How to get a file's name from FILE* struct in C
FILE *f = fopen ("foo.txt", "r");

struct file_with_name {
   FILE *f;
   char *name; /* OR char name[MAX] */
}

char buf[PATH_MAX];
snprintf(buf, sizeof buf, "/proc/self/fd/%d", fileno(f));
readlink(buf, buf, sizeof buf);