popen-safer: prevent popen from clobbering std descriptors

[gnulib.git] / tests / test-popen-safer.c

diff --git a/tests/test-popen-safer.c b/tests/test-popen-safer.c
new file mode 100644 (file)
index 0000000..281dae9
--- /dev/null
+++ b/tests/test-popen-safer.c
@@ -0,0 +1,86 @@
+/* Test of opening a subcommand stream.
+   Copyright (C) 2009 Free Software Foundation, Inc.
+
+   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/>.  */
+
+/* Written by Eric Blake <ebb9@byu.net>, 2009.  */
+
+#include <config.h>
+
+/* Specification.  */
+#include "stdio--.h"
+
+/* Helpers.  */
+#include <stdlib.h>
+#include <sys/wait.h>
+#include <unistd.h>
+
+/* This test intentionally closes stderr.  So, we arrange to have fd 10
+   (outside the range of interesting fd's during the test) set up to
+   duplicate the original stderr.  */
+
+#define BACKUP_STDERR_FILENO 10
+static FILE *myerr;
+
+#define ASSERT(expr) \
+  do                                                                         \
+    {                                                                        \
+      if (!(expr))                                                           \
+        {                                                                    \
+          fprintf (myerr, "%s:%d: assertion failed\n", __FILE__, __LINE__);  \
+          fflush (myerr);                                                    \
+          abort ();                                                          \
+        }                                                                    \
+    }                                                                        \
+  while (0)
+
+int
+main (int argc, char **argv)
+{
+  FILE *fp;
+  int status;
+
+  /* We close fd 2 later, so save it in fd 10.  */
+  if (dup2 (STDERR_FILENO, BACKUP_STDERR_FILENO) != BACKUP_STDERR_FILENO
+      || (myerr = fdopen (BACKUP_STDERR_FILENO, "w")) == NULL)
+    return 2;
+
+  ASSERT (fp = popen ("exit 0", "r"));
+  ASSERT (STDERR_FILENO < fileno (fp));
+  status = pclose (fp);
+  ASSERT (WIFEXITED (status));
+  ASSERT (!WEXITSTATUS (status));
+
+  ASSERT (fclose (stdin) == 0);
+  ASSERT (fp = popen ("exit 0", "r"));
+  ASSERT (STDERR_FILENO < fileno (fp));
+  status = pclose (fp);
+  ASSERT (WIFEXITED (status));
+  ASSERT (!WEXITSTATUS (status));
+
+  ASSERT (fclose (stdout) == 0);
+  ASSERT (fp = popen ("exit 0", "r"));
+  ASSERT (STDERR_FILENO < fileno (fp));
+  status = pclose (fp);
+  ASSERT (WIFEXITED (status));
+  ASSERT (!WEXITSTATUS (status));
+
+  ASSERT (fclose (stderr) == 0);
+  ASSERT (fp = popen ("exit 0", "r"));
+  ASSERT (STDERR_FILENO < fileno (fp));
+  status = pclose (fp);
+  ASSERT (WIFEXITED (status));
+  ASSERT (!WEXITSTATUS (status));
+  return 0;
+}