posix_ioutils.c

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#include <sys/select.h>
#include <unistd.h>

#include <assert.h>

#include <hipc/posix/ioutils.h>

int hipcPosixReadReady(int fd)
{
    fd_set fds;
    struct timeval timeout;

    FD_ZERO(&fds);
    FD_SET(fd, &fds);
    timeout.tv_sec = 0;
    timeout.tv_usec = 0;
    return select(fd + 1, &fds, NULL, NULL, &timeout);
}

ssize_t hipcPosixReadExactly(const int fd, void *buf, const size_t count)
{
    ssize_t n;
    ssize_t i;

    n = count;
    while (0 < n) {
        i = read(fd, buf, n);
        if (0 >= i) {           /* read(2) returns 0 when fd is at the end of the file */
            return i;
        }
        buf = ((unsigned char *) buf) + i;
        assert(n >= i);
        n -= i;
    }
    assert(0 == n);
    return count - n;
}

ssize_t hipcPosixWriteExactly(const int fd,
                              void const *buf, const size_t count)
{
    ssize_t n;
    ssize_t i;

    n = count;
    while (0 < n) {
        i = write(fd, buf, n);
        if (0 > i) {
            return i;
        }
        buf = ((unsigned char *) buf) + i;
        assert(n >= i);
        n -= i;
    }
    assert(0 == n);
    return count - n;
}