Fix possible memory overwrite in init_from_environment().

It was possible for a user to overwrite memory at a relative location
with 1 by passing a negative file descriptor.

tests/Makefile.am

@@ -1,4 +1,5 @@
-TESTS = test_example.sh \
+TESTS = test_environment.sh \
+        test_example.sh \
         test_exec.sh \
         test_noforce.sh \
         test_redirects.sh \
@@ -21,6 +22,8 @@ endif
 
 dist_check_SCRIPTS = $(TESTS) lib.sh
 dist_check_DATA = example.expected \
+                  example_environment.expected \
+                  example_environment_empty.expected \
                   example_error.expected \
                   example_exec.expected \
                   example_noforce.sh \

tests/example_environment.expected

@@ -0,0 +1 @@
+example.expected

tests/example_environment_empty.expected

@@ -0,0 +1,9 @@
+write to stderr: 1
+write to stdout
+error!: Success
+write to stderr 2write to stdout 2
+
+more on stderr
+stderr ...
+more on stdout
+x

tests/lib.sh

@@ -40,6 +40,9 @@ fi
 LC_ALL=C
 unset LANGUAGE
 
+# Set default COLORED_STDERR_FDS value.
+fds=2,
+
 
 die() {
     echo "$@" >&2
@@ -75,7 +78,7 @@ run_test() {
     (
         # Standard setup.
         LD_PRELOAD="$library"
-        COLORED_STDERR_FDS=2,
+        COLORED_STDERR_FDS="$fds"
         export LD_PRELOAD
         export COLORED_STDERR_FDS
 
@@ -101,17 +104,27 @@ run_test() {
 
 test_script() {
     testcase="$1"
-    shift
-    run_test "$srcdir/$testcase" "$srcdir/$testcase.expected" "$@"
+    expected="$2"
+    shift; shift || true
+
+    if test -z "$expected"; then
+        expected="$testcase"
+    fi
+    run_test "$srcdir/$testcase" "$srcdir/$expected.expected" "$@"
 }
 test_script_subshell() {
-    test_script "$1" bash -c 'bash $1' ''
+    test_script "$1" "$2" bash -c 'bash $1' ''
 }
 test_program() {
     testcase="$1"
-    shift
-    run_test "$builddir/$testcase" "$srcdir/$testcase.expected" "$@"
+    expected="$2"
+    shift; shift || true
+
+    if test -z "$expected"; then
+        expected="$testcase"
+    fi
+    run_test "$builddir/$testcase" "$srcdir/$expected.expected" "$@"
 }
 test_program_subshell() {
-    test_program "$1" sh -c '$1' ''
+    test_program "$1" "$2" sh -c '$1' ''
 }

tests/test_environment.sh

@@ -0,0 +1,46 @@
+#!/bin/sh
+
+# Copyright (C) 2013  Simon Ruderich
+#
+# This program is free software: you can redistribute it and/or modify
+# it under the terms of the GNU General Public License as published by
+# the Free Software Foundation, either version 3 of the License, or
+# (at your option) any later version.
+#
+# This program is distributed in the hope that it will be useful,
+# but WITHOUT ANY WARRANTY; without even the implied warranty of
+# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+# GNU General Public License for more details.
+#
+# You should have received a copy of the GNU General Public License
+# along with this program.  If not, see <http://www.gnu.org/licenses/>.
+
+test "x$srcdir" = x && srcdir=.
+. "$srcdir/lib.sh"
+
+# Test unexpected values for COLORED_STDERR_FDS environment variable.
+
+# Empty fields.
+fds=
+test_program          example example_environment_empty
+test_program_subshell example example_environment_empty
+fds=,,,
+test_program          example example_environment_empty
+test_program_subshell example example_environment_empty
+fds=,,,2
+test_program          example example_environment_empty
+test_program_subshell example example_environment_empty
+fds=2,,,
+test_program          example example_environment
+test_program_subshell example example_environment
+
+# Invalid fds.
+fds=-20,-30
+test_program          example example_environment_empty
+test_program_subshell example example_environment_empty
+fds=-20,-30,2,
+test_program          example example_environment
+test_program_subshell example example_environment
+fds=-20,-30,2,-1,
+test_program          example example_environment
+test_program_subshell example example_environment