linux-kernel - [PATCH v3] gen_compile_commands.py: fix path resolve with symlinks in it

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Date:   Wed,  6 Dec 2023 09:20:36 +0800
From:   Jialu Xu <xujialu@...ux.org>
To:     nathan@...nel.org
Cc:     justinstitt@...gle.com, linux-kbuild@...r.kernel.org,
        linux-kernel@...r.kernel.org, llvm@...ts.linux.dev,
        masahiroy@...nel.org, morbo@...gle.com, ndesaulniers@...gle.com,
        xujialu@...ux.org
Subject: [PATCH v3] gen_compile_commands.py: fix path resolve with symlinks in it

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>
---
 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 {
-- 
2.39.2