linux-kernel - Re: [PATCH v4] gen_compile_commands.py: fix path resolve with symlinks in it

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Message-ID: <CAK7LNAQAAZXV3i1sM0ZTFDC3eOaDWBVzOV9FmiLUM5YoX=89Wg@mail.gmail.com>
Date:   Sun, 10 Dec 2023 14:52:13 +0900
From:   Masahiro Yamada <masahiroy@...nel.org>
To:     Jialu Xu <xujialu@...ux.org>
Cc:     nathan@...nel.org, justinstitt@...gle.com,
        linux-kbuild@...r.kernel.org, linux-kernel@...r.kernel.org,
        llvm@...ts.linux.dev, morbo@...gle.com, ndesaulniers@...gle.com
Subject: Re: [PATCH v4] gen_compile_commands.py: fix path resolve with
 symlinks in it

On Wed, Dec 6, 2023 at 10:26 AM Jialu Xu <xujialu@...ux.org> wrote:
>
> When a path contains relative symbolic links, os.path.abspath() might
> not follow the symlinks and instead return the absolute path with just
> the relative paths resolved, resulting in an incorrect path.
>
> 1. Say "drivers/hdf/" has some symlinks:
>
>     # ls -l drivers/hdf/
>     total 364
>     drwxrwxr-x 2 ...   4096 ... evdev
>     lrwxrwxrwx 1 ...     44 ... framework -> ../../../../../../drivers/hdf_core/framework
>     -rw-rw-r-- 1 ... 359010 ... hdf_macro_test.h
>     lrwxrwxrwx 1 ...     55 ... inner_api -> ../../../../../../drivers/hdf_core/interfaces/inner_api
>     lrwxrwxrwx 1 ...     53 ... khdf -> ../../../../../../drivers/hdf_core/adapter/khdf/linux
>     -rw-r--r-- 1 ...     74 ... Makefile
>     drwxrwxr-x 3 ...   4096 ... wifi
>
> 2. One .cmd file records that:
>
>     # head -1 ./framework/core/manager/src/.devmgr_service.o.cmd
>     cmd_drivers/hdf/khdf/manager/../../../../framework/core/manager/src/devmgr_service.o := ... \
>     /path/to/out/drivers/hdf/khdf/manager/../../../../framework/core/manager/src/devmgr_service.c
>
> 3. os.path.abspath returns "/path/to/out/framework/core/manager/src/devmgr_service.c", not correct:
>
>     # ./scripts/clang-tools/gen_compile_commands.py
>     INFO: Could not add line from ./framework/core/manager/src/.devmgr_service.o.cmd: File \
>         /path/to/out/framework/core/manager/src/devmgr_service.c not found
>
> Use pathlib.Path.resolve(), which resolves the symlinks and normalizes
> the paths correctly.
>
>     # cat compile_commands.json
>     ...
>     {
>       "command": ...
>       "directory": ...
>       "file": "/path/to/blabla/drivers/hdf_core/framework/core/manager/src/devmgr_service.c"
>     },
>     ...
>
> Reviewed-by: Nathan Chancellor <nathan@...nel.org>
> Signed-off-by: Jialu Xu <xujialu@...ux.org>
> ---
>  scripts/clang-tools/gen_compile_commands.py | 6 ++++--
>  1 file changed, 4 insertions(+), 2 deletions(-)
>
> diff --git a/scripts/clang-tools/gen_compile_commands.py b/scripts/clang-tools/gen_compile_commands.py
> index 180952fb91c1b..99e28b7152c19 100755
> --- a/scripts/clang-tools/gen_compile_commands.py
> +++ b/scripts/clang-tools/gen_compile_commands.py
> @@ -11,6 +11,7 @@ import argparse
>  import json
>  import logging
>  import os
> +from pathlib import Path
>  import re
>  import subprocess
>  import sys
> @@ -172,8 +173,9 @@ def process_line(root_directory, command_prefix, file_path):
>      # by Make, so this code replaces the escaped version with '#'.
>      prefix = command_prefix.replace('\#', '#').replace('$(pound)', '#')
>
> -    # Use os.path.abspath() to normalize the path resolving '.' and '..' .
> -    abs_path = os.path.abspath(os.path.join(root_directory, file_path))
> +    # Make the path absolute, resolving all symlinks on the way and also normalizing it.
> +    # Convert Path object to a string because 'PosixPath' is not JSON serializable.
> +    abs_path = str(Path(root_directory, file_path).resolve())
>      if not os.path.exists(abs_path):
>          raise ValueError('File %s not found' % abs_path)
>      return {





Is there any reason why you didn't simply replace
os.path.abspath() with os.path.realpath() ?



This patch uses pathlib.Path() just in one place,
leaving many call-sites of os.path.*() functions.

If it is just a matter of your preference,
you need to convert os.path.*() for consistency
(as a follow-up patch).





I see one more os.path.abspath()



    return (args.log_level,
            os.path.abspath(args.directory),
            args.output,
            args.ar,
            args.paths if len(args.paths) > 0 else [args.directory])




Does it cause a similar issue for the 'directory' field
with symbolic link jungles?







--
Best Regards
Masahiro Yamada