Use Visual Studio exception in C - visual-studio

Question

I use С language in project. Eventually, I began to notice that most of the code is check. In the project the return type of the function bool. Because we are working with the media and if function read or write return false we must break programm,
Some time ago I learned that in Visual Studio has built-in exception (Use Visual Studio 2008)
__try
__finally
In the project, we use the log. All functions use log.
We decided to combine the Log and exception. Use preprocessor
#define try do \
{ \
Int32_T __FUNCTION__##ReturnValue = -1; \
LOG_BEGIN(); \
__try \
{
#define finally } \
__finally \
{
#define end_try } \
if( __FUNCTION__##ReturnValue != -1 ) \
{ \
return LOG_END_WITH(__FUNCTION__##ReturnValue); \
} \
else \
{ \
LOG_END(); \
return; \
} \
}while(0)
#define raise(e) RaiseException( e, EXCEPTION_NONCONTINUABLE, 0, NULL )
#define return_false __FUNCTION__##ReturnValue = 0; \
__leave
#define return_true ##__FUNCTION__##ReturnValue = 1; \
__leave
#define return_void ##__FUNCTION__##ReturnValue = -1; \
__leave
Example of use. Function return the bool value
Bool_T Node_Insert( IN OUT Tree_T * tree, IN Text_T fullPath, ... )
{
Text_T itemName = NULL;
int * delimiterPos = NULL;
try
{
// if tree is empty we should add ROOT_PATH
//
if( Tree_IsEmpty( IN *tree ) )
{
if( failed Tree_CreateRoot( IN OUT *tree, IN datafield ) )
{
LOG_ERROR( "Node_Insert FAILURE --> Tree_CreateRoot failed" );
return_false;
}
}
if( Text_Length( IN fullPath ) > 1 )
{
...
// Allocate memory for Text
//
item = Text_New();
// Allocate for delimeterPos array
//
delimiterPos = NEW(n, sizeof(elem));
...
while( i < nDelimiter )
{
...
...
...
}
}
else if ( Text_Length( IN fullPath ) == 1 )
{
// we have already added ROOT
//
return_true;
}else{
LOG_ERROR( "Node_Insert FAILURE --> Path length is not correct" );
return_false;
}
}
// In the end we need free allocated memory
//
finally
{
Text_Delete( IN OUT &itemName );
free( delimiterPos );
}
// in end_try preprocessor we write log and return true or false
//
end_try;
}
Example of use. Method that don't return value
void Ifo_ReadBufferHeader( IN Uint8_T * buffer, ... IN OUT Int32_T * position )
{
Text_T fullPath = NULL;
try
{
// getting buffer size
//
Uint32_T size = Buffer_GetSize( IN buffer );
// getting mode
//
Uint8_T writeMode = Buffer_GetWritingMode( IN buffer );
if( Ifo_IsAddMode( IN static_cast(DataIfoMode_T, writeMode) ) )
{
Uint32_T pos = 1 + Ifo_GetLabelLength() + 23;
// getting path length
//
fullPath = Text_New( IN "", IN mp );
Buffer_GetNameField( IN buffer, OUT &fullPath, IN OUT &pos );
*parentFolderPath = fullPath;
*position = pos;
} else if( Ifo_IsRenameMode( IN static_cast(DataIfoMode_T, writeMode ) )
{
*position = 1 + Ifo_GetLabelLength() + 23;
}
*bufferSize = size;
*mode = static_cast(DataIfoMode_T, writeMode);
// return_void preprocessor that use
//
return_void;
}
finally
{
// After run the main code you must free allocated memory
//
Text_Delete( IN OUT &fullPath );
}
end_try;
}
My question is. How do I design what would it would return a value? That is, the function will return a value, such as calculate buffer CRC return as a value. How do I do this by using these macros.
int GetCrcBuffer( IN Uint32_T buffer, IN Tree_T tree )
{
Text_T itemName = NULL;
int crc = 0;
try
{
...
...
itemName = Text_New();
if( crc != 12 )
{
return_value(crc); // ???? return value of crc and delete text??? how???
}
...
...
}
finally
{
Text_Delete( IN OUT itemName );
}
end_try;
}
How to make it run finally block and return value crc??
How write the preprocessor return_value() ???

Answer 1

Your finally block will properly delete itemname, so you don't have to worry about that part. The only trick is that your return value cannot be -1 (that is: -1 cannot be a legitimate return value) as that signals error in end_try. Then just like with raise(e), you can specify a parameter to the macro:
#define return_value(v) ##__FUNCTION__##ReturnValue = (v); \
__leave
If you want to write a function that can return nnon-integral types, you can do this trick: have the function actually return an int, signalling success/failure, and in the case of success, pass the actual "return value" (the non-integral type one) back via a pointer parameter:
#define return_value2(v) *ret_val=(v); \
##__FUNCTION__##ReturnValue = 1; \
__leave
int GetMyType( IN Uint32_T buffer, IN Tree_T tree, MyType* ret_val )
{
...
}
Note: the value ret_val points to is valid only if the function did not return -1