Merge EDSP 0.5 w/ multi-arch support for external solvers

"I am going to merge it tomorrow…"

apt-pkg/edsp.cc

@@ -18,6 +18,7 @@
 #include <apt-pkg/pkgcache.h>
 #include <apt-pkg/cacheiterators.h>
 #include <apt-pkg/strutl.h>
+#include <apt-pkg/pkgrecords.h>
 
 #include <ctype.h>
 #include <stddef.h>
@@ -87,7 +88,12 @@ bool EDSP::WriteLimitedScenario(pkgDepCache &Cache, FILE* output,
 void EDSP::WriteScenarioVersion(pkgDepCache &Cache, FILE* output, pkgCache::PkgIterator const &Pkg,
 				pkgCache::VerIterator const &Ver)
 {
+   pkgRecords Recs(Cache);
+   pkgRecords::Parser &rec = Recs.Lookup(Ver.FileList());
+   string srcpkg = rec.SourcePkg().empty() ? Pkg.Name() : rec.SourcePkg();
+
    fprintf(output, "Package: %s\n", Pkg.Name());
+   fprintf(output, "Source: %s\n", srcpkg.c_str());
    fprintf(output, "Architecture: %s\n", Ver.Arch());
    fprintf(output, "Version: %s\n", Ver.VerStr());
    if (Pkg.CurrentVer() == Ver)
@@ -107,10 +113,22 @@ void EDSP::WriteScenarioVersion(pkgDepCache &Cache, FILE* output, pkgCache::PkgI
    else if ((Ver->MultiArch & pkgCache::Version::Same) == 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());
+   std::set<string> Releases;
+   for (pkgCache::VerFileIterator I = Ver.FileList(); I.end() == false; ++I) {
+      pkgCache::PkgFileIterator File = I.File();
+      signed short const p = Cache.GetPolicy().GetPriority(File);
       if (Pin < p)
 	 Pin = p;
+      if ((File->Flags & pkgCache::Flag::NotSource) != pkgCache::Flag::NotSource) {
+	 string Release = File.RelStr();
+	 if (!Release.empty())
+	    Releases.insert(Release);
+      }
+   }
+   if (!Releases.empty()) {
+       fprintf(output, "APT-Release:\n");
+       for (std::set<string>::iterator R = Releases.begin(); R != Releases.end(); ++R)
+	   fprintf(output, " %s\n", R->c_str());
    }
    fprintf(output, "APT-Pin: %d\n", Pin);
    if (Cache.GetCandidateVer(Pkg) == Ver)
@@ -231,7 +249,16 @@ bool EDSP::WriteRequest(pkgDepCache &Cache, FILE* output, bool const Upgrade,
 	 continue;
       req->append(" ").append(Pkg.FullName());
    }
-   fprintf(output, "Request: EDSP 0.4\n");
+   fprintf(output, "Request: EDSP 0.5\n");
+
+   const char *arch = _config->Find("APT::Architecture").c_str();
+   std::vector<string> archs = APT::Configuration::getArchitectures();
+   fprintf(output, "Architecture: %s\n", arch);
+   fprintf(output, "Architectures:");
+   for (std::vector<string>::const_iterator a = archs.begin(); a != archs.end(); ++a)
+       fprintf(output, " %s", a->c_str());
+   fprintf(output, "\n");
+
    if (del.empty() == false)
       fprintf(output, "Remove: %s\n", del.c_str()+1);
    if (inst.empty() == false)

doc/external-dependency-solver-protocol.txt

@@ -1,4 +1,4 @@
-# APT External Dependency Solver Protocol (EDSP) - version 0.4
+# APT External Dependency Solver Protocol (EDSP) - version 0.5
 
 This document describes the communication protocol between APT and
 external dependency solvers. The protocol is called APT EDSP, for "APT
@@ -110,16 +110,24 @@ Within a dependency solving scenario, a request represents the action on
 installed packages requested by the user.
 
 A request is a single Deb 822 stanza opened by a mandatory Request field
-and followed by a mixture of action and preference fields.
+and followed by a mixture of action, preference, and global
+configuration fields.
 
 The value of the **Request:** field is a string describing the EDSP
 protocol which will be used to communicate. At present, the string must
-be `EDSP 0.4`.
+be `EDSP 0.5`. Request fields are mainly used to identify the beginning
+of a request stanza; their actual values are otherwise not used by the
+EDSP protocol.
 
-a unique request identifier, such as an
-UUID. Request fields are mainly used to identify the beginning of a
-request stanza; their actual values are otherwise not used by the EDSP
-protocol.
+The following **configuration fields** are supported in request stanzas:
+
+- **Architecture:** (mandatory) The name of the *native* architecture on
+  the user machine (see also: `dpkg --print-architecture`)
+
+- **Architectures:** (optional, defaults to the native architecture) A
+  space separated list of *all* architectures known to APT (this is
+  roughly equivalent to the union of `dpkg --print-architecture` and
+  `dpkg --print-foreign-architectures`)
 
 The following **action fields** are supported in request stanzas:
 
@@ -201,6 +209,15 @@ field. The following fields are supported in package stanzas:
   should be removed by the solver only when the Autoremove action is
   requested (see Request section).
 
+- **APT-Release:** (optional) The releases the package belongs to, according to
+  APT. The format of this field is multiline with one value per line and the
+  first line (the one containing the field name) empty. Each subsequent line
+  corresponds to one of the releases the package belongs to and looks like
+  this: `o=Debian,a=unstable,n=sid,l=Debian,c=main`. That is, each release line
+  is a comma-separated list of "key=value" pairs, each of which denotes a
+  Release file entry (Origin, Label, Codename, etc.) in the format of
+  APT_PREFERENCES(5).
+
 ### Answer
 
 An answer from the external solver to APT is either a *solution* or an