minix/drivers/libdriver/drvlib.c

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/* IBM device driver utility functions. Author: Kees J. Bot
* 7 Dec 1995
* Entry point:
* partition: partition a disk to the partition table(s) on it.
*/
#include "driver.h"
#include "drvlib.h"
#include <unistd.h>
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/* Extended partition? */
#define ext_part(s) ((s) == 0x05 || (s) == 0x0F)
FORWARD _PROTOTYPE( void extpartition, (struct driver *dp, int extdev,
unsigned long extbase) );
FORWARD _PROTOTYPE( int get_part_table, (struct driver *dp, int device,
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unsigned long offset, struct part_entry *table));
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FORWARD _PROTOTYPE( void sort, (struct part_entry *table) );
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#ifndef CD_SECTOR_SIZE
#define CD_SECTOR_SIZE 2048
#endif
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/*============================================================================*
* partition *
*============================================================================*/
PUBLIC void partition(dp, device, style, atapi)
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struct driver *dp; /* device dependent entry points */
int device; /* device to partition */
int style; /* partitioning style: floppy, primary, sub. */
int atapi; /* atapi device */
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{
/* This routine is called on first open to initialize the partition tables
* of a device. It makes sure that each partition falls safely within the
* device's limits. Depending on the partition style we are either making
* floppy partitions, primary partitions or subpartitions. Only primary
* partitions are sorted, because they are shared with other operating
* systems that expect this.
*/
struct part_entry table[NR_PARTITIONS], *pe;
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int disk, par;
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struct device *dv;
unsigned long base, limit, part_limit;
/* Get the geometry of the device to partition */
if ((dv = (*dp->dr_prepare)(device)) == NIL_DEV
|| cmp64u(dv->dv_size, 0) == 0) return;
base = div64u(dv->dv_base, SECTOR_SIZE);
limit = base + div64u(dv->dv_size, SECTOR_SIZE);
/* Read the partition table for the device. */
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if(!get_part_table(dp, device, 0L, table)) {
return;
}
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/* Compute the device number of the first partition. */
switch (style) {
case P_FLOPPY:
device += MINOR_fd0p0;
break;
case P_PRIMARY:
sort(table); /* sort a primary partition table */
device += 1;
break;
case P_SUB:
disk = device / DEV_PER_DRIVE;
par = device % DEV_PER_DRIVE - 1;
device = MINOR_d0p0s0 + (disk * NR_PARTITIONS + par) * NR_PARTITIONS;
}
/* Find an array of devices. */
if ((dv = (*dp->dr_prepare)(device)) == NIL_DEV) return;
/* Set the geometry of the partitions from the partition table. */
for (par = 0; par < NR_PARTITIONS; par++, dv++) {
/* Shrink the partition to fit within the device. */
pe = &table[par];
part_limit = pe->lowsec + pe->size;
if (part_limit < pe->lowsec) part_limit = limit;
if (part_limit > limit) part_limit = limit;
if (pe->lowsec < base) pe->lowsec = base;
if (part_limit < pe->lowsec) part_limit = pe->lowsec;
dv->dv_base = mul64u(pe->lowsec, SECTOR_SIZE);
dv->dv_size = mul64u(part_limit - pe->lowsec, SECTOR_SIZE);
if (style == P_PRIMARY) {
/* Each Minix primary partition can be subpartitioned. */
if (pe->sysind == MINIX_PART)
partition(dp, device + par, P_SUB, atapi);
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/* An extended partition has logical partitions. */
if (ext_part(pe->sysind))
extpartition(dp, device + par, pe->lowsec);
}
}
}
/*============================================================================*
* extpartition *
*============================================================================*/
PRIVATE void extpartition(dp, extdev, extbase)
struct driver *dp; /* device dependent entry points */
int extdev; /* extended partition to scan */
unsigned long extbase; /* sector offset of the base extended partition */
{
/* Extended partitions cannot be ignored alas, because people like to move
* files to and from DOS partitions. Avoid reading this code, it's no fun.
*/
struct part_entry table[NR_PARTITIONS], *pe;
int subdev, disk, par;
struct device *dv;
unsigned long offset, nextoffset;
disk = extdev / DEV_PER_DRIVE;
par = extdev % DEV_PER_DRIVE - 1;
subdev = MINOR_d0p0s0 + (disk * NR_PARTITIONS + par) * NR_PARTITIONS;
offset = 0;
do {
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if (!get_part_table(dp, extdev, offset, table)) return;
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sort(table);
/* The table should contain one logical partition and optionally
* another extended partition. (It's a linked list.)
*/
nextoffset = 0;
for (par = 0; par < NR_PARTITIONS; par++) {
pe = &table[par];
if (ext_part(pe->sysind)) {
nextoffset = pe->lowsec;
} else
if (pe->sysind != NO_PART) {
if ((dv = (*dp->dr_prepare)(subdev)) == NIL_DEV) return;
dv->dv_base = mul64u(extbase + offset + pe->lowsec,
SECTOR_SIZE);
dv->dv_size = mul64u(pe->size, SECTOR_SIZE);
/* Out of devices? */
if (++subdev % NR_PARTITIONS == 0) return;
}
}
} while ((offset = nextoffset) != 0);
}
/*============================================================================*
* get_part_table *
*============================================================================*/
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PRIVATE int get_part_table(dp, device, offset, table)
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struct driver *dp;
int device;
unsigned long offset; /* sector offset to the table */
struct part_entry *table; /* four entries */
{
/* Read the partition table for the device, return true iff there were no
* errors.
*/
iovec_t iovec1;
off_t position;
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static unsigned char partbuf[CD_SECTOR_SIZE];
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position = offset << SECTOR_SHIFT;
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iovec1.iov_addr = (vir_bytes) partbuf;
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iovec1.iov_size = CD_SECTOR_SIZE;
if ((*dp->dr_prepare)(device) != NIL_DEV) {
(void) (*dp->dr_transfer)(SELF, DEV_GATHER, position, &iovec1, 1, 0);
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}
if (iovec1.iov_size != 0) {
return 0;
}
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if (partbuf[510] != 0x55 || partbuf[511] != 0xAA) {
/* Invalid partition table. */
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return 0;
}
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memcpy(table, (partbuf + PART_TABLE_OFF), NR_PARTITIONS * sizeof(table[0]));
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return 1;
}
/*===========================================================================*
* sort *
*===========================================================================*/
PRIVATE void sort(table)
struct part_entry *table;
{
/* Sort a partition table. */
struct part_entry *pe, tmp;
int n = NR_PARTITIONS;
do {
for (pe = table; pe < table + NR_PARTITIONS-1; pe++) {
if (pe[0].sysind == NO_PART
|| (pe[0].lowsec > pe[1].lowsec
&& pe[1].sysind != NO_PART)) {
tmp = pe[0]; pe[0] = pe[1]; pe[1] = tmp;
}
}
} while (--n > 0);
}