cppcheck/CheckMemoryLeak.cpp

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#include "CheckMemoryLeak.h"
#include "tokenize.h"
#include "CommonCheck.h"
#include <vector>
#include <sstream>
#ifdef __BORLANDC__
#include <mem.h> // <- memset
#else
#include <string.h>
#endif
//---------------------------------------------------------------------------
enum AllocType { No, Malloc, New, NewA };
static AllocType GetAllocationType( const TOKEN *tok2 )
{
// What we may have...
// * var = (char *)malloc(10);
// * var = new char[10];
// * var = strdup("hello");
if ( tok2 && tok2->str[0] == '(' )
{
while ( tok2 && tok2->str[0] != ')' )
tok2 = tok2->next;
tok2 = tok2 ? tok2->next : NULL;
}
if ( ! tok2 )
return No;
// Does tok2 point on "malloc", "strdup" or "kmalloc"..
const char *mallocfunc[] = {"malloc",
"calloc",
"realloc",
"strdup",
"kmalloc",
"kzalloc",
"g_malloc",
0};
for ( unsigned int i = 0; mallocfunc[i]; i++ )
{
if ( strcmp(mallocfunc[i], tok2->str) == 0 )
return Malloc;
}
if ( Match( tok2, "new %type% [;(]" ) )
return New;
if ( Match( tok2, "new %type% [" ) )
return NewA;
return No;
}
static AllocType GetDeallocationType( const TOKEN *tok, const char *varnames[] )
{
if ( Match(tok, "delete %var1% ;", varnames) )
return New;
if ( Match(tok, "delete [ ] %var1% ;", varnames) )
return NewA;
if ( Match(tok, "free ( %var1% ) ;", varnames) ||
Match(tok, "kfree ( %var1% ) ;", varnames) ||
Match(tok, "g_free ( %var1% ) ;", varnames) )
{
return Malloc;
}
return No;
}
//---------------------------------------------------------------------------
static void MismatchError( const TOKEN *Tok1, const char varname[] )
{
std::ostringstream errmsg;
errmsg << FileLine(Tok1) << ": Mismatching allocation and deallocation: " << varname;
ReportErr( errmsg.str() );
}
//---------------------------------------------------------------------------
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static void MemoryLeak( const TOKEN *tok, const char varname[] )
{
std::ostringstream errmsg;
errmsg << FileLine(tok) << ": Memory leak: " << varname;
ReportErr( errmsg.str() );
}
//---------------------------------------------------------------------------
static void CheckMemoryLeak_CheckScope( const TOKEN *Tok1, const char varname[] )
{
const char *varnames[2];
varnames[0] = varname;
varnames[1] = 0;
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AllocType Alloc = No;
int alloc_indentlevel = 0;
bool isif = false;
int indentlevel = 0;
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for (const TOKEN *tok = Tok1 ; tok; tok = tok->next )
{
if (tok->str[0]=='{')
indentlevel++;
else if (tok->str[0]=='}')
{
indentlevel--;
if ( indentlevel < 0 )
{
if ( Alloc != No )
MemoryLeak( Tok1, varname );
return;
}
if ( indentlevel < alloc_indentlevel )
alloc_indentlevel = -1;
}
// Skip stuff like: if (!var) ...
if ( Match(tok, "if ( ! %var1% )", varnames) ||
Match(tok, "if ( unlikely ( ! %var1% ) )", varnames) ||
Match(tok, "if ( %var1% == NULL )", varnames) ||
Match(tok, "if ( NULL == %var1% )", varnames) ||
Match(tok, "if ( %var1% == 0 )", varnames) )
{
int _indentlevel = 0;
while ( tok )
{
if ( tok->str[0] == '{' )
_indentlevel++;
else if ( tok->str[0] == '}' )
{
_indentlevel--;
if ( _indentlevel <= 0 )
break;
}
else if (_indentlevel==0 && tok->str[0]==';')
break;
tok = tok->next;
}
}
// if..
if ( Match(tok,"if") )
isif = true;
if ( strchr(";{}", tok->str[0]) )
isif = false;
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// Allocated..
if ( Match(tok, "[(;{}] %var1% =", varnames) )
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{
AllocType alloc = GetAllocationType( gettok(tok, 3) );
if ( alloc != No )
{
tok = tok->next;
Alloc = alloc;
alloc_indentlevel = indentlevel;
if ( isif )
{
while ( tok )
{
if ( tok->str[0] == '{' )
{
indentlevel++;
}
else if ( tok->str[0] == '}' )
{
indentlevel--;
if ( indentlevel <= alloc_indentlevel )
break;
}
else if ( tok->str[0] == ';' && indentlevel == alloc_indentlevel )
{
break;
}
tok = tok->next;
}
}
}
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}
// Deallocated..
AllocType dealloc = GetDeallocationType( tok, varnames );
if ( dealloc != No )
{
if ( Alloc != No && Alloc != dealloc )
MismatchError( Tok1, varname );
return;
}
// Used..
// list.push_back( var1 );
// listtail->next = var1;
// foo( var1 );
if ( Match( tok, "[=,(] %var1% [,);]", varnames ) )
return;
if ( Match( tok, "[=,(] ( %type% * ) %var1% [,);]", varnames ) )
return;
if ( Match( tok, "[=,(] ( %type% %type% * ) %var1% [,);]", varnames ) )
return;
// Linux lists..
if ( Match( tok, "%var% ( & %var1% .", varnames ) )
{
if ( strstr(tok->str, "list_add") )
return;
}
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// continue/break loop..
if (Alloc != No &&
alloc_indentlevel == indentlevel &&
(Match(tok,"continue") || Match(tok,"break")))
{
MemoryLeak( tok, varname );
return;
}
// Return without deallocating the memory..
if ( Alloc != No && alloc_indentlevel >= 0 && Match(tok, "return") )
{
bool retvar = false;
for ( const TOKEN *tok2 = tok->next; tok2; tok2 = tok2->next )
{
if ( Match( tok2, "%var1%", varnames ) )
{
retvar = true;
break;
}
if ( tok2->str[0] == ';' )
{
break;
}
}
if ( ! retvar )
MemoryLeak( tok, varname );
if ( indentlevel <= alloc_indentlevel )
return;
}
}
}
//---------------------------------------------------------------------------
//---------------------------------------------------------------------------
// Checks for memory leaks inside function..
//---------------------------------------------------------------------------
static void CheckMemoryLeak_InFunction()
{
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bool infunc = false;
int indentlevel = 0;
for (const TOKEN *tok = tokens; tok; tok = tok->next)
{
if (tok->str[0]=='{')
indentlevel++;
else if (tok->str[0]=='}')
indentlevel--;
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// In function..
if ( indentlevel == 0 )
{
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if ( Match(tok, ") {") )
infunc = true;
if ( Match(tok, "[;}]") )
infunc = false;
}
// Declare a local variable => Check
if (indentlevel>0 && infunc)
{
if ( Match(tok, "[{};] %type% * %var% [;=]") )
CheckMemoryLeak_CheckScope( tok->next, getstr(tok, 3) );
else if ( Match(tok, "[{};] %type% %type% * %var% [;=]") )
CheckMemoryLeak_CheckScope( tok->next, getstr(tok, 4) );
}
}
}
//---------------------------------------------------------------------------
//---------------------------------------------------------------------------
// Checks for memory leaks in classes..
//---------------------------------------------------------------------------
static void CheckMemoryLeak_ClassMembers_ParseClass( const TOKEN *tok1, std::vector<const char *> &classname );
static void CheckMemoryLeak_ClassMembers_Variable( const std::vector<const char *> &classname, const char varname[] );
static void CheckMemoryLeak_ClassMembers()
{
int indentlevel = 0;
for ( const TOKEN *tok = tokens; tok; tok = tok->next )
{
if ( tok->str[0] == '{' )
indentlevel++;
else if ( tok->str[0] == '}' )
indentlevel--;
else if ( indentlevel == 0 && Match(tok, "class %var% [{:]") )
{
std::vector<const char *> classname;
classname.push_back( getstr(tok, 1) );
CheckMemoryLeak_ClassMembers_ParseClass( tok, classname );
}
}
}
static void CheckMemoryLeak_ClassMembers_ParseClass( const TOKEN *tok1, std::vector<const char *> &classname )
{
// Go into class.
while ( tok1 && tok1->str[0] != '{' )
tok1 = tok1->next;
if ( tok1 )
tok1 = tok1->next;
int indentlevel = 0;
for ( const TOKEN *tok = tok1; tok; tok = tok->next )
{
if ( tok->str[0] == '{' )
indentlevel++;
else if ( tok->str[0] == '}' )
{
indentlevel--;
if ( indentlevel < 0 )
return;
}
// Only parse this particular class.. not subclasses
if ( indentlevel > 0 )
continue;
// Declaring subclass.. recursive checking
if ( Match(tok, "class %var% [{:]") )
{
classname.push_back( getstr(tok, 1) );
CheckMemoryLeak_ClassMembers_ParseClass( tok, classname );
classname.pop_back();
}
// Declaring member variable.. check allocations and deallocations
if ( Match(tok->next, "%type% * %var% ;") )
{
if ( IsName(tok->str) || strchr(";}", tok->str[0]) )
CheckMemoryLeak_ClassMembers_Variable( classname, getstr(tok, 3) );
}
}
}
static void CheckMemoryLeak_ClassMembers_Variable( const std::vector<const char *> &classname, const char varname[] )
{
// Function pattern.. Check if member function
char fpattern[500] = {0};
for ( unsigned int i = 0; i < classname.size(); i++ )
{
strcat( fpattern, classname[i] );
strcat( fpattern, " :: " );
}
strcat( fpattern, "%var% (" );
// Destructor pattern.. Check if class destructor..
char destructor[500] = {0};
for ( unsigned int i = 0; i < classname.size(); i++ )
{
strcat( destructor, classname[i] );
strcat( destructor, " :: " );
}
strcat( destructor, " ~" );
strcat( destructor, classname.back() );
strcat( destructor, " (" );
// Pattern used in member function. "Var = ..."
std::ostringstream varname_eq;
varname_eq << varname << " =";
// Full variable name..
std::ostringstream FullVariableName;
for ( unsigned int i = 0; i < classname.size(); i++ )
FullVariableName << classname[i] << "::";
FullVariableName << varname;
// Check if member variable has been allocated and deallocated..
AllocType Alloc = No;
AllocType Dealloc = No;
// Loop through all tokens. Inspect member functions
bool memberfunction = false;
int indentlevel = 0;
for ( const TOKEN *tok = tokens; tok; tok = tok->next )
{
if ( tok->str[0] == '{' )
indentlevel++;
else if ( tok->str[0] == '}' )
indentlevel--;
// Set the 'memberfunction' variable..
if ( indentlevel == 0 )
{
if ( strchr(";}", tok->str[0]) )
memberfunction = false;
else if ( Match( tok, fpattern ) || Match( tok, destructor ) )
memberfunction = true;
}
// Parse member function..
if ( indentlevel > 0 && memberfunction )
{
// Allocate..
if ( Match( tok, varname_eq.str().c_str() ) )
{
AllocType alloc = GetAllocationType( gettok( tok, 2 ) );
if ( alloc != No )
{
if ( Dealloc != No && Dealloc != alloc )
MismatchError( tok, FullVariableName.str().c_str() );
if ( Alloc != No && Alloc != alloc )
MismatchError( tok, FullVariableName.str().c_str() );
Alloc = alloc;
}
}
// Deallocate..
const char *varnames[2] = { "var", 0 };
varnames[0] = varname;
AllocType dealloc = GetDeallocationType( tok, varnames );
if ( dealloc != No )
{
if ( Dealloc != No && Dealloc != dealloc )
MismatchError( tok, FullVariableName.str().c_str() );
if ( Alloc != No && Alloc != dealloc )
MismatchError( tok, FullVariableName.str().c_str() );
Dealloc = dealloc;
}
}
}
if ( Alloc != No && Dealloc == No )
{
MemoryLeak( tokens, FullVariableName.str().c_str() );
}
}
//---------------------------------------------------------------------------
// Checks for memory leaks..
//---------------------------------------------------------------------------
void CheckMemoryLeak()
{
// Check for memory leaks inside functions..
CheckMemoryLeak_InFunction();
// Check that all class members are deallocated..
CheckMemoryLeak_ClassMembers();
}
//---------------------------------------------------------------------------