Minix1.5/commands/de/de_diskio.c
/****************************************************************/
/* */
/* de_diskio.c */
/* */
/* Reading and writing to a file system device. */
/* */
/****************************************************************/
/* origination 1989-Jan-15 Terrence W. Holm */
/****************************************************************/
#include <minix/config.h>
#include <sys/types.h>
#include <unistd.h>
#include <limits.h>
#include <stdio.h>
#include <minix/const.h>
#include <minix/type.h>
#include "../../fs/const.h"
#include "../../fs/type.h"
#include "../../fs/super.h"
#include "de.h"
/****************************************************************/
/* */
/* Read_Disk( state, block_addr, buffer ) */
/* */
/* Reads a 1k block at "block_addr" into "buffer". */
/* */
/****************************************************************/
void Read_Disk( s, block_addr, buffer )
de_state *s;
off_t block_addr;
char *buffer;
{
if ( lseek( s->device_d, block_addr, SEEK_SET ) == -1 )
Error( "Error seeking %s", s->device_name );
if ( read( s->device_d, buffer, K ) != K )
Error( "Error reading %s", s->device_name );
}
/****************************************************************/
/* */
/* Read_Block( state, buffer ) */
/* */
/* Reads a 1k block from "state->address" into */
/* "buffer". Checks "address", and updates */
/* "block" and "offset". */
/* */
/****************************************************************/
void Read_Block( s, buffer )
de_state *s;
char *buffer;
{
off_t end_addr = (long) s->device_size * K - 1;
off_t block_addr;
if ( s->address < 0 )
s->address = 0L;
if ( s->address > end_addr )
s->address = end_addr;
/* The address must be rounded off for */
/* certain visual display modes. */
if ( s->mode == WORD )
s->address &= ~1L;
else if ( s->mode == MAP )
s->address &= ~3L;
block_addr = s->address & K_MASK;
s->block = (unsigned) (block_addr >> K_SHIFT);
s->offset = (unsigned) (s->address - block_addr);
Read_Disk( s, block_addr, buffer );
}
/****************************************************************/
/* */
/* Read_Super_Block( state ) */
/* */
/* Read and check the super block. */
/* */
/****************************************************************/
void Read_Super_Block( s )
de_state *s;
{
struct super_block *super = (struct super_block *) s->buffer;
Read_Disk( s, (long) 1 * K, s->buffer );
s->inodes = super->s_ninodes;
s->zones = super->s_nzones;
s->inode_maps = bitmapsize(1 + s->inodes);
s->zone_maps = bitmapsize(s->zones);
s->inode_blocks = (s->inodes + INODES_PER_BLOCK - 1) / INODES_PER_BLOCK;
s->first_data = 2 + s->inode_maps + s->zone_maps + s->inode_blocks;
s->inodes_in_map = s->inodes + 1;
s->zones_in_map = s->zones + 1 - s->first_data;
/*
if ( s->zones != s->device_size )
Warning( "Zone count does not equal device size" );
*/
s->device_size = s->zones;
if ( s->inode_maps != super->s_imap_blocks )
Warning( "Corrupted inode map count in super block" );
if ( s->zone_maps != super->s_zmap_blocks )
Warning( "Corrupted zone map count in super block" );
if ( s->first_data != super->s_firstdatazone )
Warning( "Corrupted first data zone count in super block" );
if ( super->s_log_zone_size != 0 )
Warning( "Can not handle multiple blocks per zone" );
if ( super->s_magic != SUPER_MAGIC )
Warning( "Corrupted magic number in super block" );
}
/****************************************************************/
/* */
/* Read_Bit_Maps( state ) */
/* */
/* Read in the i-node and zone bit maps from the */
/* specified file system device. */
/* */
/****************************************************************/
void Read_Bit_Maps( s )
de_state *s;
{
int i;
if ( s->inode_maps > I_MAP_SLOTS || s->zone_maps > ZMAP_SLOTS )
{
Warning( "Super block specifies too many bit map blocks" );
return;
}
for ( i = 0; i < s->inode_maps; ++i )
{
Read_Disk( s, (long) (2 + i) * K, &s->inode_map[ i * K ] );
}
for ( i = 0; i < s->zone_maps; ++i )
{
Read_Disk( s, (long) (2 + s->inode_maps + i) * K, &s->zone_map[ i * K ] );
}
}
/****************************************************************/
/* */
/* Search( state, string ) */
/* */
/* Search from the current address for the ASCII */
/* "string" on the device. */
/* */
/****************************************************************/
off_t Search( s, string )
de_state *s;
char *string;
{
off_t address = s->address + 1;
off_t last_addr = address;
char buffer[ SEARCH_BUFFER ];
int offset;
int tail_length = strlen( string ) - 1;
int count = SEARCH_BUFFER;
int last_offset;
for ( ; count == SEARCH_BUFFER; address += SEARCH_BUFFER - tail_length )
{
if ( lseek( s->device_d, address, SEEK_SET ) == -1 )
Error( "Error seeking %s", s->device_name );
if ( (count = read( s->device_d, buffer, SEARCH_BUFFER)) == -1 )
Error( "Error reading %s", s->device_name );
if ( address - last_addr >= 500L * K )
{
putchar( '.' );
fflush( stdout );
last_addr += 500L * K;
}
last_offset = count - tail_length;
for ( offset = 0; offset < last_offset; ++offset )
{
register char c = buffer[ offset ];
if ( c == *string )
{
char *tail_buffer = &buffer[ offset + 1 ];
char *tail_string = string + 1;
do
{
if ( *tail_string == '\0' )
return( address + offset );
}
while ( *tail_buffer++ == *tail_string++ );
}
} /* end for ( offset ) */
} /* end for ( address ) */
return( -1L );
}
/****************************************************************/
/* */
/* Write_Word( state, word ) */
/* */
/* Write a word at address. */
/* */
/****************************************************************/
void Write_Word( s, word )
de_state *s;
unsigned word;
{
if ( s->address & 01 )
Error( "Internal fault (unaligned address)" );
if ( lseek( s->device_d, s->address, SEEK_SET ) == -1 )
Error( "Error seeking %s", s->device_name );
if ( write( s->device_d, (char *) &word, 2 ) != 2 )
Error( "Error writing %s", s->device_name );
}
/* The next routine is copied from fsck.c and mkfs.c... (Re)define some
* things for consistency. This sharing should be done better in a library
* library routine. In the library routine, the shifts should be replaced
* by multiplications and divisions by MAP_BITS_PER_BLOCK since log2 of
* this is too painful to get right.
*/
#define BITMAPSHIFT 13 /* = log2(MAP_BITS_PER_BLOCK) */
#define bit_nr unsigned
/* Convert from bit count to a block count. The usual expression
*
* (nr_bits + (1 << BITMAPSHIFT) - 1) >> BITMAPSHIFT
*
* doesn't work because of overflow.
*
* Other overflow bugs, such as the expression for N_ILIST overflowing when
* s_inodes is just over INODES_PER_BLOCK less than the maximum+1, are not
* fixed yet, because that number of inodes is silly.
*/
int bitmapsize(nr_bits)
bit_nr nr_bits;
{
int nr_blocks;
nr_blocks = nr_bits >> BITMAPSHIFT;
if ((nr_blocks << BITMAPSHIFT) < nr_bits)
++nr_blocks;
return(nr_blocks);
}