361 lines
12 KiB
C++
361 lines
12 KiB
C++
//---------------------------------------------------------------------------
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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 <sstream>
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#include <stdlib.h> // <- strtoul
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//---------------------------------------------------------------------------
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TOKEN *findfunction(TOKEN *tok)
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{
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int indentlevel = 0, parlevel = 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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indentlevel++;
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else if (tok->str[0] == '}')
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indentlevel--;
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else if (tok->str[0] == '(')
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parlevel++;
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else if (tok->str[0] == ')')
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parlevel--;
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if (!tok->next)
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break;
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if (indentlevel==0 && parlevel==0 && IsName(tok->str) && tok->next->str[0]=='(')
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{
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for (TOKEN *tok2 = tok->next; tok2; tok2 = tok2->next)
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{
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if (tok2->str[0] == ')')
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{
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if (tok2->next->str[0] == '{')
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return tok;
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break;
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}
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}
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}
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}
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return 0;
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}
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//---------------------------------------------------------------------------
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// Writing dynamic data in buffer without bounds checking
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//---------------------------------------------------------------------------
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extern bool ShowWarnings;
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static void _DynamicDataCheck(TOKEN *ftok, TOKEN *tok)
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{
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const char *var2 = tok->str;
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bool decl = false;
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unsigned int Var2Count = 0;
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for ( TOKEN *tok2 = ftok; tok2; tok2 = tok2->next )
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{
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if (tok2 == tok)
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break;
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if (match(tok2,"char * var"))
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{
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decl |= (strcmp(getstr(tok2,2),var2)==0);
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tok2 = gettok(tok2,3);
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if ( strcmp(tok2->str, "=") == 0 )
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{
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Var2Count++;
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break;
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}
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}
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if (match(tok2,"char var [ ]"))
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{
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decl |= (strcmp(getstr(tok2,1),var2)==0);
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tok2 = gettok(tok2,3);
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}
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// If ShowWarnings, only strlen(var2) counts
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if ( ShowWarnings )
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{
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if (match(tok2,"strlen ( var )") &&
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strcmp(getstr(tok2,2),var2)==0)
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{
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Var2Count++;
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break;
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}
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}
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// If not ShowWarnings, all usage of "var2" counts
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else
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{
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if (strcmp(tok2->str,var2)==0)
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{
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Var2Count++;
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break;
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}
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}
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}
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// The size of Var2 isn't checked, is it?
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if (decl && Var2Count == 0)
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{
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std::ostringstream ostr;
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ostr << FileLine(tok) << ": A string with unknown length is copied to buffer.";
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ReportErr(ostr.str());
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}
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}
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static void _DynamicData()
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{
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for (TOKEN *ftok = findfunction(tokens); ftok; ftok = findfunction(ftok->next))
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{
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int indentlevel = 0;
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for (TOKEN *tok = ftok; 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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{
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indentlevel--;
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if (indentlevel <= 0)
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break;
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}
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if (match(tok,"strcpy ( var , var )") ||
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match(tok,"strcat ( var , var )") )
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{
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_DynamicDataCheck(ftok,gettok(tok,4));
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}
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if (match(tok,"sprintf ( var"))
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{
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for ( TOKEN *tok2 = gettok(tok,3); 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 (match(tok2,", var ,") || match(tok2,", var )"))
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{
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_DynamicDataCheck(ftok,tok2->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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}
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//---------------------------------------------------------------------------
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//---------------------------------------------------------------------------
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// Buffer overrun..
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//---------------------------------------------------------------------------
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void CheckBufferOverrun()
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{
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_DynamicData();
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int indentlevel = 0;
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for (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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// Declaring array..
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if (match(tok, "type var [ num ] ;"))
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{
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const char *varname = getstr(tok,1);
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unsigned int size = strtoul(getstr(tok,3), NULL, 10);
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int total_size = size * SizeOfType(tok->str);
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if (total_size == 0)
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continue;
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int _indentlevel = indentlevel;
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for (TOKEN *tok2 = gettok(tok,5); tok2; tok2 = tok2->next)
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{
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if (tok2->str[0]=='{')
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{
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_indentlevel++;
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}
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else if (tok2->str[0]=='}')
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{
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_indentlevel--;
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if (_indentlevel < indentlevel)
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break;
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}
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else
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{
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// Array index..
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if (strcmp(tok2->str,varname)==0 &&
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strcmp(getstr(tok2,1),"[")==0 &&
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IsNumber(getstr(tok2,2)) &&
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strcmp(getstr(tok2,3),"]")==0 )
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{
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const char *str = getstr(tok2, 2);
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if (strtoul(str, NULL, 10) >= size)
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{
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std::ostringstream ostr;
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ostr << FileLine(tok2) << ": Array index out of bounds";
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ReportErr(ostr.str());
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}
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}
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// memset, memcmp, memcpy, strncpy, fgets..
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if (strcmp(tok2->str,"memset")==0 ||
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strcmp(tok2->str,"memcpy")==0 ||
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strcmp(tok2->str,"memmove")==0 ||
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strcmp(tok2->str,"memcmp")==0 ||
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strcmp(tok2->str,"strncpy")==0 ||
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strcmp(tok2->str,"fgets")==0 )
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{
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if (match(tok2->next,"( var , num , num )") ||
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match(tok2->next,"( var , var , num )") )
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{
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const char *var1 = getstr(tok2, 2);
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const char *var2 = getstr(tok2, 4);
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const char *num = getstr(tok2, 6);
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if ( atoi(num)>total_size &&
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(strcmp(var1,varname)==0 ||
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strcmp(var2,varname)==0 ) )
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{
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std::ostringstream ostr;
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ostr << FileLine(tok2) << ": Buffer overrun";
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ReportErr(ostr.str());
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}
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}
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}
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// Loop..
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const char *strindex = 0;
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int value = 0;
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if ( match(tok2, "for ( var = 0 ;") )
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{
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if (match(tok2,"for ( var = 0 ; var < num ; var + + )"))
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{
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strindex = getstr(tok2,2);
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value = atoi(getstr(tok2,8));
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}
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else if (match(tok2,"for ( var = 0 ; var <= num ; var + + )"))
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{
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strindex = getstr(tok2,2);
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value = 1 + atoi(getstr(tok2,8));
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}
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else if (match(tok2,"for ( var = 0 ; var < num ; + + var )"))
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{
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strindex = getstr(tok2,2);
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value = atoi(getstr(tok2,8));
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}
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else if (match(tok2,"for ( var = 0 ; var <= num ; + + var )"))
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{
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strindex = getstr(tok2,2);
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value = 1 + atoi(getstr(tok2,8));
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}
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}
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if (strindex && value>(int)size)
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{
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TOKEN *tok3 = tok2;
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while (tok3 && strcmp(tok3->str,")"))
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tok3 = tok3->next;
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if (!tok3)
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break;
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tok3 = tok3->next;
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if (tok3->str[0] == '{')
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tok3 = tok3->next;
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while (tok3 && !strchr(";}",tok3->str[0]))
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{
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if (strcmp(tok3->str,varname)==0 &&
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strcmp(getstr(tok3,1),"[")==0 &&
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strcmp(getstr(tok3,2),strindex)==0 &&
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strcmp(getstr(tok3,3),"]")==0 )
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{
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std::ostringstream ostr;
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ostr << FileLine(tok3) << ": Buffer overrun";
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ReportErr(ostr.str());
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break;
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}
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tok3 = tok3->next;
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}
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}
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// Writing data into array..
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if (match(tok2,"strcpy ( var , "))
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{
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int len = 0;
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if (strcmp(getstr(tok2, 2), varname) == 0)
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{
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const char *str = getstr(tok2, 4);
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if (str[0] == '\"')
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{
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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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}
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}
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if (len > 2 && len >= (int)size + 2)
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{
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std::ostringstream ostr;
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ostr << FileLine(tok2) << ": Buffer overrun";
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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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}
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}
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}
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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 (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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