source: MondoRescue/branches/3.2/mindi-busybox/libbb/read.c

/* vi: set sw=4 ts=4: */
/*
 * Utility routines.
 *
 * Copyright (C) 1999-2004 by Erik Andersen <andersen@codepoet.org>
 *
 * Licensed under GPLv2 or later, see file LICENSE in this source tree.
 */
#include "libbb.h"

ssize_t FAST_FUNC safe_read(int fd, void *buf, size_t count)
{
    ssize_t n;

    do {
        n = read(fd, buf, count);
    } while (n < 0 && errno == EINTR);

    return n;
}

/*
 * Read all of the supplied buffer from a file.
 * This does multiple reads as necessary.
 * Returns the amount read, or -1 on an error.
 * A short read is returned on an end of file.
 */
ssize_t FAST_FUNC full_read(int fd, void *buf, size_t len)
{
    ssize_t cc;
    ssize_t total;

    total = 0;

    while (len) {
        cc = safe_read(fd, buf, len);

        if (cc < 0) {
            if (total) {
                /* we already have some! */
                /* user can do another read to know the error code */
                return total;
            }
            return cc; /* read() returns -1 on failure. */
        }
        if (cc == 0)
            break;
        buf = ((char *)buf) + cc;
        total += cc;
        len -= cc;
    }

    return total;
}

ssize_t FAST_FUNC read_close(int fd, void *buf, size_t size)
{
    /*int e;*/
    size = full_read(fd, buf, size);
    /*e = errno;*/
    close(fd);
    /*errno = e;*/
    return size;
}

ssize_t FAST_FUNC open_read_close(const char *filename, void *buf, size_t size)
{
    int fd = open(filename, O_RDONLY);
    if (fd < 0)
        return fd;
    return read_close(fd, buf, size);
}