libdiskconfig/config_mbr.c - android-core - Git at Google

 /* libs/diskconfig/diskconfig.c
  *
  * Copyright 2008, The Android Open Source Project
  *
  * Licensed under the Apache License, Version 2.0 (the "License");
  * you may not use this file except in compliance with the License.
  * You may obtain a copy of the License at
  *
  *     http://www.apache.org/licenses/LICENSE-2.0
  *
  * Unless required by applicable law or agreed to in writing, software
  * distributed under the License is distributed on an "AS IS" BASIS,
  * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
  * See the License for the specific language governing permissions and
  * limitations under the License.
  */

 #define LOG_TAG "config_mbr"
 #include <stdint.h>
 #include <stdlib.h>
 #include <string.h>
 #include <stdio.h>

 #include <cutils/log.h>

 #include <diskconfig/diskconfig.h>


 /* start and len are in LBA units */
 static void
 cfg_pentry(struct pc_partition *pentry, uint8_t status, uint8_t type,
            uint32_t start, uint32_t len)
 {
     if (len > 0) {
         /* seems that somes BIOSens can get wedged on boot while verifying
          * the mbr if these are 0 */
         memset(&pentry->start, 0xff, sizeof(struct chs));
         memset(&pentry->end, 0xff, sizeof(struct chs));
     } else {
         /* zero out the c/h/s entries.. they are not used */
         memset(&pentry->start, 0, sizeof(struct chs));
         memset(&pentry->end, 0, sizeof(struct chs));
     }

     pentry->status = status;
     pentry->type = type;
     pentry->start_lba = start;
     pentry->len_lba = len;

     ALOGI("Configuring pentry. status=0x%x type=0x%x start_lba=%u len_lba=%u",
          pentry->status, pentry->type, pentry->start_lba, pentry->len_lba);
 }


 static inline uint32_t
 kb_to_lba(uint32_t len_kb, uint32_t sect_size)
 {
     uint64_t lba;

     lba = (uint64_t)len_kb * 1024;
     /* bump it up to the next LBA boundary just in case  */
     lba = (lba + (uint64_t)sect_size - 1) & ~((uint64_t)sect_size - 1);
     lba /= (uint64_t)sect_size;
     if (lba >= 0xffffffffULL)
         ALOGE("Error converting kb -> lba. 32bit overflow, expect weirdness");
     return (uint32_t)(lba & 0xffffffffULL);
 }


 static struct write_list *
 mk_pri_pentry(struct disk_info *dinfo, struct part_info *pinfo, int pnum,
               uint32_t *lba)
 {
     struct write_list *item;
     struct pc_partition *pentry;

     if (pnum >= PC_NUM_BOOT_RECORD_PARTS) {
         ALOGE("Maximum number of primary partition exceeded.");
         return NULL;
     }

     if (!(item = alloc_wl(sizeof(struct pc_partition)))) {
         ALOGE("Unable to allocate memory for partition entry.");
         return NULL;
     }

     {
         /* DO NOT DEREFERENCE */
         struct pc_boot_record *mbr = (void *)PC_MBR_DISK_OFFSET;
         /* grab the offset in mbr where to write this partition entry. */
         item->offset = (loff_t)((uintptr_t)((uint8_t *)(&mbr->ptable[pnum])));
     }

     pentry = (struct pc_partition *) &item->data;

     /* need a standard primary partition entry */
     if (pinfo) {
         /* need this to be 64 bit in case len_kb is large */
         uint64_t len_lba;

         if (pinfo->len_kb != (uint32_t)-1) {
             /* bump it up to the next LBA boundary just in case */
             len_lba = ((uint64_t)pinfo->len_kb * 1024);
             len_lba += ((uint64_t)dinfo->sect_size - 1);
             len_lba &= ~((uint64_t)dinfo->sect_size - 1);
             len_lba /= (uint64_t)dinfo->sect_size;
         } else {
             /* make it fill the rest of disk */
             len_lba = dinfo->num_lba - *lba;
         }

         cfg_pentry(pentry, ((pinfo->flags & PART_ACTIVE_FLAG) ?
                             PC_PART_ACTIVE : PC_PART_NORMAL),
                    pinfo->type, *lba, (uint32_t)len_lba);

         pinfo->start_lba = *lba;
         *lba += (uint32_t)len_lba;
     } else {
         /* this should be made an extended partition, and should take
          * up the rest of the disk as a primary partition */
         cfg_pentry(pentry, PC_PART_NORMAL, PC_PART_TYPE_EXTENDED,
                    *lba, dinfo->num_lba - *lba);

         /* note that we do not update the *lba because we now have to
          * create a chain of extended partition tables, and first one is at
          * *lba */
     }

     return item;
 }


 /* This function configures an extended boot record at the beginning of an
  * extended partition. This creates a logical partition and a pointer to
  * the next EBR.
  *
  * ext_lba == The start of the toplevel extended partition (pointed to by the
  * entry in the MBR).
  */
 static struct write_list *
 mk_ext_pentry(struct disk_info *dinfo, struct part_info *pinfo, uint32_t *lba,
               uint32_t ext_lba, struct part_info *pnext)
 {
     struct write_list *item;
     struct pc_boot_record *ebr;
     uint32_t len; /* in lba units */

     if (!(item = alloc_wl(sizeof(struct pc_boot_record)))) {
         ALOGE("Unable to allocate memory for EBR.");
         return NULL;
     }

     /* we are going to write the ebr at the current LBA, and then bump the
      * lba counter since that is where the logical data partition will start */
     item->offset = ((loff_t)(*lba)) * dinfo->sect_size;
     (*lba)++;

     ebr = (struct pc_boot_record *) &item->data;
     memset(ebr, 0, sizeof(struct pc_boot_record));
     ebr->mbr_sig = PC_BIOS_BOOT_SIG;

     if (pinfo->len_kb != (uint32_t)-1)
         len = kb_to_lba(pinfo->len_kb, dinfo->sect_size);
     else {
         if (pnext) {
             ALOGE("Only the last partition can be specified to fill the disk "
                  "(name = '%s')", pinfo->name);
             goto fail;
         }
         len = dinfo->num_lba - *lba;
         /* update the pinfo structure to reflect the new size, for
          * bookkeeping */
         pinfo->len_kb =
             (uint32_t)(((uint64_t)len * (uint64_t)dinfo->sect_size) /
                        ((uint64_t)1024));
     }

     cfg_pentry(&ebr->ptable[PC_EBR_LOGICAL_PART], PC_PART_NORMAL,
                pinfo->type, 1, len);

     pinfo->start_lba = *lba;
     *lba += len;

     /* If this is not the last partition, we have to create a link to the
      * next extended partition.
      *
      * Otherwise, there's nothing to do since the "pointer entry" is
      * already zero-filled.
      */
     if (pnext) {
         /* The start lba for next partition is an offset from the beginning
          * of the top-level extended partition */
         uint32_t next_start_lba = *lba - ext_lba;
         uint32_t next_len_lba;
         if (pnext->len_kb != (uint32_t)-1)
             next_len_lba = 1 + kb_to_lba(pnext->len_kb, dinfo->sect_size);
         else
             next_len_lba = dinfo->num_lba - *lba;
         cfg_pentry(&ebr->ptable[PC_EBR_NEXT_PTR_PART], PC_PART_NORMAL,
                    PC_PART_TYPE_EXTENDED, next_start_lba, next_len_lba);
     }

     return item;

 fail:
     free_wl(item);
     return NULL;
 }


 static struct write_list *
 mk_mbr_sig()
 {
     struct write_list *item;
     if (!(item = alloc_wl(sizeof(uint16_t)))) {
         ALOGE("Unable to allocate memory for MBR signature.");
         return NULL;
     }

     {
         /* DO NOT DEREFERENCE */
         struct pc_boot_record *mbr = (void *)PC_MBR_DISK_OFFSET;
         /* grab the offset in mbr where to write mbr signature. */
         item->offset = (loff_t)((uintptr_t)((uint8_t *)(&mbr->mbr_sig)));
     }

     *((uint16_t*)item->data) = PC_BIOS_BOOT_SIG;
     return item;
 }

 struct write_list *
 config_mbr(struct disk_info *dinfo)
 {
     struct part_info *pinfo;
     uint32_t cur_lba = dinfo->skip_lba;
     uint32_t ext_lba = 0;
     struct write_list *wr_list = NULL;
     struct write_list *temp_wr = NULL;
     int cnt = 0;
     int extended = 0;

     if (!dinfo->part_lst)
         return NULL;

     for (cnt = 0; cnt < dinfo->num_parts; ++cnt) {
         pinfo = &dinfo->part_lst[cnt];

         /* Should we create an extedned partition? */
         if (cnt == (PC_NUM_BOOT_RECORD_PARTS - 1)) {
             if (cnt + 1 < dinfo->num_parts) {
                 extended = 1;
                 ext_lba = cur_lba;
                 if ((temp_wr = mk_pri_pentry(dinfo, NULL, cnt, &cur_lba)))
                     wlist_add(&wr_list, temp_wr);
                 else {
                     ALOGE("Cannot create primary extended partition.");
                     goto fail;
                 }
             }
         }

         /* if extended, need 1 lba for ebr */
         if ((cur_lba + extended) >= dinfo->num_lba)
             goto nospace;
         else if (pinfo->len_kb != (uint32_t)-1) {
             uint32_t sz_lba = (pinfo->len_kb / dinfo->sect_size) * 1024;
             if ((cur_lba + sz_lba + extended) > dinfo->num_lba)
                 goto nospace;
         }

         if (!extended)
             temp_wr = mk_pri_pentry(dinfo, pinfo, cnt, &cur_lba);
         else {
             struct part_info *pnext;
             pnext = cnt + 1 < dinfo->num_parts ? &dinfo->part_lst[cnt+1] : NULL;
             temp_wr = mk_ext_pentry(dinfo, pinfo, &cur_lba, ext_lba, pnext);
         }

         if (temp_wr)
             wlist_add(&wr_list, temp_wr);
         else {
             ALOGE("Cannot create partition %d (%s).", cnt, pinfo->name);
             goto fail;
         }
     }

     /* fill in the rest of the MBR with empty parts (if needed). */
     for (; cnt < PC_NUM_BOOT_RECORD_PARTS; ++cnt) {
         struct part_info blank;
         cur_lba = 0;
         memset(&blank, 0, sizeof(struct part_info));
         if (!(temp_wr = mk_pri_pentry(dinfo, &blank, cnt, &cur_lba))) {
             ALOGE("Cannot create blank partition %d.", cnt);
             goto fail;
         }
         wlist_add(&wr_list, temp_wr);
     }

     if ((temp_wr = mk_mbr_sig()))
         wlist_add(&wr_list, temp_wr);
     else {
         ALOGE("Cannot set MBR signature");
         goto fail;
     }

     return wr_list;

 nospace:
     ALOGE("Not enough space to add parttion '%s'.", pinfo->name);

 fail:
     wlist_free(wr_list);
     return NULL;
 }


 /* Returns the device path of the partition referred to by 'name'
  * Must be freed by the caller.
  */
 char *
 find_mbr_part(struct disk_info *dinfo, const char *name)
 {
     struct part_info *plist = dinfo->part_lst;
     int num = 0;
     char *dev_name = NULL;
     int has_extended = (dinfo->num_parts > PC_NUM_BOOT_RECORD_PARTS);

     for(num = 1; num <= dinfo->num_parts; ++num) {
         if (!strcmp(plist[num-1].name, name))
             break;
     }

     if (num > dinfo->num_parts)
         return NULL;

     if (has_extended && (num >= PC_NUM_BOOT_RECORD_PARTS))
         num++;

     if (!(dev_name = malloc(MAX_NAME_LEN))) {
         ALOGE("Cannot allocate memory.");
         return NULL;
     }

     num = snprintf(dev_name, MAX_NAME_LEN, "%s%d", dinfo->device, num);
     if (num >= MAX_NAME_LEN) {
         ALOGE("Device name is too long?!");
         free(dev_name);
         return NULL;
     }

     return dev_name;
 }
	/* libs/diskconfig/diskconfig.c
	*
	* Copyright 2008, The Android Open Source Project
	*
	* Licensed under the Apache License, Version 2.0 (the "License");
	* you may not use this file except in compliance with the License.
	* You may obtain a copy of the License at
	*
	* http://www.apache.org/licenses/LICENSE-2.0
	*
	* Unless required by applicable law or agreed to in writing, software
	* distributed under the License is distributed on an "AS IS" BASIS,
	* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
	* See the License for the specific language governing permissions and
	* limitations under the License.
	*/

	#define LOG_TAG "config_mbr"
	#include <stdint.h>
	#include <stdlib.h>
	#include <string.h>
	#include <stdio.h>

	#include <cutils/log.h>

	#include <diskconfig/diskconfig.h>


	/* start and len are in LBA units */
	static void
	cfg_pentry(struct pc_partition *pentry, uint8_t status, uint8_t type,
	uint32_t start, uint32_t len)
	{
	if (len > 0) {
	/* seems that somes BIOSens can get wedged on boot while verifying
	* the mbr if these are 0 */
	memset(&pentry->start, 0xff, sizeof(struct chs));
	memset(&pentry->end, 0xff, sizeof(struct chs));
	} else {
	/* zero out the c/h/s entries.. they are not used */
	memset(&pentry->start, 0, sizeof(struct chs));
	memset(&pentry->end, 0, sizeof(struct chs));
	}

	pentry->status = status;
	pentry->type = type;
	pentry->start_lba = start;
	pentry->len_lba = len;

	ALOGI("Configuring pentry. status=0x%x type=0x%x start_lba=%u len_lba=%u",
	pentry->status, pentry->type, pentry->start_lba, pentry->len_lba);
	}


	static inline uint32_t
	kb_to_lba(uint32_t len_kb, uint32_t sect_size)
	{
	uint64_t lba;

	lba = (uint64_t)len_kb * 1024;
	/* bump it up to the next LBA boundary just in case */
	lba = (lba + (uint64_t)sect_size - 1) & ~((uint64_t)sect_size - 1);
	lba /= (uint64_t)sect_size;
	if (lba >= 0xffffffffULL)
	ALOGE("Error converting kb -> lba. 32bit overflow, expect weirdness");
	return (uint32_t)(lba & 0xffffffffULL);
	}


	static struct write_list *
	mk_pri_pentry(struct disk_info dinfo, struct part_info pinfo, int pnum,
	uint32_t *lba)
	{
	struct write_list *item;
	struct pc_partition *pentry;

	if (pnum >= PC_NUM_BOOT_RECORD_PARTS) {
	ALOGE("Maximum number of primary partition exceeded.");
	return NULL;
	}

	if (!(item = alloc_wl(sizeof(struct pc_partition)))) {
	ALOGE("Unable to allocate memory for partition entry.");
	return NULL;
	}

	{
	/* DO NOT DEREFERENCE */
	struct pc_boot_record mbr = (void )PC_MBR_DISK_OFFSET;
	/* grab the offset in mbr where to write this partition entry. */
	item->offset = (loff_t)((uintptr_t)((uint8_t *)(&mbr->ptable[pnum])));
	}

	pentry = (struct pc_partition *) &item->data;

	/* need a standard primary partition entry */
	if (pinfo) {
	/* need this to be 64 bit in case len_kb is large */
	uint64_t len_lba;

	if (pinfo->len_kb != (uint32_t)-1) {
	/* bump it up to the next LBA boundary just in case */
	len_lba = ((uint64_t)pinfo->len_kb * 1024);
	len_lba += ((uint64_t)dinfo->sect_size - 1);
	len_lba &= ~((uint64_t)dinfo->sect_size - 1);
	len_lba /= (uint64_t)dinfo->sect_size;
	} else {
	/* make it fill the rest of disk */
	len_lba = dinfo->num_lba - *lba;
	}

	cfg_pentry(pentry, ((pinfo->flags & PART_ACTIVE_FLAG) ?
	PC_PART_ACTIVE : PC_PART_NORMAL),
	pinfo->type, *lba, (uint32_t)len_lba);

	pinfo->start_lba = *lba;
	*lba += (uint32_t)len_lba;
	} else {
	/* this should be made an extended partition, and should take
	* up the rest of the disk as a primary partition */
	cfg_pentry(pentry, PC_PART_NORMAL, PC_PART_TYPE_EXTENDED,
	lba, dinfo->num_lba - lba);

	/* note that we do not update the *lba because we now have to
	* create a chain of extended partition tables, and first one is at
	* lba /
	}

	return item;
	}


	/* This function configures an extended boot record at the beginning of an
	* extended partition. This creates a logical partition and a pointer to
	* the next EBR.
	*
	* ext_lba == The start of the toplevel extended partition (pointed to by the
	* entry in the MBR).
	*/
	static struct write_list *
	mk_ext_pentry(struct disk_info dinfo, struct part_info pinfo, uint32_t *lba,
	uint32_t ext_lba, struct part_info *pnext)
	{
	struct write_list *item;
	struct pc_boot_record *ebr;
	uint32_t len; /* in lba units */

	if (!(item = alloc_wl(sizeof(struct pc_boot_record)))) {
	ALOGE("Unable to allocate memory for EBR.");
	return NULL;
	}

	/* we are going to write the ebr at the current LBA, and then bump the
	* lba counter since that is where the logical data partition will start */
	item->offset = ((loff_t)(lba)) dinfo->sect_size;
	(*lba)++;

	ebr = (struct pc_boot_record *) &item->data;
	memset(ebr, 0, sizeof(struct pc_boot_record));
	ebr->mbr_sig = PC_BIOS_BOOT_SIG;

	if (pinfo->len_kb != (uint32_t)-1)
	len = kb_to_lba(pinfo->len_kb, dinfo->sect_size);
	else {
	if (pnext) {
	ALOGE("Only the last partition can be specified to fill the disk "
	"(name = '%s')", pinfo->name);
	goto fail;
	}
	len = dinfo->num_lba - *lba;
	/* update the pinfo structure to reflect the new size, for
	* bookkeeping */
	pinfo->len_kb =
	(uint32_t)(((uint64_t)len * (uint64_t)dinfo->sect_size) /
	((uint64_t)1024));
	}

	cfg_pentry(&ebr->ptable[PC_EBR_LOGICAL_PART], PC_PART_NORMAL,
	pinfo->type, 1, len);

	pinfo->start_lba = *lba;
	*lba += len;

	/* If this is not the last partition, we have to create a link to the
	* next extended partition.
	*
	* Otherwise, there's nothing to do since the "pointer entry" is
	* already zero-filled.
	*/
	if (pnext) {
	/* The start lba for next partition is an offset from the beginning
	* of the top-level extended partition */
	uint32_t next_start_lba = *lba - ext_lba;
	uint32_t next_len_lba;
	if (pnext->len_kb != (uint32_t)-1)
	next_len_lba = 1 + kb_to_lba(pnext->len_kb, dinfo->sect_size);
	else
	next_len_lba = dinfo->num_lba - *lba;
	cfg_pentry(&ebr->ptable[PC_EBR_NEXT_PTR_PART], PC_PART_NORMAL,
	PC_PART_TYPE_EXTENDED, next_start_lba, next_len_lba);
	}

	return item;

	fail:
	free_wl(item);
	return NULL;
	}


	static struct write_list *
	mk_mbr_sig()
	{
	struct write_list *item;
	if (!(item = alloc_wl(sizeof(uint16_t)))) {
	ALOGE("Unable to allocate memory for MBR signature.");
	return NULL;
	}

	{
	/* DO NOT DEREFERENCE */
	struct pc_boot_record mbr = (void )PC_MBR_DISK_OFFSET;
	/* grab the offset in mbr where to write mbr signature. */
	item->offset = (loff_t)((uintptr_t)((uint8_t *)(&mbr->mbr_sig)));
	}

	((uint16_t)item->data) = PC_BIOS_BOOT_SIG;
	return item;
	}

	struct write_list *
	config_mbr(struct disk_info *dinfo)
	{
	struct part_info *pinfo;
	uint32_t cur_lba = dinfo->skip_lba;
	uint32_t ext_lba = 0;
	struct write_list *wr_list = NULL;
	struct write_list *temp_wr = NULL;
	int cnt = 0;
	int extended = 0;

	if (!dinfo->part_lst)
	return NULL;

	for (cnt = 0; cnt < dinfo->num_parts; ++cnt) {
	pinfo = &dinfo->part_lst[cnt];

	/* Should we create an extedned partition? */
	if (cnt == (PC_NUM_BOOT_RECORD_PARTS - 1)) {
	if (cnt + 1 < dinfo->num_parts) {
	extended = 1;
	ext_lba = cur_lba;
	if ((temp_wr = mk_pri_pentry(dinfo, NULL, cnt, &cur_lba)))
	wlist_add(&wr_list, temp_wr);
	else {
	ALOGE("Cannot create primary extended partition.");
	goto fail;
	}
	}
	}

	/* if extended, need 1 lba for ebr */
	if ((cur_lba + extended) >= dinfo->num_lba)
	goto nospace;
	else if (pinfo->len_kb != (uint32_t)-1) {
	uint32_t sz_lba = (pinfo->len_kb / dinfo->sect_size) * 1024;
	if ((cur_lba + sz_lba + extended) > dinfo->num_lba)
	goto nospace;
	}

	if (!extended)
	temp_wr = mk_pri_pentry(dinfo, pinfo, cnt, &cur_lba);
	else {
	struct part_info *pnext;
	pnext = cnt + 1 < dinfo->num_parts ? &dinfo->part_lst[cnt+1] : NULL;
	temp_wr = mk_ext_pentry(dinfo, pinfo, &cur_lba, ext_lba, pnext);
	}

	if (temp_wr)
	wlist_add(&wr_list, temp_wr);
	else {
	ALOGE("Cannot create partition %d (%s).", cnt, pinfo->name);
	goto fail;
	}
	}

	/* fill in the rest of the MBR with empty parts (if needed). */
	for (; cnt < PC_NUM_BOOT_RECORD_PARTS; ++cnt) {
	struct part_info blank;
	cur_lba = 0;
	memset(&blank, 0, sizeof(struct part_info));
	if (!(temp_wr = mk_pri_pentry(dinfo, &blank, cnt, &cur_lba))) {
	ALOGE("Cannot create blank partition %d.", cnt);
	goto fail;
	}
	wlist_add(&wr_list, temp_wr);
	}

	if ((temp_wr = mk_mbr_sig()))
	wlist_add(&wr_list, temp_wr);
	else {
	ALOGE("Cannot set MBR signature");
	goto fail;
	}

	return wr_list;

	nospace:
	ALOGE("Not enough space to add parttion '%s'.", pinfo->name);

	fail:
	wlist_free(wr_list);
	return NULL;
	}


	/* Returns the device path of the partition referred to by 'name'
	* Must be freed by the caller.
	*/
	char *
	find_mbr_part(struct disk_info dinfo, const char name)
	{
	struct part_info *plist = dinfo->part_lst;
	int num = 0;
	char *dev_name = NULL;
	int has_extended = (dinfo->num_parts > PC_NUM_BOOT_RECORD_PARTS);

	for(num = 1; num <= dinfo->num_parts; ++num) {
	if (!strcmp(plist[num-1].name, name))
	break;
	}

	if (num > dinfo->num_parts)
	return NULL;

	if (has_extended && (num >= PC_NUM_BOOT_RECORD_PARTS))
	num++;

	if (!(dev_name = malloc(MAX_NAME_LEN))) {
	ALOGE("Cannot allocate memory.");
	return NULL;
	}

	num = snprintf(dev_name, MAX_NAME_LEN, "%s%d", dinfo->device, num);
	if (num >= MAX_NAME_LEN) {
	ALOGE("Device name is too long?!");
	free(dev_name);
	return NULL;
	}

	return dev_name;
	}