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Diffstat (limited to 'e2fsprogs/ext2fs/dosio.c')
| -rw-r--r-- | e2fsprogs/ext2fs/dosio.c | 456 |
1 files changed, 456 insertions, 0 deletions
diff --git a/e2fsprogs/ext2fs/dosio.c b/e2fsprogs/ext2fs/dosio.c new file mode 100644 index 000000000..d695b18ef --- /dev/null +++ b/e2fsprogs/ext2fs/dosio.c @@ -0,0 +1,456 @@ +/* + * dosio.c -- Disk I/O module for the ext2fs/DOS library. + * + * Copyright (c) 1997 by Theodore Ts'o. + * + * Copyright (c) 1997 Mark Habersack + * This file may be distributed under the terms of the GNU Public License. + * + */ + +#include <stdio.h> +#include <bios.h> +#include <string.h> +#include <ctype.h> +#include <io.h> +#ifdef HAVE_ERRNO_H +#include <errno.h> +#endif + +#include <ext2fs/ext2_types.h> +#include "utils.h" +#include "dosio.h" +#include "et/com_err.h" +#include "ext2_err.h" +#include "ext2fs/io.h" + +/* + * Some helper macros + */ +#define LINUX_EXT2FS 0x83 +#define LINUX_SWAP 0x82 +#define WRITE_ERR(_msg_) write(2, _msg_, strlen(_msg_)) +#define WRITE_ERR_S(_msg_) write(2, _msg_, sizeof(_msg_)) + +/* + * Exported variables + */ +unsigned long _dio_error; +unsigned long _dio_hw_error; + +/* + * Array of all opened partitions + */ +static PARTITION **partitions = NULL; +static unsigned short npart = 0; /* Number of mapped partitions */ +static PARTITION *active = NULL; + +/* + * I/O Manager routine prototypes + */ +static errcode_t dos_open(const char *dev, int flags, io_channel *channel); +static errcode_t dos_close(io_channel channel); +static errcode_t dos_set_blksize(io_channel channel, int blksize); +static errcode_t dos_read_blk(io_channel channel, unsigned long block, + int count, void *buf); +static errcode_t dos_write_blk(io_channel channel, unsigned long block, + int count, const void *buf); +static errcode_t dos_flush(io_channel channel); + +static struct struct_io_manager struct_dos_manager = { + EXT2_ET_MAGIC_IO_MANAGER, + "DOS I/O Manager", + dos_open, + dos_close, + dos_set_blksize, + dos_read_blk, + dos_write_blk, + dos_flush +}; +io_manager dos_io_manager = &struct_dos_manager; + +/* + * Macro taken from unix_io.c + */ +/* + * For checking structure magic numbers... + */ + +#define EXT2_CHECK_MAGIC(struct, code) \ + if ((struct)->magic != (code)) return (code) + +/* + * Calculates a CHS address of a sector from its LBA + * offset for the given partition. + */ +static void lba2chs(unsigned long lba_addr, CHS *chs, PARTITION *part) +{ + unsigned long abss; + + chs->offset = lba_addr & 0x000001FF; + abss = (lba_addr >> 9) + part->start; + chs->cyl = abss / (part->sects * part->heads); + chs->head = (abss / part->sects) % part->heads; + chs->sector = (abss % part->sects) + 1; +} + +#ifdef __TURBOC__ +#pragma argsused +#endif +/* + * Scans the passed partition table looking for *pno partition + * that has LINUX_EXT2FS type. + * + * TODO: + * For partition numbers >5 Linux uses DOS extended partitions - + * dive into them an return an appropriate entry. Also dive into + * extended partitions when scanning for a first Linux/ext2fs. + */ +static PTABLE_ENTRY *scan_partition_table(PTABLE_ENTRY *pentry, + unsigned short phys, + unsigned char *pno) +{ + unsigned i; + + if(*pno != 0xFF && *pno >= 5) + return NULL; /* We don't support extended partitions for now */ + + if(*pno != 0xFF) + { + if(pentry[*pno].type == LINUX_EXT2FS) + return &pentry[*pno]; + else + { + if(!pentry[*pno].type) + *pno = 0xFE; + else if(pentry[*pno].type == LINUX_SWAP) + *pno = 0xFD; + return NULL; + } + } + + for(i = 0; i < 4; i++) + if(pentry[i].type == LINUX_EXT2FS) + { + *pno = i; + return &pentry[i]; + } + + return NULL; +} + +/* + * Allocate libext2fs structures associated with I/O manager + */ +static io_channel alloc_io_channel(PARTITION *part) +{ + io_channel ioch; + + ioch = (io_channel)malloc(sizeof(struct struct_io_channel)); + if (!ioch) + return NULL; + memset(ioch, 0, sizeof(struct struct_io_channel)); + ioch->magic = EXT2_ET_MAGIC_IO_CHANNEL; + ioch->manager = dos_io_manager; + ioch->name = (char *)malloc(strlen(part->dev)+1); + if (!ioch->name) { + free(ioch); + return NULL; + } + strcpy(ioch->name, part->dev); + ioch->private_data = part; + ioch->block_size = 1024; /* The smallest ext2fs block size */ + ioch->read_error = 0; + ioch->write_error = 0; + + return ioch; +} + +#ifdef __TURBOC__ +#pragma argsused +#endif +/* + * Open the 'name' partition, initialize all information structures + * we need to keep and create libext2fs I/O manager. + */ +static errcode_t dos_open(const char *dev, int flags, io_channel *channel) +{ + unsigned char *tmp, sec[512]; + PARTITION *part; + PTABLE_ENTRY *pent; + PARTITION **newparts; + + if(!dev) + { + _dio_error = ERR_BADDEV; + return EXT2_ET_BAD_DEVICE_NAME; + } + + /* + * First check whether the dev name is OK + */ + tmp = (unsigned char*)strrchr(dev, '/'); + if(!tmp) + { + _dio_error = ERR_BADDEV; + return EXT2_ET_BAD_DEVICE_NAME; + } + *tmp = 0; + if(strcmp(dev, "/dev")) + { + _dio_error = ERR_BADDEV; + return EXT2_ET_BAD_DEVICE_NAME; + } + *tmp++ = '/'; + + /* + * Check whether the partition data is already in cache + */ + + part = (PARTITION*)malloc(sizeof(PARTITION)); + if (!part) + return ENOMEM; + { + int i = 0; + + for(;i < npart; i++) + if(!strcmp(partitions[i]->dev, dev)) + { + /* Found it! Make it the active one */ + active = partitions[i]; + *channel = alloc_io_channel(active); + if (!*channel) + return ENOMEM; + return 0; + } + } + + /* + * Drive number & optionally partn number + */ + switch(tmp[0]) + { + case 'h': + case 's': + part->phys = 0x80; + part->phys += toupper(tmp[2]) - 'A'; + /* + * Do we have the partition number? + */ + if(tmp[3]) + part->pno = isdigit((int)tmp[3]) ? tmp[3] - '0' - 1: 0; + else + part->pno = 0xFF; + break; + + case 'f': + if(tmp[2]) + part->phys = isdigit((int)tmp[2]) ? tmp[2] - '0' : 0; + else + part->phys = 0x00; /* We'll assume /dev/fd0 */ + break; + + default: + _dio_error = ERR_BADDEV; + return ENODEV; + } + + if(part->phys < 0x80) + { + /* We don't support floppies for now */ + _dio_error = ERR_NOTSUPP; + return EINVAL; + } + + part->dev = strdup(dev); + + /* + * Get drive's geometry + */ + _dio_hw_error = biosdisk(DISK_GET_GEOMETRY, + part->phys, + 0, /* head */ + 0, /* cylinder */ + 1, /* sector */ + 1, /* just one sector */ + sec); + + if(!HW_OK()) + { + _dio_error = ERR_HARDWARE; + if (part) + free(part); + return EFAULT; + } + + /* + * Calculate the geometry + */ + part->cyls = (unsigned short)(((sec[0] >> 6) << 8) + sec[1] + 1); + part->heads = sec[3] + 1; + part->sects = sec[0] & 0x3F; + + /* + * Now that we know all we need, let's look for the partition + */ + _dio_hw_error = biosdisk(DISK_READ, part->phys, 0, 0, 1, 1, sec); + + if(!HW_OK()) + { + _dio_error = ERR_HARDWARE; + if (part) + free(part); + return EFAULT; + } + + pent = (PTABLE_ENTRY*)&sec[0x1BE]; + pent = scan_partition_table(pent, part->phys, &part->pno); + + if(!pent) + { + _dio_error = part->pno == 0xFE ? ERR_EMPTYPART : + part->pno == 0xFD ? ERR_LINUXSWAP : ERR_NOTEXT2FS; + if (part) + free(part); + return ENODEV; + } + + /* + * Calculate the remaining figures + */ + { + unsigned long fsec, fhead, fcyl; + + fsec = (unsigned long)(pent->start_sec & 0x3F); + fhead = (unsigned long)pent->start_head; + fcyl = ((pent->start_sec >> 6) << 8) + pent->start_cyl; + part->start = fsec + fhead * part->sects + fcyl * + (part->heads * part->sects) - 1; + part->len = pent->size; + } + + /* + * Add the partition to the table + */ + newparts = (PARTITION**)realloc(partitions, sizeof(PARTITION) * npart); + if (!newparts) { + free(part); + return ENOMEM; + } + partitions = newparts; + partitions[npart++] = active = part; + + /* + * Now alloc all libe2fs structures + */ + *channel = alloc_io_channel(active); + if (!*channel) + return ENOMEM; + + return 0; +} + +static errcode_t dos_close(io_channel channel) +{ + if (channel->name) + free(channel->name); + if (channel) + free(channel); + + return 0; +} + +static errcode_t dos_set_blksize(io_channel channel, int blksize) +{ + channel->block_size = blksize; + + return 0; +} + +static errcode_t dos_read_blk(io_channel channel, unsigned long block, + int count, void *buf) +{ + PARTITION *part; + size_t size; + ext2_loff_t loc; + CHS chs; + + EXT2_CHECK_MAGIC(channel, EXT2_ET_MAGIC_IO_CHANNEL); + part = (PARTITION*)channel->private_data; + + size = (size_t)((count < 0) ? -count : count * channel->block_size); + loc = (ext2_loff_t) block * channel->block_size; + + lba2chs(loc, &chs, part); + /* + * Potential bug here: + * If DJGPP is used then reads of >18 sectors will fail! + * Have to rewrite biosdisk. + */ + _dio_hw_error = biosdisk(DISK_READ, + part->phys, + chs.head, + chs.cyl, + chs.sector, + size < 512 ? 1 : size/512, + buf); + + if(!HW_OK()) + { + _dio_error = ERR_HARDWARE; + return EFAULT; + } + + return 0; +} + +static errcode_t dos_write_blk(io_channel channel, unsigned long block, + int count, const void *buf) +{ + PARTITION *part; + size_t size; + ext2_loff_t loc; + CHS chs; + + EXT2_CHECK_MAGIC(channel, EXT2_ET_MAGIC_IO_CHANNEL); + part = (PARTITION*)channel->private_data; + + if(count == 1) + size = (size_t)channel->block_size; + else + { + if (count < 0) + size = (size_t)-count; + else + size = (size_t)(count * channel->block_size); + } + + loc = (ext2_loff_t)block * channel->block_size; + lba2chs(loc, &chs, part); + _dio_hw_error = biosdisk(DISK_WRITE, + part->phys, + chs.head, + chs.cyl, + chs.sector, + size < 512 ? 1 : size/512, + (void*)buf); + + if(!HW_OK()) + { + _dio_error = ERR_HARDWARE; + return EFAULT; + } + + return 0; +} + +#ifdef __TURBOC__ +#pragma argsused +#endif +static errcode_t dos_flush(io_channel channel) +{ + /* + * No buffers, no flush... + */ + return 0; +} |