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mtools_3.6.src.lzh
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MTOOLS_3.6
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init.c
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1997-11-12
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/*
* Initialize an MSDOS diskette. Read the boot sector, and switch to the
* proper floppy disk device to match the format on the disk. Sets a bunch
* of global variables. Returns 0 on success, or 1 on failure.
*/
#include "sysincludes.h"
#include "msdos.h"
#include "stream.h"
#include "mtools.h"
#include "fsP.h"
#include "plain_io.h"
#include "xdf_io.h"
#include "buffer.h"
extern int errno;
#define FULL_CYL
unsigned int num_clus; /* total number of cluster */
#ifndef linux
#define BOOTSIZE 512
#else
#define BOOTSIZE 256
#endif
/*
* Read the boot sector. We glean the disk parameters from this sector.
*/
static int read_boot(Stream_t *Stream, struct bootsector * boot)
{
/* read the first sector, or part of it */
if (force_read(Stream, (char *) boot, 0, BOOTSIZE) !=
BOOTSIZE)
return -1;
return 0;
}
static int fs_flush(Stream_t *Stream)
{
DeclareThis(Fs_t);
fat_write(This);
return 0;
}
Class_t FsClass = {
read_pass_through, /* read */
write_pass_through, /* write */
fs_flush,
0, /* free */
0, /* set geometry */
get_data_pass_through
};
static int get_media_type(Stream_t *St, struct bootsector *boot)
{
int media;
media = boot->descr;
if(media < 0xf0){
char temp[512];
/* old DOS disk. Media descriptor in the first FAT byte */
/* old DOS disk always have 512-byte sectors */
if (force_read(St,temp,512,512) == 512)
media = (unsigned char) temp[0];
else
media = 0;
} else
media += 0x100;
return media;
}
Stream_t *GetFs(Stream_t *Fs)
{
while(Fs && Fs->Class != &FsClass)
Fs = Fs->Next;
return Fs;
}
Stream_t *find_device(char drive, int mode, struct device *out_dev,
struct bootsector *boot,
char *name, int *media)
{
char errmsg[80];
Stream_t *Stream;
struct device *dev;
Stream = NULL;
sprintf(errmsg, "Drive '%c:' not supported", drive);
/* open the device */
for (dev=devices; dev->name; dev++) {
FREE(&Stream);
if (dev->drive != drive)
continue;
*out_dev = *dev;
expand(dev->name,name);
#ifdef USE_XDF
Stream = XdfOpen(out_dev, name, mode, errmsg, 0);
#else
Stream = 0;
#endif
if (!Stream)
Stream = SimpleFileOpen(out_dev, dev, name, mode,
errmsg, 0);
else
out_dev->use_2m = 0x7f;
if( !Stream)
continue;
/* read the boot sector */
if (read_boot(Stream, boot)){
sprintf(errmsg,
"init %c: could not read boot sector",
drive);
continue;
}
if((*media= get_media_type(Stream, boot)) <= 0xf0 ){
sprintf(errmsg,"init %c: unknown media type", drive);
continue;
}
/* set new parameters, if needed */
errno = 0;
if(SET_GEOM(Stream, out_dev, dev, *media, boot)){
sprintf(errmsg, "Can't set disk parameters for %c: %s",
drive, strerror(errno));
continue;
}
break;
}
/* print error msg if needed */
if ( dev->drive == 0 ){
FREE(&Stream);
fprintf(stderr,"%s\n",errmsg);
return NULL;
}
return Stream;
}
Stream_t *fs_init(char drive, int mode)
{
int media,i;
int nhs;
int disk_size = 0; /* In case we don't happen to set this below */
size_t tot_sectors;
char name[EXPAND_BUF];
int cylinder_size;
struct device dev;
struct bootsector boot0;
#define boot (&boot0)
Fs_t *This;
This = New(Fs_t);
if (!This)
return NULL;
This->Direct = NULL;
This->Next = NULL;
This->refs = 1;
This->Buffer = 0;
This->Class = &FsClass;
This->drive = drive;
This->Direct = find_device(drive, mode, &dev, &boot0, name, &media);
if(!This->Direct)
return NULL;
This->sector_size = WORD(secsiz);
if(This->sector_size > MAX_SECTOR){
fprintf(stderr,"init %c: sector size too big\n", drive);
return NULL;
}
cylinder_size = dev.heads * dev.sectors;
This->serialized = 0;
if ((media & ~7) == 0xf8){
i = media & 3;
This->cluster_size = old_dos[i].cluster_size;
tot_sectors = cylinder_size * old_dos[i].tracks;
This->fat_start = 1;
This->fat_len = old_dos[i].fat_len;
This->dir_len = old_dos[i].dir_len;
This->num_fat = 2;
This->sector_size = 512;
This->fat_bits = 12;
nhs = 0;
} else {
/*
* all numbers are in sectors, except num_clus
* (which is in clusters)
*/
tot_sectors = WORD(psect);
if(!tot_sectors) {
tot_sectors = DWORD(bigsect);
nhs = DWORD(nhs);
} else
nhs = WORD(nhs);
if(boot0.ext.old.dos4 == 0x29 && WORD(fatlen)) {
This->serialized = 1;
This->serial_number = DWORD(ext.old.serial);
}
This->cluster_size = boot0.clsiz;
This->fat_start = WORD(nrsvsect);
This->fat_len = WORD(fatlen);
This->dir_len = WORD(dirents) * MDIR_SIZE / This->sector_size;
This->num_fat = boot0.nfat;
}
cylinder_size = dev.sectors * dev.heads;
if(!mtools_skip_check && (tot_sectors % dev.sectors)){
fprintf(stderr,
"Total number of sectors not a multiple of"
" sectors per track!\n");
exit(1);
}
/* full cylinder buffering */
#ifdef FULL_CYL
disk_size = (dev.tracks) ? cylinder_size : 512;
#else /* FULL_CYL */
disk_size = (dev.tracks) ? dev.sectors : 512;
#endif /* FULL_CYL */
#if (defined sysv4 && !defined(solaris))
/*
* The driver in Dell's SVR4 v2.01 is unreliable with large writes.
*/
disk_size = 0;
#endif /* (defined sysv4 && !defined(solaris)) */
#ifdef linux
disk_size = cylinder_size;
#endif
#if 1
if(disk_size > 256) {
disk_size = dev.sectors;
if(dev.sectors % 2)
disk_size <<= 1;
}
#endif
if (disk_size % 2)
disk_size *= 2;
if (disk_size)
This->Next = buf_init(This->Direct,
disk_size * This->sector_size,
This->sector_size,
disk_size * This->sector_size);
else
This->Next = This->Direct;
if (This->Next == NULL) {
perror("init: allocate buffer");
This->Next = This->Direct;
}
/* read the FAT sectors */
if(fat_read(This, &boot0, dev.fat_bits, tot_sectors, dev.use_2m&0x7f)){
This->num_fat = 1;
FREE(&This->Next);
Free(This->Next);
return NULL;
}
return (Stream_t *) This;
}