File: policy.cc

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// -*- mode: cpp; mode: fold -*-
// Description								/*{{{*/
// $Id: policy.cc,v 1.10 2003/08/12 00:17:37 mdz Exp $
/* ######################################################################

   Package Version Policy implementation
   
   This is just a really simple wrapper around pkgVersionMatch with
   some added goodies to manage the list of things..
   
   Priority Table:
   
   1000 -> inf = Downgradeable priorities
   1000        = The 'no downgrade' pseduo-status file
   100 -> 1000 = Standard priorities
   990         = Config file override package files
   989         = Start for preference auto-priorities
   500         = Default package files
   100         = The status file and ButAutomaticUpgrades sources
   0 -> 100    = NotAutomatic sources like experimental
   -inf -> 0   = Never selected   
   
   ##################################################################### */
									/*}}}*/
// Include Files							/*{{{*/
#include<config.h>

#include <apt-pkg/policy.h>
#include <apt-pkg/configuration.h>
#include <apt-pkg/cachefilter.h>
#include <apt-pkg/tagfile.h>
#include <apt-pkg/strutl.h>
#include <apt-pkg/fileutl.h>
#include <apt-pkg/error.h>
#include <apt-pkg/sptr.h>
#include <apt-pkg/cacheiterators.h>
#include <apt-pkg/pkgcache.h>
#include <apt-pkg/versionmatch.h>

#include <ctype.h>
#include <stddef.h>
#include <string.h>
#include <string>
#include <vector>
#include <iostream>
#include <sstream>

#include <apti18n.h>
									/*}}}*/

using namespace std;

// Policy::Init - Startup and bind to a cache				/*{{{*/
// ---------------------------------------------------------------------
/* Set the defaults for operation. The default mode with no loaded policy
   file matches the V0 policy engine. */
pkgPolicy::pkgPolicy(pkgCache *Owner) : Pins(0), PFPriority(0), Cache(Owner)
{
   if (Owner == 0 || &(Owner->Head()) == 0)
      return;
   PFPriority = new signed short[Owner->Head().PackageFileCount];
   Pins = new Pin[Owner->Head().PackageCount];

   for (unsigned long I = 0; I != Owner->Head().PackageCount; I++)
      Pins[I].Type = pkgVersionMatch::None;

   // The config file has a master override.
   string DefRel = _config->Find("APT::Default-Release");
   if (DefRel.empty() == false)
   {
      bool found = false;
      // FIXME: make ExpressionMatches static to use it here easily
      pkgVersionMatch vm("", pkgVersionMatch::None);
      for (pkgCache::PkgFileIterator F = Cache->FileBegin(); F != Cache->FileEnd(); ++F)
      {
	 if ((F->Archive != 0 && vm.ExpressionMatches(DefRel, F.Archive()) == true) ||
	     (F->Codename != 0 && vm.ExpressionMatches(DefRel, F.Codename()) == true) ||
	     (F->Version != 0 && vm.ExpressionMatches(DefRel, F.Version()) == true) ||
	     (DefRel.length() > 2 && DefRel[1] == '='))
	    found = true;
      }
      if (found == false)
	 _error->Error(_("The value '%s' is invalid for APT::Default-Release as such a release is not available in the sources"), DefRel.c_str());
      else
	 CreatePin(pkgVersionMatch::Release,"",DefRel,990);
   }
   InitDefaults();
}
									/*}}}*/
// Policy::InitDefaults - Compute the default selections		/*{{{*/
// ---------------------------------------------------------------------
/* */
bool pkgPolicy::InitDefaults()
{   
   // Initialize the priorities based on the status of the package file
   for (pkgCache::PkgFileIterator I = Cache->FileBegin(); I != Cache->FileEnd(); ++I)
   {
      PFPriority[I->ID] = 500;
      if ((I->Flags & pkgCache::Flag::NotSource) == pkgCache::Flag::NotSource)
	 PFPriority[I->ID] = 100;
      else if ((I->Flags & pkgCache::Flag::ButAutomaticUpgrades) == pkgCache::Flag::ButAutomaticUpgrades)
	 PFPriority[I->ID] = 100;
      else if ((I->Flags & pkgCache::Flag::NotAutomatic) == pkgCache::Flag::NotAutomatic)
	 PFPriority[I->ID] = 1;
   }

   // Apply the defaults..
   SPtrArray<bool> Fixed = new bool[Cache->HeaderP->PackageFileCount];
   memset(Fixed,0,sizeof(*Fixed)*Cache->HeaderP->PackageFileCount);
   signed Cur = 989;
   StatusOverride = false;
   for (vector<Pin>::const_iterator I = Defaults.begin(); I != Defaults.end();
	++I, --Cur)
   {
      pkgVersionMatch Match(I->Data,I->Type);
      for (pkgCache::PkgFileIterator F = Cache->FileBegin(); F != Cache->FileEnd(); ++F)
      {
	 if (Match.FileMatch(F) == true && Fixed[F->ID] == false)
	 {
	    if (I->Priority != 0 && I->Priority > 0)
	       Cur = I->Priority;
	    
	    if (I->Priority < 0)
	       PFPriority[F->ID] =  I->Priority;
	    else
	       PFPriority[F->ID] = Cur;
	    
	    if (PFPriority[F->ID] > 1000)
	       StatusOverride = true;
	    
	    Fixed[F->ID] = true;
	 }      
      }      
   }

   if (_config->FindB("Debug::pkgPolicy",false) == true)
      for (pkgCache::PkgFileIterator F = Cache->FileBegin(); F != Cache->FileEnd(); ++F)
	 std::clog << "Prio of " << F.FileName() << ' ' << PFPriority[F->ID] << std::endl; 
   
   return true;   
}
									/*}}}*/
// Policy::GetCandidateVer - Get the candidate install version		/*{{{*/
// ---------------------------------------------------------------------
/* Evaluate the package pins and the default list to deteremine what the
   best package is. */
pkgCache::VerIterator pkgPolicy::GetCandidateVer(pkgCache::PkgIterator const &Pkg)
{
   // Look for a package pin and evaluate it.
   signed Max = GetPriority(Pkg);
   pkgCache::VerIterator Pref = GetMatch(Pkg);

   // Alternatives in case we can not find our package pin (Bug#512318).
   signed MaxAlt = 0;
   pkgCache::VerIterator PrefAlt;

   // no package = no candidate version
   if (Pkg.end() == true)
      return Pref;

   // packages with a pin lower than 0 have no newer candidate than the current version
   if (Max < 0)
      return Pkg.CurrentVer();

   /* Falling through to the default version.. Setting Max to zero
      effectively excludes everything <= 0 which are the non-automatic
      priorities.. The status file is given a prio of 100 which will exclude
      not-automatic sources, except in a single shot not-installed mode.
      The second pseduo-status file is at prio 1000, above which will permit
      the user to force-downgrade things.
      
      The user pin is subject to the same priority rules as default 
      selections. Thus there are two ways to create a pin - a pin that
      tracks the default when the default is taken away, and a permanent
      pin that stays at that setting.
    */
   bool PrefSeen = false;
   for (pkgCache::VerIterator Ver = Pkg.VersionList(); Ver.end() == false; ++Ver)
   {
      /* Lets see if this version is the installed version */
      bool instVer = (Pkg.CurrentVer() == Ver);

      if (Pref == Ver)
	 PrefSeen = true;

      for (pkgCache::VerFileIterator VF = Ver.FileList(); VF.end() == false; ++VF)
      {
	 /* If this is the status file, and the current version is not the
	    version in the status file (ie it is not installed, or somesuch)
	    then it is not a candidate for installation, ever. This weeds
	    out bogus entries that may be due to config-file states, or
	    other. */
	 if ((VF.File()->Flags & pkgCache::Flag::NotSource) == pkgCache::Flag::NotSource &&
	     instVer == false)
	    continue;

	 signed Prio = PFPriority[VF.File()->ID];
	 if (Prio > Max)
	 {
	    Pref = Ver;
	    Max = Prio;
	    PrefSeen = true;
	 }
	 if (Prio > MaxAlt)
	 {
	    PrefAlt = Ver;
	    MaxAlt = Prio;
	 }
      }

      if (instVer == true && Max < 1000)
      {
	 /* Not having seen the Pref yet means we have a specific pin below 1000
	    on a version below the current installed one, so ignore the specific pin
	    as this would be a downgrade otherwise */
	 if (PrefSeen == false || Pref.end() == true)
	 {
	    Pref = Ver;
	    PrefSeen = true;
	 }
	 /* Elevate our current selection (or the status file itself)
	    to the Pseudo-status priority. */
	 Max = 1000;

	 // Fast path optimize.
	 if (StatusOverride == false)
	    break;
      }
   }
   // If we do not find our candidate, use the one with the highest pin.
   // This means that if there is a version available with pin > 0; there
   // will always be a candidate (Closes: #512318)
   if (!Pref.IsGood() && MaxAlt > 0)
       Pref = PrefAlt;

   return Pref;
}
									/*}}}*/
// Policy::CreatePin - Create an entry in the pin table..		/*{{{*/
// ---------------------------------------------------------------------
/* For performance we have 3 tables, the default table, the main cache
   table (hashed to the cache). A blank package name indicates the pin
   belongs to the default table. Order of insertion matters here, the
   earlier defaults override later ones. */
void pkgPolicy::CreatePin(pkgVersionMatch::MatchType Type,string Name,
			  string Data,signed short Priority)
{
   if (Name.empty() == true)
   {
      Pin *P = &*Defaults.insert(Defaults.end(),Pin());
      P->Type = Type;
      P->Priority = Priority;
      P->Data = Data;
      return;
   }

   size_t found = Name.rfind(':');
   string Arch;
   if (found != string::npos) {
      Arch = Name.substr(found+1);
      Name.erase(found);
   }

   // Allow pinning by wildcards
   // TODO: Maybe we should always prefer specific pins over non-
   // specific ones.
   if (Name[0] == '/' || Name.find_first_of("*[?") != string::npos)
   {
      pkgVersionMatch match(Data, Type);
      for (pkgCache::GrpIterator G = Cache->GrpBegin(); G.end() != true; ++G)
	 if (match.ExpressionMatches(Name, G.Name()))
	 {
	    if (Arch.empty() == false)
	       CreatePin(Type, string(G.Name()).append(":").append(Arch), Data, Priority);
	    else
	       CreatePin(Type, G.Name(), Data, Priority);
	 }
      return;
   }

   // find the package (group) this pin applies to
   pkgCache::GrpIterator Grp = Cache->FindGrp(Name);
   bool matched = false;
   if (Grp.end() == false)
   {
      std::string MatchingArch;
      if (Arch.empty() == true)
	 MatchingArch = Cache->NativeArch();
      else
	 MatchingArch = Arch;
      APT::CacheFilter::PackageArchitectureMatchesSpecification pams(MatchingArch);
      for (pkgCache::PkgIterator Pkg = Grp.PackageList(); Pkg.end() != true; Pkg = Grp.NextPkg(Pkg))
      {
	 if (pams(Pkg.Arch()) == false)
	    continue;
	 Pin *P = Pins + Pkg->ID;
	 // the first specific stanza for a package is the ruler,
	 // all others need to be ignored
	 if (P->Type != pkgVersionMatch::None)
	    P = &*Unmatched.insert(Unmatched.end(),PkgPin(Pkg.FullName()));
	 P->Type = Type;
	 P->Priority = Priority;
	 P->Data = Data;
	 matched = true;
      }
   }

   if (matched == false)
   {
      PkgPin *P = &*Unmatched.insert(Unmatched.end(),PkgPin(Name));
      if (Arch.empty() == false)
	 P->Pkg.append(":").append(Arch);
      P->Type = Type;
      P->Priority = Priority;
      P->Data = Data;
      return;
   }
}
									/*}}}*/
// Policy::GetMatch - Get the matching version for a package pin	/*{{{*/
// ---------------------------------------------------------------------
/* */
pkgCache::VerIterator pkgPolicy::GetMatch(pkgCache::PkgIterator const &Pkg)
{
   const Pin &PPkg = Pins[Pkg->ID];
   if (PPkg.Type == pkgVersionMatch::None)
      return pkgCache::VerIterator(*Pkg.Cache());

   pkgVersionMatch Match(PPkg.Data,PPkg.Type);
   return Match.Find(Pkg);
}
									/*}}}*/
// Policy::GetPriority - Get the priority of the package pin		/*{{{*/
// ---------------------------------------------------------------------
/* */
APT_PURE signed short pkgPolicy::GetPriority(pkgCache::PkgIterator const &Pkg)
{
   if (Pins[Pkg->ID].Type != pkgVersionMatch::None)
   {
      // In this case 0 means default priority
      if (Pins[Pkg->ID].Priority == 0)
	 return 989;
      return Pins[Pkg->ID].Priority;
   }
   
   return 0;
}
APT_PURE signed short pkgPolicy::GetPriority(pkgCache::PkgFileIterator const &File)
{
   return PFPriority[File->ID];
}
									/*}}}*/
// PreferenceSection class - Overriding the default TrimRecord method	/*{{{*/
// ---------------------------------------------------------------------
/* The preference file is a user generated file so the parser should
   therefore be a bit more friendly by allowing comments and new lines
   all over the place rather than forcing a special format */
class PreferenceSection : public pkgTagSection
{
   void TrimRecord(bool /*BeforeRecord*/, const char* &End)
   {
      for (; Stop < End && (Stop[0] == '\n' || Stop[0] == '\r' || Stop[0] == '#'); Stop++)
	 if (Stop[0] == '#')
	    Stop = (const char*) memchr(Stop,'\n',End-Stop);
   }
};
									/*}}}*/
// ReadPinDir - Load the pin files from this dir into a Policy		/*{{{*/
// ---------------------------------------------------------------------
/* This will load each pin file in the given dir into a Policy. If the
   given dir is empty the dir set in Dir::Etc::PreferencesParts is used.
   Note also that this method will issue a warning if the dir does not
   exists but it will return true in this case! */
bool ReadPinDir(pkgPolicy &Plcy,string Dir)
{
   if (Dir.empty() == true)
      Dir = _config->FindDir("Dir::Etc::PreferencesParts");

   if (DirectoryExists(Dir) == false)
   {
      _error->WarningE("DirectoryExists",_("Unable to read %s"),Dir.c_str());
      return true;
   }

   vector<string> const List = GetListOfFilesInDir(Dir, "pref", true, true);

   // Read the files
   for (vector<string>::const_iterator I = List.begin(); I != List.end(); ++I)
      if (ReadPinFile(Plcy, *I) == false)
	 return false;
   return true;
}
									/*}}}*/
// ReadPinFile - Load the pin file into a Policy			/*{{{*/
// ---------------------------------------------------------------------
/* I'd like to see the preferences file store more than just pin information
   but right now that is the only stuff I have to store. Later there will
   have to be some kind of combined super parser to get the data into all
   the right classes.. */
bool ReadPinFile(pkgPolicy &Plcy,string File)
{
   if (File.empty() == true)
      File = _config->FindFile("Dir::Etc::Preferences");

   if (RealFileExists(File) == false)
      return true;
   
   FileFd Fd(File,FileFd::ReadOnly);
   pkgTagFile TF(&Fd);
   if (_error->PendingError() == true)
      return false;
   
   PreferenceSection Tags;
   while (TF.Step(Tags) == true)
   {
      // can happen when there are only comments in a record
      if (Tags.Count() == 0)
         continue;

      string Name = Tags.FindS("Package");
      if (Name.empty() == true)
	 return _error->Error(_("Invalid record in the preferences file %s, no Package header"), File.c_str());
      if (Name == "*")
	 Name = string();
      
      const char *Start;
      const char *End;
      if (Tags.Find("Pin",Start,End) == false)
	 continue;
	 
      const char *Word = Start;
      for (; Word != End && isspace(*Word) == 0; Word++);

      // Parse the type..
      pkgVersionMatch::MatchType Type;
      if (stringcasecmp(Start,Word,"version") == 0 && Name.empty() == false)
	 Type = pkgVersionMatch::Version;
      else if (stringcasecmp(Start,Word,"release") == 0)
	 Type = pkgVersionMatch::Release;
      else if (stringcasecmp(Start,Word,"origin") == 0)
	 Type = pkgVersionMatch::Origin;
      else
      {
	 _error->Warning(_("Did not understand pin type %s"),string(Start,Word).c_str());
	 continue;
      }
      for (; Word != End && isspace(*Word) != 0; Word++);

      short int priority = Tags.FindI("Pin-Priority", 0);
      if (priority == 0)
      {
         _error->Warning(_("No priority (or zero) specified for pin"));
         continue;
      }

      istringstream s(Name);
      string pkg;
      while(!s.eof())
      {
	 s >> pkg;
         Plcy.CreatePin(Type, pkg, string(Word,End),priority);
      };
   }

   Plcy.InitDefaults();
   return true;
}
									/*}}}*/