))
+            break;
+          sprintf(linebuf, _("  %.250s (version %.250s) is to be installed.\n"),
+                  pkgbin_name(pkg_pos, &pkg_pos->available, pnaw_nonambig),
+                  versiondescribe(&pkg_pos->available.version, vdew_nonambig));
+          varbuf_add_str(whynot, linebuf);
+          if (!canfixbyremove) {
+            deppossi_pkg_iter_free(possi_iter);
+            return false;
+          }
+          nconflicts++;
+          *canfixbyremove = pkg_pos;
+          break;
+        case PKG_ISTOBE_DECONFIGURE:
+          if (dep->type == dep_breaks)
+            break; /* Already deconfiguring this. */
+          /* Fall through. */
+        case PKG_ISTOBE_NORMAL:
+        case PKG_ISTOBE_PREINSTALL:
+          switch (pkg_pos->status) {
+          case PKG_STAT_NOTINSTALLED:
+          case PKG_STAT_CONFIGFILES:
+            break;
+          case PKG_STAT_HALFINSTALLED:
+          case PKG_STAT_UNPACKED:
+          case PKG_STAT_HALFCONFIGURED:
+            if (dep->type == dep_breaks)
+              break; /* No problem. */
+            /* Fall through. */
+          case PKG_STAT_INSTALLED:
+          case PKG_STAT_TRIGGERSPENDING:
+          case PKG_STAT_TRIGGERSAWAITED:
+            if (!versionsatisfied(&pkg_pos->installed, possi))
+              break;
+            sprintf(linebuf, _("  %.250s (version %.250s) is present and %s.\n"),
+                    pkg_name(pkg_pos, pnaw_nonambig),
+                    versiondescribe(&pkg_pos->installed.version, vdew_nonambig),
+                    gettext(statusstrings[pkg_pos->status]));
+            varbuf_add_str(whynot, linebuf);
+            if (!canfixbyremove) {
+              deppossi_pkg_iter_free(possi_iter);
+              return false;
+            }
+            nconflicts++;
+            *canfixbyremove = pkg_pos;
+          }
+          break;
+        default:
+          internerr("unknown istobe conflict '%d'", pkg_pos->clientdata->istobe);
+        }
+      }
+      deppossi_pkg_iter_free(possi_iter);
+    }
+
+      /* See if the package we're about to install Provides it. */
+      for (provider = possi->ed->depended.available;
+           provider;
+           provider = provider->rev_next) {
+        if (provider->up->type != dep_provides) continue;
+        if (provider->up->up->clientdata->istobe != PKG_ISTOBE_INSTALLNEW)
+          continue;
+        if (provider->up->up->set == dep->up->set)
+          continue; /* Conflicts and provides the same. */
+        if (!pkg_virtual_deppossi_satisfied(possi, provider))
+          continue;
+        sprintf(linebuf, _("  %.250s provides %.250s and is to be installed.\n"),
+                pkgbin_name(provider->up->up, &provider->up->up->available,
+                            pnaw_nonambig), possi->ed->name);
+        varbuf_add_str(whynot, linebuf);
+        /* We can't remove the one we're about to install: */
+        if (canfixbyremove)
+          *canfixbyremove = NULL;
+        return false;
+      }
+
+      /* Now look at the packages already on the system. */
+      for (provider = possi->ed->depended.installed;
+           provider;
+           provider = provider->rev_next) {
+        if (provider->up->type != dep_provides) continue;
+
+        if (provider->up->up->set == dep->up->set)
+          continue; /* Conflicts and provides the same. */
+
+        if (!pkg_virtual_deppossi_satisfied(possi, provider))
+          continue;
+
+        switch (provider->up->up->clientdata->istobe) {
+        case PKG_ISTOBE_INSTALLNEW:
+          /* Don't pay any attention to the Provides field of the
+           * currently-installed version of the package we're trying
+           * to install. We dealt with that package by using the
+           * available information above. */
+          continue;
+        case PKG_ISTOBE_REMOVE:
+          continue;
+        case PKG_ISTOBE_DECONFIGURE:
+          if (dep->type == dep_breaks)
+            continue; /* Already deconfiguring. */
+          /* Fall through. */
+        case PKG_ISTOBE_NORMAL:
+        case PKG_ISTOBE_PREINSTALL:
+          switch (provider->up->up->status) {
+          case PKG_STAT_NOTINSTALLED:
+          case PKG_STAT_CONFIGFILES:
+            continue;
+          case PKG_STAT_HALFINSTALLED:
+          case PKG_STAT_UNPACKED:
+          case PKG_STAT_HALFCONFIGURED:
+            if (dep->type == dep_breaks)
+              break; /* No problem. */
+            /* Fall through. */
+          case PKG_STAT_INSTALLED:
+          case PKG_STAT_TRIGGERSPENDING:
+          case PKG_STAT_TRIGGERSAWAITED:
+            sprintf(linebuf,
+                    _("  %.250s provides %.250s and is present and %s.\n"),
+                    pkg_name(provider->up->up, pnaw_nonambig), possi->ed->name,
+                    gettext(statusstrings[provider->up->up->status]));
+            varbuf_add_str(whynot, linebuf);
+            if (!canfixbyremove)
+              return false;
+            nconflicts++;
+            *canfixbyremove= provider->up->up;
+            break;
+          }
+          break;
+        default:
+          internerr("unknown istobe conflict provider '%d'",
+                    provider->up->up->clientdata->istobe);
+        }
+      }
+
+    if (!nconflicts)
+      return true;
+    if (nconflicts > 1)
+      *canfixbyremove = NULL;
+    return false;
+
+  } /* if (dependency) {...} else {...} */
+}