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326
study/linux-travel/MINIX-1.5/1.5/Source/commands/de/de_diskio.c
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326
study/linux-travel/MINIX-1.5/1.5/Source/commands/de/de_diskio.c
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/****************************************************************/
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/* */
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/* de_diskio.c */
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/* */
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/* Reading and writing to a file system device. */
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/* */
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/****************************************************************/
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/* origination 1989-Jan-15 Terrence W. Holm */
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/****************************************************************/
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#include <minix/config.h>
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#include <sys/types.h>
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#include <unistd.h>
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#include <limits.h>
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#include <stdio.h>
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#include <minix/const.h>
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#include <minix/type.h>
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#include "../../fs/const.h"
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#include "../../fs/type.h"
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#include "../../fs/super.h"
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#include "de.h"
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/****************************************************************/
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/* */
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/* Read_Disk( state, block_addr, buffer ) */
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/* */
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/* Reads a 1k block at "block_addr" into "buffer". */
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/* */
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/****************************************************************/
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void Read_Disk( s, block_addr, buffer )
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de_state *s;
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off_t block_addr;
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char *buffer;
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{
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if ( lseek( s->device_d, block_addr, SEEK_SET ) == -1 )
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Error( "Error seeking %s", s->device_name );
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if ( read( s->device_d, buffer, K ) != K )
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Error( "Error reading %s", s->device_name );
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}
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/****************************************************************/
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/* */
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/* Read_Block( state, buffer ) */
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/* */
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/* Reads a 1k block from "state->address" into */
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/* "buffer". Checks "address", and updates */
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/* "block" and "offset". */
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/* */
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/****************************************************************/
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void Read_Block( s, buffer )
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de_state *s;
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char *buffer;
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{
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off_t end_addr = (long) s->device_size * K - 1;
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off_t block_addr;
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if ( s->address < 0 )
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s->address = 0L;
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if ( s->address > end_addr )
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s->address = end_addr;
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/* The address must be rounded off for */
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/* certain visual display modes. */
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if ( s->mode == WORD )
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s->address &= ~1L;
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else if ( s->mode == MAP )
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s->address &= ~3L;
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block_addr = s->address & K_MASK;
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s->block = (unsigned) (block_addr >> K_SHIFT);
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s->offset = (unsigned) (s->address - block_addr);
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Read_Disk( s, block_addr, buffer );
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}
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/****************************************************************/
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/* */
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/* Read_Super_Block( state ) */
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/* */
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/* Read and check the super block. */
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/* */
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/****************************************************************/
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void Read_Super_Block( s )
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de_state *s;
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{
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struct super_block *super = (struct super_block *) s->buffer;
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Read_Disk( s, (long) 1 * K, s->buffer );
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s->inodes = super->s_ninodes;
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s->zones = super->s_nzones;
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s->inode_maps = bitmapsize(1 + s->inodes);
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s->zone_maps = bitmapsize(s->zones);
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s->inode_blocks = (s->inodes + INODES_PER_BLOCK - 1) / INODES_PER_BLOCK;
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s->first_data = 2 + s->inode_maps + s->zone_maps + s->inode_blocks;
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s->inodes_in_map = s->inodes + 1;
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s->zones_in_map = s->zones + 1 - s->first_data;
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/*
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if ( s->zones != s->device_size )
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Warning( "Zone count does not equal device size" );
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*/
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s->device_size = s->zones;
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if ( s->inode_maps != super->s_imap_blocks )
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Warning( "Corrupted inode map count in super block" );
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if ( s->zone_maps != super->s_zmap_blocks )
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Warning( "Corrupted zone map count in super block" );
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if ( s->first_data != super->s_firstdatazone )
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Warning( "Corrupted first data zone count in super block" );
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if ( super->s_log_zone_size != 0 )
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Warning( "Can not handle multiple blocks per zone" );
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if ( super->s_magic != SUPER_MAGIC )
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Warning( "Corrupted magic number in super block" );
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}
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/****************************************************************/
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/* */
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/* Read_Bit_Maps( state ) */
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/* */
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/* Read in the i-node and zone bit maps from the */
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/* specified file system device. */
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/* */
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/****************************************************************/
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void Read_Bit_Maps( s )
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de_state *s;
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{
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int i;
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if ( s->inode_maps > I_MAP_SLOTS || s->zone_maps > ZMAP_SLOTS )
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{
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Warning( "Super block specifies too many bit map blocks" );
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return;
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}
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for ( i = 0; i < s->inode_maps; ++i )
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{
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Read_Disk( s, (long) (2 + i) * K, &s->inode_map[ i * K ] );
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}
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for ( i = 0; i < s->zone_maps; ++i )
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{
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Read_Disk( s, (long) (2 + s->inode_maps + i) * K, &s->zone_map[ i * K ] );
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}
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}
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/****************************************************************/
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/* */
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/* Search( state, string ) */
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/* */
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/* Search from the current address for the ASCII */
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/* "string" on the device. */
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/* */
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/****************************************************************/
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off_t Search( s, string )
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de_state *s;
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char *string;
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{
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off_t address = s->address + 1;
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off_t last_addr = address;
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char buffer[ SEARCH_BUFFER ];
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int offset;
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int tail_length = strlen( string ) - 1;
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int count = SEARCH_BUFFER;
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int last_offset;
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for ( ; count == SEARCH_BUFFER; address += SEARCH_BUFFER - tail_length )
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{
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if ( lseek( s->device_d, address, SEEK_SET ) == -1 )
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Error( "Error seeking %s", s->device_name );
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if ( (count = read( s->device_d, buffer, SEARCH_BUFFER)) == -1 )
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Error( "Error reading %s", s->device_name );
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if ( address - last_addr >= 500L * K )
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{
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putchar( '.' );
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fflush( stdout );
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last_addr += 500L * K;
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}
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last_offset = count - tail_length;
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for ( offset = 0; offset < last_offset; ++offset )
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{
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register char c = buffer[ offset ];
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if ( c == *string )
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{
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char *tail_buffer = &buffer[ offset + 1 ];
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char *tail_string = string + 1;
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do
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{
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if ( *tail_string == '\0' )
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return( address + offset );
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}
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while ( *tail_buffer++ == *tail_string++ );
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}
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} /* end for ( offset ) */
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} /* end for ( address ) */
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return( -1L );
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}
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/****************************************************************/
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/* */
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/* Write_Word( state, word ) */
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/* */
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/* Write a word at address. */
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/* */
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/****************************************************************/
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void Write_Word( s, word )
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de_state *s;
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unsigned word;
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{
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if ( s->address & 01 )
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Error( "Internal fault (unaligned address)" );
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if ( lseek( s->device_d, s->address, SEEK_SET ) == -1 )
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Error( "Error seeking %s", s->device_name );
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if ( write( s->device_d, (char *) &word, 2 ) != 2 )
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Error( "Error writing %s", s->device_name );
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}
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/* The next routine is copied from fsck.c and mkfs.c... (Re)define some
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* things for consistency. This sharing should be done better in a library
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* library routine. In the library routine, the shifts should be replaced
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* by multiplications and divisions by MAP_BITS_PER_BLOCK since log2 of
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* this is too painful to get right.
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*/
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#define BITMAPSHIFT 13 /* = log2(MAP_BITS_PER_BLOCK) */
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#define bit_nr unsigned
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/* Convert from bit count to a block count. The usual expression
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*
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* (nr_bits + (1 << BITMAPSHIFT) - 1) >> BITMAPSHIFT
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*
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* doesn't work because of overflow.
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*
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* Other overflow bugs, such as the expression for N_ILIST overflowing when
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* s_inodes is just over INODES_PER_BLOCK less than the maximum+1, are not
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* fixed yet, because that number of inodes is silly.
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*/
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int bitmapsize(nr_bits)
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bit_nr nr_bits;
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{
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int nr_blocks;
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nr_blocks = nr_bits >> BITMAPSHIFT;
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if ((nr_blocks << BITMAPSHIFT) < nr_bits)
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++nr_blocks;
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return(nr_blocks);
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}
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