Question

fclose() is causing a segfault. I have :

char buffer[L_tmpnam];
char *pipeName = tmpnam(buffer);
FILE *pipeFD = fopen(pipeName, "w"); // open for writing
...
...
...
fclose(pipeFD); 

I don’t do any file related stuff in the … yet so that doesn’t affect it. However, my MAIN process communicates with another process through shared memory where pipeName is stored; the other process fopen’s this pipe for reading to communicated with MAIN.

Any ideas why this is causing a segfault?

Thanks,
Hristo

Answer 1

1. Pass pipeFD to fclose. fclose closes the file by file handle FILE* not filename char*. With C (unlike C++) you can do implicit type conversions of pointer types (in this case char* to FILE*), so that’s where the bug comes from.

2. Check if pepeFD is non NULL before calling fclose.

Edit: You confirmed that the error was due to fopen failing, you need to check the error like so:

 pipeFD = fopen(pipeName, "w");
 if (pipeFD == NULL)
 {
   perror ("The following error occurred");
 }
 else
 {
   fclose (pipeFD);
 }

Example output:

The following error occurred: No such file or directory