int main()

in boot/tools/mkbb.c [86:151]

• 49 lines of code
• 8 McCabe index (conditional complexity)

int main(int argc, char ** argv)
{
    bootblock		bootblock_from_disk;
    bootblock		bootloader_image;
    int			dev, fd;
    int			i;
    int			nread;

    /* Make sure of the arg count */
    if(argc != 3) {
	fprintf(stderr, "Usage: %s device lxboot\n", argv[0]);
	exit(0);
    }

    /* First, open the device and make sure it's accessible */
    dev = open(argv[1], O_RDWR);
    if(dev < 0) {
	perror(argv[1]);
	exit(0);
    }

    /* Now open the lxboot and make sure it's reasonable */
    fd = open(argv[2], O_RDONLY);
    if(fd < 0) {
	perror(argv[2]);
	close(dev);
	exit(0);
    }

    /* Read in the lxboot */
    nread = read(fd, &bootloader_image, sizeof(bootblock));
    if(nread != sizeof(bootblock)) {
	perror("lxboot read");
	fprintf(stderr, "expected %zd, got %d\n", sizeof(bootblock), nread);
	exit(0);
    }

    /* Read in the bootblock from disk. */
    nread = read(dev, &bootblock_from_disk, sizeof(bootblock));
    if(nread != sizeof(bootblock)) {
	perror("bootblock read");
	fprintf(stderr, "expected %zd, got %d\n", sizeof(bootblock), nread);
	exit(0);
    }

    /* Swap the bootblock's disklabel into the bootloader */
    bootloader_image.bootblock_label = bootblock_from_disk.bootblock_label;

    /* Calculate the bootblock checksum */
    bootloader_image.bootblock_checksum = 0;
    for(i = 0; i < 63; i++) {
	bootloader_image.bootblock_checksum += 
			bootloader_image.bootblock_quadwords[i];
    }

    /* Write the whole thing out! */
    lseek(dev, 0L, SEEK_SET);
    if(write(dev, &bootloader_image, sizeof(bootblock)) != sizeof(bootblock)) {
	perror("bootblock write");
	exit(0);
    }

    close(fd);
    close(dev);
    exit(0);
}