460 lines
10 KiB
C
460 lines
10 KiB
C
/*
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* dosio.c -- Disk I/O module for the ext2fs/DOS library.
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*
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* Copyright (c) 1997 by Theodore Ts'o.
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*
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* Copyright (c) 1997 Mark Habersack
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*
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* %Begin-Header%
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* This file may be redistributed under the terms of the GNU Library
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* General Public License, version 2.
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* %End-Header%
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*/
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#include "config.h"
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#include <stdio.h>
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#include <bios.h>
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#include <string.h>
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#include <ctype.h>
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#include <io.h>
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#ifdef HAVE_ERRNO_H
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#include <errno.h>
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#endif
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#include <ext2fs/ext2_types.h>
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#include "utils.h"
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#include "dosio.h"
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#include "et/com_err.h"
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#include "ext2_err.h"
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#include "ext2fs/io.h"
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/*
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* Some helper macros
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*/
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#define LINUX_EXT2FS 0x83
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#define LINUX_SWAP 0x82
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#define WRITE_ERR(_msg_) write(2, _msg_, strlen(_msg_))
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#define WRITE_ERR_S(_msg_) write(2, _msg_, sizeof(_msg_))
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/*
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* Exported variables
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*/
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unsigned long _dio_error;
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unsigned long _dio_hw_error;
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/*
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* Array of all opened partitions
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*/
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static PARTITION **partitions = NULL;
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static unsigned short npart = 0; /* Number of mapped partitions */
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static PARTITION *active = NULL;
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/*
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* I/O Manager routine prototypes
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*/
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static errcode_t dos_open(const char *dev, int flags, io_channel *channel);
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static errcode_t dos_close(io_channel channel);
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static errcode_t dos_set_blksize(io_channel channel, int blksize);
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static errcode_t dos_read_blk(io_channel channel, unsigned long block,
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int count, void *buf);
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static errcode_t dos_write_blk(io_channel channel, unsigned long block,
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int count, const void *buf);
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static errcode_t dos_flush(io_channel channel);
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static struct struct_io_manager struct_dos_manager = {
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.magic = EXT2_ET_MAGIC_IO_MANAGER,
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.name = "DOS I/O Manager",
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.open = dos_open,
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.close = dos_close,
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.set_blksize = dos_set_blksize,
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.read_blk = dos_read_blk,
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.write_blk = dos_write_blk,
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.flush = dos_flush
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};
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io_manager dos_io_manager = &struct_dos_manager;
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/*
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* Macro taken from unix_io.c
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*/
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/*
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* For checking structure magic numbers...
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*/
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#define EXT2_CHECK_MAGIC(struct, code) \
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if ((struct)->magic != (code)) return (code)
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/*
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* Calculates a CHS address of a sector from its LBA
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* offset for the given partition.
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*/
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static void lba2chs(unsigned long lba_addr, CHS *chs, PARTITION *part)
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{
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unsigned long abss;
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chs->offset = lba_addr & 0x000001FF;
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abss = (lba_addr >> 9) + part->start;
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chs->cyl = abss / (part->sects * part->heads);
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chs->head = (abss / part->sects) % part->heads;
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chs->sector = (abss % part->sects) + 1;
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}
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#ifdef __TURBOC__
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#pragma argsused
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#endif
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/*
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* Scans the passed partition table looking for *pno partition
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* that has LINUX_EXT2FS type.
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*
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* TODO:
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* For partition numbers >5 Linux uses DOS extended partitions -
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* dive into them an return an appropriate entry. Also dive into
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* extended partitions when scanning for a first Linux/ext2fs.
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*/
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static PTABLE_ENTRY *scan_partition_table(PTABLE_ENTRY *pentry,
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unsigned short phys,
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unsigned char *pno)
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{
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unsigned i;
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if(*pno != 0xFF && *pno >= 5)
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return NULL; /* We don't support extended partitions for now */
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if(*pno != 0xFF)
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{
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if(pentry[*pno].type == LINUX_EXT2FS)
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return &pentry[*pno];
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else
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{
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if(!pentry[*pno].type)
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*pno = 0xFE;
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else if(pentry[*pno].type == LINUX_SWAP)
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*pno = 0xFD;
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return NULL;
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}
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}
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for(i = 0; i < 4; i++)
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if(pentry[i].type == LINUX_EXT2FS)
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{
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*pno = i;
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return &pentry[i];
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}
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return NULL;
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}
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/*
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* Allocate libext2fs structures associated with I/O manager
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*/
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static io_channel alloc_io_channel(PARTITION *part)
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{
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io_channel ioch;
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ioch = (io_channel)malloc(sizeof(struct struct_io_channel));
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if (!ioch)
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return NULL;
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memset(ioch, 0, sizeof(struct struct_io_channel));
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ioch->magic = EXT2_ET_MAGIC_IO_CHANNEL;
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ioch->manager = dos_io_manager;
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ioch->name = (char *)malloc(strlen(part->dev)+1);
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if (!ioch->name) {
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free(ioch);
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return NULL;
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}
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strcpy(ioch->name, part->dev);
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ioch->private_data = part;
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ioch->block_size = 1024; /* The smallest ext2fs block size */
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ioch->read_error = 0;
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ioch->write_error = 0;
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return ioch;
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}
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#ifdef __TURBOC__
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#pragma argsused
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#endif
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/*
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* Open the 'name' partition, initialize all information structures
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* we need to keep and create libext2fs I/O manager.
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*/
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static errcode_t dos_open(const char *dev, int flags, io_channel *channel)
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{
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unsigned char *tmp, sec[512];
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PARTITION *part;
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PTABLE_ENTRY *pent;
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PARTITION **newparts;
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if(!dev)
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{
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_dio_error = ERR_BADDEV;
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return EXT2_ET_BAD_DEVICE_NAME;
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}
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/*
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* First check whether the dev name is OK
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*/
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tmp = (unsigned char*)strrchr(dev, '/');
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if(!tmp)
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{
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_dio_error = ERR_BADDEV;
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return EXT2_ET_BAD_DEVICE_NAME;
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}
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*tmp = 0;
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if(strcmp(dev, "/dev"))
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{
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_dio_error = ERR_BADDEV;
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return EXT2_ET_BAD_DEVICE_NAME;
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}
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*tmp++ = '/';
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/*
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* Check whether the partition data is already in cache
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*/
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part = (PARTITION*)malloc(sizeof(PARTITION));
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if (!part)
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return ENOMEM;
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{
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int i = 0;
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for(;i < npart; i++)
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if(!strcmp(partitions[i]->dev, dev))
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{
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/* Found it! Make it the active one */
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active = partitions[i];
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*channel = alloc_io_channel(active);
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if (!*channel)
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return ENOMEM;
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return 0;
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}
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}
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/*
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* Drive number & optionally partn number
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*/
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switch(tmp[0])
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{
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case 'h':
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case 's':
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part->phys = 0x80;
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part->phys += toupper(tmp[2]) - 'A';
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/*
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* Do we have the partition number?
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*/
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if(tmp[3])
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part->pno = isdigit((int)tmp[3]) ? tmp[3] - '0' - 1: 0;
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else
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part->pno = 0xFF;
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break;
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case 'f':
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if(tmp[2])
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part->phys = isdigit((int)tmp[2]) ? tmp[2] - '0' : 0;
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else
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part->phys = 0x00; /* We'll assume /dev/fd0 */
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break;
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default:
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_dio_error = ERR_BADDEV;
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return ENODEV;
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}
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if(part->phys < 0x80)
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{
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/* We don't support floppies for now */
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_dio_error = ERR_NOTSUPP;
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return EINVAL;
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}
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part->dev = strdup(dev);
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/*
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* Get drive's geometry
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*/
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_dio_hw_error = biosdisk(DISK_GET_GEOMETRY,
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part->phys,
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0, /* head */
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0, /* cylinder */
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1, /* sector */
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1, /* just one sector */
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sec);
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if(!HW_OK())
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{
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_dio_error = ERR_HARDWARE;
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free(part->dev);
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free(part);
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return EFAULT;
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}
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/*
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* Calculate the geometry
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*/
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part->cyls = (unsigned short)(((sec[0] >> 6) << 8) + sec[1] + 1);
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part->heads = sec[3] + 1;
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part->sects = sec[0] & 0x3F;
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/*
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* Now that we know all we need, let's look for the partition
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*/
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_dio_hw_error = biosdisk(DISK_READ, part->phys, 0, 0, 1, 1, sec);
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if(!HW_OK())
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{
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_dio_error = ERR_HARDWARE;
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free(part->dev);
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free(part);
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return EFAULT;
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}
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pent = (PTABLE_ENTRY*)&sec[0x1BE];
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pent = scan_partition_table(pent, part->phys, &part->pno);
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if(!pent)
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{
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_dio_error = part->pno == 0xFE ? ERR_EMPTYPART :
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part->pno == 0xFD ? ERR_LINUXSWAP : ERR_NOTEXT2FS;
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free(part->dev);
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free(part);
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return ENODEV;
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}
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/*
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* Calculate the remaining figures
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*/
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{
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unsigned long fsec, fhead, fcyl;
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fsec = (unsigned long)(pent->start_sec & 0x3F);
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fhead = (unsigned long)pent->start_head;
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fcyl = ((pent->start_sec >> 6) << 8) + pent->start_cyl;
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part->start = fsec + fhead * part->sects + fcyl *
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(part->heads * part->sects) - 1;
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part->len = pent->size;
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}
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/*
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* Add the partition to the table
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*/
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newparts = (PARTITION**)realloc(partitions, sizeof(PARTITION) * npart);
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if (!newparts) {
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free(part);
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return ENOMEM;
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}
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partitions = newparts;
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partitions[npart++] = active = part;
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/*
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* Now alloc all libe2fs structures
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*/
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*channel = alloc_io_channel(active);
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if (!*channel)
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return ENOMEM;
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return 0;
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}
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static errcode_t dos_close(io_channel channel)
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{
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free(channel->name);
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free(channel);
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return 0;
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}
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static errcode_t dos_set_blksize(io_channel channel, int blksize)
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{
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channel->block_size = blksize;
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return 0;
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}
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static errcode_t dos_read_blk(io_channel channel, unsigned long block,
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int count, void *buf)
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{
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PARTITION *part;
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size_t size;
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ext2_loff_t loc;
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CHS chs;
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EXT2_CHECK_MAGIC(channel, EXT2_ET_MAGIC_IO_CHANNEL);
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part = (PARTITION*)channel->private_data;
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size = (size_t)((count < 0) ? -count : count * channel->block_size);
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loc = (ext2_loff_t) block * channel->block_size;
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lba2chs(loc, &chs, part);
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/*
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* Potential bug here:
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* If DJGPP is used then reads of >18 sectors will fail!
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* Have to rewrite biosdisk.
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*/
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_dio_hw_error = biosdisk(DISK_READ,
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part->phys,
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chs.head,
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chs.cyl,
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chs.sector,
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size < 512 ? 1 : size/512,
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buf);
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if(!HW_OK())
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{
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_dio_error = ERR_HARDWARE;
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return EFAULT;
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}
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return 0;
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}
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static errcode_t dos_write_blk(io_channel channel, unsigned long block,
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int count, const void *buf)
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{
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PARTITION *part;
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size_t size;
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ext2_loff_t loc;
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CHS chs;
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EXT2_CHECK_MAGIC(channel, EXT2_ET_MAGIC_IO_CHANNEL);
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part = (PARTITION*)channel->private_data;
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if(count == 1)
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size = (size_t)channel->block_size;
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else
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{
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if (count < 0)
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size = (size_t)-count;
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else
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size = (size_t)(count * channel->block_size);
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}
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loc = (ext2_loff_t)block * channel->block_size;
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lba2chs(loc, &chs, part);
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_dio_hw_error = biosdisk(DISK_WRITE,
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part->phys,
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chs.head,
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chs.cyl,
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chs.sector,
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size < 512 ? 1 : size/512,
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(void*)buf);
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if(!HW_OK())
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{
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_dio_error = ERR_HARDWARE;
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return EFAULT;
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}
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return 0;
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}
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#ifdef __TURBOC__
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#pragma argsused
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#endif
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static errcode_t dos_flush(io_channel channel)
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{
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/*
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* No buffers, no flush...
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*/
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return 0;
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}
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