elf: Check that --list-diagnostics output has the expected syntax

Parts of elf/tst-rtld-list-diagnostics.py have been copied from
scripts/tst-ld-trace.py.

The abnf module is entirely optional and used to verify the
ABNF grammar as included in the manual.

Reviewed-by: Adhemerval Zanella  <adhemerval.zanella@linaro.org>

INSTALL

@@ -585,6 +585,13 @@ build the GNU C Library:
      in your system.  As of release time PExpect 4.8.0 is the newest
      verified to work to test the pretty printers.
 
+   • The Python ‘abnf’ module.
+
+     This module is optional and used to verify some ABNF grammars in
+     the manual.  Version 2.2.0 has been confirmed to work as expected.
+     A missing ‘abnf’ module does not reduce the test coverage of the
+     library itself.
+
    • GDB 7.8 or later with support for Python 2.7/3.4 or later
 
      GDB itself needs to be configured with Python support in order to

elf/Makefile

@@ -1123,6 +1123,7 @@ tests-special += \
   $(objpfx)argv0test.out \
   $(objpfx)tst-pathopt.out \
   $(objpfx)tst-rtld-help.out \
+  $(objpfx)tst-rtld-list-diagnostics.out \
   $(objpfx)tst-rtld-load-self.out \
   $(objpfx)tst-rtld-preload.out \
   $(objpfx)tst-sprof-basic.out \
@@ -2799,6 +2800,14 @@ $(objpfx)tst-ro-dynamic-mod.so: $(objpfx)tst-ro-dynamic-mod.os \
 		-Wl,--script=tst-ro-dynamic-mod.map \
 		$(objpfx)tst-ro-dynamic-mod.os
 
+$(objpfx)tst-rtld-list-diagnostics.out: tst-rtld-list-diagnostics.py \
+  $(..)manual/dynlink.texi $(objpfx)$(rtld-installed-name)
+	$(PYTHON) tst-rtld-list-diagnostics.py \
+	  --manual=$(..)manual/dynlink.texi \
+	  "$(test-wrapper-env) $(objpfx)$(rtld-installed-name) --list-diagnostics" \
+	  > $@; \
+	$(evaluate-test)
+
 $(objpfx)tst-rtld-run-static.out: $(objpfx)/ldconfig
 
 $(objpfx)tst-dl_find_object.out: \

elf/tst-rtld-list-diagnostics.py

@@ -0,0 +1,303 @@
+#!/usr/bin/python3
+# Test that the ld.so --list-diagnostics output has the expected syntax.
+# Copyright (C) 2022-2023 Free Software Foundation, Inc.
+# Copyright The GNU Toolchain Authors.
+# 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
+# <https://www.gnu.org/licenses/>.
+
+import argparse
+import collections
+import subprocess
+import sys
+
+try:
+    subprocess.run
+except:
+    class _CompletedProcess:
+        def __init__(self, args, returncode, stdout=None, stderr=None):
+            self.args = args
+            self.returncode = returncode
+            self.stdout = stdout
+            self.stderr = stderr
+
+    def _run(*popenargs, input=None, timeout=None, check=False, **kwargs):
+        assert(timeout is None)
+        with subprocess.Popen(*popenargs, **kwargs) as process:
+            try:
+                stdout, stderr = process.communicate(input)
+            except:
+                process.kill()
+                process.wait()
+                raise
+            returncode = process.poll()
+            if check and returncode:
+                raise subprocess.CalledProcessError(returncode, popenargs)
+        return _CompletedProcess(popenargs, returncode, stdout, stderr)
+
+    subprocess.run = _run
+
+# Number of errors encountered.  Zero means no errors (test passes).
+errors = 0
+
+def parse_line(line):
+    """Parse a line of --list-diagnostics output.
+
+    This function returns a pair (SUBSCRIPTS, VALUE).  VALUE is either
+    a byte string or an integer.  SUBSCRIPT is a tuple of (LABEL,
+    INDEX) pairs, where LABEL is a field identifier (a string), and
+    INDEX is an integer or None, to indicate that this field is not
+    indexed.
+
+    """
+
+    # Extract the list of subscripts before the value.
+    idx = 0
+    subscripts = []
+    while line[idx] != '=':
+        start_idx = idx
+
+        # Extract the label.
+        while line[idx] not in '[.=':
+            idx += 1
+        label = line[start_idx:idx]
+
+        if line[idx] == '[':
+            # Subscript with a 0x index.
+            assert label
+            close_bracket = line.index(']', idx)
+            index = line[idx + 1:close_bracket]
+            assert index.startswith('0x')
+            index = int(index, 0)
+            subscripts.append((label, index))
+            idx = close_bracket + 1
+        else: # '.' or '='.
+            if label:
+                subscripts.append((label, None))
+            if line[idx] == '.':
+                idx += 1
+
+    # The value is either a string or a 0x number.
+    value = line[idx + 1:]
+    if value[0] == '"':
+        # Decode the escaped string into a byte string.
+        assert value[-1] == '"'
+        idx = 1
+        result = []
+        while True:
+            ch = value[idx]
+            if ch == '\\':
+                if value[idx + 1] in '"\\':
+                    result.append(ord(value[idx + 1]))
+                    idx += 2
+                else:
+                    result.append(int(value[idx + 1:idx + 4], 8))
+                    idx += 4
+            elif ch == '"':
+                assert idx == len(value) - 1
+                break
+            else:
+                result.append(ord(value[idx]))
+                idx += 1
+        value = bytes(result)
+    else:
+        # Convert the value into an integer.
+        assert value.startswith('0x')
+        value = int(value, 0)
+    return (tuple(subscripts), value)
+
+assert parse_line('a.b[0x1]=0x2') == ((('a', None), ('b', 1)), 2)
+assert parse_line(r'b[0x3]="four\040\"\\"') == ((('b', 3),), b'four \"\\')
+
+# ABNF for a line of --list-diagnostics output.
+diagnostics_abnf = r"""
+HEXDIG = %x30-39 / %x61-6f ; lowercase a-f only
+ALPHA = %x41-5a / %x61-7a / %x7f ; letters and underscore
+ALPHA-NUMERIC = ALPHA / %x30-39 / "_"
+DQUOTE = %x22 ; "
+
+; Numbers are always hexadecimal and use a 0x prefix.
+hex-value-prefix = %x30 %x78
+hex-value = hex-value-prefix 1*HEXDIG
+
+; Strings use octal escape sequences and \\, \".
+string-char = %x20-21 / %x23-5c / %x5d-7e ; printable but not "\
+string-quoted-octal = %x30-33 2*2%x30-37
+string-quoted = "\" ("\" / DQUOTE / string-quoted-octal)
+string-value = DQUOTE *(string-char / string-quoted) DQUOTE
+
+value = hex-value / string-value
+
+label = ALPHA *ALPHA-NUMERIC
+index = "[" hex-value "]"
+subscript = label [index]
+
+line = subscript *("." subscript) "=" value
+"""
+
+def check_consistency_with_manual(manual_path):
+    """Verify that the code fragments in the manual match this script.
+
+    The code fragments are duplicated to clarify the dual license.
+    """
+
+    global errors
+
+    def extract_lines(path, start_line, end_line, skip_lines=()):
+        result = []
+        with open(path) as inp:
+            capturing = False
+            for line in inp:
+                if line.strip() == start_line:
+                    capturing = True
+                elif not capturing or line.strip() in skip_lines:
+                    continue
+                elif line.strip() == end_line:
+                    capturing = False
+                else:
+                    result.append(line)
+        if not result:
+            raise ValueError('{!r} not found in {!r}'.format(start_line, path))
+        if capturing:
+            raise ValueError('{!r} not found in {!r}'.format(end_line, path))
+        return result
+
+    def check(name, manual, script):
+        global errors
+
+        if manual == script:
+            return
+        print('error: {} fragment in manual is different'.format(name))
+        import difflib
+        sys.stdout.writelines(difflib.unified_diff(
+            manual, script, fromfile='manual', tofile='script'))
+        errors += 1
+
+    manual_abnf = extract_lines(manual_path,
+                                '@c ABNF-START', '@end smallexample',
+                                skip_lines=('@smallexample',))
+    check('ABNF', diagnostics_abnf.splitlines(keepends=True)[1:], manual_abnf)
+
+# If the abnf module can be imported, run an additional check that the
+# 'line' production from the ABNF grammar matches --list-diagnostics
+# output lines.
+try:
+    import abnf
+except ImportError:
+    abnf = None
+    print('info: skipping ABNF validation because the abnf module is missing')
+
+if abnf is not None:
+    class Grammar(abnf.Rule):
+        pass
+
+    Grammar.load_grammar(diagnostics_abnf)
+
+    def parse_abnf(line):
+        global errors
+
+        # Just verify that the line parses.
+        try:
+            Grammar('line').parse_all(line)
+        except abnf.ParseError:
+            print('error: ABNF parse error:', repr(line))
+            errors += 1
+else:
+    def parse_abnf(line):
+        pass
+
+
+def parse_diagnostics(cmd):
+    global errors
+    diag_out = subprocess.run(cmd, stdout=subprocess.PIPE, check=True,
+                              universal_newlines=True).stdout
+    if diag_out[-1] != '\n':
+        print('error: ld.so output does not end in newline')
+        errors += 1
+
+    PathType = collections.namedtuple('PathType',
+                                      'has_index value_type original_line')
+    # Mapping tuples of labels to PathType values.
+    path_types = {}
+
+    seen_subscripts = {}
+
+    for line in diag_out.splitlines():
+        parse_abnf(line)
+        subscripts, value = parse_line(line)
+
+        # Check for duplicates.
+        if subscripts in seen_subscripts:
+            print('error: duplicate value assignment:', repr(line))
+            print('  previous line:,', repr(seen_subscripts[line]))
+            errors += 1
+        else:
+            seen_subscripts[subscripts] = line
+
+        # Compare types against the previously seen labels.
+        labels = tuple([label for label, index in subscripts])
+        has_index = tuple([index is not None for label, index in subscripts])
+        value_type = type(value)
+        if labels in path_types:
+            previous_type = path_types[labels]
+            if has_index != previous_type.has_index:
+                print('error: line has mismatch of indexing:', repr(line))
+                print('  index types:', has_index)
+                print('  previous:   ', previous_type.has_index)
+                print('  previous line:', repr(previous_type.original_line))
+                errors += 1
+            if value_type != previous_type.value_type:
+                print('error: line has mismatch of value type:', repr(line))
+                print('  value type:', value_type.__name__)
+                print('  previous:  ', previous_type.value_type.__name__)
+                print('  previous line:', repr(previous_type.original_line))
+                errors += 1
+        else:
+            path_types[labels] = PathType(has_index, value_type, line)
+
+        # Check that this line does not add indexing to a previous value.
+        for idx in range(1, len(subscripts) - 1):
+            if subscripts[:idx] in path_types:
+                print('error: line assigns to atomic value:', repr(line))
+                print('  previous line:', repr(previous_type.original_line))
+                errors += 1
+
+    if errors:
+        sys.exit(1)
+
+def get_parser():
+    parser = argparse.ArgumentParser(description=__doc__)
+    parser.add_argument('--manual',
+                        help='path to .texi file for consistency checks')
+    parser.add_argument('command',
+                        help='comand to run')
+    return parser
+
+
+def main(argv):
+    parser = get_parser()
+    opts = parser.parse_args(argv)
+
+    if opts.manual:
+        check_consistency_with_manual(opts.manual)
+
+    # Remove the initial 'env' command.
+    parse_diagnostics(opts.command.split()[1:])
+
+    if errors:
+        sys.exit(1)
+
+if __name__ == '__main__':
+    main(sys.argv[1:])

manual/install.texi

@@ -632,6 +632,14 @@ GDB, and should be compatible with the Python version in your system.
 As of release time PExpect 4.8.0 is the newest verified to work to test
 the pretty printers.
 
+@item
+The Python @code{abnf} module.
+
+This module is optional and used to verify some ABNF grammars in the
+manual.  Version 2.2.0 has been confirmed to work as expected.  A
+missing @code{abnf} module does not reduce the test coverage of the
+library itself.
+
 @item
 GDB 7.8 or later with support for Python 2.7/3.4 or later