Introduction to Kernel Hacking

#include "types.h" #include "user.h" #include "param.h" #define assert(x) if (x) { /* pass */ } else { \ printf(1, "assert failed %s %s %d\n", #x , __FILE__, __LINE__); \ exit(); \ } void readfile(char *file, int howmany) { int i; // assumes file opens successfully... int fd = open(file, 0); char buf; // assumes file is big enough... for (i = 0; i < howmany; i++) (void) read(fd, &buf, 1); close(fd); } int main(int argc, char *argv[]) { int rc1 = getreadcount(); printf(1, "Read count %d\n", rc1); int rc = fork(); if (rc < 0) { printf(1, "Fork failed!\n"); exit(); } readfile("README", 5); if (rc > 0) { wait(); int rc2 = getreadcount(); printf(1, "Read count %d\n", rc2); assert((rc2 - rc1) == 10); printf(1, "TEST PASSED\n"); int fd1 = open("ls", 0); int fd2 = open("syscallTest", 0); int fd3 = open("cat", 0); if(fd1 * fd2 * fd3 < 0){ printf(1, "Open failed!\n"); exit(); } close(fd1); int of = getopenfilecount(); printf(1, "Number of opened files %d\n", of - 3); assert(of == 5); printf(1, "TEST PASSED\n"); close(fd2); close(fd3); } exit(); }