* Implement EDSP in libapt-pkg so that all front-ends which

  use the internal resolver can now be used also with external
  ones as the usage is hidden in between the old API
* provide two edsp solvers in apt-utils:
  - 'dump' to quickly output a complete scenario and
  - 'apt' to use the internal as an external resolver

1 files changed, 564 insertions, 0 deletions

diff --git a/apt-pkg/edsp.cc b/apt-pkg/edsp.cc
new file mode 100644
index 000000000..218ce9f24
--- /dev/null
+++ b/apt-pkg/edsp.cc
@@ -0,0 +1,564 @@
+// -*- mode: cpp; mode: fold -*-
+// Description								/*{{{*/
+/* ######################################################################
+   Set of methods to help writing and reading everything needed for EDSP
+   ##################################################################### */
+									/*}}}*/
+// Include Files							/*{{{*/
+#include <apt-pkg/edsp.h>
+#include <apt-pkg/error.h>
+#include <apt-pkg/configuration.h>
+#include <apt-pkg/version.h>
+#include <apt-pkg/policy.h>
+#include <apt-pkg/tagfile.h>
+
+#include <apti18n.h>
+#include <limits>
+
+#include <stdio.h>
+									/*}}}*/
+
+// we could use pkgCache::DepType and ::Priority, but these would be localized strings…
+const char * const EDSP::PrioMap[] = {0, "important", "required", "standard",
+				      "optional", "extra"};
+const char * const EDSP::DepMap[] = {"", "Depends", "Pre-Depends", "Suggests",
+				     "Recommends" , "Conflicts", "Replaces",
+				     "Obsoletes", "Breaks", "Enhances"};
+
+// EDSP::WriteScenario - to the given file descriptor			/*{{{*/
+bool EDSP::WriteScenario(pkgDepCache &Cache, FILE* output, OpProgress *Progress)
+{
+   if (Progress != NULL)
+      Progress->SubProgress(Cache.Head().VersionCount, _("Send scenario to solver"));
+   unsigned long p = 0;
+   for (pkgCache::PkgIterator Pkg = Cache.PkgBegin(); Pkg.end() == false; ++Pkg)
+      for (pkgCache::VerIterator Ver = Pkg.VersionList(); Ver.end() == false; ++Ver, ++p)
+      {
+	 WriteScenarioVersion(Cache, output, Pkg, Ver);
+	 WriteScenarioDependency(Cache, output, Pkg, Ver);
+	 fprintf(output, "\n");
+	 if (Progress != NULL && p % 100 == 0)
+	    Progress->Progress(p);
+      }
+   return true;
+}
+									/*}}}*/
+// EDSP::WriteLimitedScenario - to the given file descriptor		/*{{{*/
+bool EDSP::WriteLimitedScenario(pkgDepCache &Cache, FILE* output,
+				APT::PackageSet const &pkgset,
+				OpProgress *Progress)
+{
+   if (Progress != NULL)
+      Progress->SubProgress(Cache.Head().VersionCount, _("Send scenario to solver"));
+   unsigned long p  = 0;
+   for (APT::PackageSet::const_iterator Pkg = pkgset.begin(); Pkg != pkgset.end(); ++Pkg, ++p)
+      for (pkgCache::VerIterator Ver = Pkg.VersionList(); Ver.end() == false; ++Ver)
+      {
+	 WriteScenarioVersion(Cache, output, Pkg, Ver);
+	 WriteScenarioLimitedDependency(Cache, output, Pkg, Ver, pkgset);
+	 fprintf(output, "\n");
+	 if (Progress != NULL && p % 100 == 0)
+	    Progress->Progress(p);
+      }
+   if (Progress != NULL)
+      Progress->Done();
+   return true;
+}
+									/*}}}*/
+// EDSP::WriteScenarioVersion						/*{{{*/
+void EDSP::WriteScenarioVersion(pkgDepCache &Cache, FILE* output, pkgCache::PkgIterator const &Pkg,
+				pkgCache::VerIterator const &Ver)
+{
+   fprintf(output, "Package: %s\n", Pkg.Name());
+   fprintf(output, "Architecture: %s\n", Ver.Arch());
+   fprintf(output, "Version: %s\n", Ver.VerStr());
+   if (Pkg.CurrentVer() == Ver)
+      fprintf(output, "Installed: yes\n");
+   if (Pkg->SelectedState == pkgCache::State::Hold ||
+       (Cache[Pkg].Keep() == true && Cache[Pkg].Protect() == true))
+      fprintf(output, "Hold: yes\n");
+   fprintf(output, "APT-ID: %d\n", Ver->ID);
+   fprintf(output, "Priority: %s\n", PrioMap[Ver->Priority]);
+   if ((Pkg->Flags & pkgCache::Flag::Essential) == pkgCache::Flag::Essential)
+      fprintf(output, "Essential: yes\n");
+   fprintf(output, "Section: %s\n", Ver.Section());
+   if (Ver->MultiArch == pkgCache::Version::Allowed || Ver->MultiArch == pkgCache::Version::AllAllowed)
+      fprintf(output, "Multi-Arch: allowed\n");
+   else if (Ver->MultiArch == pkgCache::Version::Foreign || Ver->MultiArch == pkgCache::Version::AllForeign)
+      fprintf(output, "Multi-Arch: foreign\n");
+   else if (Ver->MultiArch == pkgCache::Version::Same)
+      fprintf(output, "Multi-Arch: same\n");
+   signed short Pin = std::numeric_limits<signed short>::min();
+   for (pkgCache::VerFileIterator File = Ver.FileList(); File.end() == false; ++File) {
+      signed short const p = Cache.GetPolicy().GetPriority(File.File());
+      if (Pin < p)
+	 Pin = p;
+   }
+   fprintf(output, "APT-Pin: %d\n", Pin);
+   if (Cache.GetCandidateVer(Pkg) == Ver)
+      fprintf(output, "APT-Candidate: yes\n");
+   if ((Cache[Pkg].Flags & pkgCache::Flag::Auto) == pkgCache::Flag::Auto)
+      fprintf(output, "APT-Automatic: yes\n");
+}
+									/*}}}*/
+// EDSP::WriteScenarioDependency					/*{{{*/
+void EDSP::WriteScenarioDependency(pkgDepCache &Cache, FILE* output, pkgCache::PkgIterator const &Pkg,
+				pkgCache::VerIterator const &Ver)
+{
+   std::string dependencies[pkgCache::Dep::Enhances + 1];
+   bool orGroup = false;
+   for (pkgCache::DepIterator Dep = Ver.DependsList(); Dep.end() == false; ++Dep)
+   {
+      // Ignore implicit dependencies for multiarch here
+      if (strcmp(Pkg.Arch(), Dep.TargetPkg().Arch()) != 0)
+	 continue;
+      if (orGroup == false)
+	 dependencies[Dep->Type].append(", ");
+      dependencies[Dep->Type].append(Dep.TargetPkg().Name());
+      if (Dep->Version != 0)
+	 dependencies[Dep->Type].append(" (").append(pkgCache::CompTypeDeb(Dep->CompareOp)).append(" ").append(Dep.TargetVer()).append(")");
+      if ((Dep->CompareOp & pkgCache::Dep::Or) == pkgCache::Dep::Or)
+      {
+	 dependencies[Dep->Type].append(" | ");
+	 orGroup = true;
+      }
+      else
+	 orGroup = false;
+   }
+   for (int i = 1; i < pkgCache::Dep::Enhances + 1; ++i)
+      if (dependencies[i].empty() == false)
+	 fprintf(output, "%s: %s\n", DepMap[i], dependencies[i].c_str()+2);
+   string provides;
+   for (pkgCache::PrvIterator Prv = Ver.ProvidesList(); Prv.end() == false; ++Prv)
+   {
+      // Ignore implicit provides for multiarch here
+      if (strcmp(Pkg.Arch(), Prv.ParentPkg().Arch()) != 0 || strcmp(Pkg.Name(),Prv.Name()) == 0)
+	 continue;
+      provides.append(", ").append(Prv.Name());
+   }
+   if (provides.empty() == false)
+      fprintf(output, "Provides: %s\n", provides.c_str()+2);
+}
+									/*}}}*/
+// EDSP::WriteScenarioLimitedDependency					/*{{{*/
+void EDSP::WriteScenarioLimitedDependency(pkgDepCache &Cache, FILE* output,
+					  pkgCache::PkgIterator const &Pkg,
+					  pkgCache::VerIterator const &Ver,
+					  APT::PackageSet const &pkgset)
+{
+   std::string dependencies[pkgCache::Dep::Enhances + 1];
+   bool orGroup = false;
+   for (pkgCache::DepIterator Dep = Ver.DependsList(); Dep.end() == false; ++Dep)
+   {
+      // Ignore implicit dependencies for multiarch here
+      if (strcmp(Pkg.Arch(), Dep.TargetPkg().Arch()) != 0)
+	 continue;
+      if (orGroup == false)
+      {
+	 if (pkgset.find(Dep.TargetPkg()) == pkgset.end())
+	    continue;
+	 dependencies[Dep->Type].append(", ");
+      }
+      else if (pkgset.find(Dep.TargetPkg()) == pkgset.end())
+      {
+	 if ((Dep->CompareOp & pkgCache::Dep::Or) == pkgCache::Dep::Or)
+	    continue;
+	 dependencies[Dep->Type].erase(dependencies[Dep->Type].end()-3, dependencies[Dep->Type].end());
+	 orGroup = false;
+	 continue;
+      }
+      dependencies[Dep->Type].append(Dep.TargetPkg().Name());
+      if (Dep->Version != 0)
+	 dependencies[Dep->Type].append(" (").append(pkgCache::CompTypeDeb(Dep->CompareOp)).append(" ").append(Dep.TargetVer()).append(")");
+      if ((Dep->CompareOp & pkgCache::Dep::Or) == pkgCache::Dep::Or)
+      {
+	 dependencies[Dep->Type].append(" | ");
+	 orGroup = true;
+      }
+      else
+	 orGroup = false;
+   }
+   for (int i = 1; i < pkgCache::Dep::Enhances + 1; ++i)
+      if (dependencies[i].empty() == false)
+	 fprintf(output, "%s: %s\n", DepMap[i], dependencies[i].c_str()+2);
+   string provides;
+   for (pkgCache::PrvIterator Prv = Ver.ProvidesList(); Prv.end() == false; ++Prv)
+   {
+      // Ignore implicit provides for multiarch here
+      if (strcmp(Pkg.Arch(), Prv.ParentPkg().Arch()) != 0 || strcmp(Pkg.Name(),Prv.Name()) == 0)
+	 continue;
+      if (pkgset.find(Prv.ParentPkg()) == pkgset.end())
+	 continue;
+      provides.append(", ").append(Prv.Name());
+   }
+   if (provides.empty() == false)
+      fprintf(output, "Provides: %s\n", provides.c_str()+2);
+}
+									/*}}}*/
+// EDSP::WriteRequest - to the given file descriptor			/*{{{*/
+bool EDSP::WriteRequest(pkgDepCache &Cache, FILE* output, bool const Upgrade,
+			bool const DistUpgrade, bool const AutoRemove,
+			OpProgress *Progress)
+{
+   if (Progress != NULL)
+      Progress->SubProgress(Cache.Head().PackageCount, _("Send request to solver"));
+   unsigned long p = 0;
+   string del, inst;
+   for (pkgCache::PkgIterator Pkg = Cache.PkgBegin(); Pkg.end() == false; ++Pkg, ++p)
+   {
+      if (Progress != NULL && p % 100 == 0)
+         Progress->Progress(p);
+      string* req;
+      if (Cache[Pkg].Delete() == true)
+	 req = &del;
+      else if (Cache[Pkg].NewInstall() == true || Cache[Pkg].Upgrade() == true)
+	 req = &inst;
+      else
+	 continue;
+      req->append(" ").append(Pkg.FullName());
+   }
+   fprintf(output, "Request: EDSP 0.4\n");
+   if (del.empty() == false)
+      fprintf(output, "Remove: %s\n", del.c_str()+1);
+   if (inst.empty() == false)
+      fprintf(output, "Install: %s\n", inst.c_str()+1);
+   if (Upgrade == true)
+      fprintf(output, "Upgrade: yes\n");
+   if (DistUpgrade == true)
+      fprintf(output, "Dist-Upgrade: yes\n");
+   if (AutoRemove == true)
+      fprintf(output, "Autoremove: yes\n");
+   if (_config->FindB("APT::Solver::Strict-Pinning", true) == false)
+      fprintf(output, "Strict-Pinning: no\n");
+   string solverpref("APT::Solver::");
+   solverpref.append(_config->Find("APT::Solver::Name", "internal")).append("::Preferences");
+   if (_config->Exists(solverpref) == true)
+      fprintf(output, "Preferences: %s\n", _config->Find(solverpref,"").c_str());
+   fprintf(output, "\n");
+
+   return true;
+}
+									/*}}}*/
+// EDSP::ReadResponse - from the given file descriptor			/*{{{*/
+bool EDSP::ReadResponse(int const input, pkgDepCache &Cache, OpProgress *Progress) {
+	/* We build an map id to mmap offset here
+	   In theory we could use the offset as ID, but then VersionCount
+	   couldn't be used to create other versionmappings anymore and it
+	   would be too easy for a (buggy) solver to segfault APT… */
+	unsigned long long const VersionCount = Cache.Head().VersionCount;
+	unsigned long VerIdx[VersionCount];
+	for (pkgCache::PkgIterator P = Cache.PkgBegin(); P.end() == false; ++P) {
+		for (pkgCache::VerIterator V = P.VersionList(); V.end() == false; ++V)
+			VerIdx[V->ID] = V.Index();
+		Cache[P].Marked = true;
+		Cache[P].Garbage = false;
+	}
+
+	FileFd in;
+	in.OpenDescriptor(input, FileFd::ReadOnly);
+	pkgTagFile response(&in, 100);
+	pkgTagSection section;
+
+	while (response.Step(section) == true) {
+		std::string type;
+		if (section.Exists("Install") == true)
+			type = "Install";
+		else if (section.Exists("Remove") == true)
+			type = "Remove";
+		else if (section.Exists("Progress") == true) {
+			if (Progress != NULL) {
+				string msg = section.FindS("Message");
+				if (msg.empty() == true)
+					msg = _("Prepare for receiving solution");
+				Progress->SubProgress(100, msg, section.FindI("Percentage", 0));
+			}
+			continue;
+		} else if (section.Exists("Error") == true) {
+			std::string msg = SubstVar(SubstVar(section.FindS("Message"), "\n .\n", "\n\n"), "\n ", "\n");
+			if (msg.empty() == true) {
+				msg = _("External solver failed without a proper error message");
+				_error->Error(msg.c_str());
+			} else
+				_error->Error("External solver failed with: %s", msg.substr(0,msg.find('\n')).c_str());
+			if (Progress != NULL)
+				Progress->Done();
+			std::cerr << "The solver encountered an error of type: " << section.FindS("Error") << std::endl;
+			std::cerr << "The following information might help you to understand what is wrong:" << std::endl;
+			std::cerr << msg << std::endl << std::endl;
+			return false;
+		} else if (section.Exists("Autoremove") == true)
+			type = "Autoremove";
+		else
+			continue;
+
+		size_t const id = section.FindULL(type.c_str(), VersionCount);
+		if (id == VersionCount) {
+			_error->Warning("Unable to parse %s request with id value '%s'!", type.c_str(), section.FindS(type.c_str()).c_str());
+			continue;
+		} else if (id > Cache.Head().VersionCount) {
+			_error->Warning("ID value '%s' in %s request stanza is to high to refer to a known version!", section.FindS(type.c_str()).c_str(), type.c_str());
+			continue;
+		}
+
+		pkgCache::VerIterator Ver(Cache.GetCache(), Cache.GetCache().VerP + VerIdx[id]);
+		Cache.SetCandidateVersion(Ver);
+		if (type == "Install")
+			Cache.MarkInstall(Ver.ParentPkg(), false, 0, false);
+		else if (type == "Remove")
+			Cache.MarkDelete(Ver.ParentPkg(), false);
+		else if (type == "Autoremove") {
+			Cache[Ver.ParentPkg()].Marked = false;
+			Cache[Ver.ParentPkg()].Garbage = true;
+		}
+	}
+	return true;
+}
+									/*}}}*/
+// EDSP::ReadLine - first line from the given file descriptor		/*{{{*/
+// ---------------------------------------------------------------------
+/* Little helper method to read a complete line into a string. Similar to
+   fgets but we need to use the low-level read() here as otherwise the
+   listparser will be confused later on as mixing of fgets and read isn't
+   a supported action according to the manpages and results are undefined */
+bool EDSP::ReadLine(int const input, std::string &line) {
+	char one;
+	ssize_t data = 0;
+	line.erase();
+	line.reserve(100);
+	while ((data = read(input, &one, sizeof(one))) != -1) {
+		if (data != 1)
+			continue;
+		if (one == '\n')
+			return true;
+		if (one == '\r')
+			continue;
+		if (line.empty() == true && isblank(one) != 0)
+			continue;
+		line += one;
+	}
+	return false;
+}
+									/*}}}*/
+// EDSP::StringToBool - convert yes/no to bool				/*{{{*/
+// ---------------------------------------------------------------------
+/* we are not as lazy as we are in the global StringToBool as we really
+   only accept yes/no here - but we will ignore leading spaces */
+bool EDSP::StringToBool(char const *answer, bool const defValue) {
+   for (; isspace(*answer) != 0; ++answer);
+   if (strncasecmp(answer, "yes", 3) == 0)
+      return true;
+   else if (strncasecmp(answer, "no", 2) == 0)
+      return false;
+   else
+      _error->Warning("Value '%s' is not a boolean 'yes' or 'no'!", answer);
+   return defValue;
+}
+									/*}}}*/
+// EDSP::ReadRequest - first stanza from the given file descriptor	/*{{{*/
+bool EDSP::ReadRequest(int const input, std::list<std::string> &install,
+			std::list<std::string> &remove, bool &upgrade,
+			bool &distUpgrade, bool &autoRemove)
+{
+   install.clear();
+   remove.clear();
+   upgrade = false;
+   distUpgrade = false;
+   autoRemove = false;
+   std::string line;
+   while (ReadLine(input, line) == true)
+   {
+      // Skip empty lines before request
+      if (line.empty() == true)
+	 continue;
+      // The first Tag must be a request, so search for it
+      if (line.compare(0, 8, "Request:") != 0)
+	 continue;
+
+      while (ReadLine(input, line) == true)
+      {
+	 // empty lines are the end of the request
+	 if (line.empty() == true)
+	    return true;
+
+	 std::list<std::string> *request = NULL;
+	 if (line.compare(0, 8, "Install:") == 0)
+	 {
+	    line.erase(0, 8);
+	    request = &install;
+	 }
+	 else if (line.compare(0, 7, "Remove:") == 0)
+	 {
+	    line.erase(0, 7);
+	    request = &remove;
+	 }
+	 else if (line.compare(0, 8, "Upgrade:") == 0)
+	    upgrade = EDSP::StringToBool(line.c_str() + 9, false);
+	 else if (line.compare(0, 13, "Dist-Upgrade:") == 0)
+	    distUpgrade = EDSP::StringToBool(line.c_str() + 14, false);
+	 else if (line.compare(0, 11, "Autoremove:") == 0)
+	    autoRemove = EDSP::StringToBool(line.c_str() + 12, false);
+	 else
+	    _error->Warning("Unknown line in EDSP Request stanza: %s", line.c_str());
+
+	 if (request == NULL)
+	    continue;
+	 size_t end = line.length();
+	 do {
+	    size_t begin = line.rfind(' ');
+	    if (begin == std::string::npos)
+	    {
+	       request->push_back(line.substr(0, end));
+	       break;
+	    }
+	    else if (begin < end)
+	       request->push_back(line.substr(begin + 1, end));
+	    line.erase(begin);
+	    end = line.find_last_not_of(' ');
+	 } while (end != std::string::npos);
+      }
+   }
+   return false;
+}
+									/*}}}*/
+// EDSP::ApplyRequest - first stanza from the given file descriptor	/*{{{*/
+bool EDSP::ApplyRequest(std::list<std::string> const &install,
+			 std::list<std::string> const &remove,
+			 pkgDepCache &Cache)
+{
+	for (std::list<std::string>::const_iterator i = install.begin();
+	     i != install.end(); ++i) {
+		pkgCache::PkgIterator P = Cache.FindPkg(*i);
+		if (P.end() == true)
+			_error->Warning("Package %s is not known, so can't be installed", i->c_str());
+		else
+			Cache.MarkInstall(P, false);
+	}
+
+	for (std::list<std::string>::const_iterator i = remove.begin();
+	     i != remove.end(); ++i) {
+		pkgCache::PkgIterator P = Cache.FindPkg(*i);
+		if (P.end() == true)
+			_error->Warning("Package %s is not known, so can't be installed", i->c_str());
+		else
+			Cache.MarkDelete(P);
+	}
+	return true;
+}
+									/*}}}*/
+// EDSP::WriteSolution - to the given file descriptor			/*{{{*/
+bool EDSP::WriteSolution(pkgDepCache &Cache, FILE* output)
+{
+   bool const Debug = _config->FindB("Debug::EDSP::WriteSolution", false);
+   for (pkgCache::PkgIterator Pkg = Cache.PkgBegin(); Pkg.end() == false; ++Pkg)
+   {
+      if (Cache[Pkg].Delete() == true)
+      {
+	 fprintf(output, "Remove: %d\n", Pkg.CurrentVer()->ID);
+	 if (Debug == true)
+	    fprintf(output, "Package: %s\nVersion: %s\n", Pkg.FullName().c_str(), Pkg.CurrentVer().VerStr());
+      }
+      else if (Cache[Pkg].NewInstall() == true || Cache[Pkg].Upgrade() == true)
+      {
+	 fprintf(output, "Install: %d\n", Cache.GetCandidateVer(Pkg)->ID);
+	 if (Debug == true)
+	    fprintf(output, "Package: %s\nVersion: %s\n", Pkg.FullName().c_str(), Cache.GetCandidateVer(Pkg).VerStr());
+      }
+      else if (Cache[Pkg].Garbage == true)
+      {
+	 fprintf(output, "Autoremove: %d\n", Pkg.CurrentVer()->ID);
+	 if (Debug == true)
+	    fprintf(output, "Package: %s\nVersion: %s\n", Pkg.FullName().c_str(), Pkg.CurrentVer().VerStr());
+	    fprintf(stderr, "Autoremove: %s\nVersion: %s\n", Pkg.FullName().c_str(), Pkg.CurrentVer().VerStr());
+      }
+      else
+	 continue;
+      fprintf(output, "\n");
+   }
+
+   return true;
+}
+									/*}}}*/
+// EDSP::WriteProgess - pulse to the given file descriptor		/*{{{*/
+bool EDSP::WriteProgress(unsigned short const percent, const char* const message, FILE* output) {
+	fprintf(output, "Progress: %s\n", TimeRFC1123(time(NULL)).c_str());
+	fprintf(output, "Percentage: %d\n", percent);
+	fprintf(output, "Message: %s\n\n", message);
+	fflush(output);
+	return true;
+}
+									/*}}}*/
+// EDSP::WriteError - format an error message to be send to file descriptor /*{{{*/
+bool EDSP::WriteError(char const * const uuid, std::string const &message, FILE* output) {
+	fprintf(output, "Error: %s\n", uuid);
+	fprintf(output, "Message: %s\n\n", SubstVar(SubstVar(message, "\n\n", "\n.\n"), "\n", "\n ").c_str());
+	return true;
+}
+									/*}}}*/
+// EDSP::ExecuteSolver - fork requested solver and setup ipc pipes	{{{*/
+bool EDSP::ExecuteSolver(const char* const solver, int *solver_in, int *solver_out) {
+	std::vector<std::string> const solverDirs = _config->FindVector("Dir::Bin::Solvers");
+	std::string file;
+	for (std::vector<std::string>::const_iterator dir = solverDirs.begin();
+	     dir != solverDirs.end(); ++dir) {
+		file = flCombine(*dir, solver);
+		if (RealFileExists(file.c_str()) == true)
+			break;
+		file.clear();
+	}
+
+	if (file.empty() == true)
+		return _error->Error("Can't call external solver '%s' as it is not in a configured directory!", solver);
+	int external[4] = {-1, -1, -1, -1};
+	if (pipe(external) != 0 || pipe(external + 2) != 0)
+		return _error->Errno("Resolve", "Can't create needed IPC pipes for EDSP");
+	for (int i = 0; i < 4; ++i)
+		SetCloseExec(external[i], true);
+
+	pid_t Solver = ExecFork();
+	if (Solver == 0) {
+		dup2(external[0], STDIN_FILENO);
+		dup2(external[3], STDOUT_FILENO);
+		const char* calling[2] = { file.c_str(), 0 };
+		execv(calling[0], (char**) calling);
+		std::cerr << "Failed to execute solver '" << solver << "'!" << std::endl;
+		_exit(100);
+	}
+	close(external[0]);
+	close(external[3]);
+
+	if (WaitFd(external[1], true, 5) == false)
+		return _error->Errno("Resolve", "Timed out while Waiting on availability of solver stdin");
+
+	*solver_in = external[1];
+	*solver_out = external[2];
+	return true;
+}
+									/*}}}*/
+// EDSP::ResolveExternal - resolve problems by asking external for help	{{{*/
+bool EDSP::ResolveExternal(const char* const solver, pkgDepCache &Cache,
+			 bool const upgrade, bool const distUpgrade,
+			 bool const autoRemove, OpProgress *Progress) {
+	int solver_in, solver_out;
+	if (EDSP::ExecuteSolver(solver, &solver_in, &solver_out) == false)
+		return false;
+
+	FILE* output = fdopen(solver_in, "w");
+	if (output == NULL)
+		return _error->Errno("Resolve", "fdopen on solver stdin failed");
+
+	if (Progress != NULL)
+		Progress->OverallProgress(0, 100, 5, _("Execute external solver"));
+	EDSP::WriteRequest(Cache, output, upgrade, distUpgrade, autoRemove, Progress);
+	if (Progress != NULL)
+		Progress->OverallProgress(5, 100, 20, _("Execute external solver"));
+	EDSP::WriteScenario(Cache, output, Progress);
+	fclose(output);
+
+	if (Progress != NULL)
+		Progress->OverallProgress(25, 100, 75, _("Execute external solver"));
+	if (EDSP::ReadResponse(solver_out, Cache, Progress) == false)
+		return false;
+
+	return true;
+}
+									/*}}}*/