Add test that MAP_* constants agree with kernel.

Continuing the process of building up and using Python infrastructure
for extracting and using values in headers, this patch adds a test
that MAP_* constants from sys/mman.h agree with those in the Linux
kernel headers.  (Other sys/mman.h constants could be added to the
test separately.)

This set of constants has grown over time, so the generic code is
enhanced to allow saying extra constants are OK on either side of the
comparison (where the caller sets those parameters based on the Linux
kernel headers version, compared with the version the headers were
last updated from).  Although the test is a custom Python file, my
intention is to move in future to a single Python script for such
tests and text files it takes as inputs, once there are enough
examples to provide a guide to the common cases in such tests (I'd
like to end up with most or all such sets of constants copied from
kernel headers having such tests, and likewise for structure layouts
from the kernel).

The Makefile code is essentially the same as for tst-signal-numbers,
but I didn't try to find an object file to depend on to represent the
dependency on the headers used by the test (the conform/ tests don't
try to represent such header dependencies at all, for example).

Tested with build-many-glibcs.py, and also for x86_64 with older
kernel headers.

	* scripts/glibcextract.py (compare_macro_consts): Take parameters
	to allow extra macros from first or second sources.
	* sysdeps/unix/sysv/linux/tst-mman-consts.py: New file.
	* sysdeps/unix/sysv/linux/Makefile [$(subdir) = misc]
	(tests-special): Add $(objpfx)tst-mman-consts.out.
	($(objpfx)tst-mman-consts.out): New makefile target.

2 files changed, 74 insertions, 0 deletions

diff --git a/sysdeps/unix/sysv/linux/Makefile b/sysdeps/unix/sysv/linux/Makefile
index 2c1a7dd274..f8274552a7 100644
--- a/sysdeps/unix/sysv/linux/Makefile
+++ b/sysdeps/unix/sysv/linux/Makefile
@@ -100,6 +100,15 @@ $(objpfx)tst-sysconf-iov_max: $(objpfx)tst-sysconf-iov_max-uapi.o
 
 $(objpfx)tst-pkey: $(shared-thread-library)
 
+tests-special += $(objpfx)tst-mman-consts.out
+$(objpfx)tst-mman-consts.out: ../sysdeps/unix/sysv/linux/tst-mman-consts.py
+	PYTHONPATH=../scripts \
+	$(PYTHON) ../sysdeps/unix/sysv/linux/tst-mman-consts.py \
+		   --cc="$(CC) $(patsubst -DMODULE_NAME=%, \
+					  -DMODULE_NAME=testsuite, \
+					  $(CPPFLAGS))" \
+	< /dev/null > $@ 2>&1; $(evaluate-test)
+
 endif # $(subdir) == misc
 
 ifeq ($(subdir),time)
diff --git a/sysdeps/unix/sysv/linux/tst-mman-consts.py b/sysdeps/unix/sysv/linux/tst-mman-consts.py
new file mode 100644
index 0000000000..1a613beec0
--- /dev/null
+++ b/sysdeps/unix/sysv/linux/tst-mman-consts.py
@@ -0,0 +1,65 @@
+#!/usr/bin/python3
+# Test that glibc's sys/mman.h constants match the kernel's.
+# Copyright (C) 2018 Free Software Foundation, Inc.
+# This file is part of the GNU C Library.
+#
+# The GNU C Library is free software; you can redistribute it and/or
+# modify it under the terms of the GNU Lesser General Public
+# License as published by the Free Software Foundation; either
+# version 2.1 of the License, or (at your option) any later version.
+#
+# The GNU C Library 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
+# Lesser General Public License for more details.
+#
+# You should have received a copy of the GNU Lesser General Public
+# License along with the GNU C Library; if not, see
+# <http://www.gnu.org/licenses/>.
+
+import argparse
+import sys
+
+import glibcextract
+
+
+def linux_kernel_version(cc):
+    """Return the (major, minor) version of the Linux kernel headers."""
+    sym_data = ['#include <linux/version.h>', 'START',
+                ('LINUX_VERSION_CODE', 'LINUX_VERSION_CODE')]
+    val = glibcextract.compute_c_consts(sym_data, cc)['LINUX_VERSION_CODE']
+    val = int(val)
+    return ((val & 0xff0000) >> 16, (val & 0xff00) >> 8)
+
+
+def main():
+    """The main entry point."""
+    parser = argparse.ArgumentParser(
+        description="Test that glibc's sys/mman.h constants "
+        "match the kernel's.")
+    parser.add_argument('--cc', metavar='CC',
+                        help='C compiler (including options) to use')
+    args = parser.parse_args()
+    linux_version_headers = linux_kernel_version(args.cc)
+    linux_version_glibc = (4, 19)
+    sys.exit(glibcextract.compare_macro_consts(
+        '#define _GNU_SOURCE 1\n'
+        '#include <sys/mman.h>\n',
+        '#define _GNU_SOURCE 1\n'
+        '#include <linux/mman.h>\n',
+        args.cc,
+        'MAP_.*',
+        # A series of MAP_HUGE_<size> macros are defined by the kernel
+        # but not by glibc.  MAP_UNINITIALIZED is kernel-only.
+        # MAP_FAILED is not a MAP_* flag and is glibc-only, as is the
+        # MAP_ANON alias for MAP_ANONYMOUS.  MAP_RENAME, MAP_AUTOGROW,
+        # MAP_LOCAL and MAP_AUTORSRV are in the kernel header for
+        # MIPS, marked as "not used by linux"; SPARC has MAP_INHERIT
+        # in the kernel header, but does not use it.
+        'MAP_HUGE_[0-9].*|MAP_UNINITIALIZED|MAP_FAILED|MAP_ANON'
+        '|MAP_RENAME|MAP_AUTOGROW|MAP_LOCAL|MAP_AUTORSRV|MAP_INHERIT',
+        linux_version_glibc > linux_version_headers,
+        linux_version_headers > linux_version_glibc))
+
+if __name__ == '__main__':
+    main()