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

/*
 * volume_id - reads filesystem label and uuid
 *
 * Copyright (C) 2005 Kay Sievers <kay.sievers@vrfy.org>
 *
 *  This library is free software; you can redistribute it and/or
 *  modify it under the terms of the GNU Lesser General Public
 *  License as published by the Free Software Foundation; either
 *  version 2.1 of the License, or (at your option) any later version.
 *
 *  This library is distributed in the hope that it will be useful,
 *  but WITHOUT ANY WARRANTY; without even the implied warranty of
 *  MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
 *  Lesser General Public License for more details.
 *
 *  You should have received a copy of the GNU Lesser General Public
 *  License along with this library; if not, write to the Free Software
 *  Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA
 */

#include "volume_id_internal.h"

void volume_id_set_unicode16(char *str, size_t len, const uint8_t *buf, enum endian endianess, size_t count)
{
    unsigned i, j;
    unsigned c;

    j = 0;
    for (i = 0; i + 2 <= count; i += 2) {
        if (endianess == LE)
            c = (buf[i+1] << 8) | buf[i];
        else
            c = (buf[i] << 8) | buf[i+1];
        if (c == 0)
            break;
        if (j+1 >= len)
            break;
        if (c < 0x80) {
            /* 0xxxxxxx */
        } else {
            uint8_t topbits = 0xc0;
            if (j+2 >= len)
                break;
            if (c < 0x800) {
                /* 110yyyxx 10xxxxxx */
            } else {
                if (j+3 >= len)
                    break;
                /* 1110yyyy 10yyyyxx 10xxxxxx */
                str[j++] = (uint8_t) (0xe0 | (c >> 12));
                topbits = 0x80;
            }
            str[j++] = (uint8_t) (topbits | ((c >> 6) & 0x3f));
            c = 0x80 | (c & 0x3f);
        }
        str[j++] = (uint8_t) c;
    }
    str[j] = '\0';
}

#ifdef UNUSED
static const char *usage_to_string(enum volume_id_usage usage_id)
{
    switch (usage_id) {
    case VOLUME_ID_FILESYSTEM:
        return "filesystem";
    case VOLUME_ID_PARTITIONTABLE:
        return "partitiontable";
    case VOLUME_ID_OTHER:
        return "other";
    case VOLUME_ID_RAID:
        return "raid";
    case VOLUME_ID_DISKLABEL:
        return "disklabel";
    case VOLUME_ID_CRYPTO:
        return "crypto";
    case VOLUME_ID_UNPROBED:
        return "unprobed";
    case VOLUME_ID_UNUSED:
        return "unused";
    }
    return NULL;
}

void volume_id_set_usage_part(struct volume_id_partition *part, enum volume_id_usage usage_id)
{
    part->usage_id = usage_id;
    part->usage = usage_to_string(usage_id);
}

void volume_id_set_usage(struct volume_id *id, enum volume_id_usage usage_id)
{
    id->usage_id = usage_id;
    id->usage = usage_to_string(usage_id);
}

void volume_id_set_label_raw(struct volume_id *id, const uint8_t *buf, size_t count)
{
    memcpy(id->label_raw, buf, count);
    id->label_raw_len = count;
}
#endif

#ifdef NOT_NEEDED
static size_t strnlen(const char *s, size_t maxlen)
{
    size_t i;
    if (!maxlen) return 0;
    if (!s) return 0;
    for (i = 0; *s && i < maxlen; ++s) ++i;
    return i;
}
#endif

void volume_id_set_label_string(struct volume_id *id, const uint8_t *buf, size_t count)
{
    unsigned i;

    memcpy(id->label, buf, count);

    /* remove trailing whitespace */
    i = strnlen(id->label, count);
    while (i--) {
        if (!isspace(id->label[i]))
            break;
    }
    id->label[i+1] = '\0';
}

void volume_id_set_label_unicode16(struct volume_id *id, const uint8_t *buf, enum endian endianess, size_t count)
{
    volume_id_set_unicode16(id->label, sizeof(id->label), buf, endianess, count);
}

void volume_id_set_uuid(struct volume_id *id, const uint8_t *buf, enum uuid_format format)
{
    unsigned i;
    unsigned count = (format == UUID_DCE_STRING ? VOLUME_ID_UUID_SIZE : 4 << format);

//  memcpy(id->uuid_raw, buf, count);
//  id->uuid_raw_len = count;

    /* if set, create string in the same format, the native platform uses */
    for (i = 0; i < count; i++)
        if (buf[i] != 0)
            goto set;
    return; /* all bytes are zero, leave it empty ("") */

set:
    switch (format) {
    case UUID_DOS:
        sprintf(id->uuid, "%02X%02X-%02X%02X",
            buf[3], buf[2], buf[1], buf[0]);
        break;
    case UUID_NTFS:
        sprintf(id->uuid, "%02X%02X%02X%02X%02X%02X%02X%02X",
            buf[7], buf[6], buf[5], buf[4],
            buf[3], buf[2], buf[1], buf[0]);
        break;
    case UUID_DCE:
        sprintf(id->uuid,
            "%02x%02x%02x%02x-%02x%02x-%02x%02x-%02x%02x-%02x%02x%02x%02x%02x%02x",
            buf[0], buf[1], buf[2], buf[3],
            buf[4], buf[5],
            buf[6], buf[7],
            buf[8], buf[9],
            buf[10], buf[11], buf[12], buf[13], buf[14], buf[15]);
        break;
    case UUID_DCE_STRING:
        memcpy(id->uuid, buf, count);
        id->uuid[count] = '\0';
        break;
    }
}

/* Do not use xlseek here. With it, single corrupted filesystem
 * may result in attempt to seek past device -> exit.
 * It's better to ignore such fs and continue.  */
void *volume_id_get_buffer(struct volume_id *id, uint64_t off, size_t len)
{
    uint8_t *dst;
    unsigned small_off;
    ssize_t read_len;

    dbg("get buffer off 0x%llx(%llu), len 0x%zx",
        (unsigned long long) off, (unsigned long long) off, len);

    /* check if requested area fits in superblock buffer */
    if (off + len <= SB_BUFFER_SIZE
     /* && off <= SB_BUFFER_SIZE - want this paranoid overflow check? */
    ) {
        if (id->sbbuf == NULL) {
            id->sbbuf = xmalloc(SB_BUFFER_SIZE);
        }
        small_off = off;
        dst = id->sbbuf;

        /* check if we need to read */
        len += off;
        if (len <= id->sbbuf_len)
            goto ret; /* we already have it */

        dbg("read sbbuf len:0x%x", (unsigned) len);
        id->sbbuf_len = len;
        off = 0;
        goto do_read;
    }

    if (len > SEEK_BUFFER_SIZE) {
        dbg("seek buffer too small %d", SEEK_BUFFER_SIZE);
        return NULL;
    }
    dst = id->seekbuf;

    /* check if we need to read */
    if ((off >= id->seekbuf_off)
     && ((off + len) <= (id->seekbuf_off + id->seekbuf_len))
    ) {
        small_off = off - id->seekbuf_off; /* can't overflow */
        goto ret; /* we already have it */
    }

    id->seekbuf_off = off;
    id->seekbuf_len = len;
    id->seekbuf = xrealloc(id->seekbuf, len);
    small_off = 0;
    dst = id->seekbuf;
    dbg("read seekbuf off:0x%llx len:0x%zx",
                (unsigned long long) off, len);
 do_read:
    if (lseek(id->fd, off, SEEK_SET) != off) {
        dbg("seek(0x%llx) failed", (unsigned long long) off);
        goto err;
    }
    read_len = full_read(id->fd, dst, len);
    if (read_len != len) {
        dbg("requested 0x%x bytes, got 0x%x bytes",
                (unsigned) len, (unsigned) read_len);
 err:
        /* No filesystem can be this tiny. It's most likely
         * non-associated loop device, empty drive and so on.
         * Flag it, making it possible to short circuit future
         * accesses. Rationale:
         * users complained of slow blkid due to empty floppy drives.
         */
        if (off < 64*1024)
            id->error = 1;
        /* id->seekbuf_len or id->sbbuf_len is wrong now! Fixing. */
        volume_id_free_buffer(id);
        return NULL;
    }
 ret:
    return dst + small_off;
}

void volume_id_free_buffer(struct volume_id *id)
{
    free(id->sbbuf);
    id->sbbuf = NULL;
    id->sbbuf_len = 0;
    free(id->seekbuf);
    id->seekbuf = NULL;
    id->seekbuf_len = 0;
    id->seekbuf_off = 0; /* paranoia */
}