how to handle "Buffer too small" exception in c++

Question

2.00/5 (1 vote)

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Hi there,

please find the below code,

C++

char l_Title_ca[10];
try{
	 sprintf_s(l_Title_ca,"Version %d.%02d [MemberId :- %s]",Ver,Rel,MemID);
 }
catch(char* str)
{
     cout << "error: ";
    // if(errn == BUFFER_TOO_SMALL)
     {
          cout << "storage buffer too small.\n";
          return 0;
     }
}catch(...)
{
	cout<<"caught..."<<endl;
}

while executing the code at runtime, i am getting the error message "buffer too small" and not able to catch the exception using above method.

Please any can guide me how can i catch the exception?

Regards,
Ranjith

Posted 10-Dec-13 18:52pm

ranjithkumar81

Updated 10-Dec-13 21:43pm

CPallini

v3

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Comments

Philippe Mori 11-Dec-13 23:37pm

As explained by other, no exceptions are thrown... Also, you should fix the real problem which is that the buffer is too small.

4 solutions

Solution 1

hi,
the second argument of sprintf_s should be some integer value. Take a look here for example[^]

hope this helps !

Posted 10-Dec-13 19:07pm

chandanadhikari

Comments

ranjithkumar81 11-Dec-13 1:13am

that is correct, actually without any changes in the code, i need to handle the exception.

chandanadhikari 11-Dec-13 1:54am

sprintf_s returns -1 if errors occur (see the 'Return value' section in the link). maybe checking for this return value might help you but then again that will involve some code change. may i know why you do not want to use sprintf_s as recommended .

CPallini 11-Dec-13 3:48am

"actually without any changes in the code"
Why? The code is apparently wrong.

ranjithkumar81 11-Dec-13 4:14am

good question.

currently application is running on production , i can not touch the code to do any changes

CPallini 11-Dec-13 4:23am

However you could add an exception handler...

Philippe Mori 11-Dec-13 23:35pm

The code is broken so you have to fix it. As far as I can tell, the debugging stuff is not enable in release version and I'm not sure that those debug assertion are based on exceptions. In fact as pointed out earlier, in released, the string will probably simply be truncated. You'll have to provided a bigger buffer if it is a problem for you.

ranjithkumar81 11-Dec-13 2:41am

yes, i can do that way, but while i put the code in debug mode and cursor is cross this line(sprintf_s(l_Title_ca,"Version %d.%02d [MemberId :- %s]",Ver,Rel,MemID);) .I am gettting the "Assertion Debug Failed!".

message: "buffer too small".

CPallini 11-Dec-13 3:48am

My 5.

chandanadhikari 11-Dec-13 6:38am

thanks CPallini

Solution 3

Simply provide a bigger buffer. If you really want to write an error the check the length of the string and use a buffer slight bigger that want you really want to allows.

For example, if the buffer size is 11, then if the length of the string is 10, then you know that the formated string is too big to fit maximum desired size.

On the other hand, if there are no limit on string size, then you might consider using C++ code to create the string (like a string stream)or a relatively large buffer so that it would always be big enough to handled valid case.

Typically in a case like the one above you probably should have an idea of the maximum length of each part... thus you be able to figure out required buffer size so that an error would never occurs because the buffer would be big enough for the worst case.

Posted 11-Dec-13 17:45pm

Philippe Mori

Solution 4

solution below,

const char* chText[33] = "Version %d.%02d [MemberId :- %s]";
char l_Title_ca[10];
try{
sprintf_s(l_Title_ca,sizeof(chText),chText,Ver,Rel,MemID);
}
catch(char* str)
{
cout << "error: ";
// if(errn == BUFFER_TOO_SMALL)
{
cout << "storage buffer too small.\n";
return 0;
}
}catch(...)
{
cout<<"caught..."<<endl;
}

currently i am not getting any error message , which is like "buffer too small"

Posted 11-Dec-13 18:00pm

ranjithkumar81

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Jochen Arndt · Accepted Answer · 2013-12-10T21:01:00

Solution 2

sprintf_s() is not throwing exceptions. Instead the Invalid Parameter Handler[^] is called when the buffer is too small. To change the behaviour you can install your own handler with _set_invalid_parameter_handler[^].

Posted 10-Dec-13 21:01pm

Jochen Arndt

Updated 11-Dec-13 0:24am

v2