--- /dev/null
+/*
+ * versionhelpers.h
+ *
+ * A MinGW emulation of the API implementation, first provided by Microsoft
+ * as a component of the Windows-8.1 software development kit, with addition
+ * of fail-safe support for use on legacy Windows versions.
+ *
+ * Note that use of the APIs, declared herein, is NOT recommended; usually,
+ * there are better ways to check for availablity of specific features, than
+ * to blindly rely on OS version number comparisons.
+ *
+ *
+ * $Id$
+ *
+ * Written by Keith Marshall <keith@users.osdn.me>
+ * Copyright (C) 2021, MinGW.org Project
+ *
+ *
+ * Permission is hereby granted, free of charge, to any person obtaining a
+ * copy of this software and associated documentation files (the "Software"),
+ * to deal in the Software without restriction, including without limitation
+ * the rights to use, copy, modify, merge, publish, distribute, sublicense,
+ * and/or sell copies of the Software, and to permit persons to whom the
+ * Software is furnished to do so, subject to the following conditions:
+ *
+ * The above copyright notice and this permission notice (including the next
+ * paragraph) shall be included in all copies or substantial portions of the
+ * Software.
+ *
+ * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
+ * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
+ * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
+ * AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
+ * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING
+ * FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER
+ * DEALINGS IN THE SOFTWARE.
+ *
+ */
+#ifndef _VERSIONHELPERS_H
+#define _VERSIONHELPERS_H
+#pragma GCC system_header
+
+#include <windef.h>
+
+_BEGIN_C_DECLS
+
+/* These API declarations have been written from scratch, without reference,
+ * in any way, to the original Microsoft implementation. Although Microsoft
+ * did not provide their implementation until publication of the Win-8.1 SDK,
+ * it is understood, from their public documentation, that the underlying API
+ * has been available since Win-2K, and that the Win-8.1 SDK implementation
+ * is backward-compatible with all Win-NT versions since then; however, it
+ * is not clear how fail-safe it may be, should a dependent application be
+ * deployed on Win-9x, Win-NT4, or earlier.
+ *
+ * To address this uncertainty, this MinGW implementation is based on the
+ * following pair of wrapper functions, provided in LIBMINGW32.A; these will
+ * delegate to the VerifyVersionInfo() API, after confirming that the host
+ * platform supports it, while exhibiting suitable fail-safe behaviour, in
+ * case it does not.
+ */
+BOOL __mingw_osver_at_least( DWORD, DWORD, DWORD );
+BOOL __mingw_osver_server( void );
+
+/* The actual version helper APIs take the form of in-line functions.
+ */
+#define VERSIONHELPERAPI \
+static __inline__ __attribute__((__always_inline__)) BOOL
+
+/* This first pair of functions require distinct implementations...
+ */
+VERSIONHELPERAPI IsWindowsServer()
+{ return __mingw_osver_server(); }
+
+VERSIONHELPERAPI
+IsWindowsVersionOrGreater( WORD __major, WORD __minor, WORD __sp )
+{ return __mingw_osver_at_least( __major, __minor, __sp ); }
+
+/* ...while the remainder are sufficiently generic to lend themselves to
+ * instantiation by use of a common convenience macro:
+ */
+#undef __mingw_generic_version_helper
+#define __mingw_generic_version_helper( FUNCTION, M, N, S ) \
+VERSIONHELPERAPI FUNCTION( void ){ return __mingw_osver_at_least( M, N, S ); }
+
+__mingw_generic_version_helper( IsWindowsXPOrGreater, 5, 1, 0 )
+__mingw_generic_version_helper( IsWindowsXPSP1OrGreater, 5, 1, 1 )
+__mingw_generic_version_helper( IsWindowsXPSP2OrGreater, 5, 1, 2 )
+__mingw_generic_version_helper( IsWindowsXPSP3OrGreater, 5, 1, 3 )
+__mingw_generic_version_helper( IsWindowsVistaOrGreater, 6, 0, 0 )
+__mingw_generic_version_helper( IsWindowsVistaSP1OrGreater, 6, 0, 0 )
+__mingw_generic_version_helper( IsWindowsVistaSP2OrGreater, 6, 0, 2 )
+__mingw_generic_version_helper( IsWindows7OrGreater, 6, 1, 0 )
+__mingw_generic_version_helper( IsWindows7SP1OrGreater, 6, 1, 1 )
+__mingw_generic_version_helper( IsWindows8OrGreater, 6, 2, 0 )
+__mingw_generic_version_helper( IsWindows8Point1OrGreater, 6, 3, 0 )
+__mingw_generic_version_helper( IsWindows10OrGreater, 10, 0, 0 )
+
+#undef __mingw_generic_version_helper
+
+_END_C_DECLS
+
+#endif /* !_VERSIONHELPERS_H: $RCSfile$: end of file */
--- /dev/null
+/*
+ * osvercmp.c
+ *
+ * Implements a pair of wrappers for the WinAPI VerifyVersionInfo() API,
+ * to facilitate provision of support for a MinGW emulation of Microsoft's
+ * <versionhelpers.h>. Although Microsoft first provided this as part of
+ * the SDK for Windows-8.1, the underlying VerifyVersionInfo() API has
+ * been supported since Win2K; the wrappers, implemented herein, extend
+ * support to legacy platforms, providing fail-safe handling on earlier
+ * platforms, which lack the VerifyVersionInfo() API.
+ *
+ *
+ * $Id$
+ *
+ * Written by Keith Marshall <keith@users.osdn.me>
+ * Copyright (C) 2021, MinGW.org Project
+ *
+ *
+ * Permission is hereby granted, free of charge, to any person obtaining a
+ * copy of this software and associated documentation files (the "Software"),
+ * to deal in the Software without restriction, including without limitation
+ * the rights to use, copy, modify, merge, publish, distribute, sublicense,
+ * and/or sell copies of the Software, and to permit persons to whom the
+ * Software is furnished to do so, subject to the following conditions:
+ *
+ * The above copyright notice and this permission notice (including the next
+ * paragraph) shall be included in all copies or substantial portions of the
+ * Software.
+ *
+ * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
+ * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
+ * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
+ * AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
+ * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING
+ * FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER
+ * DEALINGS IN THE SOFTWARE.
+ *
+ *
+ * Since the underlying VerifyVersionInfo() API was not introduced until
+ * Win-2K, and MinGW's WinAPI is nominally compiled with legacy version
+ * guarantees for Win-NT4 only, we must create a clean slate...
+ *
+ */
+#undef NTDDI_VERSION
+#undef _WIN32_WINDOWS
+#undef _WIN32_WINNT
+
+/* ...whence we may request exposure of, and access to, the necessary
+ * Win-2K API features; (note that this does not preclude use on earlier
+ * legacy platforms, since the implementation incorporates appropriate
+ * fail-safe handling).
+ */
+#define _WIN32_WINNT _WIN32_WINNT_WIN2K
+
+#include <winbase.h>
+#include <versionhelpers.h>
+
+#include "legacy.h"
+
+/* We need a function pointer type definition, matching the signature of
+ * VerifyVersionInfo(), so that we may verify its availability, BEFORE we
+ * attempt to invoke it indirectly.
+ */
+typedef BOOL WINAPI (*validator_fn)( OSVERSIONINFOEXA *, DWORD, DWORDLONG );
+
+static validator_fn __mingw_osver_comparator( void )
+{
+ /* Internal helper function, to look up, and store, the entry point
+ * address of VerifyVersionInfo(), if it is available in KERNEL32.DLL;
+ * (note that this is a one-time initialization, within the lifetime
+ * of the calling process).
+ */
+ static void *entry = API_UNCHECKED;
+ entry = __kernel32_entry_point( entry, "VerifyVersionInfoA" );
+ return (validator_fn)(entry);
+}
+
+/* For OS version comparisons, we need to inspect the major, and minor
+ * version numbers, both for the base OS, and any applied service packs...
+ */
+static const WORD __mingw_osver_mask = VER_MAJORVERSION
+| VER_MINORVERSION | VER_SERVICEPACKMAJOR | VER_SERVICEPACKMINOR;
+
+static DWORDLONG __mingw_osver_test( void )
+{ /* ...selecting the "greater-than-or-equal" comparison mode for each,
+ * in turn, as facilitated by this internal helper function; (note
+ * that, once again, this performs a one-time initialization of the
+ * comparison selector, for each item of version information).
+ */
+ static DWORDLONG test = 0LL;
+ if( test == 0LL )
+ { /* We need to initialize it, on this occasion; loop over the bits
+ * of the comparison selector mask, associating the appropriate
+ * comparison type with each which is set.
+ */
+ for( DWORD mask = 1; mask < __mingw_osver_mask; mask <<= 1 )
+ if( (mask & __mingw_osver_mask) != 0 )
+ VER_SET_CONDITION( test, mask, VER_GREATER_EQUAL );
+ }
+ return test;
+}
+
+BOOL __mingw_osver_at_least( DWORD __major, DWORD __minor, DWORD __sp )
+{
+ /* This is the public entry point, through which OS version number
+ * comparison requests may be directed to VerifyVersionInfo()...
+ */
+ validator_fn chk;
+ if( (chk = __mingw_osver_comparator()) != (validator_fn)(API_UNSUPPORTED) )
+ {
+ /* ...subject to initialization having established a valid entry
+ * point address, to which we pass the request via the pointer.
+ */
+ OSVERSIONINFOEXA osinfo =
+ { sizeof osinfo, __major, __minor, 0, 0, "", __sp, 0, 0, 0, 0 };
+ return chk( &osinfo, __mingw_osver_mask, __mingw_osver_test() );
+ }
+
+ /* If we get to here, initialization failed to identify a valid
+ * entry point address, for VerifyVersionInfo(); this represents
+ * the fail-safe handling, for legacy platforms.
+ */
+ SetLastError( ERROR_OLD_WIN_VERSION );
+ return FALSE;
+}
+
+/* In the case of the server platform identification test, we again
+ * must perform an OS version check, but this must be augmented by a
+ * product type assessment...
+ */
+static const WORD __mingw_osplatform_mask = VER_PRODUCT_TYPE
+| __mingw_osver_mask;
+
+static DWORDLONG __mingw_osplatform_test( void )
+{ /* ...for which (a copy of) the version number comparison selector
+ * must be augmented by addition of an equality comparator selector
+ * for the server product type identifier; (as previously, this is
+ * again established as a one-time initialization).
+ */
+ static DWORDLONG test = 0LL;
+ if( test == 0LL )
+ { /* We need to initialize it, on this occasion.
+ */
+ test = __mingw_osver_test();
+ VER_SET_CONDITION( test, VER_PRODUCT_TYPE, VER_EQUAL );
+ }
+ return test;
+}
+
+BOOL __mingw_osver_server( void )
+{ /* This alternative public entry point is specific to the server
+ * platform identification test; as in the preceding case of more
+ * generalized version number comparisons, this is also delegated
+ * to the VerifyVersionInfo() API, using the same entry point
+ * reference pointer...
+ */
+ validator_fn chk;
+ if( (chk = __mingw_osver_comparator()) != (validator_fn)(API_UNSUPPORTED) )
+ {
+ /* ...once again, subject to successful initialization; in this
+ * case, it is the server characterization property which is of
+ * primary interest, but we do also require an OS version which
+ * corresponds to Win-2K, or later.
+ */
+ OSVERSIONINFOEXA osinfo =
+ { sizeof osinfo, 5, 0, 0, 0, "", 0, 0, 0, VER_NT_SERVER, 0 };
+ return chk( &osinfo, __mingw_osplatform_mask, __mingw_osplatform_test() );
+ }
+
+ /* If we get to here, initialization failed to identify a valid
+ * entry point address, for VerifyVersionInfo(); this represents
+ * the fail-safe handling, for legacy platforms.
+ */
+ SetLastError( ERROR_OLD_WIN_VERSION );
+ return FALSE;
+}
+
+/* $RCSfile$: end of file */
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