440 lines
16 KiB
Python
Executable File
440 lines
16 KiB
Python
Executable File
#!/usr/bin/env python3
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#
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# Cert: Some extra CERT checkers
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#
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# Cppcheck itself handles many CERT rules. Cppcheck warns when there is undefined behaviour.
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# CERT Homepage: https://www.cert.org/secure-coding/
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#
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# Example usage of this addon (scan a sourcefile main.cpp)
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# cppcheck --dump main.cpp
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# python cert.py main.cpp.dump
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import argparse
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from . import cppcheckdata
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import sys
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import re
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VERIFY = ('-verify' in sys.argv)
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VERIFY_EXPECTED = []
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VERIFY_ACTUAL = []
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def reportError(token, severity, msg, id):
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if VERIFY:
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VERIFY_ACTUAL.append(str(token.linenr) + ':cert-' + id)
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else:
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cppcheckdata.reportError(token, severity, msg, 'cert', id)
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def simpleMatch(token, pattern):
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for p in pattern.split(' '):
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if not token or token.str != p:
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return False
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token = token.next
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return True
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def isUnpackedStruct(token):
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if token.valueType is None:
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return False
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if token.valueType.typeScope is None:
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return False
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if token.valueType.typeScope.type != "Struct":
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return False
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startToken = token.valueType.typeScope.bodyStart
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linenr = int(startToken.linenr)
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for line in open(startToken.file):
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linenr -= 1
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if linenr == 0:
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return True
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if linenr < 3 and re.match(r'#pragma\s+pack\s*\(', line):
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return False
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return True
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def isLocalUnpackedStruct(arg):
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if arg and arg.str == '&' and not arg.astOperand2:
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arg = arg.astOperand1
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return arg and arg.variable and (arg.variable.isLocal or arg.variable.isArgument) and isUnpackedStruct(arg)
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def isBitwiseOp(token):
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return token and (token.str in {'&', '|', '^'})
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def isComparisonOp(token):
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return token and (token.str in {'==', '!=', '>', '>=', '<', '<='})
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def isCast(expr):
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if not expr or expr.str != '(' or not expr.astOperand1 or expr.astOperand2:
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return False
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if simpleMatch(expr, '( )'):
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return False
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return True
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def isStandardFunction(token):
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if token.function:
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return False
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prev = token.previous
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if prev:
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if prev.str == '.':
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return False
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if prev.str == '::':
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prevprev = prev.previous
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if prevprev and not prevprev.str == 'std':
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return False
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return True
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# Is this a function call
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def isFunctionCall(token, function_names, number_of_arguments=None):
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if not token.isName:
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return False
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if token.str not in function_names:
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return False
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if (token.next is None) or token.next.str != '(' or token.next != token.astParent:
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return False
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if number_of_arguments is None:
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return True
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return len(cppcheckdata.getArguments(token)) == number_of_arguments
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# EXP05-C
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# do not attempt to cast away const
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def exp05(data):
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# TODO Reuse code in misra rule 11.8
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for token in data.tokenlist:
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if isCast(token):
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# C-style cast
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if not token.valueType:
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continue
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if not token.astOperand1.valueType:
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continue
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if token.valueType.pointer == 0:
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continue
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if token.astOperand1.valueType.pointer == 0:
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continue
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const1 = token.valueType.constness
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const2 = token.astOperand1.valueType.constness
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if (const1 % 2) < (const2 % 2):
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reportError(token, 'style', "Attempt to cast away const", 'EXP05-C')
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elif token.str == '(' and token.astOperand1 and token.astOperand2 and token.astOperand1.function:
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function = token.astOperand1.function
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arguments = cppcheckdata.getArguments(token.previous)
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if not arguments:
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continue
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for argnr, argvar in function.argument.items():
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if argnr < 1 or argnr > len(arguments):
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continue
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if not argvar.isPointer:
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continue
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if (argvar.constness % 2) == 1: # data is const
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continue
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argtok = arguments[argnr - 1]
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if not argtok.valueType:
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continue
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if argtok.valueType.pointer == 0:
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continue
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const2 = arguments[argnr - 1].valueType.constness
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if (const2 % 2) == 1:
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reportError(token, 'style', "Attempt to cast away const", 'EXP05-C')
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# EXP42-C
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# do not compare padding data
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def exp42(data):
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for token in data.tokenlist:
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if token.str != '(' or not token.astOperand1 or token.astOperand1.str != 'memcmp':
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continue
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arg1 = None
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arg2 = None
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if token.astOperand2 and token.astOperand2.str == ',':
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if token.astOperand2.astOperand1 and token.astOperand2.astOperand1.str == ',':
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arg1 = token.astOperand2.astOperand1.astOperand1
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arg2 = token.astOperand2.astOperand1.astOperand2
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if isLocalUnpackedStruct(arg1) or isLocalUnpackedStruct(arg2):
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reportError(
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token, 'style', "Comparison of struct padding data " +
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"(fix either by packing the struct using '#pragma pack' or by rewriting the comparison)", 'EXP42-C')
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# EXP15-C
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# Do not place a semicolon on the same line as an if, for or while statement
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def exp15(data):
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for scope in data.scopes:
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if scope.type in ('If', 'For', 'While'):
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token = scope.bodyStart.next
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if token.str==';' and token.linenr==scope.bodyStart.linenr:
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reportError(token, 'style', 'Do not place a semicolon on the same line as an IF, FOR or WHILE', 'EXP15-C')
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# EXP46-C
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# Do not use a bitwise operator with a Boolean-like operand
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# int x = (a == b) & c;
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def exp46(data):
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for token in data.tokenlist:
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if isBitwiseOp(token) and (isComparisonOp(token.astOperand1) or isComparisonOp(token.astOperand2)):
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reportError(
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token, 'style', 'Bitwise operator is used with a Boolean-like operand', 'EXP46-c')
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# INT31-C
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# Ensure that integer conversions do not result in lost or misinterpreted data
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def int31(data, platform):
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if not platform:
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return
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for token in data.tokenlist:
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if not isCast(token):
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continue
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if not token.valueType or not token.astOperand1.values:
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continue
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bits = None
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if token.valueType.type == 'char':
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bits = platform.char_bit
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elif token.valueType.type == 'short':
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bits = platform.short_bit
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elif token.valueType.type == 'int':
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bits = platform.int_bit
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elif token.valueType.type == 'long':
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bits = platform.long_bit
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elif token.valueType.type == 'long long':
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bits = platform.long_long_bit
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else:
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continue
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if token.valueType.sign == 'unsigned':
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found = False
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for value in token.astOperand1.values:
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if value.intvalue and value.intvalue < 0:
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found = True
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reportError(
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token,
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'style',
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'Ensure that integer conversions do not result in lost or misinterpreted data (casting ' + str(value.intvalue) + ' to unsigned ' + token.valueType.type + ')',
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'INT31-c')
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break
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if found:
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continue
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if bits >= 64:
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continue
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minval = 0
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maxval = 1
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if token.valueType.sign == 'signed':
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minval = -(1 << (bits - 1))
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maxval = ((1 << (bits - 1)) - 1)
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else:
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minval = 0
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maxval = ((1 << bits) - 1)
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for value in token.astOperand1.values:
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if value.intvalue and (value.intvalue < minval or value.intvalue > maxval):
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destType = ''
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if token.valueType.sign:
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destType = token.valueType.sign + ' ' + token.valueType.type
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else:
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destType = token.valueType.type
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reportError(
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token,
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'style',
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'Ensure that integer conversions do not result in lost or misinterpreted data (casting ' + str(value.intvalue) + ' to ' + destType + ')',
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'INT31-c')
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break
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# ENV33-C
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# Do not call system()
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def env33(data):
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for token in data.tokenlist:
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if isFunctionCall(token, ('system',), 1):
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# Invalid syntax
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if not token.next.astOperand2:
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continue
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# ENV33-C-EX1: It is permissible to call system() with a null
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# pointer argument to determine the presence of a command processor
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# for the system.
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argValue = token.next.astOperand2.getValue(0)
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if argValue and argValue.intvalue == 0 and argValue.isKnown():
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continue
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reportError(token, 'style', 'Do not call system()', 'ENV33-C')
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# MSC24-C
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# Do not use deprecated or obsolescent functions
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def msc24(data):
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for token in data.tokenlist:
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if isFunctionCall(token, ('asctime',), 1):
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reportError(token,'style','Do not use asctime() better use asctime_s()', 'MSC24-C')
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elif isFunctionCall(token, ('atof',), 1):
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reportError(token,'style','Do not use atof() better use strtod()', 'MSC24-C')
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elif isFunctionCall(token, ('atoi',), 1):
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reportError(token,'style','Do not use atoi() better use strtol()', 'MSC24-C')
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elif isFunctionCall(token, ('atol',), 1):
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reportError(token,'style','Do not use atol() better use strtol()', 'MSC24-C')
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elif isFunctionCall(token, ('atoll',), 1):
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reportError(token,'style','Do not use atoll() better use strtoll()', 'MSC24-C')
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elif isFunctionCall(token, ('ctime',), 1):
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reportError(token,'style','Do not use ctime() better use ctime_s()', 'MSC24-C')
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elif isFunctionCall(token, ('fopen',), 2):
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reportError(token,'style','Do not use fopen() better use fopen_s()', 'MSC24-C')
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elif isFunctionCall(token, ('freopen',), 3):
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reportError(token,'style','Do not use freopen() better use freopen_s()', 'MSC24-C')
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elif isFunctionCall(token, ('rewind',), 1):
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reportError(token,'style','Do not use rewind() better use fseek()', 'MSC24-C')
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elif isFunctionCall(token, ('setbuf',), 2):
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reportError(token,'style','Do not use setbuf() better use setvbuf()', 'MSC24-C')
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# MSC30-C
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# Do not use the rand() function for generating pseudorandom numbers
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def msc30(data):
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for token in data.tokenlist:
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if simpleMatch(token, "rand ( )") and isStandardFunction(token):
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reportError(token, 'style', 'Do not use the rand() function for generating pseudorandom numbers', 'MSC30-c')
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# STR03-C
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# Do not inadvertently truncate a string
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def str03(data):
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for token in data.tokenlist:
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if not isFunctionCall(token, 'strncpy'):
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continue
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arguments = cppcheckdata.getArguments(token)
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if len(arguments)!=3:
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continue
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if arguments[2].str=='(' and arguments[2].astOperand1.str=='sizeof':
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reportError(token, 'style', 'Do not inadvertently truncate a string', 'STR03-C')
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# STR05-C
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# Use pointers to const when referring to string literals
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def str05(data):
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for token in data.tokenlist:
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if token.isString:
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parent = token.astParent
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if parent is None:
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continue
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parentOp1 = parent.astOperand1
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if parent.isAssignmentOp and parentOp1.valueType:
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if (parentOp1.valueType.type in ('char', 'wchar_t')) and parentOp1.valueType.pointer and not parentOp1.valueType.constness:
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reportError(parentOp1, 'style', 'Use pointers to const when referring to string literals', 'STR05-C')
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# STR07-C
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# Use the bounds-checking interfaces for string manipulation
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def str07(data):
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for token in data.tokenlist:
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if not isFunctionCall(token, ('strcpy', 'strcat')):
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continue
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args = cppcheckdata.getArguments(token)
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if len(args)!=2:
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continue
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if args[1].isString:
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continue
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reportError(token, 'style', 'Use the bounds-checking interfaces %s_s()' % (token.str), 'STR07-C')
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# STR11-C
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# Do not specify the bound of a character array initialized with a string literal
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def str11(data):
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for token in data.tokenlist:
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if not token.isString:
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continue
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strlen = token.strlen
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parent = token.astParent
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if parent is None:
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continue
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parentOp1 = parent.astOperand1
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if parentOp1 is None or parentOp1.str!='[':
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continue
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if not parent.isAssignmentOp:
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continue
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varToken = parentOp1.astOperand1
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if varToken is None or not varToken.isName:
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continue
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if varToken.variable is None:
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continue
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if varToken != varToken.variable.nameToken:
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continue
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valueToken = parentOp1.astOperand2
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if valueToken is None:
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continue
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if valueToken.isNumber and int(valueToken.str)==strlen:
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reportError(valueToken, 'style', 'Do not specify the bound of a character array initialized with a string literal', 'STR11-C')
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# API01-C
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# Avoid laying out strings in memory directly before sensitive data
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def api01(data):
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for scope in data.scopes:
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if scope.type!='Struct':
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continue
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token = scope.bodyStart
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arrayFound=False
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# loop through the complete struct
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while token != scope.bodyEnd:
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if token.isName and token.variable:
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if token.variable.isArray:
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arrayFound=True
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elif arrayFound and not token.variable.isArray and not token.variable.isConst:
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reportError(token, 'style', 'Avoid laying out strings in memory directly before sensitive data', 'API01-C')
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# reset flags to report other positions in the same struct
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arrayFound=False
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token = token.next
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def get_args():
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parser = cppcheckdata.ArgumentParser()
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parser.add_argument("-verify", help=argparse.SUPPRESS, action="store_true")
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return parser.parse_args()
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if __name__ == '__main__':
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args = get_args()
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if args.verify:
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VERIFY = True
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if not args.dumpfile:
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if not args.quiet:
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print("no input files.")
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sys.exit(0)
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for dumpfile in args.dumpfile:
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if not args.quiet:
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print('Checking %s...' % dumpfile)
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data = cppcheckdata.CppcheckData(dumpfile)
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if VERIFY:
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VERIFY_ACTUAL = []
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VERIFY_EXPECTED = []
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for tok in data.rawTokens:
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if tok.str.startswith('//') and 'TODO' not in tok.str:
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for word in tok.str[2:].split(' '):
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if re.match(r'cert-[A-Z][A-Z][A-Z][0-9][0-9].*',word):
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VERIFY_EXPECTED.append(str(tok.linenr) + ':' + word)
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for cfg in data.iterconfigurations():
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if not args.quiet:
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print('Checking %s, config %s...' % (dumpfile, cfg.name))
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exp05(cfg)
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exp42(cfg)
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exp46(cfg)
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exp15(cfg)
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int31(cfg, data.platform)
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str03(cfg)
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str05(cfg)
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str07(cfg)
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str11(cfg)
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env33(cfg)
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msc24(cfg)
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msc30(cfg)
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api01(cfg)
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if VERIFY:
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for expected in VERIFY_EXPECTED:
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if expected not in VERIFY_ACTUAL:
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print('Expected but not seen: ' + expected)
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sys.exit(1)
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for actual in VERIFY_ACTUAL:
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if actual not in VERIFY_EXPECTED:
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print('Not expected: ' + actual)
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sys.exit(1)
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