initrd.c

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/*
 * Copyright (C) 2000 - 2007 Jeff Dike (jdike@{addtoit,linux.intel}.com)
 * Licensed under the GPL
 */

#include <linux/init.h>
#include <linux/bootmem.h>
#include <linux/initrd.h>
#include <asm/types.h>
#include <init.h>
#include <os.h>

/* Changed by uml_initrd_setup, which is a setup */
static char *initrd __initdata = NULL;
static int load_initrd(char *filename, void *buf, int size);

static int __init read_initrd(void)
{
    void *area;
    long long size;
    int err;

    if (initrd == NULL)
        return 0;

    err = os_file_size(initrd, &size);
    if (err)
        return 0;

    /*
     * This is necessary because alloc_bootmem craps out if you
     * ask for no memory.
     */
    if (size == 0) {
        printk(KERN_ERR "\"%s\" is a zero-size initrd\n", initrd);
        return 0;
    }

    area = alloc_bootmem(size);
    if (area == NULL)
        return 0;

    if (load_initrd(initrd, area, size) == -1)
        return 0;

    initrd_start = (unsigned long) area;
    initrd_end = initrd_start + size;
    return 0;
}

__uml_postsetup(read_initrd);

static int __init uml_initrd_setup(char *line, int *add)
{
    initrd = line;
    return 0;
}

__uml_setup("initrd=", uml_initrd_setup,
"initrd=<initrd image>\n"
"    This is used to boot UML from an initrd image.  The argument is the\n"
"    name of the file containing the image.\n\n"
);

static int load_initrd(char *filename, void *buf, int size)
{
    int fd, n;

    fd = os_open_file(filename, of_read(OPENFLAGS()), 0);
    if (fd < 0) {
        printk(KERN_ERR "Opening '%s' failed - err = %d\n", filename,
               -fd);
        return -1;
    }
    n = os_read_file(fd, buf, size);
    if (n != size) {
        printk(KERN_ERR "Read of %d bytes from '%s' failed, "
               "err = %d\n", size,
               filename, -n);
        return -1;
    }

    os_close_file(fd);
    return 0;
}