gptextend.c

#define _FILE_OFFSET_BITS 64
#define _GNU_SOURCE
#include <unistd.h>
#include <stdio.h>
#include <errno.h>
#include "filesize.h"
#include "part.h"
#include "gpt.h"

#ifdef static_assert
static_assert(sizeof(loff_t)==sizeof(off_t));
#endif

static void
usage(void)
{
    dprintf(2, "usage: gptextend [-n part] disk\n");
    exit(1);
}

int
main(int argc, char **argv)
{
    long long start, length;
    const char *disk;
    bool tellkernel;
    off_t disksize;
    int fd, part;
    char c;

    tellkernel = false;
    part = -1;
    while ((c = getopt(argc, argv, "+n:k")) != -1) {
	switch (c) {
	case 'k':
	    tellkernel = true;
	    break;
	case 'n':
	    part = atoi(optarg);
	    break;
	default:
	    usage();
	}
    }
    argc -= optind;
    argv += optind;
    if (argc <= 0)
	usage();
    disk = argv[0];
    fd = open(disk, O_RDWR|O_CLOEXEC);
    if (fd < 0)
	err(1, "open %s", disk);
    disksize = fgetsize(fd);
    if (!disksize)
	err(1, "computing disk size");

    if ((part = gpt_add_lastpart(fd, part, disksize>>9, &start, &length)) < 0)
	err(1, "adding partition");

    if (tellkernel && kernel_add_part(fd, part, start, length) < 0)
	err(1, "couldn't update kernel partition table");
    close(fd);
    return 0;
}