add hidden config to set packages as Essential/Important

You can pretty much achieve the same with a local dummy package if you
want to, but libapt has an inbuilt setting for essential: "apt" which
can be overridden with this option as well – it could be helpful in
quick tests and what not so adding this alternative shouldn't really
hurt much.

We aren't going to document them much through as care must be taken in
regards to the binary caches as they aren't invalidated by config
options alone, so the effects of old settings could still be in them,
similar to the other already existing pkgCacheGen option(s).

Closes: 767891
Thanks: Anthony Towns for initial patch

2 files changed, 16 insertions, 4 deletions

diff --git a/apt-pkg/deb/deblistparser.cc b/apt-pkg/deb/deblistparser.cc
index 99e806470..0f9fe310f 100644
--- a/apt-pkg/deb/deblistparser.cc
+++ b/apt-pkg/deb/deblistparser.cc
@@ -50,8 +50,18 @@ static const debListParser::WordList PrioList[] = {
    in Step(), if no Architecture is given we will accept every arch
    we would accept in general with checkArchitecture() */
 debListParser::debListParser(FileFd *File) :
-   pkgCacheListParser(), d(NULL), Tags(File)
+   pkgCacheListParser(), Tags(File)
 {
+   // this dance allows an empty value to override the default
+   if (_config->Exists("pkgCacheGen::ForceEssential"))
+   {
+      forceEssential = _config->FindVector("pkgCacheGen::ForceEssential");
+      if (forceEssential.empty() == false && _config->Find("pkgCacheGen::ForceEssential").empty())
+	 forceEssential.emplace_back("apt");
+   }
+   else
+      forceEssential.emplace_back("apt");
+   forceImportant = _config->FindVector("pkgCacheGen::ForceImportant");
 }
 									/*}}}*/
 // ListParser::Package - Return the package name			/*{{{*/
@@ -311,7 +321,7 @@ bool debListParser::UsePackage(pkgCache::PkgIterator &Pkg,
    if (Section.FindFlag("Important",Pkg->Flags,pkgCache::Flag::Important) == false)
       return false;
 
-   if (strcmp(Pkg.Name(),"apt") == 0)
+   if (std::find(forceEssential.begin(), forceEssential.end(), Pkg.Name()) != forceEssential.end())
    {
       if ((essential == "native" && Pkg->Arch != 0 && myArch == Pkg.Arch()) ||
 	  essential == "all")
@@ -319,6 +329,8 @@ bool debListParser::UsePackage(pkgCache::PkgIterator &Pkg,
       else
 	 Pkg->Flags |= pkgCache::Flag::Important;
    }
+   else if (std::find(forceImportant.begin(), forceImportant.end(), Pkg.Name()) != forceImportant.end())
+      Pkg->Flags |= pkgCache::Flag::Important;
 
    if (ParseStatus(Pkg,Ver) == false)
       return false;
diff --git a/apt-pkg/deb/deblistparser.h b/apt-pkg/deb/deblistparser.h
index a78312f9d..102cd62aa 100644
--- a/apt-pkg/deb/deblistparser.h
+++ b/apt-pkg/deb/deblistparser.h
@@ -43,8 +43,8 @@ class APT_HIDDEN debListParser : public pkgCacheListParser
 #endif
 
    private:
-   /** \brief dpointer placeholder (for later in case we need it) */
-   void * const d;
+   std::vector<std::string> forceEssential;
+   std::vector<std::string> forceImportant;
 
    protected:
    pkgTagFile Tags;