utils.cpp

#include <stdio.h>
#include <errno.h>
#include <stdlib.h>
#include <stdint.h>
#include <assert.h>
#include <unistd.h>

#include "utils.h"

void msg(const char *msg)
{
    fprintf(stderr, "%s\n", msg);
}

void die(const char *msg)
{
    int err = errno;
    fprintf(stderr, "[%d] %s\n", err, msg);
    abort();
}

// The read_full() function reads from the kernel until it gets exactly n bytes.
int32_t read_full(int fd, char *buf, size_t n)
{
    while (n > 0)
    {
        ssize_t rv = read(fd, buf, n);
        if (rv <= 0)
            return -1; // error, or unexpected EOF

        assert((size_t)rv <= n);

        n -= (size_t)rv;
        buf += rv;
    }

    return 0;
}

int32_t write_full(int fd, char *buf, size_t n)
{
    while (n > 0)
    {
        ssize_t rv = write(fd, buf, n);
        if (rv <= 0)
            return -1; // error, or unexpected EOF

        assert((size_t)rv <= n);

        n -= (size_t)rv;
        buf += rv;
    }

    return 0;
}