[pp:hash] add 'hash' post processor (#6099)

docs/configuration.rst

@@ -5586,6 +5586,63 @@ Description
     See `metadata.event`_ for a list of available events.
 
 
+hash.chunk-size
+---------------
+Type
+    ``integer``
+Default
+    ``32768``
+Description
+    Number of bytes read per chunk during file hash computation.
+
+
+hash.event
+----------
+Type
+    * ``string``
+    * ``list`` of ``strings``
+Default
+    ``"file"``
+Description
+    The event(s) for which `file hashes <hash.hashes_>`__ are computed.
+
+    See `metadata.event`_ for a list of available events.
+
+
+hash.filename
+-------------
+Type
+    * ``bool``
+Default
+    ``false``
+Description
+    Rebuild `filenames <extractor.*.filename_>`__ after computing
+    `hash digests <hash.hashes_>`__ and adding them to the metadata dict.
+
+
+hash.hashes
+-----------
+Type
+    * ``string``
+    * ``object`` (`field name` -> `hash algorithm`)
+Default
+    ``"md5,sha1"``
+Example
+    .. code:: json
+
+        "sha256:hash_sha,sha3_512:hash_sha3"
+
+    .. code:: json
+
+        {
+            "hash_sha" : "sha256",
+            "hash_sha3": "sha3_512"
+        }
+
+Description
+    Hash digests to compute.
+
+
 metadata.mode
 -------------
 Type
@@ -6694,6 +6751,8 @@ Description
         | (requires `downloader.*.part`_ = ``true`` and `extractor.*.skip`_ = ``false``)
     ``exec``
         Execute external commands
+    ``hash``
+        Compute file hash digests
     ``metadata``
         Write metadata to separate files
     ``mtime``

gallery_dl/postprocessor/__init__.py

@@ -12,6 +12,7 @@ modules = [
     "classify",
     "compare",
     "exec",
+    "hash",
     "metadata",
     "mtime",
     "python",

gallery_dl/postprocessor/hash.py

@@ -0,0 +1,71 @@
+# -*- coding: utf-8 -*-
+
+# Copyright 2024 Mike Fährmann
+#
+# This program is free software; you can redistribute it and/or modify
+# it under the terms of the GNU General Public License version 2 as
+# published by the Free Software Foundation.
+
+"""Compute file hash digests"""
+
+from .common import PostProcessor
+import hashlib
+
+
+class HashPP(PostProcessor):
+
+    def __init__(self, job, options):
+        PostProcessor.__init__(self, job)
+
+        self.chunk_size = options.get("chunk-size", 32768)
+        self.filename = options.get("filename")
+
+        hashes = options.get("hashes")
+        if isinstance(hashes, dict):
+            self.hashes = list(hashes.items())
+        elif isinstance(hashes, str):
+            self.hashes = []
+            for h in hashes.split(","):
+                name, sep, key = h.partition(":")
+                self.hashes.append((key if sep else name, name))
+        elif hashes:
+            self.hashes = hashes
+        else:
+            self.hashes = (("md5", "md5"), ("sha1", "sha1"))
+
+        events = options.get("event")
+        if events is None:
+            events = ("file",)
+        elif isinstance(events, str):
+            events = events.split(",")
+        job.register_hooks({event: self.run for event in events}, options)
+
+    def run(self, pathfmt):
+        hashes = [
+            (key, hashlib.new(name))
+            for key, name in self.hashes
+        ]
+
+        size = self.chunk_size
+        with self._open(pathfmt) as fp:
+            while True:
+                data = fp.read(size)
+                if not data:
+                    break
+                for _, h in hashes:
+                    h.update(data)
+
+        for key, h in hashes:
+            pathfmt.kwdict[key] = h.hexdigest()
+
+        if self.filename:
+            pathfmt.build_path()
+
+    def _open(self, pathfmt):
+        try:
+            return open(pathfmt.temppath, "rb")
+        except OSError:
+            return open(pathfmt.realpath, "rb")
+
+
+__postprocessor__ = HashPP

test/test_postprocessor.py

@@ -240,6 +240,57 @@ class ExecTest(BasePostprocessorTest):
         self.assertFalse(i.wait.called)
 
 
+class HashTest(BasePostprocessorTest):
+
+    def test_default(self):
+        self._create({})
+
+        with self.pathfmt.open() as fp:
+            fp.write(b"Foo Bar\n")
+
+        self._trigger()
+
+        kwdict = self.pathfmt.kwdict
+        self.assertEqual(
+            "35c9c9c7c90ad764bae9e2623f522c24", kwdict["md5"], "md5")
+        self.assertEqual(
+            "14d3d804494ef4e57d72de63e4cfee761240471a", kwdict["sha1"], "sha1")
+
+    def test_custom_hashes(self):
+        self._create({"hashes": "sha256:a,sha512:b"})
+
+        with self.pathfmt.open() as fp:
+            fp.write(b"Foo Bar\n")
+
+        self._trigger()
+
+        kwdict = self.pathfmt.kwdict
+        self.assertEqual(
+            "4775b55be17206445d7015a5fc7656f38a74b880670523c3b175455f885f2395",
+            kwdict["a"], "sha256")
+        self.assertEqual(
+            "6028f9e6957f4ca929941318c4bba6258713fd5162f9e33bd10e1c456d252700"
+            "3e1095b50736c4fd1e2deea152e3c8ecd5993462a747208e4d842659935a1c62",
+            kwdict["b"], "sha512")
+
+    def test_custom_hashes_dict(self):
+        self._create({"hashes": {"a": "sha256", "b": "sha512"}})
+
+        with self.pathfmt.open() as fp:
+            fp.write(b"Foo Bar\n")
+
+        self._trigger()
+
+        kwdict = self.pathfmt.kwdict
+        self.assertEqual(
+            "4775b55be17206445d7015a5fc7656f38a74b880670523c3b175455f885f2395",
+            kwdict["a"], "sha256")
+        self.assertEqual(
+            "6028f9e6957f4ca929941318c4bba6258713fd5162f9e33bd10e1c456d252700"
+            "3e1095b50736c4fd1e2deea152e3c8ecd5993462a747208e4d842659935a1c62",
+            kwdict["b"], "sha512")
+
+
 class MetadataTest(BasePostprocessorTest):
 
     def test_metadata_default(self):