A3

A3/python/filegen/filegen.py

@@ -0,0 +1,64 @@
+#!/bin/python3
+
+import argparse
+import hashlib
+import os
+import shutil
+import struct
+
+
+def gen_cascade_file(sourcefile, targetfile, cascade_file, blocksize):
+    with open(sourcefile, 'rb') as src:
+        # Place entire file in memory :)
+        data = src.read()
+        fullsize = len(data)
+        fullhash = hashlib.sha256(data).digest()
+
+    with open(cascade_file, 'wb') as dst:
+        # Header part
+        dst.write(bytes('CASCADE1', 'ascii')) # Magic signature
+        dst.write(struct.pack('!Q', 0)) # Reserved
+        dst.write(struct.pack('!Q', fullsize)) # File length
+        dst.write(struct.pack('!Q', blocksize)) # Block size
+        dst.write(fullhash)
+
+        with open(sourcefile, 'rb') as src:
+            while True:
+                data = src.read(blocksize)
+                if not data:
+                    break
+                dst.write(hashlib.sha256(data).digest())
+
+    if not os.path.exists(targetfile):
+        shutil.copy(sourcefile, targetfile)
+
+blocksizes = [
+    (1024, '1kib'), 
+    (10240, '10kib'), 
+    (102400, '100kib'), 
+    (1048576, '1mib'), 
+    (10485760, '10mib')
+]
+
+if __name__ == "__main__":
+    parser = argparse.ArgumentParser()
+    parser.add_argument("source", help="The file to generate the cascade file for")
+    args = parser.parse_args()
+
+    sourcefile = os.path.abspath(args.source)
+    if not os.path.isfile(sourcefile):
+        print(f"Source file not found: {sourcefile}")
+        exit(1)
+
+    for bs in blocksizes:
+        basename, ext = os.path.splitext(sourcefile)
+        targetfile = f"{basename}.{bs[1]}{ext}"
+        cascade_file = f"{targetfile}.cascade"
+        if os.path.isfile(targetfile):
+            print(f"File already exists, deleting: {targetfile}")
+            os.unlink(targetfile)
+
+        print(f"Generating file: {targetfile}")
+        gen_cascade_file(sourcefile, targetfile, cascade_file, bs[0])
+
+    print("Done!")