Support non-blocking pipe I/O in read() on native Windows.

[gnulib.git] / lib / stdio-read.c

diff --git a/lib/stdio-read.c b/lib/stdio-read.c
new file mode 100644 (file)
index 0000000..d7901dd
--- /dev/null
+++ b/lib/stdio-read.c
@@ -0,0 +1,148 @@
+/* POSIX compatible FILE stream read function.
+   Copyright (C) 2008-2011 Free Software Foundation, Inc.
+   Written by Bruno Haible <bruno@clisp.org>, 2011.
+
+   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 <stdio.h>
+
+/* Replace these functions only if module 'nonblocking' is requested.  */
+#if GNULIB_NONBLOCKING
+
+/* On native Windows platforms, when read() is called on a non-blocking pipe
+   with an empty buffer, ReadFile() fails with error GetLastError() =
+   ERROR_NO_DATA, and read() in consequence fails with error EINVAL.  This
+   read() function is at the basis of the function which fills the buffer of
+   a FILE stream.  */
+
+# if (defined _WIN32 || defined __WIN32__) && ! defined __CYGWIN__
+
+#  include <errno.h>
+#  include <io.h>
+
+#  define WIN32_LEAN_AND_MEAN  /* avoid including junk */
+#  include <windows.h>
+
+#  define CALL_WITH_ERRNO_FIX(RETTYPE, EXPRESSION, FAILED) \
+  if (ferror (stream))                                                        \
+    return (EXPRESSION);                                                      \
+  else                                                                        \
+    {                                                                         \
+      RETTYPE ret;                                                            \
+      SetLastError (0);                                                       \
+      ret = (EXPRESSION);                                                     \
+      if (FAILED)                                                             \
+        {                                                                     \
+          if (GetLastError () == ERROR_NO_DATA && ferror (stream))            \
+            {                                                                 \
+              int fd = fileno (stream);                                       \
+              if (fd >= 0)                                                    \
+                {                                                             \
+                  HANDLE h = (HANDLE) _get_osfhandle (fd);                    \
+                  if (GetFileType (h) == FILE_TYPE_PIPE)                      \
+                    {                                                         \
+                      /* h is a pipe or socket.  */                           \
+                      DWORD state;                                            \
+                      if (GetNamedPipeHandleState (h, &state, NULL, NULL,     \
+                                                   NULL, NULL, 0)             \
+                          && (state & PIPE_NOWAIT) != 0)                      \
+                        /* h is a pipe in non-blocking mode.                  \
+                           Change errno from EINVAL to EAGAIN.  */            \
+                        errno = EAGAIN;                                       \
+                    }                                                         \
+                }                                                             \
+            }                                                                 \
+        }                                                                     \
+      return ret;                                                             \
+    }
+
+int
+scanf (const char *format, ...)
+{
+  int retval;
+  va_list args;
+
+  va_start (args, format);
+  retval = vfscanf (stdin, format, args);
+  va_end (args);
+
+  return retval;
+}
+
+int
+fscanf (FILE *stream, const char *format, ...)
+{
+  int retval;
+  va_list args;
+
+  va_start (args, format);
+  retval = vfscanf (stream, format, args);
+  va_end (args);
+
+  return retval;
+}
+
+int
+vscanf (const char *format, va_list args)
+{
+  return vfscanf (stdin, format, args);
+}
+
+int
+vfscanf (FILE *stream, const char *format, va_list args)
+#undef vfscanf
+{
+  CALL_WITH_ERRNO_FIX (int, vfscanf (stream, format, args), ret == EOF)
+}
+
+int
+getchar (void)
+{
+  return fgetc (stdin);
+}
+
+int
+fgetc (FILE *stream)
+#undef fgetc
+{
+  CALL_WITH_ERRNO_FIX (int, fgetc (stream), ret == EOF)
+}
+
+char *
+fgets (char *s, int n, FILE *stream)
+#undef fgets
+{
+  CALL_WITH_ERRNO_FIX (char *, fgets (s, n, stream), ret == NULL)
+}
+
+char *
+gets (char *s)
+#undef gets
+{
+  FILE *stream = stdin;
+  CALL_WITH_ERRNO_FIX (char *, gets (s), ret == NULL)
+}
+
+size_t
+fread (void *ptr, size_t s, size_t n, FILE *stream)
+#undef fread
+{
+  CALL_WITH_ERRNO_FIX (size_t, fread (ptr, s, n, stream), ret < n)
+}
+
+# endif
+#endif