source: mainline/uspace/lib/gpt/libgpt.c@ 6e8e4e19

/*
 * Copyright (c) 2011, 2012, 2013 Dominik Taborsky
 * All rights reserved.
 *
 * Redistribution and use in source and binary forms, with or without
 * modification, are permitted provided that the following conditions
 * are met:
 *
 * - Redistributions of source code must retain the above copyright
 *   notice, this list of conditions and the following disclaimer.
 * - Redistributions in binary form must reproduce the above copyright
 *   notice, this list of conditions and the following disclaimer in the
 *   documentation and/or other materials provided with the distribution.
 * - The name of the author may not be used to endorse or promote products
 *   derived from this software without specific prior written permission.
 *
 * THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR
 * IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
 * OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED.
 * IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT,
 * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT
 * NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
 * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
 * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
 * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF
 * THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
 */

/** @addtogroup libgpt
 * @{
 */
/** @file
 */

/* TODO:
 * This implementation only supports fixed size partition entries. Specification
 * requires otherwise, though. Use void * array and casting to achieve that.
 */

#include <ipc/bd.h>
#include <async.h>
#include <stdio.h>
#include <block.h>
#include <errno.h>
#include <stdlib.h>
#include <assert.h>
#include <byteorder.h>
#include <checksum.h>
#include <mem.h>

#include "libgpt.h"

static int load_and_check_header(service_id_t handle, aoff64_t addr, size_t b_size, gpt_header_t * header);
static gpt_partitions_t * alloc_part_array(uint32_t num);
static int extend_part_array(gpt_partitions_t * p);
static int reduce_part_array(gpt_partitions_t * p);
static long long nearest_larger_int(double a);
static int gpt_memcmp(const void * a, const void * b, size_t len);

/** Allocate memory for gpt header */
gpt_t * gpt_alloc_gpt_header(void)
{
        return malloc(sizeof(gpt_t));
}

/** Read GPT from specific device
 * @param       dev_handle      device to read GPT from
 *
 * @return                              GPT record on success, NULL on error
 */
gpt_t * gpt_read_gpt_header(service_id_t dev_handle)
{
        int rc;
        size_t b_size;
        
        rc = block_init(EXCHANGE_ATOMIC, dev_handle, 512);
        if (rc != EOK)
                return NULL;
        
        rc = block_get_bsize(dev_handle, &b_size);
        if (rc != EOK) {
                errno = rc;
                return NULL;
        }
        
        gpt_t * gpt = malloc(sizeof(gpt_t));
        if (gpt == NULL) {
                errno = ENOMEM;
                return NULL;
        }

        gpt->raw_data = malloc(b_size); // We might need only sizeof(gpt_header_t),
        if (gpt == NULL) {                              // but we should follow specs and have
                free(gpt);                                      // zeroes through all the rest of the block
                errno = ENOMEM;
                return NULL;
        }
        
        
        rc = load_and_check_header(dev_handle, GPT_HDR_BA, b_size, gpt->raw_data);
        if (rc == EBADCHECKSUM || rc == EINVAL) {
                aoff64_t n_blocks;
                rc = block_get_nblocks(dev_handle, &n_blocks);
                if (rc != EOK) {
                        errno = rc;
                        goto fail;
                }

                rc = load_and_check_header(dev_handle, n_blocks - 1, b_size, gpt->raw_data);
                if (rc == EBADCHECKSUM || rc == EINVAL) {
                        errno = rc;
                        goto fail;
                }
        }
        
        gpt->device = dev_handle;
        block_fini(dev_handle);
        return gpt;
        
fail:
        block_fini(dev_handle);
        gpt_free_gpt(gpt);
        return NULL;
}

/** Write GPT header to device
 * @param header                GPT header to be written
 * @param dev_handle    device handle to write the data to
 *
 * @return                              0 on success, libblock error code otherwise
 *
 * Note: Firstly write partitions (if changed), then gpt header.
 */
int gpt_write_gpt_header(gpt_t * gpt, service_id_t dev_handle)
{
        int rc;
        size_t b_size;

        gpt->raw_data->header_crc32 = 0;
        gpt->raw_data->header_crc32 = compute_crc32((uint8_t *) gpt->raw_data,
                                        uint32_t_le2host(gpt->raw_data->header_size));

        rc = block_init(EXCHANGE_ATOMIC, dev_handle, b_size);
        if (rc != EOK)
                return rc;

        rc = block_get_bsize(dev_handle, &b_size);
        if (rc != EOK)
                return rc;

        /* Write to main GPT header location */
        rc = block_write_direct(dev_handle, GPT_HDR_BA, GPT_HDR_BS, gpt->raw_data);
        if (rc != EOK)
                block_fini(dev_handle);
                return rc;

        aoff64_t n_blocks;
        rc = block_get_nblocks(dev_handle, &n_blocks);
        if (rc != EOK)
                return rc;

        /* Write to backup GPT header location */
        //FIXME: those idiots thought it would be cool to have these fields in reverse order...
        rc = block_write_direct(dev_handle, n_blocks - 1, GPT_HDR_BS, gpt->raw_data);
        block_fini(dev_handle);
        if (rc != EOK)
                return rc;

        return 0;
}

/** Alloc partition array */
gpt_partitions_t *      gpt_alloc_partitions()
{
        return alloc_part_array(128);
}

/** Parse partitions from GPT
 * @param gpt   GPT to be parsed
 *
 * @return              partition linked list pointer or NULL on error
 *                              error code is stored in errno
 */
gpt_partitions_t * gpt_read_partitions(gpt_t * gpt)
{
        int rc;
        unsigned int i;
        gpt_partitions_t * res;
        uint32_t fill = uint32_t_le2host(gpt->raw_data->fillries);
        uint32_t ent_size = uint32_t_le2host(gpt->raw_data->entry_size);
        uint64_t ent_lba = uint64_t_le2host(gpt->raw_data->entry_lba);

        res = alloc_part_array(fill);
        if (res == NULL) {
                //errno = ENOMEM; // already set in alloc_part_array()
                return NULL;
        }

        /* We can limit comm_size like this:
         *  - we don't need more bytes
         *  - the size of GPT partition entry can be different to 128 bytes */
        rc = block_init(EXCHANGE_SERIALIZE, gpt->device, sizeof(gpt_entry_t));
        if (rc != EOK) {
                gpt_free_partitions(res);
                errno = rc;
                return NULL;
        }

        size_t block_size;
        rc = block_get_bsize(gpt->device, &block_size);
        if (rc != EOK) {
                gpt_free_partitions(res);
                errno = rc;
                return NULL;
        }

        //size_t bufpos = 0;
        //size_t buflen = 0;
        aoff64_t pos = ent_lba * block_size;

        /* Now we read just sizeof(gpt_entry_t) bytes for each entry from the device.
         * Hopefully, this does not bypass cache (no mention in libblock.c),
         * and also allows us to have variable partition entry size (but we
         * will always read just sizeof(gpt_entry_t) bytes - hopefully they
         * don't break backward compatibility) */
        for (i = 0; i < fill; ++i) {
                //FIXME: this does bypass cache...
                rc = block_read_bytes_direct(gpt->device, pos, sizeof(gpt_entry_t), res->part_array + i);
                //FIXME: but seqread() is just too complex...
                //rc = block_seqread(gpt->device, &bufpos, &buflen, &pos, res->part_array[i], sizeof(gpt_entry_t));
                pos += ent_size;

                if (rc != EOK) {
                        gpt_free_partitions(res);
                        errno = rc;
                        return NULL;
                }
        }

        /* FIXME: so far my boasting about variable partition entry size
         * will not work. The CRC32 checksums will be different.
         * This can't be fixed easily - we'd have to run the checksum
         * on all of the partition entry array.
         */
        uint32_t crc = compute_crc32((uint8_t *) res->part_array, res->fill * sizeof(gpt_entry_t));

        if(uint32_t_le2host(gpt->raw_data->pe_array_crc32) != crc)
        {
                gpt_free_partitions(res);
                errno = EBADCHECKSUM;
                return NULL;
        }

        return res;
}

/** Write GPT and partitions to device
 * @param parts                 partition list to be written
 * @param header                GPT header belonging to the 'parts' partitions
 * @param dev_handle    device to write the data to
 *
 * @return                              returns EOK on succes, specific error code otherwise
 */
int gpt_write_partitions(gpt_partitions_t * parts, gpt_t * gpt, service_id_t dev_handle)
{
        int rc;
        size_t b_size;

        gpt->raw_data->pe_array_crc32 = compute_crc32((uint8_t *) parts->part_array, parts->fill * gpt->raw_data->entry_size);

        rc = block_init(EXCHANGE_ATOMIC, dev_handle, b_size);
        if (rc != EOK)
                return rc;

        rc = block_get_bsize(dev_handle, &b_size);
        if (rc != EOK)
                return rc;

        /* Write to main GPT partition array location */
        rc = block_write_direct(dev_handle, uint64_t_le2host(gpt->raw_data->entry_lba),
                        nearest_larger_int((uint64_t_le2host(gpt->raw_data->entry_size) * parts->fill) / b_size),
                        parts->part_array);
        if (rc != EOK)
                block_fini(dev_handle);
                return rc;

        aoff64_t n_blocks;
        rc = block_get_nblocks(dev_handle, &n_blocks);
        if (rc != EOK)
                return rc;

        /* Write to backup GPT partition array location */
        //rc = block_write_direct(dev_handle, n_blocks - 1, GPT_HDR_BS, header->raw_data);
        block_fini(dev_handle);
        if (rc != EOK)
                return rc;


        return gpt_write_gpt_header(gpt, dev_handle);
}

/** Alloc new partition
 *
 * @param parts         partition table to carry new partition
 *
 * @return                      returns pointer to the new partition or NULL on ENOMEM
 *
 * Note: use either gpt_alloc_partition or gpt_add_partition. The first
 * returns a pointer to write your data to, the second copies the data
 * (and does not free the memory).
 */
gpt_part_t * gpt_alloc_partition(gpt_partitions_t * parts)
{
        if (parts->fill == parts->arr_size) {
                if (extend_part_array(parts) == -1)
                        return NULL;
        }

        return parts->part_array + parts->fill++;
}

/** Copy partition into partition array
 *
 * @param parts                 target partition array
 * @param partition             source partition to copy
 *
 * @return                              -1 on error, 0 otherwise
 *
 * Note: use either gpt_alloc_partition or gpt_add_partition. The first
 * returns a pointer to write your data to, the second copies the data
 * (and does not free the memory).
 */
int gpt_add_partition(gpt_partitions_t * parts, gpt_part_t * partition)
{
        if (parts->fill == parts->arr_size) {
                if (extend_part_array(parts) == -1)
                        return ENOMEM;
        }
        extend_part_array(parts);
        return EOK;;
}

/** Remove partition from array
 *
 * @param idx           index of the partition to remove
 *
 * @return                      -1 on error, 0 otherwise
 *
 * Note: even if it fails, the partition still gets removed. Only
 * reducing the array failed.
 */
int gpt_remove_partition(gpt_partitions_t * parts, size_t idx)
{
        if (idx != parts->fill - 1) {
                memcpy(parts->part_array + idx, parts->part_array + parts->fill - 1, sizeof(gpt_entry_t));
                parts->fill -= 1;
        }

        if (parts->fill < (parts->arr_size / 2) - GPT_IGNORE_FILL_NUM) {
                if (reduce_part_array(parts) == -1)
                        return -1;
        }

        return 0;
}

/** free() GPT header including gpt->header_lba */
void gpt_free_gpt(gpt_t * gpt)
{
        free(gpt->raw_data);
        free(gpt);
}

/** Free partition list
 *
 * @param parts         partition list to be freed
 */
void gpt_free_partitions(gpt_partitions_t * parts)
{
        free(parts->part_array);
        free(parts);
}

/** Get partition type by linear search
 * (hopefully this doesn't get slow)
 */
size_t gpt_get_part_type(gpt_part_t * p)
{
        size_t i;
        for (i = 0; gpt_ptypes[i].guid != NULL; i++) {
                if (gpt_memcmp(p->part_type, gpt_ptypes[i].guid, 16) == 0) {
                        break;
                }
        }
        return i;
}

/** Set partition type
 * @param p                     partition to be set
 * @param type          partition type to set
 *                                      - see our fine selection at gpt_ptypes to choose from
 */
void gpt_set_part_type(gpt_part_t * p, size_t type)
{
        /* Beware: first 3 blocks are byteswapped! */
        p->part_type[3] = gpt_ptypes[type].guid[0];
        p->part_type[2] = gpt_ptypes[type].guid[1];
        p->part_type[1] = gpt_ptypes[type].guid[2];
        p->part_type[0] = gpt_ptypes[type].guid[3];

        p->part_type[5] = gpt_ptypes[type].guid[4];
        p->part_type[4] = gpt_ptypes[type].guid[5];

        p->part_type[7] = gpt_ptypes[type].guid[6];
        p->part_type[6] = gpt_ptypes[type].guid[7];

        p->part_type[8] = gpt_ptypes[type].guid[8];
        p->part_type[9] = gpt_ptypes[type].guid[9];
        p->part_type[10] = gpt_ptypes[type].guid[10];
        p->part_type[11] = gpt_ptypes[type].guid[11];
        p->part_type[12] = gpt_ptypes[type].guid[12];
        p->part_type[13] = gpt_ptypes[type].guid[13];
        p->part_type[14] = gpt_ptypes[type].guid[14];
        p->part_type[15] = gpt_ptypes[type].guid[15];
}

/** Get partition starting LBA */
uint64_t gpt_get_start_lba(gpt_part_t * p)
{
        return uint64_t_le2host(p->start_lba);
}

/** Set partition starting LBA */
void gpt_set_start_lba(gpt_part_t * p, uint64_t start)
{
        p->start_lba = host2uint64_t_le(start);
}

/** Get partition ending LBA */
uint64_t gpt_get_end_lba(gpt_part_t * p)
{
        return uint64_t_le2host(p->end_lba);
}

/** Set partition ending LBA */
void gpt_set_end_lba(gpt_part_t * p, uint64_t end)
{
        p->end_lba = host2uint64_t_le(end);
}


unsigned char * gpt_get_part_name(gpt_part_t * p)
{
        return p->part_name;
}

/** Copy partition name */
void gpt_set_part_name(gpt_part_t * p, char * name[], size_t length)
{
        if (length >= 72)
                length = 71;

        memcpy(p->part_name, name, length);
        p->part_name[length] = '\0';
}

/** Get partition attribute */
bool gpt_get_flag(gpt_part_t * p, GPT_ATTR flag)
{
        return (p->attributes & (((uint64_t) 1) << flag)) ? 1 : 0;
}

/** Set partition attribute */
void gpt_set_flag(gpt_part_t * p, GPT_ATTR flag, bool value)
{
        uint64_t attr = p->attributes;

        if (value)
                attr = attr | (((uint64_t) 1) << flag);
        else
                attr = attr ^ (attr & (((uint64_t) 1) << flag));

        p->attributes = attr;
}

// Internal functions follow //

static int load_and_check_header(service_id_t dev_handle, aoff64_t addr, size_t b_size, gpt_header_t * header)
{
        int rc;

        rc = block_read_direct(dev_handle, addr, GPT_HDR_BS, header);
        if (rc != EOK)
                return rc;

        unsigned int i;
        /* Check the EFI signature */
        for (i = 0; i < 8; ++i) {
                if (header->efi_signature[i] != efi_signature[i])
                        return EINVAL;
        }

        /* Check the CRC32 of the header */
        uint32_t crc = header->header_crc32;
        header->header_crc32 = 0;
        if (crc != compute_crc32((uint8_t *) header, header->header_size))
                return EBADCHECKSUM;
        else
                header->header_crc32 = crc;

        /* Check for zeroes in the rest of the block */
        for (i = sizeof(gpt_header_t); i < b_size; ++i) {
                if (((uint8_t *) header)[i] != 0)
                        return EINVAL;
        }

        return EOK;
}

static gpt_partitions_t * alloc_part_array(uint32_t num)
{
        gpt_partitions_t * res = malloc(sizeof(gpt_partitions_t));
        if (res == NULL) {
                errno = ENOMEM;
                return NULL;
        }

        uint32_t size = num > GPT_BASE_PART_NUM ? num : GPT_BASE_PART_NUM;
        res->part_array = malloc(size * sizeof(gpt_entry_t));
        if (res->part_array == NULL) {
                free(res);
                errno = ENOMEM;
                return NULL;
        }

        res->fill = num;
        res->arr_size = size;

        return res;
}

static int extend_part_array(gpt_partitions_t * p)
{
        unsigned int nsize = p->arr_size * 2;
        gpt_entry_t * tmp = malloc(nsize * sizeof(gpt_entry_t));
        if(tmp == NULL) {
                errno = ENOMEM;
                return -1;
        }

        memcpy(tmp, p->part_array, p->fill);
        free(p->part_array);
        p->part_array = tmp;
        p->arr_size = nsize;

        return 0;
}

static int reduce_part_array(gpt_partitions_t * p)
{
        if(p->arr_size > GPT_MIN_PART_NUM) {
                unsigned int nsize = p->arr_size / 2;
                gpt_entry_t * tmp = malloc(nsize * sizeof(gpt_entry_t));
                if(tmp == NULL) {
                        errno = ENOMEM;
                        return -1;
                }

                memcpy(tmp, p->part_array, p->fill < nsize ? p->fill  : nsize);
                free(p->part_array);
                p->part_array = tmp;
                p->arr_size = nsize;
        }

        return 0;
}

//FIXME: replace this with a library call, if it exists
static long long nearest_larger_int(double a)
{
        if ((long long) a == a) {
                return (long long) a;
        }

        return ((long long) a) + 1;
}

static int gpt_memcmp(const void * a, const void * b, size_t len)
{
        size_t i;
        int diff;
        const unsigned char * x = a;
        const unsigned char * y = b;

        for (i = 0; i < len; i++) {
                diff = (int)*(x++) - (int)*(y++);
                if (diff != 0) {
                        return diff;
                }
        }
        return 0;
}