Add support for /etc/apt/auth.conf.d/*.conf (netrcparts)

This allows us to install matching auth files for sources.list.d
files, for example; very useful.

This converts aptmethod's authfd from one FileFd to a vector of
pointers to FileFd, as FileFd cannot be copied, and move operators
are hard.

(cherry picked from commit bbfcc05c1978decd28df9681fd73e2a7d9a8c2a5)
LP: #1811120
(cherry picked from commit 5629f35ecb7956b180364ebaf57e79f35885344e)

5 files changed, 56 insertions, 13 deletions

diff --git a/apt-pkg/init.cc b/apt-pkg/init.cc
index 927a5cca0..6952267cf 100644
--- a/apt-pkg/init.cc
+++ b/apt-pkg/init.cc
@@ -151,6 +151,7 @@ bool pkgInitConfig(Configuration &Cnf)
    Cnf.CndSet("Dir::Etc::sourceparts","sources.list.d");
    Cnf.CndSet("Dir::Etc::main","apt.conf");
    Cnf.CndSet("Dir::Etc::netrc", "auth.conf");
+   Cnf.CndSet("Dir::Etc::netrcparts", "auth.conf.d");
    Cnf.CndSet("Dir::Etc::parts","apt.conf.d");
    Cnf.CndSet("Dir::Etc::preferences","preferences");
    Cnf.CndSet("Dir::Etc::preferencesparts","preferences.d");
diff --git a/doc/apt_auth.conf.5.xml b/doc/apt_auth.conf.5.xml
index 8621cdee2..fc5d9d1be 100644
--- a/doc/apt_auth.conf.5.xml
+++ b/doc/apt_auth.conf.5.xml
@@ -36,7 +36,8 @@ needed to connect to a proxy or to download data from a repository on the other
 hand shouldn't always be accessible by everyone and can hence not be placed in a
 file with world-readable file permissions.</para>
 
-<para>The APT auth.conf file <filename>/etc/apt/auth.conf</filename> can be used to store
+<para>The APT auth.conf file <filename>/etc/apt/auth.conf</filename>, and .conf files inside
+<filename>/etc/apt/auth.conf.d</filename> can be used to store
 login information in a netrc-like format with restrictive file permissions.</para>
 </refsect1>
 
@@ -119,6 +120,10 @@ you need multiple they should all have a path specified in the
 	<listitem><para>Login information for APT sources and proxies in a netrc-like format.
 	Configuration Item: <literal>Dir::Etc::netrc</literal>.</para></listitem>
      </varlistentry>
+     <varlistentry><term><filename>/etc/apt/auth.conf.d/*.conf</filename></term>
+	<listitem><para>Login information for APT sources and proxies in a netrc-like format.
+	Configuration Item: <literal>Dir::Etc::netrcparts</literal>.</para></listitem>
+     </varlistentry>
   </variablelist>
 </refsect1>
 
diff --git a/doc/examples/configure-index b/doc/examples/configure-index
index 71ec57be0..df91d7738 100644
--- a/doc/examples/configure-index
+++ b/doc/examples/configure-index
@@ -398,6 +398,7 @@ Dir "<DIR>"
   Etc "<DIR>" {
      Main "<FILE>";
      Netrc "<FILE>";
+     NetrcParts "<DIR>";
      Parts "<DIR>";
      Preferences "<FILE>";
      PreferencesParts "<DIR>";
diff --git a/methods/aptmethod.h b/methods/aptmethod.h
index cb5a30e21..f6613ac3b 100644
--- a/methods/aptmethod.h
+++ b/methods/aptmethod.h
@@ -11,6 +11,7 @@
 
 #include <algorithm>
 #include <locale>
+#include <memory>
 #include <string>
 #include <vector>
 
@@ -471,8 +472,9 @@ protected:
 };
 class aptAuthConfMethod : public aptMethod
 {
-   FileFd authconf;
-public:
+   std::vector<std::unique_ptr<FileFd>> authconfs;
+
+   public:
    virtual bool Configuration(std::string Message) APT_OVERRIDE
    {
       if (pkgAcqMethod::Configuration(Message) == false)
@@ -481,14 +483,25 @@ public:
       std::string const conf = std::string("Binary::") + Binary;
       _config->MoveSubTree(conf.c_str(), NULL);
 
+      // ignore errors with opening the auth file as it doesn't need to exist
+      _error->PushToStack();
       auto const netrc = _config->FindFile("Dir::Etc::netrc");
       if (netrc.empty() == false)
       {
-	 // ignore errors with opening the auth file as it doesn't need to exist
-	 _error->PushToStack();
-	 authconf.Open(netrc, FileFd::ReadOnly);
-	 _error->RevertToStack();
+	 authconfs.emplace_back(new FileFd());
+	 authconfs.back()->Open(netrc, FileFd::ReadOnly);
+      }
+
+      auto const netrcparts = _config->FindDir("Dir::Etc::netrcparts");
+      if (netrcparts.empty() == false)
+      {
+	 for (auto const &netrc : GetListOfFilesInDir(netrcparts, "conf", true, true))
+	 {
+	    authconfs.emplace_back(new FileFd());
+	    authconfs.back()->Open(netrc, FileFd::ReadOnly);
+	 }
       }
+      _error->RevertToStack();
 
       DropPrivsOrDie();
 
@@ -500,13 +513,25 @@ public:
 
    bool MaybeAddAuthTo(URI &uri)
    {
+      bool result = true;
+
       if (uri.User.empty() == false || uri.Password.empty() == false)
 	 return true;
-      if (authconf.IsOpen() == false)
-	 return true;
-      if (authconf.Seek(0) == false)
-	 return false;
-      return MaybeAddAuth(authconf, uri);
+
+      for (auto &authconf : authconfs)
+      {
+	 if (authconf->IsOpen() == false)
+	    continue;
+	 if (authconf->Seek(0) == false)
+	 {
+	    result = false;
+	    continue;
+	 }
+
+	 result &= MaybeAddAuth(*authconf, uri);
+      }
+
+      return result;
    }
 
    aptAuthConfMethod(std::string &&Binary, char const *const Ver, unsigned long const Flags) APT_NONNULL(3)
diff --git a/test/integration/test-authentication-basic b/test/integration/test-authentication-basic
index 011f205af..211c73e35 100755
--- a/test/integration/test-authentication-basic
+++ b/test/integration/test-authentication-basic
@@ -53,7 +53,8 @@ Conf foo (1 unstable [all])' aptget install foo -s
 }
 
 authfile() {
-	local AUTHCONF='rootdir/etc/apt/auth.conf'
+	local AUTHCONF="${2:-rootdir/etc/apt/auth.conf}"
+	mkdir -p "$(dirname "$AUTHCONF")"
 	rm -f "$AUTHCONF"
 	printf '%s' "$1" > "$AUTHCONF"
 	chmod 600 "$AUTHCONF"
@@ -85,6 +86,16 @@ machine localhost
 login star@irc
 password hunter2'
 	testauthsuccess "$1"
+
+	# delete file, make sure it fails; add auth.conf.d snippet, works again.
+	rm rootdir/etc/apt/auth.conf
+	testauthfailure "$1"
+
+	authfile  'machine localhost
+login star@irc
+password hunter2' rootdir/etc/apt/auth.conf.d/myauth.conf
+	testauthsuccess "$1"
+	rm rootdir/etc/apt/auth.conf.d/myauth.conf
 }
 
 msgmsg 'server basic auth'