system.c

/**
 * Tony Givargis
 * Copyright (C), 2023
 * University of California, Irvine
 *
 * CS 238P - Operating Systems
 * system.c
 */

#define _GNU_SOURCE

#include <sys/time.h>
#include <unistd.h>
#include "system.h"

/**
 * Needs:
 *   gettimeofday()
 *   nanosleep()
 *   unlink()
 *   vsnprintf()
 *   sysconf()
 */

uint64_t
ref_time(void) {
    struct timeval timeval;

    if (gettimeofday(&timeval, 0)) {
        TRACE("gettimeofday()");
        return 0;
    }
    return (uint64_t) timeval.tv_sec * 1000000 + (uint64_t) timeval.tv_usec;
}

void
us_sleep(uint64_t us) {
    struct timespec in, out;

    in.tv_sec = (time_t) (us / 1000000);
    in.tv_nsec = (long) (us % 1000000) * 1000;
    while (nanosleep(&in, &out)) {
        in = out;
    }
}

void
file_delete(const char *pathname) {
    if (safe_strlen(pathname)) {
        if (unlink(pathname)) {
            /* ignore */
        }
    }
}

void
safe_sprintf(char *buf, size_t len, const char *format, ...) {
    va_list ap;

    assert((!len || buf) && format);

    va_start(ap, format);
    if ((int) len <= vsnprintf(buf, len, format, ap)) {
        va_end(ap);
        EXIT("software");
    }
    va_end(ap);
}

size_t
safe_strlen(const char *s) {
    return s ? strlen(s) : 0;
}

size_t
page_size(void) {
    long size;

    if ((0 >= (size = sysconf(_SC_PAGESIZE)))) {
        EXIT("sysconf()");
        return 0;
    }
    return (size_t) size;
}

void *
memory_align(void *p, size_t n) {
    size_t r;

    if ((r = (size_t) p % n)) {
        r = n - r;
    }
    return (void *) ((char *) p + r);
}