From 450af26202424bef33e0c58f3f99dfd0c21e7297 Mon Sep 17 00:00:00 2001
From: Julian Andres Klode <julian.klode@canonical.com>
Date: Fri, 17 Jan 2020 13:18:03 +0100
Subject: policy: Implement pinning by source package

This implements the src: syntax inside policy, allowing you to
pin by source package. This by default only pins the native
architecuture, use src:pkg:any to pin for all architectures
in your cache.

Closes: #166032
---
 apt-pkg/policy.cc         | 57 +++++++++++++++++++++++++++++++++++------------
 doc/apt_preferences.5.xml | 21 +++++++++++++++++
 2 files changed, 64 insertions(+), 14 deletions(-)

diff --git a/apt-pkg/policy.cc b/apt-pkg/policy.cc
index b9bdfd20f..618e17e0b 100644
--- a/apt-pkg/policy.cc
+++ b/apt-pkg/policy.cc
@@ -175,6 +175,11 @@ void pkgPolicy::CreatePin(pkgVersionMatch::MatchType Type,string Name,
       return;
    }
 
+   bool IsSourcePin = APT::String::Startswith(Name, "src:");
+   if (IsSourcePin) {
+      Name = Name.substr(sizeof("src:") - 1);
+   }
+
    size_t found = Name.rfind(':');
    string Arch;
    if (found != string::npos) {
@@ -190,10 +195,11 @@ void pkgPolicy::CreatePin(pkgVersionMatch::MatchType Type,string Name,
       for (pkgCache::GrpIterator G = Cache->GrpBegin(); G.end() != true; ++G)
 	 if (Name != G.Name() && match.ExpressionMatches(Name, G.Name()))
 	 {
+	    auto NameToPinFor = IsSourcePin ? string("src:").append(G.Name()) : string(G.Name());
 	    if (Arch.empty() == false)
-	       CreatePin(Type, string(G.Name()).append(":").append(Arch), Data, Priority);
+	       CreatePin(Type, NameToPinFor.append(":").append(Arch), Data, Priority);
 	    else
-	       CreatePin(Type, G.Name(), Data, Priority);
+	       CreatePin(Type, NameToPinFor, Data, Priority);
 	 }
       return;
    }
@@ -209,20 +215,19 @@ void pkgPolicy::CreatePin(pkgVersionMatch::MatchType Type,string Name,
       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;
-
-	 PkgPin P(Pkg.FullName());
-	 P.Type = Type;
-	 P.Priority = Priority;
-	 P.Data = Data;
 
-	 // Find matching version(s) and copy the pin into it
-	 pkgVersionMatch Match(P.Data,P.Type);
-	 for (pkgCache::VerIterator Ver = Pkg.VersionList(); Ver.end() != true; ++Ver)
+      if (IsSourcePin) {
+	 for (pkgCache::VerIterator Ver = Grp.VersionsInSource(); not Ver.end(); Ver = Ver.NextInSource())
 	 {
+	    if (pams(Ver.ParentPkg().Arch()) == false)
+	       continue;
+
+	    PkgPin P(Ver.ParentPkg().FullName());
+	    P.Type = Type;
+	    P.Priority = Priority;
+	    P.Data = Data;
+	    // Find matching version(s) and copy the pin into it
+	    pkgVersionMatch Match(P.Data,P.Type);
 	    if (Match.VersionMatches(Ver)) {
 	       Pin *VP = VerPins + Ver->ID;
 	       if (VP->Type == pkgVersionMatch::None) {
@@ -231,6 +236,30 @@ void pkgPolicy::CreatePin(pkgVersionMatch::MatchType Type,string Name,
 	       }
 	    }
 	 }
+      } else {
+	 for (pkgCache::PkgIterator Pkg = Grp.PackageList(); Pkg.end() != true; Pkg = Grp.NextPkg(Pkg))
+	 {
+	    if (pams(Pkg.Arch()) == false)
+	       continue;
+
+	    PkgPin P(Pkg.FullName());
+	    P.Type = Type;
+	    P.Priority = Priority;
+	    P.Data = Data;
+
+	    // Find matching version(s) and copy the pin into it
+	    pkgVersionMatch Match(P.Data,P.Type);
+	    for (pkgCache::VerIterator Ver = Pkg.VersionList(); Ver.end() != true; ++Ver)
+	    {
+	       if (Match.VersionMatches(Ver)) {
+		  Pin *VP = VerPins + Ver->ID;
+		  if (VP->Type == pkgVersionMatch::None) {
+		     *VP = P;
+		      matched = true;
+		  }
+	       }
+	    }
+	 }
       }
    }
 
diff --git a/doc/apt_preferences.5.xml b/doc/apt_preferences.5.xml
index cac9a96e1..dacf3dc21 100644
--- a/doc/apt_preferences.5.xml
+++ b/doc/apt_preferences.5.xml
@@ -303,7 +303,28 @@ a &glob; expression in itself.
 </para>
 </refsect2>
 
+<refsect2><title>Pinning by source package</title>
+<para>APT supports pinning by source packages. To pin by a source package,
+prepend "src:" to the package name.</para>
+<para>For example, to pin all binaries produced by the apt source package
+of this APT's version to 990, you can do:</para>
 
+<programlisting>
+Package: src:apt
+Pin: version &apt-product-version;
+Pin-Priority: 990
+</programlisting>
+
+<para>Source package pinning can be combined with regular expressions and
+glob patterns, and can also take a binary architecture.</para>
+<para>For example, let's pin all binaries for all architectures produced by
+any source package containing apt in its name to 990:</para>
+<programlisting>
+Package: src:*apt*:any
+Pin: version *
+Pin-Priority: 990
+</programlisting>
+</refsect2>
 
 
 
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