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lib/ext2fs/dosio.c
459 строк
10 KB
Theodore Ts'o
libext2fs: use C99 initializers for the io_manager structure
26 июл 2014, 08:49
26 июл 2014, 08:49
d4ecec4
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/* * dosio.c -- Disk I/O module for the ext2fs/DOS library. * * Copyright (c) 1997 by Theodore Ts'o. * * Copyright (c) 1997 Mark Habersack * * %Begin-Header% * This file may be redistributed under the terms of the GNU Library * General Public License, version 2. * %End-Header% */ #include "config.h" #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 = { .magic = EXT2_ET_MAGIC_IO_MANAGER, .name = "DOS I/O Manager", .open = dos_open, .close = dos_close, .set_blksize = dos_set_blksize, .read_blk = dos_read_blk, .write_blk = dos_write_blk, .flush = 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; free(part->dev); 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; free(part->dev); 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; free(part->dev); 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) { free(channel->name); 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; }