250 lines
8.5 KiB
Python
Executable File
250 lines
8.5 KiB
Python
Executable File
#!/usr/bin/env python
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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 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) + ':' + id)
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else:
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sys.stderr.write(
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'[' + token.file + ':' + str(token.linenr) + '] (' + severity + '): ' + msg + ' [' + id + ']\n')
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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.classStart
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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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# Get function arguments
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def getArgumentsRecursive(tok, arguments):
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if tok is None:
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return
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if tok.str == ',':
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getArgumentsRecursive(tok.astOperand1, arguments)
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getArgumentsRecursive(tok.astOperand2, arguments)
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else:
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arguments.append(tok);
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def getArguments(ftok):
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arguments = []
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getArgumentsRecursive(ftok.astOperand2, arguments)
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return 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", 'cert-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 = getArguments(token)
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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", 'cert-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)", 'cert-EXP42-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', 'cert-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 < 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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'cert-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 < 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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'cert-INT31-c')
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break
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for arg in sys.argv[1:]:
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if arg == '-verify':
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VERIFY = True
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continue
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print('Checking ' + arg + '...')
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data = cppcheckdata.parsedump(arg)
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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.configurations:
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if len(data.configurations) > 1:
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print('Checking ' + arg + ', config "' + cfg.name + '"...')
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exp05(cfg)
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exp42(cfg)
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exp46(cfg)
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int31(cfg, data.platform)
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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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