[Question][Hw3] Segmentation Fault from __coverage__

[adilb99]

When I use __coverage__ function from runtime.c , it produces a segmentation fault.

I tried checking it with if(f == NULL) fprintf(stdout, "IT'S NULL\n"); and it does print.

Therefore, the line fprintf(f, "%d,%d\n", line, col); causes a segfault due to the f file pointer being NULL.

Why does this happen?

[RiceBiscuits]

fopen returns NULL in case of failures, and set 'errno' as the corresponding error.
(See this link: https://man7.org/linux/man-pages/man3/fopen.3.html)
You can check errno to find a cause of the failure.
(See this link: https://man7.org/linux/man-pages/man3/errno.3.html)
ex)
#include <errno.h>
...
void coverage(~, ~)
{
...
f = fopen(~~~);
if (f == NULL)
printf("errno: %s\n",strerror(errno));
...
}
(see this link(strerror(errno): https://man7.org/linux/man-pages/man3/strerror.3.html)

[adilb99]

@RiceBiscuits Thanks a lot, turns out it's just a Permission denied error. Launching with sudo fixed it for me.