[OE-core] [PATCH 1/3] utils/md5_file: don't iterate line-by-line
akuster808
akuster808 at gmail.com
Mon Aug 13 18:03:02 UTC 2018
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 at 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):
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