Add gnulib modules to replace missing libc functionality

This enables us to build a fully featured elfutils package on systems
with reduced C libraries, such as windows. All the modules are built
into libgnu.a, which is then linked into all binaries if
--enable-gnulib is given on the configure line.

Change-Id: I743fd22172bc85d9f10dcc3dad8eb921f462b554
Reviewed-by: Christian Kandeler <[email protected]>

1 files changed, 67 insertions, 0 deletions

diff --git a/libgnu/lseek.c b/libgnu/lseek.c
new file mode 100644
index 00000000..3b2fdf2e
--- /dev/null
+++ b/libgnu/lseek.c
@@ -0,0 +1,67 @@
+/* An lseek() function that detects pipes.
+   Copyright (C) 2007, 2009-2017 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, 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 <unistd.h>
+
+#if (defined _WIN32 || defined __WIN32__) && ! defined __CYGWIN__
+/* Windows platforms.  */
+/* Get GetFileType.  */
+# include <windows.h>
+/* Get _get_osfhandle.  */
+# include "msvc-nothrow.h"
+#else
+# include <sys/stat.h>
+#endif
+#include <errno.h>
+
+#undef lseek
+
+off_t
+rpl_lseek (int fd, off_t offset, int whence)
+{
+#if (defined _WIN32 || defined __WIN32__) && ! defined __CYGWIN__
+  /* mingw lseek mistakenly succeeds on pipes, sockets, and terminals.  */
+  HANDLE h = (HANDLE) _get_osfhandle (fd);
+  if (h == INVALID_HANDLE_VALUE)
+    {
+      errno = EBADF;
+      return -1;
+    }
+  if (GetFileType (h) != FILE_TYPE_DISK)
+    {
+      errno = ESPIPE;
+      return -1;
+    }
+#else
+  /* BeOS lseek mistakenly succeeds on pipes...  */
+  struct stat statbuf;
+  if (fstat (fd, &statbuf) < 0)
+    return -1;
+  if (!S_ISREG (statbuf.st_mode))
+    {
+      errno = ESPIPE;
+      return -1;
+    }
+#endif
+#if _GL_WINDOWS_64_BIT_OFF_T
+  return _lseeki64 (fd, offset, whence);
+#else
+  return lseek (fd, offset, whence);
+#endif
+}