Add helpers for interfacing with dpkg

These should rather be in libapt-pkg but too late for Wheezy.

* generic/apt/dpkg.{cc,h}:
  - dpkg_base_args: base arguments for dpkg from APT conf
  - dpkg_mult_arch: true if dpkg is multi-arch aware
  - dpkg_package_name: returns the name that dpkg uses for
    a package

3 files changed, 205 insertions, 0 deletions

diff --git a/src/generic/apt/Makefile.am b/src/generic/apt/Makefile.am
index 29488f4f..4df2cfe7 100644
--- a/src/generic/apt/Makefile.am
+++ b/src/generic/apt/Makefile.am
@@ -47,6 +47,8 @@ libgeneric_apt_a_SOURCES = \
 	download_update_manager.h   \
 	download_signal_log.cc \
 	download_signal_log.h  \
+	dpkg.cc             \
+	dpkg.h              \
 	dump_packages.cc    \
 	dump_packages.h     \
 	globals.cc          \
diff --git a/src/generic/apt/dpkg.cc b/src/generic/apt/dpkg.cc
new file mode 100644
index 00000000..a777acec
--- /dev/null
+++ b/src/generic/apt/dpkg.cc
@@ -0,0 +1,150 @@
+// dpkg.cc
+//
+//  Copyright 2012 Daniel Hartwig
+//
+//  This program 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 program 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; see the file COPYING.  If not, write to
+//  the Free Software Foundation, Inc., 59 Temple Place - Suite 330,
+//  Boston, MA 02111-1307, USA.
+
+#include "dpkg.h"
+
+#include <aptitude.h>
+
+#include <apt-pkg/configuration.h>
+#include <apt-pkg/error.h>
+#include <apt-pkg/fileutl.h>
+#include <apt-pkg/pkgcache.h>
+
+#include <boost/optional.hpp>
+
+#include <cerrno>
+#include <string>
+#include <vector>
+
+#include <sys/types.h>
+#include <sys/wait.h>
+#include <fcntl.h>
+
+using namespace std;
+
+namespace aptitude {
+namespace apt {
+
+std::vector<const char *> dpkg_base_args(const bool cached)
+{
+   static std::vector<const char *> Args;
+
+   if (cached == true && Args.empty() == false)
+      return Args;
+
+   // Generate the base argument list for dpkg
+   Args.clear();
+   string Tmp = _config->Find("Dir::Bin::dpkg","dpkg");
+   {
+      string const dpkgChrootDir = _config->FindDir("DPkg::Chroot-Directory", "/");
+      size_t dpkgChrootLen = dpkgChrootDir.length();
+      if (dpkgChrootDir != "/" && Tmp.find(dpkgChrootDir) == 0)
+      {
+	 if (dpkgChrootDir[dpkgChrootLen - 1] == '/')
+	    --dpkgChrootLen;
+	 Tmp = Tmp.substr(dpkgChrootLen);
+      }
+   }
+   Args.push_back(Tmp.c_str());
+
+   // Stick in any custom dpkg options
+   Configuration::Item const *Opts = _config->Tree("DPkg::Options");
+   if (Opts != 0)
+   {
+      Opts = Opts->Child;
+      for (; Opts != 0; Opts = Opts->Next)
+      {
+	 if (Opts->Value.empty() == true)
+	    continue;
+	 Args.push_back(Opts->Value.c_str());
+      }
+   }
+
+   return Args;
+}
+
+bool dpkg_multi_arch(const bool cached)
+{
+   static boost::optional<bool> dpkgMultiArch;
+
+   if (cached == true && dpkgMultiArch)
+      return *dpkgMultiArch;
+
+   std::vector<const char *> Args(dpkg_base_args(cached));
+
+   // we need to detect if we can qualify packages with the architecture or not
+   Args.push_back("--assert-multi-arch");
+   Args.push_back(NULL);
+
+
+   pid_t dpkgAssertMultiArch = ExecFork();
+   if (dpkgAssertMultiArch == 0)
+   {
+      std::string const chrootDir = _config->FindDir("DPkg::Chroot-Directory");
+      if (chrootDir != "/" && chroot(chrootDir.c_str()) != 0)
+	 _error->WarningE("dpkg_multi_arch",
+                          _("Couldn't chroot into %s for %s"),
+                          chrootDir.c_str(),
+                          "dpkg --assert-multi-arch");
+      // redirect everything to the ultimate sink as we only need the exit-status
+      int const nullfd = open("/dev/null", O_RDONLY);
+      dup2(nullfd, STDIN_FILENO);
+      dup2(nullfd, STDOUT_FILENO);
+      dup2(nullfd, STDERR_FILENO);
+      execvp(Args[0], (char**) &Args[0]);
+      _error->WarningE("dpkg_multi_arch", "Can't detect if dpkg supports multi-arch!");
+      _exit(2);
+   }
+
+   dpkgMultiArch.reset(false);
+   if (dpkgAssertMultiArch > 0)
+   {
+      int Status = 0;
+      while (waitpid(dpkgAssertMultiArch, &Status, 0) != dpkgAssertMultiArch)
+      {
+	 if (errno == EINTR)
+	    continue;
+	 _error->WarningE("dpkg_multi_arch",
+                          _("Waited for %s but it wasn't there"),
+                          "dpkg --assert-multi-arch");
+	 break;
+      }
+      if (WIFEXITED(Status) == true && WEXITSTATUS(Status) == 0)
+         dpkgMultiArch.reset(true);
+   }
+
+   return *dpkgMultiArch;
+}
+
+std::string dpkg_package_name(const pkgCache::PkgIterator &pkg)
+{
+  if(dpkg_multi_arch() == false)
+    return pkg.FullName(true);
+  else
+    {
+      if(pkg->CurrentVer != 0)
+        return string(pkg.Name()).append(":").append(pkg.CurrentVer().Arch());
+      else if(pkg.VersionList().end() == false)
+        return string(pkg.Name()).append(":").append(pkg.VersionList().Arch());
+      else
+        return pkg.FullName(false);
+    }
+}
+
+}} // namespace aptitude { namespace apt {
diff --git a/src/generic/apt/dpkg.h b/src/generic/apt/dpkg.h
new file mode 100644
index 00000000..53a2d9bc
--- /dev/null
+++ b/src/generic/apt/dpkg.h
@@ -0,0 +1,53 @@
+// dpkg.h  -*-c++-*-
+//
+//  Copyright 2012 Daniel Hartwig
+//
+//  This program 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 program 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; see the file COPYING.  If not, write to
+//  the Free Software Foundation, Inc., 59 Temple Place - Suite 330,
+//  Boston, MA 02111-1307, USA.
+//
+//  Helpers for interfacing with dpkg.
+//  Based on APT: dpkgpm.cc, apt-mark.cc
+
+// FIXME: These should really go in libapt-pkg.
+
+#ifndef APTITUDE_GENERIC_APT_DPKG_H
+#define APTITUDE_GENERIC_APT_DPKG_H
+
+#include <apt-pkg/pkgcache.h>
+
+#include <string>
+#include <vector>
+
+namespace aptitude {
+namespace apt {
+
+/** \brief Base arguments that should be passed to dpkg.  Append
+ *         additional arguments, followed by NULL, then pass to
+ *         execvp(3).
+ */
+std::vector<const char *> dpkg_base_args(const bool cached = true);
+
+/** \brief Returns \b true if dpkg is multi-arch aware.
+ */
+bool dpkg_multi_arch(const bool cached = true);
+
+/** \brief Returns the name by which dpkg knows /b pkg.  Note that
+ *         this is different to PkgIterator::FullName.
+ */
+std::string dpkg_package_name(const pkgCache::PkgIterator &pkg);
+
+}} // namespace aptitude { namespace apt {
+
+#endif // APTITUDE_GENERIC_APT_DPKG_H