[PATCH] Add sysconf replacement for win32

[Ulf Hermann <ulf.hermann@qt.io>]

We cannot get sysconf() from gnulib and the only thing we need it for
is getting the page size. Therefore, of the various possible sysconf
parameters we only define and implement _SC_PAGESIZE in our replacement.

Signed-off-by: Ulf Hermann <ulf.hermann@qt.io>
---
 ChangeLog              |  6 ++++++
 configure.ac           | 20 ++++++++++++++++++++
 libgnu/ChangeLog       |  6 ++++++
 libgnu/Makefile.am     |  8 +++++++-
 libgnu/sysconf_win32.c | 42 ++++++++++++++++++++++++++++++++++++++++++
 5 files changed, 81 insertions(+), 1 deletion(-)
 create mode 100644 libgnu/sysconf_win32.c

diff --git a/ChangeLog b/ChangeLog
index 2c0e34d..71c73e5 100644
--- a/ChangeLog
+++ b/ChangeLog
@@ -1,5 +1,11 @@
 2017-05-04  Ulf Hermann  <ulf.hermann@qt.io>
 
+	* configure.ac: Check for sysconf() and GetSystemInfo(). Add a
+	declaration of sysconf to config.h if GetSystemInfo() is available,
+	but not sysconf().
+
+2017-05-04  Ulf Hermann  <ulf.hermann@qt.io>
+
 	* configure.ac: Check for sys/mman.h or alternatively MapViewOfFile().
 
 2017-05-03  Ulf Hermann  <ulf.hermann@qt.io>
diff --git a/configure.ac b/configure.ac
index 6a2f991..2d3ad04 100644
--- a/configure.ac
+++ b/configure.ac
@@ -557,6 +557,26 @@ if test "x$ac_cv_header_sys_mman_h" != "xyes"; then
 fi
 AM_CONDITIONAL(USE_WIN32_MMAN, [test "x$ac_cv_have_decl_MapViewOfFile" = "xyes"])
 
+AC_CHECK_DECLS([sysconf], [], [], [[#include <unistd.h>]])
+AM_CONDITIONAL(HAVE_SYSCONF, [test "x$ac_cv_have_decl_sysconf" = "xyes"])
+if test "x$ac_cv_have_decl_sysconf" != "xyes"; then
+	AC_CHECK_DECLS([GetSystemInfo], [], [], [[#include <sysinfoapi.h>]])
+fi
+AM_CONDITIONAL(USE_WIN32_SYSCONF, [test "x$ac_cv_have_decl_GetSystemInfo" = "xyes"])
+
+if test "x$ac_cv_have_decl_GetSystemInfo" = "xyes"; then
+	AC_DEFINE([USE_WIN32_SYSCONF], [1], [Use sysconf replacement for win32])
+fi
+
+AH_VERBATIM([USE_WIN32_SYSCONF],
+	[/* Define sysconf(3) here if it is not available from a system header. */
+#undef USE_WIN32_SYSCONF
+#ifdef USE_WIN32_SYSCONF
+#define _SC_PAGESIZE 1
+long sysconf(int name);
+#endif
+])
+
 dnl Check if we have <linux/bpf.h> for EM_BPF disassembly.
 AC_CHECK_HEADERS(linux/bpf.h)
 AM_CONDITIONAL(HAVE_LINUX_BPF_H, [test "x$ac_cv_header_linux_bpf_h" = "xyes"])
diff --git a/libgnu/ChangeLog b/libgnu/ChangeLog
index 60a049f..aa0e603 100644
--- a/libgnu/ChangeLog
+++ b/libgnu/ChangeLog
@@ -1,5 +1,11 @@
 2017-05-04  Ulf Hermann  <ulf.hermann@qt.io>
 
+	* Makefile.am: If sysconf() is unavailable, but GetSystemInfo() is
+	available, compile the win32 version of sysconf.
+	* sysconf_win32.c: New file.
+
+2017-05-04  Ulf Hermann  <ulf.hermann@qt.io>
+
 	* Makefile.am: If sys/mman.h is unavailable, but MapViewOfFile is,
 	then use our own implementation of mmap and related functions.
 	* mman_win32.c: New file.
diff --git a/libgnu/Makefile.am b/libgnu/Makefile.am
index 5af121a..05a8f61 100644
--- a/libgnu/Makefile.am
+++ b/libgnu/Makefile.am
@@ -35,7 +35,7 @@ noinst_LIBRARIES =
 MOSTLYCLEANFILES =
 MOSTLYCLEANDIRS =
 BUILT_SOURCES =
-EXTRA_DIST = endian.in.h byteswap.in.h sys_mman.win32.h mman_win32.c
+EXTRA_DIST = endian.in.h byteswap.in.h sys_mman.win32.h mman_win32.c sysconf_win32.c
 CLEANFILES =
 SUFFIXES =
 
@@ -69,3 +69,9 @@ if USE_WIN32_MMAN
 libgnu_a_SOURCES += mman_win32.c
 endif
 endif
+
+if !HAVE_SYSCONF
+if USE_WIN32_SYSCONF
+libgnu_a_SOURCES += sysconf_win32.c
+endif
+endif
diff --git a/libgnu/sysconf_win32.c b/libgnu/sysconf_win32.c
new file mode 100644
index 0000000..34ddf4b
--- /dev/null
+++ b/libgnu/sysconf_win32.c
@@ -0,0 +1,42 @@
+/* Replacement for sysconf() on windows
+   Copyright (C) 2017 The Qt Company Ltd.
+   This file is part of elfutils.
+
+   This file is free software; you can redistribute it and/or modify
+   it under the terms of either
+
+     * the GNU Lesser General Public License as published by the Free
+       Software Foundation; either version 3 of the License, or (at
+       your option) any later version
+
+   or
+
+     * the GNU General Public License as published by the Free
+       Software Foundation; either version 2 of the License, or (at
+       your option) any later version
+
+   or both in parallel, as here.
+
+   elfutils 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 copies of the GNU General Public License and
+   the GNU Lesser General Public License along with this program.  If
+   not, see <http://www.gnu.org/licenses/>.  */
+
+#include <config.h>
+#include <sysinfoapi.h>
+#include <errno.h>
+
+long int sysconf(int name) {
+  if (name == _SC_PAGESIZE) {
+    SYSTEM_INFO info;
+    GetSystemInfo(&info);
+    return info.dwPageSize;
+  } else {
+    errno = EINVAL;
+    return -1;
+  }
+}
-- 
2.1.4