source: MondoRescue/branches/3.2/mindi-busybox/util-linux/volume_id/get_devname.c@ 3186

/* vi: set sw=4 ts=4: */
/*
 * Support functions for mounting devices by label/uuid
 *
 * Copyright (C) 2006 by Jason Schoon <floydpink@gmail.com>
 * Some portions cribbed from e2fsprogs, util-linux, dosfstools
 *
 * Licensed under GPLv2 or later, see file LICENSE in this source tree.
 */
#include <sys/mount.h> /* BLKGETSIZE64 */
#if !defined(BLKGETSIZE64)
# define BLKGETSIZE64 _IOR(0x12,114,size_t)
#endif
#include "volume_id_internal.h"

static struct uuidCache_s {
    struct uuidCache_s *next;
//  int major, minor;
    char *device;
    char *label;
    char *uc_uuid; /* prefix makes it easier to grep for */
} *uuidCache;

/* Returns !0 on error.
 * Otherwise, returns malloc'ed strings for label and uuid
 * (and they can't be NULL, although they can be "").
 * NB: closes fd. */
static int
get_label_uuid(int fd, char **label, char **uuid)
{
    int rv = 1;
    uint64_t size;
    struct volume_id *vid;

    /* fd is owned by vid now */
    vid = volume_id_open_node(fd);

    if (ioctl(/*vid->*/fd, BLKGETSIZE64, &size) != 0)
        size = 0;

    if (volume_id_probe_all(vid, /*0,*/ size) != 0)
        goto ret;

    if (vid->label[0] != '\0' || vid->uuid[0] != '\0') {
        *label = xstrndup(vid->label, sizeof(vid->label));
        *uuid  = xstrndup(vid->uuid, sizeof(vid->uuid));
        dbg("found label '%s', uuid '%s'", *label, *uuid);
        rv = 0;
    }
 ret:
    free_volume_id(vid); /* also closes fd */
    return rv;
}

/* NB: we take ownership of (malloc'ed) label and uuid */
static void
uuidcache_addentry(char *device, /*int major, int minor,*/ char *label, char *uuid)
{
    struct uuidCache_s *last;

    if (!uuidCache) {
        last = uuidCache = xzalloc(sizeof(*uuidCache));
    } else {
        for (last = uuidCache; last->next; last = last->next)
            continue;
        last->next = xzalloc(sizeof(*uuidCache));
        last = last->next;
    }
    /*last->next = NULL; - xzalloc did it*/
//  last->major = major;
//  last->minor = minor;
    last->device = device;
    last->label = label;
    last->uc_uuid = uuid;
}

/* If get_label_uuid() on device_name returns success,
 * add a cache entry for this device.
 * If device node does not exist, it will be temporarily created. */
static int FAST_FUNC
uuidcache_check_device(const char *device,
        struct stat *statbuf,
        void *userData UNUSED_PARAM,
        int depth UNUSED_PARAM)
{
    char *uuid = uuid; /* for compiler */
    char *label = label;
    int fd;

    /* note: this check rejects links to devices, among other nodes */
    if (!S_ISBLK(statbuf->st_mode))
        return TRUE;

    /* Users report that mucking with floppies (especially non-present
     * ones) is significant PITA. This is a horribly dirty hack,
     * but it is very useful in real world.
     * If this will ever need to be enabled, consider using O_NONBLOCK.
     */
    if (major(statbuf->st_rdev) == 2)
        return TRUE;

    fd = open(device, O_RDONLY);
    if (fd < 0)
        return TRUE;

    /* get_label_uuid() closes fd in all cases (success & failure) */
    if (get_label_uuid(fd, &label, &uuid) == 0) {
        /* uuidcache_addentry() takes ownership of all three params */
        uuidcache_addentry(xstrdup(device), /*ma, mi,*/ label, uuid);
    }
    return TRUE;
}

static void
uuidcache_init(void)
{
    if (uuidCache)
        return;

    /* We were scanning /proc/partitions
     * and /proc/sys/dev/cdrom/info here.
     * Missed volume managers. I see that "standard" blkid uses these:
     * /dev/mapper/control
     * /proc/devices
     * /proc/evms/volumes
     * /proc/lvm/VGs
     * This is unacceptably complex. Let's just scan /dev.
     * (Maybe add scanning of /sys/block/XXX/dev for devices
     * somehow not having their /dev/XXX entries created?) */

    recursive_action("/dev", ACTION_RECURSE,
        uuidcache_check_device, /* file_action */
        NULL, /* dir_action */
        NULL, /* userData */
        0 /* depth */);
}

#define UUID   1
#define VOL    2

#ifdef UNUSED
static char *
get_spec_by_x(int n, const char *t, int *majorPtr, int *minorPtr)
{
    struct uuidCache_s *uc;

    uuidcache_init();
    uc = uuidCache;

    while (uc) {
        switch (n) {
        case UUID:
            if (strcmp(t, uc->uc_uuid) == 0) {
                *majorPtr = uc->major;
                *minorPtr = uc->minor;
                return uc->device;
            }
            break;
        case VOL:
            if (strcmp(t, uc->label) == 0) {
                *majorPtr = uc->major;
                *minorPtr = uc->minor;
                return uc->device;
            }
            break;
        }
        uc = uc->next;
    }
    return NULL;
}

static unsigned char
fromhex(char c)
{
    if (isdigit(c))
        return (c - '0');
    return ((c|0x20) - 'a' + 10);
}

static char *
get_spec_by_uuid(const char *s, int *major, int *minor)
{
    unsigned char uuid[16];
    int i;

    if (strlen(s) != 36 || s[8] != '-' || s[13] != '-'
     || s[18] != '-' || s[23] != '-'
    ) {
        goto bad_uuid;
    }
    for (i = 0; i < 16; i++) {
        if (*s == '-')
            s++;
        if (!isxdigit(s[0]) || !isxdigit(s[1]))
            goto bad_uuid;
        uuid[i] = ((fromhex(s[0]) << 4) | fromhex(s[1]));
        s += 2;
    }
    return get_spec_by_x(UUID, (char *)uuid, major, minor);

 bad_uuid:
    fprintf(stderr, _("mount: bad UUID"));
    return 0;
}

static char *
get_spec_by_volume_label(const char *s, int *major, int *minor)
{
    return get_spec_by_x(VOL, s, major, minor);
}
#endif // UNUSED

/* Used by blkid */
void display_uuid_cache(void)
{
    struct uuidCache_s *u;

    uuidcache_init();
    u = uuidCache;
    while (u) {
        printf("%s:", u->device);
        if (u->label[0])
            printf(" LABEL=\"%s\"", u->label);
        if (u->uc_uuid[0])
            printf(" UUID=\"%s\"", u->uc_uuid);
        bb_putchar('\n');
        u = u->next;
    }
}

/* Used by mount and findfs */

char *get_devname_from_label(const char *spec)
{
    struct uuidCache_s *uc;

    uuidcache_init();
    uc = uuidCache;
    while (uc) {
        if (uc->label[0] && strcmp(spec, uc->label) == 0) {
            return xstrdup(uc->device);
        }
        uc = uc->next;
    }
    return NULL;
}

char *get_devname_from_uuid(const char *spec)
{
    struct uuidCache_s *uc;

    uuidcache_init();
    uc = uuidCache;
    while (uc) {
        /* case of hex numbers doesn't matter */
        if (strcasecmp(spec, uc->uc_uuid) == 0) {
            return xstrdup(uc->device);
        }
        uc = uc->next;
    }
    return NULL;
}

int resolve_mount_spec(char **fsname)
{
    char *tmp = *fsname;

    if (strncmp(*fsname, "UUID=", 5) == 0)
        tmp = get_devname_from_uuid(*fsname + 5);
    else if (strncmp(*fsname, "LABEL=", 6) == 0)
        tmp = get_devname_from_label(*fsname + 6);

    if (tmp == *fsname)
        return 0; /* no UUID= or LABEL= prefix found */

    if (tmp)
        *fsname = tmp;
    return 1;
}