If - is specified as a config file, we will use stdin instead, after
seeking to 0. This will be used to implement configuration passing
for apt-key.

apt-pkg/contrib/configuration.cc

@@ -681,8 +681,13 @@ static void leaveCurrentScope(std::stack<std::string> &Stack, std::string &Paren
 bool ReadConfigFile(Configuration &Conf,const string &FName,bool const &AsSectional,
 		    unsigned const &Depth)
 {
-   // Open the stream for reading
-   ifstream F(FName.c_str(),ios::in);
+   if (FName == "-") {
+      lseek(STDIN_FILENO, 0, SEEK_SET);
+   }
+
+   ifstream FStream(FName.c_str(),ios::in);
+   istream &F = FName == "-" ? cin : FStream;
+
    if (F.fail() == true)
       return _error->Errno("ifstream::ifstream",_("Opening configuration file %s"),FName.c_str());
 

apt-pkg/contrib/gpgv.cc

@@ -18,9 +18,11 @@
 #include <stddef.h>
 
 #include <algorithm>
+#include <fstream>
 #include <iostream>
 #include <string>
 #include <vector>
+#include <ext/stdio_filebuf.h>
 
 #include <apti18n.h>
 									/*}}}*/
@@ -32,6 +34,22 @@ static char * GenerateTemporaryFileTemplate(const char *basename)	/*{{{*/
    return strdup(out.c_str());
 }
 									/*}}}*/
+static int OpenAnonymousTemporaryFile(const char *basename)	/*{{{*/
+{
+   char * filename = GenerateTemporaryFileTemplate(basename);
+
+   if (filename == nullptr)
+      return -1;
+
+   int const fd = mkstemp(filename);
+   if (fd == -1)
+      return -1;
+
+   unlink(filename);
+   free(filename);
+   return fd;
+}
+									/*}}}*/
 // ExecGPGV - returns the command needed for verify			/*{{{*/
 // ---------------------------------------------------------------------
 /* Generating the commandline for calling gpg is somehow complicated as
@@ -98,6 +116,29 @@ void ExecGPGV(std::string const &File, std::string const &FileGPG,
    char * sig = NULL;
    char * data = NULL;
 
+   int confFd = OpenAnonymousTemporaryFile("apt.conf");
+
+   if (confFd == -1) {
+      ioprintf(std::cerr, "Couldn't create tempfile names for passing config to apt-key during verification of %s", File.c_str());
+      exit(EINTERNAL);
+   }
+
+   __gnu_cxx::stdio_filebuf<char> filebuf(confFd, std::ios::out);
+   std::ostream configStream(&filebuf);
+   {
+      _config->Dump(configStream);
+      configStream.flush();
+
+      if (configStream.fail() == true) {
+	 ioprintf(std::cerr, "Couldn't write temporary apt config file to pass to apt-key");
+	 exit(EINTERNAL);
+      }
+
+      setenv("APT_CONFIG", "-", 1);
+      // Dup the conf fd to stdin, so we can pass it to apt-key anonymously
+      dup2(confFd, STDIN_FILENO);
+   }
+
    if (releaseSignature == DETACHED)
    {
       Args.push_back(FileGPG.c_str());

apt-pkg/init.cc

@@ -128,7 +128,7 @@ bool pkgInitConfig(Configuration &Cnf)
    const char *Cfg = getenv("APT_CONFIG");
    if (Cfg != 0 && strlen(Cfg) != 0)
    {
-      if (RealFileExists(Cfg) == true)
+      if (RealFileExists(Cfg) == true || strcmp(Cfg, "-") == 0)
 	 Res &= ReadConfigFile(Cnf,Cfg);
       else
 	 _error->WarningE("RealFileExists",_("Unable to read %s"),Cfg);