Add check for missing wrapper headers

Message ID 87o97mhqom.fsf@oldenburg2.str.redhat.com
State New
Headers show
Series
  • Add check for missing wrapper headers
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Commit Message

Florian Weimer Feb. 8, 2019, 10:16 p.m.
If building on a subset of architectures only, it is easy to miss
wrapper headers which are required by other architectures because
they lack the corresponding sysdeps header.  The check ensures
that every installed header which is not itself a sysdeps header
has a header under include/ (that presumably wraps the header,
and perhaps also adding declarations and definitions for !_ISOMAC).

Also check for the absence of the sysdeps/generic/bits directory
removed in commit c72565e5f1124c2dc72573e83406fe999e56091f, to make
accidental re-introduction more difficult.

2019-02-08  Florian Weimer  <fweimer@redhat.com>

	Check that non-sysdeps headers have wrapper headers.
	* scripts/check-wrapper-headers.py: New file.
	* Makefile (tests-special): Add check-wrapper-headers.out.
	(check-wrapper-headers.out): New target.
	* Rules (tests-special): Add check-wrapper-headers.out.
	(check-wrapper-headers.out): New target.

Comments

Joseph Myers Feb. 8, 2019, 10:23 p.m. | #1
On Fri, 8 Feb 2019, Florian Weimer wrote:

> diff --git a/Makefile b/Makefile
> index 1bfe7fefe1..dc5de7aa6b 100644
> --- a/Makefile
> +++ b/Makefile
> @@ -331,8 +331,13 @@ $(objpfx)check-installed-headers-cxx.out: \
>  	  "$(CXX) $(filter-out -std=%,$(CXXFLAGS)) -D_ISOMAC $(+includes)" \
>  	  $(headers) > $@; \
>  	$(evaluate-test)
> -endif
> -endif
> +endif # $(CXX)
> +
> +tests-special += $(objpfx)check-wrapper-headers.out
> +$(objpfx)check-wrapper-headers.out: scripts/check-wrapper-headers.py $(headers)
> +	$(PYTHON) $< --root=. --subdir=. $(headers) \
> +	  --generated $(common-generated) > $@; $(evaluate-test)
> +endif # $(headers)

This isn't a new issue, so not an objection to this patch, but I'd like us 
to move away from having tests in the top-level Makefile, so we can also 
eliminate the Makefile logic that only exists for top-level tests 
(instead, the top-level Makefile would just have the logic for combining 
test results from subdirectories).

That would presumably require moving the logic for installation of a few 
headers from top-level to some subdirectory such as include/ or misc/, so 
that tests of the headers a directory installs can get run naturally by 
that subdirectory Makefile and it's no longer necessary to have two copies 
of the rules for each such test.
Florian Weimer Feb. 12, 2019, 2:13 p.m. | #2
* Florian Weimer:

> If building on a subset of architectures only, it is easy to miss
> wrapper headers which are required by other architectures because
> they lack the corresponding sysdeps header.  The check ensures
> that every installed header which is not itself a sysdeps header
> has a header under include/ (that presumably wraps the header,
> and perhaps also adding declarations and definitions for !_ISOMAC).
>
> Also check for the absence of the sysdeps/generic/bits directory
> removed in commit c72565e5f1124c2dc72573e83406fe999e56091f, to make
> accidental re-introduction more difficult.
>
> 2019-02-08  Florian Weimer  <fweimer@redhat.com>
>
> 	Check that non-sysdeps headers have wrapper headers.
> 	* scripts/check-wrapper-headers.py: New file.
> 	* Makefile (tests-special): Add check-wrapper-headers.out.
> 	(check-wrapper-headers.out): New target.
> 	* Rules (tests-special): Add check-wrapper-headers.out.
> 	(check-wrapper-headers.out): New target.

It turns out that we should .x pseudo-headers for obsolete sunrpc/nis
builds.  The patch below does this.

Thanks,
Florian

Add check for missing wrapper headers

If building on a subset of architectures only, it is easy to miss
wrapper headers which are required by other architectures because
they lack the corresponding sysdeps header.  The check ensures
that every installed header which is not itself a sysdeps header
has a header under include/ (that presumably wraps the header,
and perhaps also adding declarations and definitions for !_ISOMAC).

Also check for the absence of the sysdeps/generic/bits directory
removed in commit c72565e5f1124c2dc72573e83406fe999e56091f, to make
accidental re-introduction more difficult.

2019-02-08  Florian Weimer  <fweimer@redhat.com>

	Check that non-sysdeps headers have wrapper headers.
	* scripts/check-wrapper-headers.py: New file.
	* Makefile (tests-special): Add check-wrapper-headers.out.
	(check-wrapper-headers.out): New target.
	* Rules (tests-special): Add check-wrapper-headers.out.
	(check-wrapper-headers.out): New target.

diff --git a/Makefile b/Makefile
index 1bfe7fefe1..dc5de7aa6b 100644
--- a/Makefile
+++ b/Makefile
@@ -331,8 +331,13 @@ $(objpfx)check-installed-headers-cxx.out: \
 	  "$(CXX) $(filter-out -std=%,$(CXXFLAGS)) -D_ISOMAC $(+includes)" \
 	  $(headers) > $@; \
 	$(evaluate-test)
-endif
-endif
+endif # $(CXX)
+
+tests-special += $(objpfx)check-wrapper-headers.out
+$(objpfx)check-wrapper-headers.out: scripts/check-wrapper-headers.py $(headers)
+	$(PYTHON) $< --root=. --subdir=. $(headers) \
+	  --generated $(common-generated) > $@; $(evaluate-test)
+endif # $(headers)
 
 define summarize-tests
 @egrep -v '^(PASS|XFAIL):' $(objpfx)$1 || true
diff --git a/Rules b/Rules
index 1562f2ce6d..e08a28d9f3 100644
--- a/Rules
+++ b/Rules
@@ -101,8 +101,15 @@ $(objpfx)check-installed-headers-cxx.out: \
 	  "$(CXX) $(filter-out -std=%,$(CXXFLAGS)) -D_ISOMAC $(+includes)" \
 	  $(headers) > $@; \
 	$(evaluate-test)
-endif
-endif
+endif # $(CXX)
+
+tests-special += $(objpfx)check-wrapper-headers.out
+$(objpfx)check-wrapper-headers.out: \
+  $(..)scripts/check-wrapper-headers.py $(headers)
+	$(PYTHON) $< --root=$(..) --subdir=$(subdir) $(headers) > $@; \
+	  $(evaluate-test)
+
+endif # $(headers)
 
 # This makes all the auxiliary and test programs.
 
diff --git a/scripts/check-wrapper-headers.py b/scripts/check-wrapper-headers.py
new file mode 100644
index 0000000000..10debbd399
--- /dev/null
+++ b/scripts/check-wrapper-headers.py
@@ -0,0 +1,113 @@
+#!/usr/bin/python3
+# Check that a wrapper header exist for each non-sysdeps header.
+# Copyright (C) 2019 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/>.
+
+# Non-sysdeps subdirectories are not on the C include path, so
+# installed headers need to have a sysdep wrapper header.
+#
+# usage: scripts/checl-wrapper-headers.py \
+#     --root=$(..) --subdir=$(subdir) $(headers) \
+#     [--generated $(common-generated)]
+#
+# If invoked with --root=., the script is invoked from the root of the
+# source tree, so paths starting with "include/" are skipped (because
+# those do not require wrappers).
+
+import argparse
+import os
+import sys
+
+# Some subdirectories are only compiled for essentially one target.
+# In this case, we do not need to check for consistent wrapper
+# headers.  Hurd uses a customer way to Hurd-specific inject wrapper
+# headers; see sysdeps/mach/Makefiles under "ifdef in-Makerules".
+SINGLE_TARGET_SUBDIRS = frozenset(("hurd", "mach"))
+
+# Name of the special subdirectory with the wrapper headers.
+INCLUDE = "include"
+
+def check_sysdeps_bits(args):
+    """Check that the directory sysdeps/generic/bits does not exist."""
+    bits = os.path.join(args.root, 'sysdeps', 'generic', 'bits')
+    if os.path.exists(bits):
+        # See commit c72565e5f1124c2dc72573e83406fe999e56091f and
+        # <https://sourceware.org/ml/libc-alpha/2016-05/msg00189.html>.
+        print('error: directory {} has been added, use bits/ instead'.format(
+            os.path.relpath(os.path.realpath(bits), args.root)))
+        return False
+    return True
+
+def check_headers_root(args):
+    """Check headers located at the top level of the source tree."""
+    good = True
+    generated = frozenset(args.generated)
+    for header in args.headers:
+        if not (header.startswith('bits/')
+                or os.path.exists(os.path.join(args.root, INCLUDE, header))
+                or header in generated):
+            print('error: top-level header {} must be in bits/ or {}/'
+                  .format(header, INCLUDE))
+            good = False
+    return good
+
+def check_headers(args):
+    """Check headers located in a subdirectory."""
+    good = True
+    for header in args.headers:
+        # Whitelist .x files, which never have include wrappers.
+        if header.endswith(".x"):
+            continue
+
+        is_nonsysdep_header = os.access(header, os.R_OK)
+        if is_nonsysdep_header:
+            include_path = os.path.join(args.root, INCLUDE, header)
+            if not os.access(include_path, os.R_OK):
+                print('error: missing wrapper header {} for {}'.format(
+                    os.path.join(INCLUDE, header),
+                    os.path.relpath(os.path.realpath(header), args.root)))
+                good = False
+    return good
+
+def main():
+    """The main entry point."""
+    parser = argparse.ArgumentParser(
+        description='Check for missing wrapper headers in include/.')
+    parser.add_argument('--root', metavar='DIRECTORY', required=True,
+                        help='Path to the top-level of the source tree')
+    parser.add_argument('--subdir', metavar='DIRECTORY', required=True,
+                        help='Name of the subdirectory being processed')
+    parser.add_argument('--generated', metavar='FILE', default="", nargs="*",
+                        help="Generated files (which are ignored)")
+    parser.add_argument('headers', help='Header files to process', nargs='+')
+    args = parser.parse_args()
+
+    good = (args.root == '.') == (args.subdir == '.')
+    if not good:
+        print('error: --root/--subdir disagree about top-of-tree location')
+
+    if args.subdir == '.':
+        good &= check_sysdeps_bits(args)
+        good &= check_headers_root(args)
+    elif args.subdir not in SINGLE_TARGET_SUBDIRS:
+        good &= check_headers(args)
+
+    if not good:
+        sys.exit(1)
+
+if __name__ == '__main__':
+    main()
Carlos O'Donell Feb. 12, 2019, 3 p.m. | #3
On 2/12/19 9:13 AM, Florian Weimer wrote:
> * Florian Weimer:
> 
>> If building on a subset of architectures only, it is easy to miss
>> wrapper headers which are required by other architectures because
>> they lack the corresponding sysdeps header.  The check ensures
>> that every installed header which is not itself a sysdeps header
>> has a header under include/ (that presumably wraps the header,
>> and perhaps also adding declarations and definitions for !_ISOMAC).
>>
>> Also check for the absence of the sysdeps/generic/bits directory
>> removed in commit c72565e5f1124c2dc72573e83406fe999e56091f, to make
>> accidental re-introduction more difficult.
>>
>> 2019-02-08  Florian Weimer  <fweimer@redhat.com>
>>
>> 	Check that non-sysdeps headers have wrapper headers.
>> 	* scripts/check-wrapper-headers.py: New file.
>> 	* Makefile (tests-special): Add check-wrapper-headers.out.
>> 	(check-wrapper-headers.out): New target.
>> 	* Rules (tests-special): Add check-wrapper-headers.out.
>> 	(check-wrapper-headers.out): New target.
> 
> It turns out that we should .x pseudo-headers for obsolete sunrpc/nis
> builds.  The patch below does this.

OK. Meets Joseph's objection about top-level tests.

Looks good to me. Thanks for the new tests to make sure we don't get
this wrong. It's bitten me in the past too.

OK for master with typo fixed.

Reviewed-by: Carlos O'Donell <carlos@redhat.com>

> Add check for missing wrapper headers
> 
> If building on a subset of architectures only, it is easy to miss
> wrapper headers which are required by other architectures because
> they lack the corresponding sysdeps header.  The check ensures
> that every installed header which is not itself a sysdeps header
> has a header under include/ (that presumably wraps the header,
> and perhaps also adding declarations and definitions for !_ISOMAC).
> 
> Also check for the absence of the sysdeps/generic/bits directory
> removed in commit c72565e5f1124c2dc72573e83406fe999e56091f, to make
> accidental re-introduction more difficult.
> 
> 2019-02-08  Florian Weimer  <fweimer@redhat.com>
> 
> 	Check that non-sysdeps headers have wrapper headers.
> 	* scripts/check-wrapper-headers.py: New file.
> 	* Makefile (tests-special): Add check-wrapper-headers.out.
> 	(check-wrapper-headers.out): New target.
> 	* Rules (tests-special): Add check-wrapper-headers.out.
> 	(check-wrapper-headers.out): New target.
> 
> diff --git a/Makefile b/Makefile
> index 1bfe7fefe1..dc5de7aa6b 100644
> --- a/Makefile
> +++ b/Makefile
> @@ -331,8 +331,13 @@ $(objpfx)check-installed-headers-cxx.out: \
>  	  "$(CXX) $(filter-out -std=%,$(CXXFLAGS)) -D_ISOMAC $(+includes)" \
>  	  $(headers) > $@; \
>  	$(evaluate-test)
> -endif
> -endif
> +endif # $(CXX)
> +
> +tests-special += $(objpfx)check-wrapper-headers.out
> +$(objpfx)check-wrapper-headers.out: scripts/check-wrapper-headers.py $(headers)
> +	$(PYTHON) $< --root=. --subdir=. $(headers) \
> +	  --generated $(common-generated) > $@; $(evaluate-test)
> +endif # $(headers)

OK.

>  
>  define summarize-tests
>  @egrep -v '^(PASS|XFAIL):' $(objpfx)$1 || true
> diff --git a/Rules b/Rules
> index 1562f2ce6d..e08a28d9f3 100644
> --- a/Rules
> +++ b/Rules
> @@ -101,8 +101,15 @@ $(objpfx)check-installed-headers-cxx.out: \
>  	  "$(CXX) $(filter-out -std=%,$(CXXFLAGS)) -D_ISOMAC $(+includes)" \
>  	  $(headers) > $@; \
>  	$(evaluate-test)
> -endif
> -endif
> +endif # $(CXX)
> +
> +tests-special += $(objpfx)check-wrapper-headers.out
> +$(objpfx)check-wrapper-headers.out: \
> +  $(..)scripts/check-wrapper-headers.py $(headers)
> +	$(PYTHON) $< --root=$(..) --subdir=$(subdir) $(headers) > $@; \
> +	  $(evaluate-test)

OK.

> +
> +endif # $(headers)
>  
>  # This makes all the auxiliary and test programs.
>  
> diff --git a/scripts/check-wrapper-headers.py b/scripts/check-wrapper-headers.py
> new file mode 100644
> index 0000000000..10debbd399
> --- /dev/null
> +++ b/scripts/check-wrapper-headers.py
> @@ -0,0 +1,113 @@
> +#!/usr/bin/python3
> +# Check that a wrapper header exist for each non-sysdeps header.
> +# Copyright (C) 2019 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/>.
> +
> +# Non-sysdeps subdirectories are not on the C include path, so
> +# installed headers need to have a sysdep wrapper header.

OK.

> +#
> +# usage: scripts/checl-wrapper-headers.py \
> +#     --root=$(..) --subdir=$(subdir) $(headers) \
> +#     [--generated $(common-generated)]
> +#
> +# If invoked with --root=., the script is invoked from the root of the
> +# source tree, so paths starting with "include/" are skipped (because
> +# those do not require wrappers).
> +
> +import argparse
> +import os
> +import sys
> +
> +# Some subdirectories are only compiled for essentially one target.
> +# In this case, we do not need to check for consistent wrapper
> +# headers.  Hurd uses a customer way to Hurd-specific inject wrapper

s/customer/custom/g

> +# headers; see sysdeps/mach/Makefiles under "ifdef in-Makerules".
> +SINGLE_TARGET_SUBDIRS = frozenset(("hurd", "mach"))
> +
> +# Name of the special subdirectory with the wrapper headers.
> +INCLUDE = "include"
> +
> +def check_sysdeps_bits(args):
> +    """Check that the directory sysdeps/generic/bits does not exist."""
> +    bits = os.path.join(args.root, 'sysdeps', 'generic', 'bits')
> +    if os.path.exists(bits):
> +        # See commit c72565e5f1124c2dc72573e83406fe999e56091f and
> +        # <https://sourceware.org/ml/libc-alpha/2016-05/msg00189.html>.
> +        print('error: directory {} has been added, use bits/ instead'.format(
> +            os.path.relpath(os.path.realpath(bits), args.root)))
> +        return False
> +    return True
> +
> +def check_headers_root(args):
> +    """Check headers located at the top level of the source tree."""
> +    good = True
> +    generated = frozenset(args.generated)
> +    for header in args.headers:
> +        if not (header.startswith('bits/')
> +                or os.path.exists(os.path.join(args.root, INCLUDE, header))
> +                or header in generated):
> +            print('error: top-level header {} must be in bits/ or {}/'
> +                  .format(header, INCLUDE))
> +            good = False
> +    return good
> +
> +def check_headers(args):
> +    """Check headers located in a subdirectory."""
> +    good = True
> +    for header in args.headers:
> +        # Whitelist .x files, which never have include wrappers.
> +        if header.endswith(".x"):
> +            continue
> +
> +        is_nonsysdep_header = os.access(header, os.R_OK)
> +        if is_nonsysdep_header:
> +            include_path = os.path.join(args.root, INCLUDE, header)
> +            if not os.access(include_path, os.R_OK):
> +                print('error: missing wrapper header {} for {}'.format(
> +                    os.path.join(INCLUDE, header),
> +                    os.path.relpath(os.path.realpath(header), args.root)))
> +                good = False
> +    return good
> +
> +def main():
> +    """The main entry point."""
> +    parser = argparse.ArgumentParser(
> +        description='Check for missing wrapper headers in include/.')
> +    parser.add_argument('--root', metavar='DIRECTORY', required=True,
> +                        help='Path to the top-level of the source tree')
> +    parser.add_argument('--subdir', metavar='DIRECTORY', required=True,
> +                        help='Name of the subdirectory being processed')
> +    parser.add_argument('--generated', metavar='FILE', default="", nargs="*",
> +                        help="Generated files (which are ignored)")
> +    parser.add_argument('headers', help='Header files to process', nargs='+')
> +    args = parser.parse_args()
> +
> +    good = (args.root == '.') == (args.subdir == '.')
> +    if not good:
> +        print('error: --root/--subdir disagree about top-of-tree location')
> +
> +    if args.subdir == '.':
> +        good &= check_sysdeps_bits(args)
> +        good &= check_headers_root(args)
> +    elif args.subdir not in SINGLE_TARGET_SUBDIRS:
> +        good &= check_headers(args)
> +

OK.

> +    if not good:
> +        sys.exit(1)
> +
> +if __name__ == '__main__':
> +    main()
>

Patch

diff --git a/Makefile b/Makefile
index 1bfe7fefe1..dc5de7aa6b 100644
--- a/Makefile
+++ b/Makefile
@@ -331,8 +331,13 @@  $(objpfx)check-installed-headers-cxx.out: \
 	  "$(CXX) $(filter-out -std=%,$(CXXFLAGS)) -D_ISOMAC $(+includes)" \
 	  $(headers) > $@; \
 	$(evaluate-test)
-endif
-endif
+endif # $(CXX)
+
+tests-special += $(objpfx)check-wrapper-headers.out
+$(objpfx)check-wrapper-headers.out: scripts/check-wrapper-headers.py $(headers)
+	$(PYTHON) $< --root=. --subdir=. $(headers) \
+	  --generated $(common-generated) > $@; $(evaluate-test)
+endif # $(headers)
 
 define summarize-tests
 @egrep -v '^(PASS|XFAIL):' $(objpfx)$1 || true
diff --git a/Rules b/Rules
index 1562f2ce6d..e08a28d9f3 100644
--- a/Rules
+++ b/Rules
@@ -101,8 +101,15 @@  $(objpfx)check-installed-headers-cxx.out: \
 	  "$(CXX) $(filter-out -std=%,$(CXXFLAGS)) -D_ISOMAC $(+includes)" \
 	  $(headers) > $@; \
 	$(evaluate-test)
-endif
-endif
+endif # $(CXX)
+
+tests-special += $(objpfx)check-wrapper-headers.out
+$(objpfx)check-wrapper-headers.out: \
+  $(..)scripts/check-wrapper-headers.py $(headers)
+	$(PYTHON) $< --root=$(..) --subdir=$(subdir) $(headers) > $@; \
+	  $(evaluate-test)
+
+endif # $(headers)
 
 # This makes all the auxiliary and test programs.
 
diff --git a/scripts/check-wrapper-headers.py b/scripts/check-wrapper-headers.py
new file mode 100644
index 0000000000..f5da95cfe6
--- /dev/null
+++ b/scripts/check-wrapper-headers.py
@@ -0,0 +1,109 @@ 
+#!/usr/bin/python3
+# Check that a wrapper header exist for each non-sysdeps header.
+# Copyright (C) 2019 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/>.
+
+# Non-sysdeps subdirectories are not on the C include path, so
+# installed headers need to have a sysdep wrapper header.
+#
+# usage: scripts/checl-wrapper-headers.py \
+#     --root=$(..) --subdir=$(subdir) $(headers) \
+#     [--generated $(common-generated)]
+#
+# If invoked with --root=., the script is invoked from the root of the
+# source tree, so paths starting with "include/" are skipped (because
+# those do not require wrappers).
+
+import argparse
+import os
+import sys
+
+# Some subdirectories are only compiled for essentially one target.
+# In this case, we do not need to check for consistent wrapper
+# headers.  Hurd uses a customer way to Hurd-specific inject wrapper
+# headers; see sysdeps/mach/Makefiles under "ifdef in-Makerules".
+SINGLE_TARGET_SUBDIRS = frozenset(("hurd", "mach"))
+
+# Name of the special subdirectory with the wrapper headers.
+INCLUDE = "include"
+
+def check_sysdeps_bits(args):
+    """Check that the directory sysdeps/generic/bits does not exist."""
+    bits = os.path.join(args.root, 'sysdeps', 'generic', 'bits')
+    if os.path.exists(bits):
+        # See commit c72565e5f1124c2dc72573e83406fe999e56091f and
+        # <https://sourceware.org/ml/libc-alpha/2016-05/msg00189.html>.
+        print('error: directory {} has been added, use bits/ instead'.format(
+            os.path.relpath(os.path.realpath(bits), args.root)))
+        return False
+    return True
+
+def check_headers_root(args):
+    """Check headers located at the top level of the source tree."""
+    good = True
+    generated = frozenset(args.generated)
+    for header in args.headers:
+        if not (header.startswith('bits/')
+                or os.path.exists(os.path.join(args.root, INCLUDE, header))
+                or header in generated):
+            print('error: top-level header {} must be in bits/ or {}/'
+                  .format(header, INCLUDE))
+            good = False
+    return good
+
+def check_headers(args):
+    """Check headers located in a subdirectory."""
+    good = True
+    for header in args.headers:
+        is_nonsysdep_header = os.access(header, os.R_OK)
+        if is_nonsysdep_header:
+            include_path = os.path.join(args.root, INCLUDE, header)
+            if not os.access(include_path, os.R_OK):
+                print('error: missing wrapper header {} for {}'.format(
+                    os.path.join(INCLUDE, header),
+                    os.path.relpath(os.path.realpath(header), args.root)))
+                good = False
+    return good
+
+def main():
+    """The main entry point."""
+    parser = argparse.ArgumentParser(
+        description='Check for missing wrapper headers in include/.')
+    parser.add_argument('--root', metavar='DIRECTORY', required=True,
+                        help='Path to the top-level of the source tree')
+    parser.add_argument('--subdir', metavar='DIRECTORY', required=True,
+                        help='Name of the subdirectory being processed')
+    parser.add_argument('--generated', metavar='FILE', default="", nargs="*",
+                        help="Generated files (which are ignored)")
+    parser.add_argument('headers', help='Header files to process', nargs='+')
+    args = parser.parse_args()
+
+    good = (args.root == '.') == (args.subdir == '.')
+    if not good:
+        print('error: --root/--subdir disagree about top-of-tree location')
+
+    if args.subdir == '.':
+        good &= check_sysdeps_bits(args)
+        good &= check_headers_root(args)
+    elif args.subdir not in SINGLE_TARGET_SUBDIRS:
+        good &= check_headers(args)
+
+    if not good:
+        sys.exit(1)
+
+if __name__ == '__main__':
+    main()