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Date:   Tue,  5 Dec 2023 10:15:23 +0800
From:   Jialu Xu <xujialu@...ux.org>
To:     nathan@...nel.org, ndesaulniers@...gle.com, morbo@...gle.com,
        justinstitt@...gle.com
Cc:     llvm@...ts.linux.dev, linux-kernel@...r.kernel.org
Subject: 

>On Mon, Dec 04, 2023 at 06:41:42PM +0800, Jialu Xu wrote:
>> When symbolic links are involved in the path, os.path.abspath might not
>> resolve the symlinks and instead return the absolute path with the
>> symlinks intact.
>
>Can you provide an example or more detailed description of how this
>behavior is currently broken? I can't really understand how having
>symlinks in the path after normalization would break anything but I am
>potentially missing something :)

Glad to show my situation:

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

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

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() instead, got the correct path

    # cat compile_commands.json
    ...
    {
      "command": ...
      "directory": ...
      "file": "/path/to/blabla/drivers/hdf_core/framework/core/manager/src/devmgr_service.c"
    },
    ...

>> -    # 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.
>> +    abs_path = str(Path(os.path.join(root_directory, file_path)).resolve())
>
>I think this can be more simply:
>
>    abs_path = str(Path(root_directory, file_path).resolve())
>
>I think there should be a comment around why we are creating a Path
>object then creating a string from it, rather than using the Path object
>directly, namely that PosixPath is not JSON serializable.

Nice, update as yours, thanks.

>>      if not os.path.exists(abs_path):
>>          raise ValueError('File %s not found' % abs_path)
>>      return {
>> -- 
>> 2.39.2
>>