add mtp plugin for exif stripping

bin/mtag/README.md

@@ -6,6 +6,7 @@ some of these rely on libraries which are not MIT-compatible
 
 * [audio-bpm.py](./audio-bpm.py) detects the BPM of music using the BeatRoot Vamp Plugin; imports GPL2
 * [audio-key.py](./audio-key.py) detects the melodic key of music using the Mixxx fork of keyfinder; imports GPL3
+* [image-noexif.py](./image-noexif.py) removes exif tags from images; is GPLv1 or artistic-license
 * [media-hash.py](./media-hash.py) generates checksums for audio and video streams; uses FFmpeg (LGPL or GPL)
 
 these do not have any problematic dependencies:

bin/mtag/image-noexif.py

@@ -0,0 +1,93 @@
+#!/usr/bin/env python3
+
+"""
+remove exif tags from uploaded images
+
+dependencies:
+  exiftool
+
+about:
+  creates a "noexif" subfolder and puts exif-stripped copies of each image there,
+  the reason for the subfolder is to avoid issues with the up2k.db / deduplication:
+
+  if the original image is modified in-place, then copyparty will keep the original
+  hash in up2k.db for a while (until the next volume rescan), so if the image is
+  reuploaded after a rescan then the upload will be renamed and kept as a dupe
+
+  alternatively you could switch the logic around, making a copy of the original
+  image into a subfolder named "exif" and modify the original in-place, but then
+  up2k.db will be out of sync until the next rescan, so any additional uploads
+  of the same image will get symlinked (deduplicated) to the modified copy
+  instead of the original in "exif"
+
+  or maybe delete the original image after processing, that would kinda work too
+
+example copyparty config to use this:
+  -v/mnt/nas/pics:pics:rwmd,ed:c,e2ts,mte=+noexif:c,mtp=noexif=ejpg,ejpeg,ad,bin/mtag/image-noexif.py
+
+explained:
+  for realpath /mnt/nas/pics (served at /pics) with read-write-modify-delete for ed,
+  enable file analysis on upload (e2ts),
+  append "noexif" to the list of known tags (mtp),
+  and use mtp plugin "bin/mtag/image-noexif.py" to provide that tag,
+  do this on all uploads with the file extension "jpg" or "jpeg",
+  ad = parse file regardless if FFmpeg thinks it is audio or not
+
+PS: this requires e2ts to be functional,
+  meaning you need to do at least one of these:
+   * apt install ffmpeg
+   * pip3 install mutagen
+  and your python must have sqlite3 support compiled in
+"""
+
+
+import os
+import sys
+import time
+import filecmp
+import subprocess as sp
+
+try:
+    from copyparty.util import fsenc
+except:
+
+    def fsenc(p):
+        return p.encode("utf-8")
+
+
+def main():
+    cwd, fn = os.path.split(sys.argv[1])
+    if os.path.basename(cwd) == "noexif":
+        return
+
+    os.chdir(cwd)
+    f1 = fsenc(fn)
+    f2 = os.path.join(b"noexif", f1)
+    cmd = [
+        b"exiftool",
+        b"-exif:all=",
+        b"-iptc:all=",
+        b"-xmp:all=",
+        b"-P",
+        b"-o",
+        b"noexif/",
+        b"--",
+        f1,
+    ]
+    sp.check_output(cmd)
+    if not os.path.exists(f2):
+        print("failed")
+        return
+
+    if filecmp.cmp(f1, f2, shallow=False):
+        print("clean")
+    else:
+        print("exif")
+
+    # lastmod = os.path.getmtime(f1)
+    # times = (int(time.time()), int(lastmod))
+    # os.utime(f2, times)
+
+
+if __name__ == "__main__":
+    main()