How to fix error checked by Parasoft

Question

In my source code (in C), there is a line as below:

char line[1000] = "";
fgets(line, sizeof(line), file)

When I use parasoft to check, I receive two error:

In 'fgets' function call, do not pass long casted to int expression as '2' function argument
The type 'unsigned long' of function argument number '2' does not match declared type 'int'

I find nothing wrong with these lines in source code, so I don't know how to fix these error. Could you please give me a suggestion?

Answer 1

fgets is accepting an int for its second parameter. (IMHO, this is a defect)

sizeof returns a value of type size_t, which in your case seems to be an alias of unsigned Iong. The issue with this is that an unsigned long can be (much) too large to be convertible to an int.

There's not much you can do about it here. To get rid of the error you might use a cast:

fgets(line, (int)sizeof(line), file);

Note that your use of sizeof might get you into trouble if at some point you decide to change that array into a dynamically allocated one or if you refractor the code into different functions.