fclose causing segmentation fault?

Question

Below is a small portion of the source code where fclose is causing error? This function is not called always, at some particular condition this function is called.

int write_into_file (char * file_name)
{       
    FILE * fp = NULL ;

    if (file_name == NULL)
    {   
        return FAIL ; 
    }   

    if ((fp = fopen (file_name , "r")) == NULL)
    {   
        if ((fp = fopen (file_name, "w")) == NULL)
        {
            return FAIL ;
        }
    }
    fclose (fp) ;
    fp = NULL ;

    return SUCESS;

}

We are passing character buffer of size 1024 to file_name. Please can anyone tell me why fclose causes segmentation fault?

Try running it through `gdb` or `valgrind` as a start. Nothing looks immediately wrong with the code, so you should provide as much information about the crash as possible. It seems unlikely that `fclose()` is the real culprit. — Dan Fego, Jan 03 '12 at 19:00
Is the character buffer null terminated? Is the character buffer a valid filename? Why are you opening the file for reading, then attempting to open it for writing if that fails? — Joseph Stine, Jan 03 '12 at 19:01
Possible duplicate of [fclose() causing segmentation fault](http://stackoverflow.com/questions/1443164/fclose-causing-segmentation-fault) — Jim Fell, Nov 13 '15 at 22:22

score 5 · Accepted Answer · answered Jan 03 '12 at 19:01

I see no possible way that fclose could be causing a segfault here, I think your problem lies somewhere else in the program.

It might be possible that the stack got corrupted elsewhere, and that the bug shows when fclose gets called. I suggest you to review your other source code once more, and step over it with a debugger/memory analyzer closely watching what happens.

The only other thing I can see that might cause a bug is file_name not being null-terminated.

thanks for the reply. Yes, file_name is been null-terminated. I think I must check with valgrind. — Nikhil, Jan 03 '12 at 19:10

score 2 · Answer 2 · answered Jan 03 '12 at 19:14

2

There is no problem with fclose(). The problem could be with your comparison of file_name to NULL or it could be with some other part of your code.

answered Jan 03 '12 at 19:14

Froyo

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fclose causing segmentation fault?

2 Answers2