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/* DOS style partitioning */
#include <fcntl.h>
#include <unistd.h>
#include "balkan.h"
struct singlePartition {
unsigned char active;
unsigned char startHead;
unsigned char startSector;
unsigned char startCyl;
unsigned char type;
unsigned char endHead;
unsigned char endSector;
unsigned char endCyl;
unsigned int start; /* in sectors */
unsigned int size; /* in sectors */
};
struct singlePartitionTable {
struct singlePartition parts[4];
};
/* Location of partition table in MBR */
#define TABLE_OFFSET 446
#define MBR_MAGIC 0x55aa
#define MBR_MAGIC_OFFSET 510
#define SECTOR_SIZE 512
#define DOSP_TYPE_EXTENDED 5
long long llseek(int fd, long long offset, int whence);
static int readSingleTable(int fd, struct singlePartitionTable * table,
long long partSector) {
unsigned char sector[SECTOR_SIZE];
unsigned short magic;
if (llseek(fd, ((long long) SECTOR_SIZE * (long long) partSector),
SEEK_SET) < 0)
return BALKAN_ERROR_ERRNO;
if (read(fd, sector, sizeof(sector)) != sizeof(sector))
return BALKAN_ERROR_ERRNO;
magic = (sector[MBR_MAGIC_OFFSET] << 8) + sector[MBR_MAGIC_OFFSET + 1];
if (magic != MBR_MAGIC)
return BALKAN_ERROR_BADMAGIC;
memcpy(table, sector + TABLE_OFFSET, sizeof(struct singlePartitionTable));
return 0;
}
static int readNextTable(int fd, struct partitionTable * table, int nextNum,
long long partSector, long long sectorOffset) {
struct singlePartitionTable singleTable;
int rc;
int i;
int gotExtended = 0;
if ((rc = readSingleTable(fd, &singleTable, partSector + sectorOffset)))
return rc;
if (nextNum > 4) {
/* This is an extended table */
if (singleTable.parts[2].size || singleTable.parts[3].size)
return BALKAN_ERROR_BADTABLE;
}
for (i = 0; i < 4; i++) {
if (!singleTable.parts[i].size) continue;
if (singleTable.parts[i].type == DOSP_TYPE_EXTENDED &&
nextNum >= 5) continue;
table->parts[nextNum].startSector = singleTable.parts[i].start +
sectorOffset;
table->parts[nextNum].size = singleTable.parts[i].size;
table->parts[nextNum].type = singleTable.parts[i].type;
nextNum++;
}
/* look for extended partitions */
for (i = 0; i < 4; i++) {
if (!singleTable.parts[i].size) continue;
if (singleTable.parts[i].type == DOSP_TYPE_EXTENDED) {
if (gotExtended) return BALKAN_ERROR_BADTABLE;
gotExtended = 1;
if (sectorOffset)
rc = readNextTable(fd, table, nextNum > 5 ? nextNum : 5,
singleTable.parts[i].start, sectorOffset);
else
rc = readNextTable(fd, table, nextNum > 5 ? nextNum : 5,
0, singleTable.parts[i].start);
if (rc) return rc;
}
}
return 0;
}
int dospReadTable(int fd, struct partitionTable * table) {
int i;
table->maxNumPartitions = 16;
for (i = 0; i < table->maxNumPartitions; i++)
table->parts[i].type = -1;
table->sectorSize = SECTOR_SIZE;
return readNextTable(fd, table, 0, 0, 0);
}
#ifdef STANDALONE_TEST
void main() {
int fd;
int i;
struct partitionTable table;
fd = open("/dev/hda", O_RDONLY);
printf("rc= %d\n", dospReadTable(fd, &table));
for (i = 0; i < table.maxNumPartitions; i++) {
if (table.parts[i].type == -1) continue;
printf("%d: %x %d\n", i, table.parts[i].type, table.parts[i].size);
}
}
#endif
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