F2F: Improve reading of dynamic arrays

Submission 253771 by N1k1tung to the challenge
https://www.topcoder.com/challenges/30064730

myth

@@ -78,7 +78,7 @@ database.add_argument('-s', '--search', help='search the contract database', met
 
 utilities = parser.add_argument_group('utilities')
 utilities.add_argument('--hash', help='calculate function signature hash', metavar='SIGNATURE')
-utilities.add_argument('--storage', help='read state variables from storage index, use with -a', metavar='INDEX,NUM_SLOTS,[array]')
+utilities.add_argument('--storage', help='read state variables from storage index, use with -a', metavar='INDEX,NUM_SLOTS,[array] / mapping,INDEX,[KEY1, KEY2...]')
 utilities.add_argument('--solv', help='specify solidity compiler version. If not present, will try to install it (Experimental)', metavar='SOLV')
 
 options = parser.add_argument_group('options')
@@ -331,9 +331,24 @@ if args.storage:
     if not args.address:
         exitWithError(args.outform, "To read storage, provide the address of a deployed contract with the -a option.")
     else:
-        (position, length) = (0, 1)
+        (position, length, mappings) = (0, 1, [])
         try:
             params = args.storage.split(",")
+            if params[0] == "mapping":
+                if len(params) < 3:
+                    exitWithError(args.outform, "Invalid number of parameters.")
+                position = int(params[1])
+                position_formatted = utils.zpad(utils.int_to_big_endian(position), 32)
+                for i in range(2, len(params)):
+                    key = bytes(params[i], 'utf8')
+                    key_formatted = utils.rzpad(key, 32)
+                    mappings.append(int.from_bytes(utils.sha3(key_formatted + position_formatted), byteorder='big'))
+
+                length = len(mappings)
+                if length == 1:
+                    position = mappings[0]
+
+            else:
                 if len(params) >= 4:
                     exitWithError(args.outform, "Invalid number of parameters.")
 
@@ -342,10 +357,7 @@ if args.storage:
                 if len(params) >= 2:
                     length = int(params[1])
                 if len(params) == 3 and params[2] == "array":
-                position_formatted = bytes(position).ljust(32, b"\x00")
-
-                print(position_formatted)
-
+                    position_formatted = utils.zpad(utils.int_to_big_endian(position), 32)
                     position = int.from_bytes(utils.sha3(position_formatted), byteorder='big')
 
         except ValueError:
@@ -354,6 +366,11 @@ if args.storage:
         try:
             if length == 1:
                 print("{}: {}".format(position, eth.eth_getStorageAt(args.address, position)))
+            else:
+                if len(mappings) > 0:
+                    for i in range(0, len(mappings)):
+                        position = mappings[i]
+                        print("{}: {}".format(hex(position), eth.eth_getStorageAt(args.address, position)))
                 else:
                     for i in range(position, position + length):
                         print("{}: {}".format(hex(i), eth.eth_getStorageAt(args.address, i)))