Re: [PATCH 1/3] utils/md5_file: don't iterate line-by-line

[akuster808 <akuster808@gmail.com>]

On 08/13/2018 10:20 AM, Ross Burton wrote:
> Opening a file in binary mode and iterating it seems like the simple solution
> but will still break on newlines, which for binary files isn't really useful as
> the size of the chunks could be huge or tiny.
>
> Instead, let's be a bit more clever: we'll be MD5ing lots of files, but we don't
> want to fill up memory: use mmap() to open the file and read the file in 8k
> blocks.
>
> Signed-off-by: Ross Burton <ross.burton@intel.com>

shouldn't this go to the bitbake mailing list ?
> ---
>  bitbake/lib/bb/utils.py | 13 +++++++++----
>  1 file changed, 9 insertions(+), 4 deletions(-)
>
> diff --git a/bitbake/lib/bb/utils.py b/bitbake/lib/bb/utils.py
> index 9903183213b..b20cdabcf01 100644
> --- a/bitbake/lib/bb/utils.py
> +++ b/bitbake/lib/bb/utils.py
> @@ -524,12 +524,17 @@ def md5_file(filename):
>      """
>      Return the hex string representation of the MD5 checksum of filename.
>      """
> -    import hashlib
> -    m = hashlib.md5()
> +    import hashlib, mmap
>  
>      with open(filename, "rb") as f:
> -        for line in f:
> -            m.update(line)
> +        m = hashlib.md5()
> +        try:
> +            with mmap.mmap(f.fileno(), 0, access=mmap.ACCESS_READ) as mm:
> +                for chunk in iter(lambda: mm.read(8192), b''):
> +                    m.update(chunk)
> +        except ValueError:
> +            # You can't mmap() an empty file so silence this exception
> +            pass
>      return m.hexdigest()
>  
>  def sha256_file(filename):