reiserfsprogs/lib/misc.c

/*
 * Copyright 1996-2004 by Hans Reiser, licensing governed by 
 * reiserfsprogs/README
 */

#define _GNU_SOURCE

#include "misc.h"

#include <stdio.h>
#include <stdarg.h>
#include <string.h>
#include <errno.h>
#include <mntent.h>
#include <sys/vfs.h>
#include <time.h>
#include <utime.h>
#include <ctype.h>
#include <linux/hdreg.h>
#include <dirent.h>
#include <assert.h>

#include <sys/ioctl.h>
#include <signal.h>


/* Debian modifications by Ed Boraas <ed@debian.org> */
#include <sys/mount.h>
/* End Debian mods */

#define STAT_FIELD(Field, Type)						\
inline Type misc_device_##Field(char *device) {				\
	struct stat st;							\
									\
	if (stat(device, &st) == 0)					\
		return st.st_##Field;					\
									\
	fprintf(stderr, "Stat of the device '%s' failed.", device);	\
	exit(8);							\
}

STAT_FIELD(mode, mode_t);
STAT_FIELD(rdev, dev_t);
STAT_FIELD(size, off_t);
STAT_FIELD(blocks, blkcnt_t);

void die (char * fmt, ...)
{
    static char buf[1024];
    va_list args;

    va_start (args, fmt);
    vsprintf (buf, fmt, args);
    va_end (args);

    fprintf (stderr, "\n%s\n", buf);
    abort ();
}


#define MEM_BEGIN "_mem_begin_"
#define MEM_END "mem_end"
#define MEM_FREED "__free_"
#define CONTROL_SIZE (strlen (MEM_BEGIN) + 1 + sizeof (int) + strlen (MEM_END) + 1)


unsigned int get_mem_size(char *p) {
    char *begin;
    
    begin = p - strlen (MEM_BEGIN) - 1 - sizeof(int);
    return *(int *)(begin + strlen (MEM_BEGIN) + 1);
}


void checkmem (char * p, int size)
{
    char * begin;
    char * end;
  
    begin = p - strlen (MEM_BEGIN) - 1 - sizeof (int);
    if (strcmp (begin, MEM_BEGIN))
	die ("checkmem: memory corrupted - invalid head sign");

    if (*(int *)(begin + strlen (MEM_BEGIN) + 1) != size)
	die ("checkmem: memory corrupted - invalid size");

    end = begin + size + CONTROL_SIZE - strlen (MEM_END) - 1;
    if (strcmp (end, MEM_END))
	die ("checkmem: memory corrupted - invalid end sign");
}


void *getmem (int size)
{
    char * mem;

    if ((mem = mem_alloc(size)) == NULL)
	die ("getmem: no more memory (%d)", size);
    
    memset (mem, 0, size);
//    checkmem (mem, size);

    return mem;
}

void *mem_alloc(int size) {
    char * p;
    char * mem;

    p = (char *)malloc (CONTROL_SIZE + size);
    if (!p)
	die ("getmem: no more memory (%d)", size);

    /* Write the MEM_BEGIN magic in the beginning of allocated memory. */
    strcpy (p, MEM_BEGIN);
    p += strlen (MEM_BEGIN) + 1;
    /* Write the size after the magic. */
    *(int *)p = size;
    p += sizeof (int);
    mem = p;
    p += size;
    strcpy (p, MEM_END);

    return mem;
}

void * expandmem (void * vp, int size, int by)
{
    int allocated;
    char * mem, * p = vp;
    int expand_by = by;

    if (p) {
	checkmem (p, size);
	allocated = CONTROL_SIZE + size;
	p -= (strlen (MEM_BEGIN) + 1 + sizeof (int));
    } else {
	allocated = 0;
	/* add control bytes to the new allocated area */
	expand_by += CONTROL_SIZE;
    }
    p = realloc (p, allocated + expand_by);
    if (!p)
	die ("expandmem: no more memory (%d)", size);
    if (!vp) {
	strcpy (p, MEM_BEGIN);
    }
    mem = p + strlen (MEM_BEGIN) + 1 + sizeof (int);

    *(int *)(p + strlen (MEM_BEGIN) + 1) = size + by;
    /* fill new allocated area by 0s */
    if(by > 0)
        memset (mem + size, 0, by);
    strcpy (mem + size + by, MEM_END);
//    checkmem (mem, size + by);

    return mem;
}


void freemem (void * vp)
{
    char * p = vp;
    int size;
  
    if (!p)
	return;
    size = get_mem_size (vp);
    checkmem (p, size);

    p -= (strlen (MEM_BEGIN) + 1 + sizeof (int));
    strcpy (p, MEM_FREED);
    strcpy (p + size + CONTROL_SIZE - strlen (MEM_END) - 1, MEM_FREED);
    free (p);
}


typedef int (*func_t) (char *);

/* Lookup the @file in the @mntfile. @file is mntent.mnt_fsname if @fsname 
   is set; mntent.mnt_dir otherwise. Return the mnt entry from the @mntfile.
   
   Warning: if the root fs is mounted RO, the content of /etc/mtab may be 
   not correct. */
static struct mntent *misc_mntent_lookup(char *mntfile, 
					 char *file, 
					 int path) 
{
	struct mntent *mnt;
	int name_match = 0;
	struct stat st;
	dev_t rdev = 0;
	dev_t dev = 0;
	ino_t ino = 0;
	char *name;
	FILE *fp;
	
	assert(mntfile != NULL);
	assert(file != NULL);

	if (stat(file, &st) == 0) {
		/* Devices is stated. */
		if (S_ISBLK(st.st_mode)) {
			rdev = st.st_rdev;
		} else {
			dev = st.st_dev;
			ino = st.st_ino;
		}
	}

	if ((fp = setmntent(mntfile, "r")) == NULL)
		return INVAL_PTR;

	while ((mnt = getmntent(fp)) != NULL) {
		/* Check if names match. */
		name = path ? mnt->mnt_dir : mnt->mnt_fsname;
		
		if (strcmp(file, name) == 0)
			name_match = 1;

		if (stat(name, &st))
			continue;
		
		/* If names do not match, check if stats match. */
		if (!name_match) {
			if (rdev && S_ISBLK(st.st_mode)) {
				if (rdev != st.st_rdev)
					continue;
			} else if (dev && !S_ISBLK(st.st_mode)) {
				if (dev != st.st_dev ||
				    ino != st.st_ino)
					continue;
			} else {
				continue;
			}
		}

		/* If not path and not block device do not check anything more. */
		if (!path && !rdev) 
			break;

		if (path) {
			/* Either names or stats match. Make sure the st_dev of 
			   the path is same as @mnt_fsname device rdev. */
			if (stat(mnt->mnt_fsname, &st) == 0 && 
			    dev == st.st_rdev)
				break;
		} else {
			/* Either names or stats match. Make sure the st_dev of 
			   the mount entry is same as the given device rdev. */
			if (stat(mnt->mnt_dir, &st) == 0 && 
			    rdev == st.st_dev)
				break;
		}
	}

	endmntent (fp);
        return mnt;
}

static int misc_root_mounted(char *device) {
	struct stat rootst, devst;
	
	assert(device != NULL);

	if (stat("/", &rootst) != 0) 
		return -1;

	if (stat(device, &devst) != 0)
		return -1;

	if (!S_ISBLK(devst.st_mode) || 
	    devst.st_rdev != rootst.st_dev)
		return 0;

	return 1;
}

static int misc_file_ro(char *file) {
	if (utime(file, 0) == -1) {
		if (errno == EROFS)
			return 1;
	}

	return 0;
}

struct mntent *misc_mntent(char *device) {
	int proc = 0, path = 0, root = 0;
	
	struct mntent *mnt;
	struct statfs stfs;

	assert(device != NULL);
	
	/* Check if the root. */
	if (misc_root_mounted(device) == 1)
		root = 1;
	
#ifdef __linux__
	/* Check if /proc is procfs. */
	if (statfs("/proc", &stfs) == 0 && stfs.f_type == 0x9fa0) {
		proc = 1;
		
		if (root) {
			/* Lookup the "/" entry in /proc/mounts. Special 
			   case as root entry can present as:
				rootfs / rootfs rw 0 0
			   Look up the mount point in this case. */
			mnt = misc_mntent_lookup("/proc/mounts", "/", 1);
		} else {
			/* Lookup the @device /proc/mounts */
			mnt = misc_mntent_lookup("/proc/mounts", device, 0);
		}
		
		if (mnt == INVAL_PTR) 
			proc = 0;
		else if (mnt)
			return mnt;
	}
#endif /* __linux__ */

#if defined(MOUNTED) || defined(_PATH_MOUNTED)

#ifndef MOUNTED
    #define MOUNTED _PATH_MOUNTED
#endif
	/* Check in MOUNTED (/etc/mtab) if RW. */
	if (!misc_file_ro(MOUNTED)) {
		path = 1;

		if (root) {
			mnt = misc_mntent_lookup(MOUNTED, "/", 1);
		} else {
			mnt = misc_mntent_lookup(MOUNTED, device, 0);
		}

		if (mnt == INVAL_PTR) 
			path = 0;
		else if (mnt)
			return mnt;
	}
#endif /* defined(MOUNTED) || defined(_PATH_MOUNTED) */
	
	/* If has not been checked in neither /proc/mounts nor /etc/mtab (or 
	   errors have occured), return INVAL_PTR, NULL otherwise. */
	return (!proc && !path) ? INVAL_PTR : NULL;
}

int misc_device_mounted(char *device) {
	struct mntent *mnt;
	
	/* Check for the "/" first to avoid any possible problem with 
	   reflecting the root fs info in mtab files. */
	if (misc_root_mounted(device) == 1) {
		return misc_file_ro("/") ? MF_RO : MF_RW;
	}
	
	/* Lookup the mount entry. */
	if ((mnt = misc_mntent(device)) == NULL) {
		return MF_NOT_MOUNTED;
	} else if (mnt == INVAL_PTR) {
		return 0;
	}

	return hasmntopt(mnt, MNTOPT_RO) ? MF_RO : MF_RW;
}

char buf1 [100];
char buf2 [100];

void print_how_fast (unsigned long passed, unsigned long total,
		     int cursor_pos, int reset_time)
{
    static time_t t0 = 0, t1 = 0, t2 = 0;
    int speed;
    int indent;

    if (reset_time)
	time (&t0);

    time (&t1);
    if (t1 != t0) {
	speed = passed / (t1 - t0);
	if (total - passed) {
	    if (t1 - t2 < 1)
	        return;
	    t2 = t1;
	}	
    } else
	speed = 0;

    /* what has to be written */
    if (total)
      sprintf (buf1, "left %lu, %d /sec", total - passed, speed);
    else {
	/*(*passed) ++;*/
	sprintf (buf1, "done %lu, %d /sec", passed, speed);
    }
    
    /* make indent */
    indent = 79 - cursor_pos - strlen (buf1);
    memset (buf2, ' ', indent);
    buf2[indent] = 0;
    fprintf (stderr, "%s%s", buf2, buf1);

    memset (buf2, '\b', indent + strlen (buf1));
    buf2 [indent + strlen (buf1)] = 0;
    fprintf (stderr, "%s", buf2);
    fflush (stderr);
}


static char * strs[] =
{"0%",".",".",".",".","20%",".",".",".",".","40%",".",".",".",".","60%",".",".",".",".","80%",".",".",".",".","100%"};

static char progress_to_be[1024];
static char current_progress[1024];

static void str_to_be (char * buf, int prosents)
{
    int i;
    prosents -= prosents % 4;
    buf[0] = 0;
    for (i = 0; i <= prosents / 4; i ++)
	strcat (buf, strs[i]);
}


void print_how_far (FILE * fp,
		    unsigned long * passed, unsigned long total,
		    unsigned int inc, int quiet)
{
    int percent;

    if (*passed == 0)
	current_progress[0] = 0;

    (*passed) += inc;
    if (*passed > total) {
/*	fprintf (fp, "\nprint_how_far: total %lu has been reached already. cur=%lu\n",
	total, *passed);*/
	return;
    }

    percent = ((*passed) * 100) / total;

    str_to_be (progress_to_be, percent);

    if (strlen (current_progress) != strlen (progress_to_be)) {
	fprintf (fp, "%s", progress_to_be + strlen (current_progress));
    }

    strcat (current_progress, progress_to_be + strlen (current_progress));

    if (!quiet) {
	print_how_fast(*passed /* - inc*/, total, strlen (progress_to_be),
	    (*passed == inc) ? 1 : 0);
    }

    fflush (fp);
}

#if defined(__linux__) && defined(_IOR) && !defined(BLKGETSIZE64)
/* Note! Despite this call being called with *64, it must be encoded to
 * return only sizeof(size_t), since in earlier kernel versions it was
 * declared _IOR(0x12, 114, sizeof(u64)), making it use sizeof(sizeof(u64)).
 *
 * However, the call itself does always return 64bit!
 */
#   define BLKGETSIZE64 _IOR(0x12, 114, size_t)
#endif

/* To not have problem with last sectors on the block device when switching 
   to smaller one. */
#define MAX_BS (64 * 1024)

int valid_offset( int fd, loff_t offset) {
    char ch;
    loff_t res;

    /*res = reiserfs_llseek (fd, offset, 0);*/
    res = lseek (fd, offset, SEEK_SET);
    if (res < 0)
	return 0;

    /* if (read (fd, &ch, 1) < 0) does not wirk on files */
    if (read (fd, &ch, 1) < 1)
	return 0;


    return 1;
}

/* calculates number of blocks in a file. Returns 0 for "sparse"
   regular files and files other than regular files and block devices */
unsigned long count_blocks (char * filename, int blocksize)
{
    loff_t high, low;
    unsigned long sz;
    __u64 size;
    int fd;

    if (!S_ISBLK(misc_device_mode(filename)) && 
	!S_ISREG(misc_device_mode(filename)))
	return 0;

    fd = open (filename, O_RDONLY);
    if (fd == -1) {
	fprintf(stderr, "Failed to open '%s': %s.\n", filename, strerror(errno));
	return 0;
    }

#ifdef BLKGETSIZE64
    {
	if (ioctl (fd, BLKGETSIZE64, &size) >= 0) {
	    size = (size / MAX_BS) * MAX_BS / blocksize;
	    sz = size;
	    if ((__u64)sz != size)
		    die ("count_blocks: block device too large");

	    close(fd);
	    return sz;
	}
    }
#endif


#ifdef BLKGETSIZE
    {
	if (ioctl (fd, BLKGETSIZE, &sz) >= 0) {
	    size = sz;

	    close(fd);
	    return (size * 512 / MAX_BS) * MAX_BS / blocksize;
	}
    }
#endif

    low = 0;
    for( high = 1; valid_offset (fd, high); high *= 2 )
	low = high;
    while (low < high - 1) {
	const loff_t mid = ( low + high ) / 2;

	if (valid_offset (fd, mid))
	    low = mid;
	else
	    high = mid;
    }
    
    valid_offset (fd, 0);

    close (fd);
    return (low + 1) * MAX_BS / MAX_BS / blocksize;
}

/* there are masks for certain bits  */
__u16 mask16 (int from, int count)
{
    __u16 mask;


    mask = (0xffff >> from);
    mask <<= from;
    mask <<= (16 - from - count);
    mask >>= (16 - from - count);
    return mask;
}


__u32 mask32 (int from, int count)
{
    __u32 mask;


    mask = (0xffffffff >> from);
    mask <<= from;
    mask <<= (32 - from - count);
    mask >>= (32 - from - count);
    return mask;
}


__u64 mask64 (int from, int count)
{
    __u64 mask;


    mask = (0xffffffffffffffffLL >> from);
    mask <<= from;
    mask <<= (64 - from - count);
    mask >>= (64 - from - count);
    return mask;
}


__u32 get_random (void)
{
    srandom (time (0));
    return random ();
}

/* this implements binary search in the array 'base' among 'num' elements each
   of those is 'width' bytes long. 'comp_func' is used to compare keys */
int reiserfs_bin_search (void * key, void * base, __u32 num, int width,
			 __u32 * ppos, comparison_fn_t comp_func)
{
    __u32 rbound, lbound, j;
    int ret;

    if (num == 0 || base == NULL) {
	/* objectid map may be 0 elements long */
	*ppos = 0;
	return POSITION_NOT_FOUND;
    }

    lbound = 0;
    rbound = num - 1;

    for (j = (rbound + lbound) / 2; lbound <= rbound; j = (rbound + lbound) / 2) {
	ret =  comp_func ((void *)((char *)base + j * width), key ) ;
	if (ret < 0) { /* second is greater */
	    lbound = j + 1;
	    continue;

	} else if (ret > 0) { /* first is greater */
	    if (j == 0)
	    	break;
	    rbound = j - 1;
	    continue;
	} else { /* equal */
	    *ppos = j;
	    return POSITION_FOUND;
	}
    }

    *ppos = lbound;
    return POSITION_NOT_FOUND;
}


#define BLOCKLIST__ELEMENT_NUMBER 10

/*element is block number and device*/
int blockdev_list_compare (const void * block1, const void * block2) {
    if (*(__u32 *)block1 < *(__u32 *)block2)
        return -1;
    if (*(__u32 *)block1 > *(__u32 *)block2)
        return 1;
        
    if (*((__u32 *)block1 + 1) < *((__u32 *)block2 + 1))
        return -1;        
    if (*((__u32 *)block1 + 1) > *((__u32 *)block2 + 1))
        return 1;
        
    return 0;
}

void blocklist__insert_in_position (void *elem, void **base, __u32 *count, 
    int elem_size, __u32 *position) 
{
    if (elem_size == 0)
    	return;
    	
    if (*base == NULL)
        *base = getmem (BLOCKLIST__ELEMENT_NUMBER * elem_size);
    
    if (*count == get_mem_size((void *)*base) / elem_size)
        *base = expandmem (*base, get_mem_size((void *)*base), 
                        BLOCKLIST__ELEMENT_NUMBER * elem_size);
    
    if (*position < *count) {
        memmove (*base + (*position + 1), 
                 *base + (*position),
                 (*count - *position) * elem_size);
    }

    memcpy (*base + (char) *position * elem_size, elem, elem_size);
    *count+=1;
}

/* 0 - dma is not supported, scsi or regular file */
/* 1 - xt drive                                   */
/* 2 - ide drive */
static void get_dma_support(dma_info_t *dma_info){
    if (S_ISREG(dma_info->st.st_mode))
	dma_info->st.st_rdev = dma_info->st.st_dev;

    if (IDE_DISK_MAJOR(major(dma_info->st.st_rdev))) {
        dma_info->support_type = 2;
	return;
    }
    
#ifdef XT_DISK_MAJOR
    if (major(dma_info->st.st_rdev) == XT_DISK_MAJOR) {
	dma_info->support_type = 1;
	return;
    }
#endif    
    dma_info->support_type = 0;
}

/* 
 * Return values: 
 * 0 - ok;
 * 1 - preparation cannot be done 
 * -1 - preparation failed
 */

int prepare_dma_check(dma_info_t *dma_info) {
    DIR *dir;
    struct dirent *dirent;
    struct stat st;
    dev_t rdev;
    int rem;
    char buf[256];

#ifndef HDIO_GET_DMA
        return -1;
#endif
	
    if (fstat(dma_info->fd, &dma_info->st))
	die("stat on device failed\n");
   
    get_dma_support(dma_info);
   
    /* dma should be supported */
    if (dma_info->support_type == 0)
	return 1;
    
    if (dma_info->support_type == 2) {
	rdev = dma_info->st.st_rdev;

	if ((rem = (minor(rdev) % 64)) != 0) {
	    rdev -= rem;
	    if(!(dir = opendir("/dev/"))) {
		dma_info->support_type = 1;
		return 0;
	    }
	    
	    while ((dirent = readdir(dir)) != NULL) {
		if (strncmp(dirent->d_name, ".", 1) == 0 || strncmp(dirent->d_name, "..", 2) == 0)
		    continue;
		memset(buf, 0, 256);
		strncat(buf, "/dev/", 5);
		strncat(buf, dirent->d_name, strlen(dirent->d_name));
		
		if (stat(buf, &st))
		    break;
		
		if (S_ISBLK(st.st_mode) && st.st_rdev == rdev) 
		{
		    dma_info->st = st;
		    dma_info->fd = open(buf, O_RDONLY
#if defined(O_LARGEFILE)
					| O_LARGEFILE
#endif
					);
		    closedir(dir);
		    return 0;
		}
	    }
	    closedir(dir);
	    dma_info->support_type = 1;
	    return 1;
	}
    }
    
    return 0;
}

static int is_dma_on (int fd) {
#ifdef HDIO_GET_DMA    
    static long parm;
    if (ioctl(fd, HDIO_GET_DMA, &parm))
	return -1;
    else 
	return parm;
#endif
    return 0;
}


static __u64 dma_speed(int fd, int support_type) {
    static struct hd_driveid id;
    __u64 speed = 0;
            
    if (support_type != 2) 
	return 0;

#ifdef HDIO_OBSOLETE_IDENTITY
    if (!ioctl(fd, HDIO_GET_IDENTITY, &id) || 
	!ioctl(fd, HDIO_OBSOLETE_IDENTITY)) {
#else
    if (!ioctl(fd, HDIO_GET_IDENTITY, &id)) {
#endif
	speed |= (__u64)id.dma_1word &  ~(__u64)0xff;
	speed |= ((__u64)id.dma_mword & ~(__u64)0xff) << 16;
	speed |= ((__u64)id.dma_ultra & ~(__u64)0xff) << 32;
    } else if (errno == -ENOMSG)
	return -1;
    else 
	return -1;
    
    return speed;
}

int get_dma_info(dma_info_t *dma_info) {
    if ((dma_info->dma = is_dma_on(dma_info->fd)) == -1)
	return -1;
    if ((dma_info->speed = dma_speed(dma_info->fd, dma_info->support_type)) == (__u64)-1) 
	return -1;
    return 0;
}

void clean_after_dma_check(int fd, dma_info_t *dma_info) {
    signal(SIGALRM, SIG_IGN);
    if (dma_info->fd && fd != dma_info->fd)
	close(dma_info->fd);
}

/* Only le bitops operations are used. */

inline int misc_set_bit (unsigned long long nr, void * addr) {
    __u8 * p, mask;
    int retval;

    p = (__u8 *)addr;
    p += nr >> 3;
    mask = 1 << (nr & 0x7);
    /*cli();*/
    retval = (mask & *p) != 0;
    *p |= mask;
    /*sti();*/
    return retval;
}


inline int misc_clear_bit (unsigned long long nr, void * addr) {
    __u8 * p, mask;
    int retval;

    p = (__u8 *)addr;
    p += nr >> 3;
    mask = 1 << (nr & 0x7);
    /*cli();*/
    retval = (mask & *p) != 0;
    *p &= ~mask;
    /*sti();*/
    return retval;
}

inline int misc_test_bit(unsigned long long nr, const void * addr) {
    __u8 * p, mask;

    p = (__u8 *)addr;
    p += nr >> 3;
    mask = 1 << (nr & 0x7);
    return ((mask & *p) != 0);
}

inline unsigned long long misc_find_first_zero_bit (const void *vaddr, 
    unsigned long long size) 
{
    const __u8 *p = vaddr, *addr = vaddr;
    unsigned long long res;

    if (!size)
        return 0;

    size = (size >> 3) + ((size & 0x7) > 0);
    while (*p++ == 255) {
        if (--size == 0)
            return (unsigned long long)(p - addr) << 3;
    }

    --p;
    for (res = 0; res < 8; res++)
        if (!misc_test_bit (res, p))
            break;
    return res + (p - addr) * 8;
}


inline unsigned long long misc_find_next_zero_bit (const void *vaddr, 
    unsigned long long size, unsigned long long offset) 
{
    const __u8 *addr = vaddr;
    const __u8 *p = addr + (offset >> 3);
    int bit = offset & 7;
    unsigned long long res;

    if (offset >= size)
        return size;

    if (bit) {
        /* Look for zero in first char */
        for (res = bit; res < 8; res++)
            if (!misc_test_bit (res, p))
                return res + (p - addr) * 8;
        p++;
    }
    /* No zero yet, search remaining full bytes for a zero */
    res = misc_find_first_zero_bit (p, size - 8 * (p - addr));
    return res + (p - addr) * 8;
}

inline unsigned long long misc_find_first_set_bit (const void *vaddr, 
    unsigned long long size) 
{
    const __u8 *p = vaddr, *addr = vaddr;
    unsigned long long res;

    if (!size)
        return 0;

    size = (size >> 3) + ((size & 0x7) > 0);
    while (*p++ == 0) {
        if (--size == 0)
            return (unsigned long long)(p - addr) << 3;
    }

    --p;
    for (res = 0; res < 8; res++)
        if (misc_test_bit (res, p))
            break;

    return res + (p - addr) * 8;
}

inline unsigned long long misc_find_next_set_bit(const void *vaddr, 
    unsigned long long size, unsigned long long offset)
{
    const __u8 *addr = vaddr;
    const __u8 *p = addr + (offset >> 3);
    int bit = offset & 7;
    unsigned long long res;

    if (offset >= size)
        return size;

    if (bit) {
        /* Look for zero in first char */
        for (res = bit; res < 8; res++)
            if (misc_test_bit (res, p))
                return res + (p - addr) * 8;
        p++;
    }
    /* No set bit yet, search remaining full bytes for a 1 */
    res = misc_find_first_set_bit (p, size - 8 * (p - addr));
    return res + (p - addr) * 8;
}

int user_confirmed (FILE * fp, char * q, char * yes) {
    char * answer = 0;
    size_t n = 0;

    fprintf (fp, "%s", q);
    if (getline (&answer, &n, stdin) != (ssize_t)strlen (yes) || strcmp (yes, answer))
	return 0;

    return 1;
}