From 11a3cc6307839d73cd6298a11d30cbe2a8fa0b86 Mon Sep 17 00:00:00 2001
From: Aleksei Nikiforov <darktemplar@altlinux.org>
Date: Fri, 27 Oct 2017 18:05:47 +0300
Subject: [PATCH] apt-get: implement 'autoremove' action.

---
 apt/apt-pkg/algorithms.cc | 66 ++++++++++++++++++++++++++++++++++++++-
 apt/apt-pkg/algorithms.h  |  1 +
 apt/cmdline/apt-get.cc    | 29 ++++++++++++++++-
 3 files changed, 94 insertions(+), 2 deletions(-)

diff --git a/apt/apt-pkg/algorithms.cc b/apt/apt-pkg/algorithms.cc
index 1abd5df..c28c233 100644
--- a/apt/apt-pkg/algorithms.cc
+++ b/apt/apt-pkg/algorithms.cc
@@ -31,6 +31,7 @@
 #include <apti18n.h>
     
 #include <iostream>
+#include <map>
 									/*}}}*/
 using namespace std;
 
@@ -590,7 +591,70 @@ bool pkgMinimizeUpgrade(pkgDepCache &Cache)
    
    return true;
 }
-									/*}}}*/
+
+static bool all_revdeps_may_be_removed(const pkgDepCache &Cache, const pkgCache::PkgIterator &pkg_iter, std::map<std::string, bool> &states_cache_map)
+{
+	// Don't try to recursively traverse dependency loops
+	{
+		auto iter = states_cache_map.find(pkg_iter.Name());
+		if (iter != states_cache_map.end())
+		{
+			return iter->second;
+		}
+	}
+
+	bool mark_auto = Cache.getMarkAuto(pkg_iter);
+
+	// set auto mark to current state (this may be used to get out of infinite dependencies loop
+	states_cache_map[pkg_iter.Name()] = mark_auto;
+
+	// recursively check all dependencies
+	if (mark_auto)
+	{
+		for (pkgCache::DepIterator dep_iter = pkg_iter.RevDependsList(); mark_auto && (not dep_iter.end()); ++dep_iter)
+		{
+			// Skip packages not installed
+			if (dep_iter.ParentPkg()->CurrentState == pkgCache::State::Installed)
+			{
+				mark_auto &= all_revdeps_may_be_removed(Cache, dep_iter.ParentPkg(), states_cache_map);
+			}
+		}
+
+		// update mark to the final value
+		states_cache_map[pkg_iter.Name()] = mark_auto;
+	}
+
+	return mark_auto;
+}
+
+bool pkgAutoremove(pkgDepCache &Cache)
+{
+	if (Cache.BrokenCount() != 0)
+	{
+		return false;
+	}
+
+	// Check every installed package
+	for (pkgCache::PkgIterator pkg_iter = Cache.PkgBegin(); not pkg_iter.end(); ++pkg_iter)
+	{
+		// Skip packages not installed
+		if (pkg_iter->CurrentState == pkgCache::State::Installed)
+		{
+			// Keep a cache of dependencies for current package.
+			// Need to create clean cache for each package,
+			// otherwise when processing cyclic dependencies
+			// it may report invalid result and remove actually still needed package
+			std::map<std::string, bool> states_cache_map;
+
+			if (all_revdeps_may_be_removed(Cache, pkg_iter, states_cache_map))
+			{
+				Cache.MarkDelete(pkg_iter, _config->FindB("APT::Get::Purge",false));
+			}
+		}
+	}
+
+	return true;
+}
 
 // ProblemResolver::pkgProblemResolver - Constructor			/*{{{*/
 // ---------------------------------------------------------------------
diff --git a/apt/apt-pkg/algorithms.h b/apt/apt-pkg/algorithms.h
index 2117f77..f7ee654 100644
--- a/apt/apt-pkg/algorithms.h
+++ b/apt/apt-pkg/algorithms.h
@@ -134,6 +134,7 @@ bool pkgApplyStatus(pkgDepCache &Cache);
 bool pkgFixBroken(pkgDepCache &Cache);
 bool pkgAllUpgrade(pkgDepCache &Cache);
 bool pkgMinimizeUpgrade(pkgDepCache &Cache);
+bool pkgAutoremove(pkgDepCache &Cache);
 
 void pkgPrioSortList(pkgCache &Cache,pkgCache::Version **List);
 		     
diff --git a/apt/cmdline/apt-get.cc b/apt/cmdline/apt-get.cc
index 2a41b88..841f89d 100644
--- a/apt/cmdline/apt-get.cc
+++ b/apt/cmdline/apt-get.cc
@@ -2525,7 +2525,33 @@ bool DoMoo(CommandLine &CmdL)
 			    
    return true;
 }
-									/*}}}*/
+
+bool DoAutoremove(CommandLine &/*CmdL*/)
+{
+	CacheFile Cache(c1out);
+
+	if ((not Cache.OpenForInstall()) || (not Cache.CheckDeps()))
+	{
+		return false;
+	}
+
+	c0out << _("Calculating Autoremove... ") << std::flush;
+	if (not pkgAutoremove(*Cache))
+	{
+		c0out << _("Failed") << std::endl;
+		ShowBroken(std::cerr, Cache, false);
+		return false;
+	}
+
+	if (CheckOnly(Cache))
+	{
+		return true;
+	}
+
+	c0out << _("Done") << std::endl;
+
+	return InstallPackages(Cache, false);
+}
 
 // CNC:2003-03-18
 // DoScript - Scripting stuff.						/*{{{*/
@@ -2747,6 +2773,7 @@ int main(int argc,const char *argv[])
                                    {"check",&DoCheck},
 				   {"source",&DoSource},
 				   {"moo",&DoMoo},
+				   {"autoremove", &DoAutoremove},
 				   {"help",&ShowHelp},
 // CNC:2003-03-19
 #ifdef WITH_LUA