[PATCH] nonblocking: new module

[Eric Blake]

This still lacks the ability to query non-blocking status of mingw
sockets; but that should be possible in a future patch in much the
same manner as fchdir.

* modules/nonblocking: New module.
* modules/nonblocking-tests: Likewise.
* lib/nonblocking.h: New file.
* lib/nonblocking.c: Likewise.
* tests/test-nonblocking.c: New test.
* lib/ioctl.c (ioctl) [mingw]: Update comment.

Signed-off-by: Eric Blake <address@hidden>
---

I've touched up your proposal, and done more testing with this.
I'll probably commit this tomorrow.

 ChangeLog                 |   11 ++++
 lib/ioctl.c               |    4 +
 lib/nonblocking.c         |  137 +++++++++++++++++++++++++++++++++++++++++++++
 lib/nonblocking.h         |   60 ++++++++++++++++++++
 modules/nonblocking       |   26 +++++++++
 modules/nonblocking-tests |   16 +++++
 tests/test-nonblocking.c  |  115 +++++++++++++++++++++++++++++++++++++
 7 files changed, 369 insertions(+), 0 deletions(-)
 create mode 100644 lib/nonblocking.c
 create mode 100644 lib/nonblocking.h
 create mode 100644 modules/nonblocking
 create mode 100644 modules/nonblocking-tests
 create mode 100644 tests/test-nonblocking.c

diff --git a/ChangeLog b/ChangeLog
index 5bc9b73..daaf7bc 100644
--- a/ChangeLog
+++ b/ChangeLog
@@ -1,4 +1,15 @@
 2011-03-30  Bruno Haible  <address@hidden>
+       and Eric Blake  <address@hidden>
+
+       nonblocking: new module
+       * modules/nonblocking: New module.
+       * modules/nonblocking-tests: Likewise.
+       * lib/nonblocking.h: New file.
+       * lib/nonblocking.c: Likewise.
+       * tests/test-nonblocking.c: New test.
+       * lib/ioctl.c (ioctl) [mingw]: Update comment.
+
+2011-03-30  Bruno Haible  <address@hidden>

        stdio: Avoid GCC >= 4.4 warnings when using %lld and similar on mingw.
        * lib/stdio.in.h (_GL_ATTRIBUTE_FORMAT_PRINTF): Use 'gnu_printf' format
diff --git a/lib/ioctl.c b/lib/ioctl.c
index 7c09d95..4bbed76 100644
--- a/lib/ioctl.c
+++ b/lib/ioctl.c
@@ -63,6 +63,10 @@ ioctl (int fd, int req, ...)
   buf = va_arg (args, void *);
   va_end (args);

+  /* We don't support FIONBIO on pipes here.  If you want to make pipe
+     fds non-blocking, use the gnulib 'nonblocking' module, until
+     gnulib implements fcntl F_GETFL / F_SETFL with O_NONBLOCK.  */
+
   sock = FD_TO_SOCKET (fd);
   r = ioctlsocket (sock, req, buf);
   if (r < 0)
diff --git a/lib/nonblocking.c b/lib/nonblocking.c
new file mode 100644
index 0000000..61ea3ca
--- /dev/null
+++ b/lib/nonblocking.c
@@ -0,0 +1,137 @@
+/* Non-blocking I/O for pipe or socket descriptors.
+   Copyright (C) 2011 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/>.  */
+
+#include <config.h>
+
+/* Specification.  */
+#include "nonblocking.h"
+
+#include <errno.h>
+
+#if (defined _WIN32 || defined __WIN32__) && ! defined __CYGWIN__
+/* Native Woe32 API.  */
+
+# include <sys/socket.h>
+# include <unistd.h>
+
+/* Get declarations of the Win32 API functions.  */
+# define WIN32_LEAN_AND_MEAN
+# include <windows.h>
+
+int
+get_nonblocking_flag (int desc)
+{
+  HANDLE h = (HANDLE) _get_osfhandle (desc);
+  if (GetFileType (h) == FILE_TYPE_PIPE)
+    {
+      /* h is a pipe or socket.  */
+      DWORD state;
+      if (GetNamedPipeHandleState (h, &state, NULL, NULL, NULL, NULL, 0))
+        /* h is a pipe.  */
+        return (state & PIPE_NOWAIT) != 0;
+      else
+        /* h is a socket.  */
+        errno = ENOSYS;
+        return -1;
+    }
+  else
+    return 0;
+}
+
+int
+set_nonblocking_flag (int desc, bool value)
+{
+  HANDLE h = (HANDLE) _get_osfhandle (desc);
+  if (GetFileType (h) == FILE_TYPE_PIPE)
+    {
+      /* h is a pipe or socket.  */
+      DWORD state;
+      if (GetNamedPipeHandleState (h, &state, NULL, NULL, NULL, NULL, 0))
+        {
+          /* h is a pipe.  */
+          if ((state & PIPE_NOWAIT) != 0)
+            {
+              if (value)
+                return 0;
+              state &= ~PIPE_NOWAIT;
+            }
+          else
+            {
+              if (!value)
+                return 0;
+              state |= PIPE_NOWAIT;
+            }
+          if (SetNamedPipeHandleState (h, &state, NULL, NULL))
+            return 0;
+          errno = EINVAL;
+          return -1;
+        }
+      else
+        {
+          /* h is a socket.  */
+          int v = value;
+          return ioctl (desc, FIONBIO, &v);
+        }
+    }
+  else
+    {
+      /* Win32 does not support non-blocking on regular files.  */
+      errno = ENOTSUP;
+      return -1;
+    }
+}
+
+#else
+/* Unix API.  */
+
+# include <fcntl.h>
+
+# if !O_NONBLOCK
+#  error Please port nonblocking to your platform
+# endif
+
+/* We don't need the gnulib replacement of fcntl() here.  */
+# undef fcntl
+
+int
+get_nonblocking_flag (int desc)
+{
+  int fcntl_flags;
+
+  fcntl_flags = fcntl (desc, F_GETFL, 0);
+  if (fcntl_flags < 0)
+    return -1;
+  return (fcntl_flags & O_NONBLOCK) != 0;
+}
+
+int
+set_nonblocking_flag (int desc, bool value)
+{
+  int fcntl_flags;
+
+  fcntl_flags = fcntl (desc, F_GETFL, 0);
+  if (fcntl_flags < 0)
+    return -1;
+  if (!!(O_NONBLOCK & fcntl_flags) == value)
+    return 0;
+  if (value)
+    fcntl_flags |= O_NONBLOCK;
+  else
+    fcntl_flags &= ~O_NONBLOCK;
+  return fcntl (desc, F_SETFL, fcntl_flags);
+}
+
+#endif
diff --git a/lib/nonblocking.h b/lib/nonblocking.h
new file mode 100644
index 0000000..ed1f317
--- /dev/null
+++ b/lib/nonblocking.h
@@ -0,0 +1,60 @@
+/* Non-blocking I/O for pipe or socket descriptors.
+   Copyright (C) 2011 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/>.  */
+
+#ifndef _NONBLOCKING_H
+#define _NONBLOCKING_H
+
+#include <stdbool.h>
+
+/* Non-blocking I/O is an I/O mode by which read(), write() calls avoid
+   blocking the current thread.  When non-blocking is enabled:
+   - A read() call returns -1 with errno set to EAGAIN when no data or EOF
+     information is immediately available.
+   - A write() call returns -1 with errno set to EAGAIN when it cannot
+     transport the requested amount of data (but at most one pipe buffer)
+     without blocking.
+
+   There are three modern alternatives to non-blocking I/O:
+     - use select() or poll() followed by read() or write() if the descriptor
+       is ready,
+     - call read() or write() in separate threads,
+     - use <aio.h> interfaces.  */
+
+
+#ifdef __cplusplus
+extern "C" {
+#endif
+
+
+/* Return 1 if I/O to the descriptor DESC is currently non-blocking, 0
+   it is blocking, or -1 with errno set if fd is invalid or blocking
+   status cannot be determined (such as with sockets on mingw).  */
+extern int get_nonblocking_flag (int desc);
+
+/* Specify the non-blocking flag for the descriptor DESC.
+   Return 0 upon success, or -1 with errno set upon failure.
+   The default depends on the presence of the O_NONBLOCK flag for files
+   or pipes opened with open() or on the presence of the SOCK_NONBLOCK
+   flag for sockets.  Regular files and directories cannot be made
+   non-blocking; block and character devices depend on the system.  */
+extern int set_nonblocking_flag (int desc, bool value);
+
+
+#ifdef __cplusplus
+}
+#endif
+
+#endif /* _NONBLOCKING_H */
diff --git a/modules/nonblocking b/modules/nonblocking
new file mode 100644
index 0000000..44ca33e
--- /dev/null
+++ b/modules/nonblocking
@@ -0,0 +1,26 @@
+Description:
+Read, set or clear the non-blocking file descriptor flag.
+
+Files:
+lib/nonblocking.c
+lib/nonblocking.h
+
+Depends-on:
+fcntl-h
+ioctl
+stdbool
+sys_socket
+
+configure.ac:
+AC_LIBOBJ([nonblocking])
+
+Makefile.am:
+
+Include:
+"nonblocking.h"
+
+License:
+LGPLv2+
+
+Maintainer:
+Bruno Haible, Eric Blake
diff --git a/modules/nonblocking-tests b/modules/nonblocking-tests
new file mode 100644
index 0000000..94fccb2
--- /dev/null
+++ b/modules/nonblocking-tests
@@ -0,0 +1,16 @@
+Files:
+tests/test-nonblocking.c
+tests/macros.h
+
+Depends-on:
+close
+open
+pipe-posix
+socket
+
+configure.ac:
+
+Makefile.am:
+TESTS += test-nonblocking
+check_PROGRAMS += test-nonblocking
+test_nonblocking_LDADD = $(LDADD) @LIBSOCKET@
diff --git a/tests/test-nonblocking.c b/tests/test-nonblocking.c
new file mode 100644
index 0000000..8ba4c9c
--- /dev/null
+++ b/tests/test-nonblocking.c
@@ -0,0 +1,115 @@
+/* Test manipulation of non-blocking flag.
+   Copyright (C) 2011 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 <address@hidden>, 2011.  */
+
+#include <config.h>
+
+#include "nonblocking.h"
+
+#include <errno.h>
+#include <fcntl.h>
+#include <sys/socket.h>
+#include <unistd.h>
+
+#include "macros.h"
+
+int
+main (void)
+{
+  const char *file = "test-nonblock.tmp";
+  int fd_file = creat (file, 0600);
+  int fd_pipe[2];
+  int fd_sock;
+  bool sock_works = true;
+
+#if (defined _WIN32 || defined __WIN32__) && ! defined __CYGWIN__
+  /* For now, we can't get nonblock status of windows sockets.  */
+  sock_works = false;
+#endif
+
+  /* Assume std descriptors were provided by invoker.  */
+  ASSERT (STDERR_FILENO < fd_file);
+
+  /* Test regular files; setting nonblock on file is unspecified.  */
+  ASSERT (get_nonblocking_flag (fd_file) == 0);
+  ASSERT (set_nonblocking_flag (fd_file, false) == 0);
+  ASSERT (get_nonblocking_flag (fd_file) == 0);
+  ASSERT (close (fd_file) == 0);
+  ASSERT (unlink (file) == 0);
+
+  /* Test directories; setting nonblock is unspecified.  */
+  fd_file = open (".", O_RDONLY);
+  ASSERT (STDERR_FILENO < fd_file);
+  ASSERT (get_nonblocking_flag (fd_file) == 0);
+  ASSERT (set_nonblocking_flag (fd_file, false) == 0);
+  ASSERT (get_nonblocking_flag (fd_file) == 0);
+  ASSERT (close (fd_file) == 0);
+
+  /* Test pipes.  */
+  ASSERT (pipe (fd_pipe) == 0);
+  ASSERT (get_nonblocking_flag (fd_pipe[0]) == 0);
+  ASSERT (get_nonblocking_flag (fd_pipe[1]) == 0);
+  ASSERT (set_nonblocking_flag (fd_pipe[0], true) == 0);
+  ASSERT (get_nonblocking_flag (fd_pipe[0]) == 1);
+  ASSERT (get_nonblocking_flag (fd_pipe[1]) == 0);
+  ASSERT (set_nonblocking_flag (fd_pipe[1], true) == 0);
+  ASSERT (set_nonblocking_flag (fd_pipe[0], false) == 0);
+  ASSERT (get_nonblocking_flag (fd_pipe[0]) == 0);
+  ASSERT (get_nonblocking_flag (fd_pipe[1]) == 1);
+  ASSERT (close (fd_pipe[0]) == 0);
+  ASSERT (close (fd_pipe[1]) == 0);
+
+#if GNULIB_TEST_PIPE2
+  /* mingw still lacks O_NONBLOCK replacement.  */
+  ASSERT (pipe2 (fd_pipe, O_NONBLOCK) == 0);
+  ASSERT (get_nonblocking_flag (fd_pipe[0]) == !!O_NONBLOCK);
+  ASSERT (get_nonblocking_flag (fd_pipe[1]) == !!O_NONBLOCK);
+  ASSERT (close (fd_pipe[0]) == 0);
+  ASSERT (close (fd_pipe[1]) == 0);
+#endif /* GNULIB_TEST_PIPE2 */
+
+  /* Test sockets.  */
+  fd_sock = socket (AF_INET, SOCK_STREAM, 0);
+  ASSERT (get_nonblocking_flag (fd_sock) == sock_works ? 0 : -1);
+  ASSERT (set_nonblocking_flag (fd_sock, true) == 0);
+  ASSERT (get_nonblocking_flag (fd_sock) == sock_works ? 1 : -1);
+  ASSERT (set_nonblocking_flag (fd_sock, false) == 0);
+  ASSERT (get_nonblocking_flag (fd_sock) == sock_works ? 0 : -1);
+  ASSERT (close (fd_sock) == 0);
+
+#if SOCK_NONBLOCK
+  fd_sock = socket (AF_INET, SOCK_STREAM | SOCK_NONBLOCK, 0);
+  ASSERT (get_nonblocking_flag (fd_sock) == sock_works ? 1 : -1);
+  ASSERT (close (fd_sock) == 0);
+#endif /* SOCK_NONBLOCK */
+
+  /* Test error handling.  */
+  errno = 0;
+  ASSERT (get_nonblocking_flag (-1) == -1);
+  ASSERT (errno == EBADF);
+  errno = 0;
+  ASSERT (set_nonblocking_flag (-1, false) == -1);
+  ASSERT (errno == EBADF);
+  errno = 0;
+  ASSERT (set_nonblocking_flag (-1, true) == -1);
+  ASSERT (errno == EBADF);
+  errno = 0;
+  ASSERT (set_nonblocking_flag (10000000, false) == -1);
+  ASSERT (errno == EBADF);
+
+  return 0;
+}
-- 
1.7.4