Do not read stderr from proxy autodetection scripts

This fixes a regression introduced in
  commit 8f858d560e3b7b475c623c4e242d1edce246025a

  don't leak FD in AutoProxyDetect command return parsing

which accidentally made the proxy autodetection code also read
the scripts output on stderr, not only on stdout when it switched
the code from popen() to Popen().

Reported-By: Tim Small <tim@seoss.co.uk>
(cherry picked from commit 0ecceb5bb9cc8727c117195945b7116aceb984fe)

2 files changed, 35 insertions, 0 deletions

diff --git a/test/libapt/apt-proxy-script b/test/libapt/apt-proxy-script
new file mode 100755
index 000000000..41cfdc30f
--- /dev/null
+++ b/test/libapt/apt-proxy-script
@@ -0,0 +1,9 @@
+#!/bin/sh
+
+if [ $1 = "http://www.debian.org:90/temp/test" ]; then
+    echo "http://example.com"
+fi
+if [ $1 = "http://www.debian.org:91/temp/test" ]; then
+    echo "This works" >&2
+    echo "http://example.com/foo"
+fi
diff --git a/test/libapt/uri_test.cc b/test/libapt/uri_test.cc
index 8296ca6a0..09d018049 100644
--- a/test/libapt/uri_test.cc
+++ b/test/libapt/uri_test.cc
@@ -1,4 +1,6 @@
 #include <config.h>
+#include <apt-pkg/configuration.h>
+#include <apt-pkg/proxy.h>
 #include <apt-pkg/strutl.h>
 #include <string>
 #include <gtest/gtest.h>
@@ -188,3 +190,27 @@ TEST(URITest, RFC2732)
    EXPECT_EQ("ftp://example.org", URI::ArchiveOnly(U));
    EXPECT_EQ("ftp://example.org/", URI::NoUserPassword(U));
 }
+TEST(URITest, AutoProxyTest)
+{
+   URI u0("http://www.debian.org:90/temp/test");
+   URI u1("http://www.debian.org:91/temp/test");
+
+   _config->Set("Acquire::http::Proxy-Auto-Detect", "./apt-proxy-script");
+
+   // Scenario 0: Autodetecting a simple proxy
+   AutoDetectProxy(u0);
+   EXPECT_EQ(_config->Find("Acquire::http::proxy::www.debian.org", ""), "http://example.com");
+
+   // Scenario 1: Proxy stays the same if it is already set
+   AutoDetectProxy(u1);
+   EXPECT_EQ(_config->Find("Acquire::http::proxy::www.debian.org", ""), "http://example.com");
+
+   // Scenario 2: Reading with stderr output works fine
+   _config->Clear("Acquire::http::proxy::www.debian.org");
+   AutoDetectProxy(u1);
+   EXPECT_EQ(_config->Find("Acquire::http::proxy::www.debian.org", ""), "http://example.com/foo");
+
+   // Scenario 1 again: Proxy stays the same if it is already set
+   AutoDetectProxy(u0);
+   EXPECT_EQ(_config->Find("Acquire::http::proxy::www.debian.org", ""), "http://example.com/foo");
+}