Working on zip

app.py

@@ -7,7 +7,7 @@ import os
 from os.path import join
 import sqlite3
 import uuid
-from . import db, config, scanner, calibration, tar
+from . import db, config, scanner, calibration, archive
 
 app = Flask(__name__)
 
@@ -285,14 +285,14 @@ def download_object(id: int):
     ]
 
     # Create archive file to send
-    archive = tar.TarSender()
+    tar = archive.TarSender()
 
     for calibration_index, (calib, acquisitions) in enumerate(acquisitions_grouped):
         calibration_dir = join(config.CALIBRATION_DIR, str(calib.id))
 
         # Add calibration images
         for image in os.listdir(calibration_dir):
-            archive.add_file(
+            tar.add_file(
                 f'object/{calibration_index}/calibration/{image}',
                 join(calibration_dir, image)
             )
@@ -302,12 +302,12 @@ def download_object(id: int):
             acquisition_dir = join(config.OBJECT_DIR, str(object.id), str(acquisition.id))
 
             for image in os.listdir(acquisition_dir):
-                archive.add_file(
+                tar.add_file(
                     f'object/{calibration_index}/{acquisition_index}/{image}',
                     join(acquisition_dir, image)
                 )
 
-    return archive.response()
+    return tar.response()
 
 
 @app.route('/static/<path:path>')

archive.py

@@ -1,7 +1,12 @@
 import builtins
+from datetime import datetime
 from flask import Response
 import functools
 import os
+import zlib
+
+# Chunks for crc 32 computation
+CRC32_CHUNK_SIZE = 65_536
 
 # 4MiB chunks
 CHUNK_SIZE = 4_194_304
@@ -12,20 +17,8 @@ SPACE = ord(' ')
 # ASCII value for zero
 ZERO = ord('0')
 
-# Specification de l'entête du fichier
-# Numéro Nom      Début   Taille   Description
-#      1 name         0      100   Nom du fichier
-#      2 mode       100        8   Permissions
-#      3 uid        108        8   Propriétaire (inutilisé si format étendu)
-#      4 gid        116        8   Groupe (inutilisé si format étendu)
-#      5 size       124       12   Taille du fichier en octets.
-#      6 mtime      136       12   Dernière modification en temps Unix.
-#      7 chksum     148        8   Somme de contrôle de l'en-tête où ce champ est considéré comme rempli d'espaces (32)
-#      8 type flag  156        1   Type de fichier
-#      9 linkname   157      100   Nom du fichier pointé par ce lien symbolique (Si le type indique un lien symbolique)
 
-
-def header_chunk(filename: str, filepath: str) -> bytes:
+def tar_header_chunk(filename: str, filepath: str) -> bytes:
 
     # Returns the octal representation without the initial
     def oct(i: int) -> str:
@@ -71,17 +64,22 @@ def header_chunk(filename: str, filepath: str) -> bytes:
     return bytes(buffer)
 
 
-class TarSender:
+class ArchiveSender:
     def __init__(self):
         self.files: dict[str, str] = {}
 
     def add_file(self, filename: str, filepath: str):
         self.files[filename] = filepath
 
+    def response(self):
+        raise NotImplementedError("Abstract method")
+
+
+class TarSender(ArchiveSender):
     def response(self):
         def generate():
             for name, file in self.files.items():
-                yield header_chunk(name, file)
+                yield tar_header_chunk(name, file)
 
                 bytes_sent = 0
 
@@ -104,3 +102,66 @@ class TarSender:
             mimetype='application/x-tar',
             headers={'Content-Disposition': 'attachment; filename="archive.tar"'}
         )
+
+
+def crc32(filename):
+    with open(filename, 'rb') as fh:
+        hash = 0
+        while True:
+            s = fh.read(CRC32_CHUNK_SIZE)
+            if not s:
+                break
+            hash = zlib.crc32(s, hash)
+        return hash
+
+
+def zip_local_file_header(filename: str, filepath: str, fileindex: int) -> bytes:
+    buffer_size = 30 + len(filename)
+    buffer = bytearray(buffer_size)
+    stat = os.stat(filepath)
+
+    # Field 1: local file header signature (buffer[0:4])
+    buffer[0:4] = b'PK\x03\x04'
+
+    # Field 2: version needed to extract (minimum) (buffer[4:6])
+    buffer[4:6] = b'\x0a'
+
+    # Field 3: general purpose bit flag (buffer[6:8]), leave at 0
+
+    # Field 4: compression mode (buffer[8:10]), leave at 0 (uncompressed)
+
+    # Field 5: file last modification time (buffer[10:14])
+    mtime = datetime.fromtimestramp(stat.st_mtime)
+    buffer[10:12] = (mtime.second // 2) | (mtime.minute << 5) | (mtime.hour << 11)
+    buffer[12:14] = mtime.day | (mtime.month << 5) | ((mtime.year - 1980) << 9)
+
+    # Field 6: crc-32 of uncompressed data (buffer[14:18])
+    buffer[14:18] = crc32(filepath).to_bytes(4)
+
+    # Field 7: compressed size (buffer[18:22])
+    buffer[18:22] = stat.st_size.to_bytes(4)
+
+    # Field 8: uncompressed size (buffer[22:26])
+    buffer[22:26] = stat.st_size.to_bytes(4)
+
+    # Field 9: filename length (buffer[26:28])
+    buffer[26:29] = len(filename).to_bytes(4)
+
+    # Field 10: extra field length (buffer[28:30])
+
+    # Field 11: filename (buffer[30:30+len(filename)])
+    buffer[30:30+len(filename)] = filename.encode('ascii')
+
+    return buffer
+
+
+class ZipSender(ArchiveSender):
+    def response(self):
+        def generate():
+            yield 'oops'
+
+        return Response(
+            generate(),
+            mimetype='application/zip',
+            headers={'Content-Disposition': 'attachment; filename="archive.zip"'}
+        )