474 lines
14 KiB
C++
474 lines
14 KiB
C++
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//---------------------------------------------------------------------------
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// Buffer overrun..
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//---------------------------------------------------------------------------
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#include "CheckBufferOverrun.h"
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#include "tokenize.h"
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#include "CommonCheck.h"
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#include <algorithm>
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#include <sstream>
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#include <list>
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#include <cstring>
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#include <stdlib.h> // <- strtoul
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//---------------------------------------------------------------------------
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extern bool ShowAll;
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//---------------------------------------------------------------------------
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// CallStack used when parsing into subfunctions.
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static std::list<const TOKEN *> CallStack;
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// Modified version of 'ReportError' that also reports the callstack
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static void ReportError(const TOKEN *tok, const char errmsg[])
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{
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std::ostringstream ostr;
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std::list<const TOKEN *>::const_iterator it;
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for ( it = CallStack.begin(); it != CallStack.end(); it++ )
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ostr << FileLine(*it) << " -> ";
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ostr << FileLine(tok) << ": " << errmsg;
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ReportErr(ostr.str());
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}
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//---------------------------------------------------------------------------
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//---------------------------------------------------------------------------
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// Check array usage..
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//---------------------------------------------------------------------------
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static void CheckBufferOverrun_CheckScope( const TOKEN *tok, const char *varname[], const int size, const int total_size )
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{
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unsigned int varc = 1;
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while ( varname[varc] )
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varc++;
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varc = 2 * ( varc - 1 );
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// Array index..
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if ( Match(tok, "%var1% [ %num% ]", varname) )
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{
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const char *num = getstr(tok, 2 + varc);
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if (strtol(num, NULL, 10) >= size)
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{
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ReportError(tok->next, "Array index out of bounds");
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}
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}
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int indentlevel = 0;
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for ( ; tok; tok = tok->next )
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{
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if (tok->str[0]=='{')
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{
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indentlevel++;
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}
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else if (tok->str[0]=='}')
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{
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indentlevel--;
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if ( indentlevel < 0 )
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return;
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}
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// Array index..
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if ( !IsName(tok->str) && tok->str[0] != '.' && Match(tok->next, "%var1% [ %num% ]", varname) )
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{
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const char *num = getstr(tok->next, 2 + varc);
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if (strtol(num, NULL, 10) >= size)
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{
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ReportError(tok->next, "Array index out of bounds");
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}
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tok = gettok(tok, 4);
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continue;
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}
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// memset, memcmp, memcpy, strncpy, fgets..
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if (strcmp(tok->str,"memset")==0 ||
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strcmp(tok->str,"memcpy")==0 ||
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strcmp(tok->str,"memmove")==0 ||
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strcmp(tok->str,"memcmp")==0 ||
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strcmp(tok->str,"strncpy")==0 ||
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strcmp(tok->str,"fgets")==0 )
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{
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if ( Match( tok->next, "( %var1% , %num% , %num% )", varname ) ||
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Match( tok->next, "( %var% , %var1% , %num% )", varname ) )
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{
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const char *num = getstr(tok, varc + 6);
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if ( atoi(num) > total_size )
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{
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ReportError(tok, "Buffer overrun");
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}
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}
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continue;
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}
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// Loop..
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if ( Match(tok, "for (") )
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{
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const TOKEN *tok2 = gettok( tok, 2 );
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// for - setup..
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if ( Match(tok2, "%var% = 0 ;") )
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tok2 = gettok(tok2, 4);
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else if ( Match(tok2, "%type% %var% = 0 ;") )
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tok2 = gettok(tok2, 5);
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else if ( Match(tok2, "%type% %type% %var% = 0 ;") )
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tok2 = gettok(tok2, 6);
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else
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continue;
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// for - condition..
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if ( ! Match(tok2, "%var% < %num% ;") && ! Match(tok2, "%var% <= %num% ;"))
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continue;
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// Get index variable and stopsize.
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const char *strindex = tok2->str;
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int value = (tok2->next->str[1] ? 1 : 0) + atoi(getstr(tok2, 2));
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if ( value <= size )
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continue;
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// Goto the end of the for loop..
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while (tok2 && strcmp(tok2->str,")"))
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tok2 = tok2->next;
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if (!gettok(tok2,5))
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break;
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std::ostringstream pattern;
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pattern << "%var1% [ " << strindex << " ]";
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int indentlevel2 = 0;
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while (tok2)
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{
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if ( tok2->str[0] == ';' && indentlevel2 == 0 )
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break;
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if ( tok2->str[0] == '{' )
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indentlevel2++;
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if ( tok2->str[0] == '}' )
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{
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indentlevel2--;
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if ( indentlevel2 <= 0 )
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break;
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}
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if ( Match( tok2, pattern.str().c_str(), varname ) )
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{
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ReportError(tok2, "Buffer overrun");
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break;
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}
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tok2 = tok2->next;
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}
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continue;
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}
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// Writing data into array..
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if ( Match(tok, "strcpy ( %var1% , %str% )", varname) )
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{
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int len = 0;
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const char *str = getstr(tok, varc + 4 );
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while ( *str )
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{
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if (*str=='\\')
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str++;
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str++;
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len++;
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}
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if (len > 2 && len >= (int)size + 2)
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{
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ReportError(tok, "Buffer overrun");
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}
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continue;
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}
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// Function call..
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// It's not interesting to check what happens when the whole struct is
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// sent as the parameter, that is checked separately anyway.
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if ( Match( tok, "%var% (" ) )
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{
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// Don't make recursive checking..
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if (std::find(CallStack.begin(), CallStack.end(), tok) != CallStack.end())
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continue;
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unsigned int parlevel = 0, par = 0;
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for ( const TOKEN *tok2 = tok; tok2; tok2 = tok2->next )
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{
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if ( tok2->str[0] == '(' )
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{
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parlevel++;
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}
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else if ( tok2->str[0] == ')' )
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{
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parlevel--;
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if ( parlevel < 1 )
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{
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par = 0;
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break;
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}
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}
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else if ( parlevel == 1 && tok2->str[0] == ',' )
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{
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par++;
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}
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if ( parlevel == 1 && Match(tok2, "[(,] %var1% [,)]", varname) )
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{
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par++;
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break;
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}
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}
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if ( par == 0 )
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continue;
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// Find function..
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const TOKEN *ftok = GetFunctionTokenByName( tok->str );
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if ( ! ftok )
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continue;
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// Parse head of function..
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ftok = gettok( ftok, 2 );
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parlevel = 1;
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while ( ftok && parlevel == 1 && par >= 1 )
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{
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if ( ftok->str[0] == '(' )
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parlevel++;
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else if ( ftok->str[0] == ')' )
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parlevel--;
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else if ( ftok->str[0] == ',' )
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par--;
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else if (par==1 && parlevel==1 && (Match(ftok, "%var% ,") || Match(ftok, "%var% )")))
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{
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// Parameter name..
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const char *parname[2];
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parname[0] = ftok->str;
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parname[1] = 0;
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// Goto function body..
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while ( ftok && ftok->str[0] != '{' )
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ftok = ftok->next;
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ftok = ftok ? ftok->next : 0;
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// Check variable usage in the function..
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CallStack.push_back( tok );
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CheckBufferOverrun_CheckScope( ftok, parname, size, total_size );
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CallStack.pop_back();
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// break out..
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break;
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}
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ftok = ftok->next;
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}
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}
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}
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}
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//---------------------------------------------------------------------------
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// Checking local variables in a scope
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//---------------------------------------------------------------------------
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static void CheckBufferOverrun_LocalVariable()
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{
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int indentlevel = 0;
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for (const TOKEN *tok = tokens; tok; tok = tok->next)
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{
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if (tok->str[0]=='{')
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indentlevel++;
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else if (tok->str[0]=='}')
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indentlevel--;
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else if (indentlevel > 0)
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{
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const char *varname[2] = {0};
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unsigned int size = 0;
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const char *type = 0;
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if (Match(tok, "%type% %var% [ %num% ] ;"))
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{
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varname[0] = getstr(tok,1);
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size = strtoul(getstr(tok,3), NULL, 10);
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type = tok->str;
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}
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else if (indentlevel > 0 && Match(tok, "[*;{}] %var% = new %type% [ %num% ]"))
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{
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varname[0] = getstr(tok,1);
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size = strtoul(getstr(tok,6), NULL, 10);
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type = getstr(tok, 4);
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}
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else
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{
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continue;
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}
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int total_size = size * SizeOfType(type);
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if (total_size == 0)
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continue;
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// The callstack is empty
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CallStack.clear();
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CheckBufferOverrun_CheckScope( gettok(tok,5), varname, size, total_size );
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}
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}
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}
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//---------------------------------------------------------------------------
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//---------------------------------------------------------------------------
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// Checking member variables of structs..
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//---------------------------------------------------------------------------
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static void CheckBufferOverrun_StructVariable()
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{
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const char *declstruct_pattern[] = {"","","{",0};
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for ( const TOKEN * tok = findtoken( tokens, declstruct_pattern );
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tok;
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tok = findtoken( tok->next, declstruct_pattern ) )
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{
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if ( strcmp(tok->str, "struct") && strcmp(tok->str, "class") )
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continue;
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const char *structname = tok->next->str;
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if ( ! IsName( structname ) )
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continue;
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// Found a struct declaration. Search for arrays..
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for ( TOKEN * tok2 = tok->next->next; tok2; tok2 = tok2->next )
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{
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if ( tok2->str[0] == '}' )
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break;
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if ( ! strchr( ";{,(", tok2->str[0] ) )
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continue;
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int ivar = 0;
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if ( Match(tok2->next, "%type% %var% [ %num% ] ;") )
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ivar = 2;
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else if ( Match(tok2->next, "%type% %type% %var% [ %num% ] ;") )
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ivar = 3;
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else if ( Match(tok2->next, "%type% * %var% [ %num% ] ;") )
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ivar = 3;
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else if ( Match(tok2->next, "%type% %type% * %var% [ %num% ] ;") )
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ivar = 4;
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else
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continue;
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const char *varname[3] = {0,0,0};
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varname[1] = getstr(tok2, ivar);
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int arrsize = atoi(getstr(tok2, ivar+2));
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int total_size = arrsize * SizeOfType(tok2->next->str);
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if (total_size == 0)
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continue;
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for ( const TOKEN *tok3 = tokens; tok3; tok3 = tok3->next )
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{
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if ( strcmp(tok3->str, structname) )
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continue;
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// Declare variable: Fred fred1;
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if ( Match( tok3->next, "%var% ;" ) )
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varname[0] = getstr(tok3, 1);
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// Declare pointer: Fred *fred1
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else if ( Match(tok3->next, "* %var% [,);=]") )
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varname[0] = getstr(tok3, 2);
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else
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continue;
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// Goto end of statement.
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const TOKEN *CheckTok = NULL;
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while ( tok3 )
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{
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// End of statement.
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if ( tok3->str[0] == ';' )
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{
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CheckTok = tok3;
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break;
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}
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// End of function declaration..
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if ( Match(tok3, ") ;") )
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break;
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// Function implementation..
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if ( Match(tok3, ") {") )
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{
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CheckTok = gettok(tok3, 2);
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break;
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}
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tok3 = tok3->next;
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}
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if ( ! CheckTok )
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continue;
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// Check variable usage..
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CheckBufferOverrun_CheckScope( CheckTok, varname, arrsize, total_size );
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}
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}
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}
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}
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//---------------------------------------------------------------------------
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void CheckBufferOverrun()
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{
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CheckBufferOverrun_LocalVariable();
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CheckBufferOverrun_StructVariable();
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}
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//---------------------------------------------------------------------------
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//---------------------------------------------------------------------------
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// Dangerous functions
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//---------------------------------------------------------------------------
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void WarningDangerousFunctions()
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{
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for (const TOKEN *tok = tokens; tok; tok = tok->next)
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{
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if (Match(tok, "gets ("))
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{
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std::ostringstream ostr;
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ostr << FileLine(tok) << ": Found 'gets'. You should use 'fgets' instead";
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ReportErr(ostr.str());
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}
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else if (Match(tok, "scanf (") && strcmp(getstr(tok,2),"\"%s\"") == 0)
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{
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std::ostringstream ostr;
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ostr << FileLine(tok) << ": Found 'scanf'. You should use 'fgets' instead";
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ReportErr(ostr.str());
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}
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}
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}
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//---------------------------------------------------------------------------
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