minix/usr.sbin/installboot/minixfs3.c

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#include <stdio.h>
#include <stdlib.h>
#include <stdint.h>
#include <errno.h>
#include <sys/stat.h>
#include <sys/bootblock.h>
#include <fcntl.h>
#include <unistd.h>
#include <string.h>
#ifndef DFL_SECSIZE
#define DFL_SECSIZE 512
#endif
#define MFS_FIRST_SUBP_OFFSET 32
static int minixfs3_read_mbr(const char* device, char* buf)
{
int fd;
int bytes;
int n;
fd = open(device, O_RDONLY);
if (fd == -1) {
fprintf(stderr, "Can't open %s: %s\n", device, strerror(errno));
return 1;
}
if (lseek(fd, MBR_PART_OFFSET, SEEK_SET) != MBR_PART_OFFSET) {
fprintf(stderr, "Can't seek in %s to %d: %s\n",
device, MBR_PART_OFFSET, strerror(errno));
close(fd);
return 1;
}
bytes = DFL_SECSIZE - MBR_PART_OFFSET;
if ((n = read(fd, buf, bytes)) != bytes) {
fprintf(stderr, "Can't read %d bytes from %s, %d read instead"
": %s\n",
bytes, device, n, strerror(errno));
close(fd);
return 1;
}
if ((uint8_t)buf[bytes-2] != 0x55 || (uint8_t)buf[bytes-1] != 0xAA) {
fprintf(stderr, "No MBR on %s, signature is %x\n",
device, *(uint16_t*)(&buf[bytes-2]));
close(fd);
return 1;
}
close(fd);
return 0;
}
int minixfs3_is_minix_partition(const char* partition)
{
char buf[DFL_SECSIZE]; /* part table + signature */
int name_length = strlen(partition);
/* partition must be 0-3 */
if (atol(&partition[name_length-1]) >= 4) {
fprintf(stderr, "Wrong device %s, must be /.../cxdyp[0-3]\n",
partition);
return 0;
}
/* it should be partition device, not disk */
if (partition[name_length-2] != 'p') {
fprintf(stderr, "Wrong device %s, must be /.../cxdyp[0-3]\n",
partition);
return 0;
}
/* MINIX 3 partition with current scheme *must* have subpartitions,
* thus MBR has signature. minixfs3_read_mbr checks the signature.
*/
if (minixfs3_read_mbr(partition, buf))
return 0;
return 1;
}
/* bootxx from NetBSD is ~8Kb, and old MINIX installations have just
* 1Kb of space for their bootblock. Check if there is enough space
* to install bootxx_minixfs3. New installation should have 16Kb before
* the first subpartition.
*/
int minixfs3_has_bootblock_space(const char* partition)
{
char buf[DFL_SECSIZE]; /* part table + signature */
char disk[NAME_MAX];
struct mbr_partition *part;
uint32_t first_subpartition = (uint32_t) ~0;
uint32_t parent_partition = 0;
int i;
int name_length = strlen(partition);
/* partition must be 0-3 */
if (atol(&partition[name_length-1]) >= 4) {
fprintf(stderr, "Wrong device %s, must be /.../cxdyp[0-3]\n",
partition);
exit(1);
}
/* it should be partition device, not disk */
if (partition[name_length-2] != 'p') {
fprintf(stderr, "Wrong device %s, must be /.../cxdyp[0-3]\n",
partition);
exit(1);
}
if (minixfs3_read_mbr(partition, buf))
exit(1);
part = (struct mbr_partition *) buf;
for (i = 0; i < 4; i++) {
if (part[i].mbrp_size && part[i].mbrp_start < first_subpartition)
first_subpartition = part[i].mbrp_start;
}
strncpy(disk, partition, name_length - 2);
disk[name_length - 2] = '\0';
if (minixfs3_read_mbr(disk, buf))
exit(1);
for (i = 0; i < 4; i++) {
struct mbr_partition *p = &part[i];
if (p->mbrp_size && p->mbrp_start <= first_subpartition
&& (p->mbrp_start + p->mbrp_size) > first_subpartition) {
parent_partition = p->mbrp_start;
break;
}
}
if ((first_subpartition - parent_partition) < MFS_FIRST_SUBP_OFFSET)
return 0;
else
return 1;
}