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Message-ID: <507f8916a05a1c3bebde2d154a06f41d17671452.1755784930.git.mchehab+huawei@kernel.org>
Date: Thu, 21 Aug 2025 16:21:08 +0200
From: Mauro Carvalho Chehab <mchehab+huawei@...nel.org>
To: Linux Doc Mailing List <linux-doc@...r.kernel.org>,
Jonathan Corbet <corbet@....net>
Cc: Mauro Carvalho Chehab <mchehab+huawei@...nel.org>,
linux-kernel@...r.kernel.org
Subject: [PATCH 02/24] docs: parse-headers.py: convert parse-headers.pl
When the Kernel started to use Sphinx, we had to come up with
a solution to parse media headers. On that time, we didn't have
much experience with Sphinx extensions. So, we came up with our
own script-based solution that were basically implementing a
set of rules we used to have at the Makefile.
Convert it to Python, keeping it bug-compatible with the
original script.
While here, try to better document it.
Signed-off-by: Mauro Carvalho Chehab <mchehab+huawei@...nel.org>
---
Documentation/sphinx/parse-headers.py | 429 ++++++++++++++++++++++++++
1 file changed, 429 insertions(+)
create mode 100755 Documentation/sphinx/parse-headers.py
diff --git a/Documentation/sphinx/parse-headers.py b/Documentation/sphinx/parse-headers.py
new file mode 100755
index 000000000000..b39284d21090
--- /dev/null
+++ b/Documentation/sphinx/parse-headers.py
@@ -0,0 +1,429 @@
+#!/usr/bin/env python3
+# SPDX-License-Identifier: GPL-2.0
+# Copyright (c) 2016 by Mauro Carvalho Chehab <mchehab@...nel.org>.
+# pylint: disable=C0103,R0902,R0912,R0914,R0915
+
+"""
+Convert a C header or source file (C_FILE), into a ReStructured Text
+included via ..parsed-literal block with cross-references for the
+documentation files that describe the API. It accepts an optional
+EXCEPTIONS_FILE with describes what elements will be either ignored or
+be pointed to a non-default reference.
+
+The output is written at the (OUT_FILE).
+
+It is capable of identifying defines, functions, structs, typedefs,
+enums and enum symbols and create cross-references for all of them.
+It is also capable of distinguish #define used for specifying a Linux
+ioctl.
+
+The EXCEPTIONS_FILE contains a set of rules like:
+
+ ignore ioctl VIDIOC_ENUM_FMT
+ replace ioctl VIDIOC_DQBUF vidioc_qbuf
+ replace define V4L2_EVENT_MD_FL_HAVE_FRAME_SEQ :c:type:`v4l2_event_motion_det`
+"""
+
+import argparse
+import os
+import re
+import sys
+
+
+class ParseHeader:
+ """
+ Creates an enriched version of a Kernel header file with cross-links
+ to each C data structure type.
+
+ It is meant to allow having a more comprehensive documentation, where
+ uAPI headers will create cross-reference links to the code.
+
+ It is capable of identifying defines, functions, structs, typedefs,
+ enums and enum symbols and create cross-references for all of them.
+ It is also capable of distinguish #define used for specifying a Linux
+ ioctl.
+
+ By default, it create rules for all symbols and defines, but it also
+ allows parsing an exception file. Such file contains a set of rules
+ using the syntax below:
+
+ 1. Ignore rules:
+
+ ignore <type> <symbol>`
+
+ Removes the symbol from reference generation.
+
+ 2. Replace rules:
+
+ replace <type> <old_symbol> <new_reference>
+
+ Replaces how old_symbol with a new reference. The new_reference can be:
+ - A simple symbol name;
+ - A full Sphinx reference.
+
+ On both cases, <type> can be:
+ - ioctl: for defines that end with _IO*, e.g. ioctl definitions
+ - define: for other defines
+ - symbol: for symbols defined within enums;
+ - typedef: for typedefs;
+ - enum: for the name of a non-anonymous enum;
+ - struct: for structs.
+
+ Examples:
+
+ ignore define __LINUX_MEDIA_H
+ ignore ioctl VIDIOC_ENUM_FMT
+ replace ioctl VIDIOC_DQBUF vidioc_qbuf
+ replace define V4L2_EVENT_MD_FL_HAVE_FRAME_SEQ :c:type:`v4l2_event_motion_det`
+ """
+
+ # Parser regexes with multiple ways to capture enums and structs
+ RE_ENUMS = [
+ re.compile(r"^\s*enum\s+([\w_]+)\s*\{"),
+ re.compile(r"^\s*enum\s+([\w_]+)\s*$"),
+ re.compile(r"^\s*typedef\s*enum\s+([\w_]+)\s*\{"),
+ re.compile(r"^\s*typedef\s*enum\s+([\w_]+)\s*$"),
+ ]
+ RE_STRUCTS = [
+ re.compile(r"^\s*struct\s+([_\w][\w\d_]+)\s*\{"),
+ re.compile(r"^\s*struct\s+([_\w][\w\d_]+)$"),
+ re.compile(r"^\s*typedef\s*struct\s+([_\w][\w\d_]+)\s*\{"),
+ re.compile(r"^\s*typedef\s*struct\s+([_\w][\w\d_]+)$"),
+ ]
+
+ # FIXME: the original code was written a long time before Sphinx C
+ # domain to have multiple namespaces. To avoid to much turn at the
+ # existing hyperlinks, the code kept using "c:type" instead of the
+ # right types. To change that, we need to change the types not only
+ # here, but also at the uAPI media documentation.
+ DEF_SYMBOL_TYPES = {
+ "ioctl": {
+ "prefix": "\\ ",
+ "suffix": "\\ ",
+ "ref_type": ":ref",
+ },
+ "define": {
+ "prefix": "\\ ",
+ "suffix": "\\ ",
+ "ref_type": ":ref",
+ },
+ # We're calling each definition inside an enum as "symbol"
+ "symbol": {
+ "prefix": "\\ ",
+ "suffix": "\\ ",
+ "ref_type": ":ref",
+ },
+ "typedef": {
+ "prefix": "\\ ",
+ "suffix": "\\ ",
+ "ref_type": ":c:type",
+ },
+ # This is the name of the enum itself
+ "enum": {
+ "prefix": "",
+ "suffix": "\\ ",
+ "ref_type": ":c:type",
+ },
+ "struct": {
+ "prefix": "",
+ "suffix": "\\ ",
+ "ref_type": ":c:type",
+ },
+ }
+
+ def __init__(self, debug: bool = False):
+ """Initialize internal vars"""
+ self.debug = debug
+ self.data = ""
+
+ self.symbols = {}
+
+ for symbol_type in self.DEF_SYMBOL_TYPES:
+ self.symbols[symbol_type] = {}
+
+ def store_type(self, symbol_type: str, symbol: str,
+ ref_name: str = None, replace_underscores: bool = True):
+ """
+ Stores a new symbol at self.symbols under symbol_type.
+
+ By default, underscores are replaced by "-"
+ """
+ defs = self.DEF_SYMBOL_TYPES[symbol_type]
+
+ prefix = defs.get("prefix", "")
+ suffix = defs.get("suffix", "")
+ ref_type = defs.get("ref_type")
+
+ # Determine ref_link based on symbol type
+ if ref_type:
+ if symbol_type == "enum":
+ ref_link = f"{ref_type}:`{symbol}`"
+ else:
+ if not ref_name:
+ ref_name = symbol.lower()
+
+ if replace_underscores:
+ ref_name = ref_name.replace("_", "-")
+
+ ref_link = f"{ref_type}:`{symbol} <{ref_name}>`"
+ else:
+ ref_link = symbol
+
+ self.symbols[symbol_type][symbol] = f"{prefix}{ref_link}{suffix}"
+
+ def store_line(self, line):
+ """Stores a line at self.data, properly indented"""
+ line = " " + line.expandtabs()
+ self.data += line.rstrip(" ")
+
+ def parse_file(self, file_in: str):
+ """Reads a C source file and get identifiers"""
+ self.data = ""
+ is_enum = False
+ is_comment = False
+ multiline = ""
+
+ with open(file_in, "r",
+ encoding="utf-8", errors="backslashreplace") as f:
+ for line_no, line in enumerate(f):
+ self.store_line(line)
+ line = line.strip("\n")
+
+ # Handle continuation lines
+ if line.endswith(r"\\"):
+ multiline += line[-1]
+ continue
+
+ if multiline:
+ line = multiline + line
+ multiline = ""
+
+ # Handle comments. They can be multilined
+ if not is_comment:
+ if re.search(r"/\*.*", line):
+ is_comment = True
+ else:
+ # Strip C99-style comments
+ line = re.sub(r"(//.*)", "", line)
+
+ if is_comment:
+ if re.search(r".*\*/", line):
+ is_comment = False
+ else:
+ multiline = line
+ continue
+
+ # At this point, line variable may be a multilined statement,
+ # if lines end with \ or if they have multi-line comments
+ # With that, it can safely remove the entire comments,
+ # and there's no need to use re.DOTALL for the logic below
+
+ line = re.sub(r"(/\*.*\*/)", "", line)
+ if not line.strip():
+ continue
+
+ # It can be useful for debug purposes to print the file after
+ # having comments stripped and multi-lines grouped.
+ if self.debug > 1:
+ print(f"line {line_no + 1}: {line}")
+
+ # Now the fun begins: parse each type and store it.
+
+ # We opted for a two parsing logic here due to:
+ # 1. it makes easier to debug issues not-parsed symbols;
+ # 2. we want symbol replacement at the entire content, not
+ # just when the symbol is detected.
+
+ if is_enum:
+ match = re.match(r"^\s*([_\w][\w\d_]+)\s*[\,=]?", line)
+ if match:
+ self.store_type("symbol", match.group(1))
+ if "}" in line:
+ is_enum = False
+ continue
+
+ match = re.match(r"^\s*#\s*define\s+([\w_]+)\s+_IO", line)
+ if match:
+ self.store_type("ioctl", match.group(1),
+ replace_underscores=False)
+ continue
+
+ match = re.match(r"^\s*#\s*define\s+([\w_]+)(\s+|$)", line)
+ if match:
+ self.store_type("define", match.group(1))
+ continue
+
+ match = re.match(r"^\s*typedef\s+([_\w][\w\d_]+)\s+(.*)\s+([_\w][\w\d_]+);",
+ line)
+ if match:
+ name = match.group(2).strip()
+ symbol = match.group(3)
+ self.store_type("typedef", symbol, ref_name=name,
+ replace_underscores=False)
+ continue
+
+ for re_enum in self.RE_ENUMS:
+ match = re_enum.match(line)
+ if match:
+ self.store_type("enum", match.group(1))
+ is_enum = True
+ break
+
+ for re_struct in self.RE_STRUCTS:
+ match = re_struct.match(line)
+ if match:
+ self.store_type("struct", match.group(1),
+ replace_underscores=False)
+ break
+
+ def process_exceptions(self, fname: str):
+ """
+ Process exceptions file with rules to ignore or replace references.
+ """
+ if not fname:
+ return
+
+ name = os.path.basename(fname)
+
+ with open(fname, "r", encoding="utf-8", errors="backslashreplace") as f:
+ for ln, line in enumerate(f):
+ ln += 1
+ line = line.strip()
+ if not line or line.startswith("#"):
+ continue
+
+ # Handle ignore rules
+ match = re.match(r"^ignore\s+(\w+)\s+(\S+)", line)
+ if match:
+ c_type = match.group(1)
+ symbol = match.group(2)
+
+ if c_type not in self.DEF_SYMBOL_TYPES:
+ sys.exit(f"{name}:{ln}: {c_type} is invalid")
+
+ d = self.symbols[c_type]
+ if symbol in d:
+ del d[symbol]
+
+ continue
+
+ # Handle replace rules
+ match = re.match(r"^replace\s+(\S+)\s+(\S+)\s+(\S+)", line)
+ if not match:
+ sys.exit(f"{name}:{ln}: invalid line: {line}")
+
+ c_type, old, new = match.groups()
+
+ if c_type not in self.DEF_SYMBOL_TYPES:
+ sys.exit(f"{name}:{ln}: {c_type} is invalid")
+
+ reftype = None
+
+ # Parse reference type when the type is specified
+
+ match = re.match(r"^\:c\:(data|func|macro|type)\:\`(.+)\`", new)
+ if match:
+ reftype = f":c:{match.group(1)}"
+ new = match.group(2)
+ else:
+ match = re.search(r"(\:ref)\:\`(.+)\`", new)
+ if match:
+ reftype = match.group(1)
+ new = match.group(2)
+
+ # If the replacement rule doesn't have a type, get default
+ if not reftype:
+ reftype = self.DEF_SYMBOL_TYPES[c_type].get("ref_type")
+ if not reftype:
+ reftype = self.DEF_SYMBOL_TYPES[c_type].get("real_type")
+
+ new_ref = f"{reftype}:`{old} <{new}>`"
+
+ # Change self.symbols to use the replacement rule
+ if old in self.symbols[c_type]:
+ self.symbols[c_type][old] = new_ref
+ else:
+ print(f"{name}:{ln}: Warning: can't find {old} {c_type}")
+
+ def debug_print(self):
+ """
+ Print debug information containing the replacement rules per symbol.
+ To make easier to check, group them per type.
+ """
+ if not self.debug:
+ return
+
+ for c_type, refs in self.symbols.items():
+ if not refs: # Skip empty dictionaries
+ continue
+
+ print(f"{c_type}:")
+
+ for symbol, ref in sorted(refs.items()):
+ print(f" {symbol} -> {ref}")
+
+ print()
+
+ def write_output(self, file_in: str, file_out: str):
+ """Write the formatted output to a file."""
+
+ # Avoid extra blank lines
+ text = re.sub(r"\s+$", "", self.data) + "\n"
+ text = re.sub(r"\n\s+\n", "\n\n", text)
+
+ # Escape Sphinx special characters
+ text = re.sub(r"([\_\`\*\<\>\&\\\\:\/\|\%\$\#\{\}\~\^])", r"\\\1", text)
+
+ # Source uAPI files may have special notes. Use bold font for them
+ text = re.sub(r"DEPRECATED", "**DEPRECATED**", text)
+
+ # Delimiters to catch the entire symbol after escaped
+ start_delim = r"([ \n\t\(=\*\@])"
+ end_delim = r"(\s|,|\\=|\\:|\;|\)|\}|\{)"
+
+ # Process all reference types
+ for ref_dict in self.symbols.values():
+ for symbol, replacement in ref_dict.items():
+ symbol = re.escape(re.sub(r"([\_\`\*\<\>\&\\\\:\/])", r"\\\1", symbol))
+ text = re.sub(fr'{start_delim}{symbol}{end_delim}',
+ fr'\1{replacement}\2', text)
+
+ # Remove "\ " where not needed: before spaces and at the end of lines
+ text = re.sub(r"\\ ([\n ])", r"\1", text)
+
+ title = os.path.basename(file_in)
+
+ with open(file_out, "w", encoding="utf-8", errors="backslashreplace") as f:
+ f.write(".. -*- coding: utf-8; mode: rst -*-\n\n")
+ f.write(f"{title}\n")
+ f.write("=" * len(title))
+ f.write("\n\n.. parsed-literal::\n\n")
+ f.write(text)
+
+
+def main():
+ """Main function"""
+ parser = argparse.ArgumentParser(description=__doc__,
+ formatter_class=argparse.RawDescriptionHelpFormatter)
+
+ parser.add_argument("-d", "--debug", action="count", default=0,
+ help="Increase debug level. Can be used multiple times")
+ parser.add_argument("file_in", help="Input C file")
+ parser.add_argument("file_out", help="Output RST file")
+ parser.add_argument("file_exceptions", nargs="?",
+ help="Exceptions file (optional)")
+
+ args = parser.parse_args()
+
+ parser = ParseHeader(debug=args.debug)
+ parser.parse_file(args.file_in)
+
+ if args.file_exceptions:
+ parser.process_exceptions(args.file_exceptions)
+
+ parser.debug_print()
+ parser.write_output(args.file_in, args.file_out)
+
+
+if __name__ == "__main__":
+ main()
--
2.50.1
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