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-rw-r--r--tests/test-dup2.c121
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diff --git a/tests/test-dup2.c b/tests/test-dup2.c
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--- /dev/null
+++ b/tests/test-dup2.c
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+/* Test duplicating file descriptors.
+ 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>
+
+#include <unistd.h>
+
+#include <errno.h>
+#include <fcntl.h>
+#include <stdio.h>
+#include <stdlib.h>
+
+#if (defined _WIN32 || defined __WIN32__) && ! defined __CYGWIN__
+/* Get declarations of the Win32 API functions. */
+# define WIN32_LEAN_AND_MEAN
+# include <windows.h>
+#endif
+
+#define ASSERT(expr) \
+ do \
+ { \
+ if (!(expr)) \
+ { \
+ fprintf (stderr, "%s:%d: assertion failed\n", __FILE__, __LINE__); \
+ fflush (stderr); \
+ abort (); \
+ } \
+ } \
+ while (0)
+
+/* Return non-zero if FD is open. */
+static int
+is_open (int fd)
+{
+#if (defined _WIN32 || defined __WIN32__) && ! defined __CYGWIN__
+ /* On Win32, the initial state of unassigned standard file
+ descriptors is that they are open but point to an
+ INVALID_HANDLE_VALUE, and there is no fcntl. */
+ return (HANDLE) _get_osfhandle (fd) != INVALID_HANDLE_VALUE;
+#else
+# ifndef F_GETFL
+# error Please port fcntl to your platform
+# endif
+ return 0 <= fcntl (fd, F_GETFL);
+#endif
+}
+
+int
+main ()
+{
+ const char *file = "test-dup2.tmp";
+ char buffer[1];
+ int fd = open (file, O_CREAT | O_RDWR, 0600);
+
+ /* Assume std descriptors were provided by invoker. */
+ ASSERT (STDERR_FILENO < fd);
+ ASSERT (is_open (fd));
+ /* Ignore any other fd's leaked into this process. */
+ close (fd + 1);
+ close (fd + 2);
+ ASSERT (!is_open (fd + 1));
+ ASSERT (!is_open (fd + 2));
+
+ /* Assigning to self must be a no-op. */
+ ASSERT (dup2 (fd, fd) == fd);
+ ASSERT (is_open (fd));
+
+ /* If the source is not open, then the destination is unaffected. */
+ errno = 0;
+ ASSERT (dup2 (fd + 1, fd + 1) == -1);
+ ASSERT (errno == EBADF);
+ ASSERT (!is_open (fd + 1));
+ errno = 0;
+ ASSERT (dup2 (fd + 1, fd) == -1);
+ ASSERT (errno == EBADF);
+ ASSERT (is_open (fd));
+
+ /* The destination must be valid. */
+ errno = 0;
+ ASSERT (dup2 (fd, -2) == -1);
+ ASSERT (errno == EBADF);
+
+ /* Using dup2 can skip fds. */
+ ASSERT (dup2 (fd, fd + 2) == fd + 2);
+ ASSERT (is_open (fd));
+ ASSERT (!is_open (fd + 1));
+ ASSERT (is_open (fd + 2));
+
+ /* Prove that dup2 closes the previous occupant of a fd. */
+ ASSERT (open ("/dev/null", O_WRONLY, 0600) == fd + 1);
+ ASSERT (dup2 (fd + 1, fd) == fd);
+ ASSERT (close (fd + 1) == 0);
+ ASSERT (write (fd, "1", 1) == 1);
+ ASSERT (dup2 (fd + 2, fd) == fd);
+ ASSERT (write (fd + 2, "2", 1) == 1);
+ ASSERT (lseek (fd, SEEK_SET, 0) == 0);
+ ASSERT (read (fd, buffer, 1) == 1);
+ ASSERT (*buffer == '2');
+
+ /* Clean up. */
+ ASSERT (close (fd + 2) == 0);
+ ASSERT (close (fd) == 0);
+ ASSERT (unlink (file) == 0);
+
+ return 0;
+}