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.

1 files changed, 17 insertions, 4 deletions

diff --git a/scripts/glibcextract.py b/scripts/glibcextract.py
index ecc4d5b6cc..06f712ad11 100644
--- a/scripts/glibcextract.py
+++ b/scripts/glibcextract.py
@@ -136,12 +136,19 @@ def compute_macro_consts(source_text, cc, macro_re, exclude_re=None):
     return compute_c_consts(sym_data, cc)
 
 
-def compare_macro_consts(source_1, source_2, cc, macro_re, exclude_re=None):
+def compare_macro_consts(source_1, source_2, cc, macro_re, exclude_re=None,
+                         allow_extra_1=False, allow_extra_2=False):
     """Compare the values of macros defined by two different sources.
 
     The sources would typically be includes of a glibc header and a
-    kernel header.  Return 1 if there were any differences, 0 if the
-    macro values were the same.
+    kernel header.  If allow_extra_1, the first source may define
+    extra macros (typically if the kernel headers are older than the
+    version glibc has taken definitions from); if allow_extra_2, the
+    second source may define extra macros (typically if the kernel
+    headers are newer than the version glibc has taken definitions
+    from).  Return 1 if there were any differences other than those
+    allowed, 0 if the macro values were the same apart from any
+    allowed differences.
 
     """
     macros_1 = compute_macro_consts(source_1, cc, macro_re, exclude_re)
@@ -150,13 +157,19 @@ def compare_macro_consts(source_1, source_2, cc, macro_re, exclude_re=None):
         return 0
     print('First source:\n%s\n' % source_1)
     print('Second source:\n%s\n' % source_2)
+    ret = 0
     for name, value in sorted(macros_1.items()):
         if name not in macros_2:
             print('Only in first source: %s' % name)
+            if not allow_extra_1:
+                ret = 1
         elif macros_1[name] != macros_2[name]:
             print('Different values for %s: %s != %s'
                   % (name, macros_1[name], macros_2[name]))
+            ret = 1
     for name in sorted(macros_2.keys()):
         if name not in macros_1:
             print('Only in second source: %s' % name)
-    return 1
+            if not allow_extra_2:
+                ret = 1
+    return ret