added example of reading .dat block file

Author: karask

examples/block_parse.py

@@ -0,0 +1,55 @@
+import os
+import struct
+import sys
+
+root_path = os.path.abspath(os.path.join(os.path.dirname(__file__), '..'))
+if root_path not in sys.path:
+    sys.path.append(root_path)
+
+from bitcoinutils.block import Block
+from bitcoinutils.constants import BLOCK_MAGIC_NUMBER
+
+def main():
+    filename = '' # Give .dat file path to run example 
+    try:
+        with open(filename, 'rb') as file:
+            while True:
+                # Read the magic number and block size (first 8 bytes: 4 bytes magic, 4 bytes size)
+                preamble = file.read(8)
+                if len(preamble) < 8:
+                    # If less than 8 bytes were read, it's the end of the file
+                    break
+                
+                # Unpack the header to get magic number and size
+                magic, size = struct.unpack('<4sI', preamble)
+                magic_hex = magic.hex()
+
+                if magic_hex not in BLOCK_MAGIC_NUMBER:
+                    raise ValueError(f"Unknown or unsupported network magic number: {magic_hex}")
+
+                print("Network:", BLOCK_MAGIC_NUMBER[magic_hex])
+                
+                # Read the block data based on the size specified
+                block_data = file.read(size)
+                if len(block_data) < size:
+                    # If the block data is less than the size specified, it means the file is truncated
+                    print("Truncated block data.")
+                    break
+                
+                # Concatenate the header and block data to parse it as a raw block
+                raw_block = preamble + block_data
+                
+                # Use the from_raw method of the Block class to parse the block
+                block = Block.from_raw(raw_block)
+                
+                # Output some information about the block (example: hash, number of transactions)
+                print("Block Hash:", block.get_block_header().get_block_hash())
+                print("Number of Transactions:", block.get_transactions_count())
+    
+    except FileNotFoundError:
+        print(f"Error: The file '{filename}' does not exist.")
+    except Exception as e:
+        print(f"An unexpected error occurred: {e}")
+
+if __name__ == '__main__':
+    main()