fdisk.c

这是一个同样来自贝尔实验室的和UNIX有着渊源的操作系统, 其简洁的设计和实现易于我们学习和理解

/*
 * fdisk - edit dos disk partition table
 */
#include <u.h>
#include <libc.h>
#include <bio.h>
#include <ctype.h>
#include <disk.h>
#include "edit.h"

typedef struct Dospart	Dospart;
enum {
	NTentry = 4,
	Mpart = 64,
};

static void rdpart(Edit*, ulong, ulong);
static void findmbr(Edit*);
static void autopart(Edit*);
static void wrpart(Edit*);
static void blankpart(Edit*);
static void cmdnamectl(Edit*);
static void recover(Edit*);
static int Dfmt(Fmt*);
static int blank;
static int dowrite;
static int file;
static int rdonly;
static int doauto;
static vlong mbroffset;
static int printflag;
static int printchs;
static int sec2cyl;
static int written;

static void 	cmdsum(Edit*, Part*, vlong, vlong);
static char 	*cmdadd(Edit*, char*, vlong, vlong);
static char 	*cmddel(Edit*, Part*);
static char 	*cmdext(Edit*, int, char**);
static char 	*cmdhelp(Edit*);
static char 	*cmdokname(Edit*, char*);
static char 	*cmdwrite(Edit*);
static void	cmdprintctl(Edit*, int);

#pragma varargck type "D" uchar*

Edit edit = {
	.add=	cmdadd,
	.del=		cmddel,
	.ext=		cmdext,
	.help=	cmdhelp,
	.okname=	cmdokname,
	.sum=	cmdsum,
	.write=	cmdwrite,
	.printctl=	cmdprintctl,

	.unit=	"cylinder",
};

/*
 * Catch the obvious error routines to fix up the disk.
 */
void
sysfatal(char *fmt, ...)
{
	char buf[1024];
	va_list arg;

	va_start(arg, fmt);
	vseprint(buf, buf+sizeof(buf), fmt, arg);
	va_end(arg);
	if(argv0)
		fprint(2, "%s: %s\n", argv0, buf);
	else
		fprint(2, "%s\n", buf);

	if(written)
		recover(&edit);

	exits(buf);
}

void
abort(void)
{
	fprint(2, "abort\n");
	recover(&edit);
}

void
usage(void)
{
	fprint(2, "usage: disk/fdisk [-abfprvw] [-s sectorsize] /dev/sdC0/data\n");
	exits("usage");
}

void
main(int argc, char **argv)
{
	vlong secsize;

	secsize = 0;
	ARGBEGIN{
	case 'a':
		doauto++;
		break;
	case 'b':
		blank++;
		break;
	case 'f':
		file++;
		break;
	case 'p':
		printflag++;
		break;
	case 'r':
		rdonly++;
		break;
	case 's':
		secsize = atoi(ARGF());
		break;
	case 'v':
		printchs++;
		break;
	case 'w':
		dowrite++;
		break;
	}ARGEND;

	fmtinstall('D', Dfmt);

	if(argc != 1)
		usage();

	edit.disk = opendisk(argv[0], rdonly, file);
	if(edit.disk == nil) {
		fprint(2, "cannot open disk: %r\n");
		exits("opendisk");
	}

	if(secsize != 0) {
		edit.disk->secsize = secsize;
		edit.disk->secs = edit.disk->size / secsize;
	}

	sec2cyl = edit.disk->h * edit.disk->s;
	edit.end = edit.disk->secs / sec2cyl;

	findmbr(&edit);

	if(blank)
		blankpart(&edit);
	else
		rdpart(&edit, 0, 0);

	if(doauto)
		autopart(&edit);

	if(dowrite)
		runcmd(&edit, "w");

	if(printflag)
		runcmd(&edit, "P");

	if(dowrite || printflag)
		exits(0);

	fprint(2, "cylinder = %lld bytes\n", sec2cyl*edit.disk->secsize);
	runcmd(&edit, "p");
	for(;;) {
		fprint(2, ">>> ");
		runcmd(&edit, getline(&edit));
	}
}

typedef struct Tentry	Tentry;
typedef struct Table	Table;
typedef struct Type	Type;
typedef struct Tab	Tab;
typedef struct Recover Recover;

struct Tentry {
	uchar	active;			/* active flag */
	uchar	starth;			/* starting head */
	uchar	starts;			/* starting sector */
	uchar	startc;			/* starting cylinder */
	uchar	type;			/* partition type */
	uchar	endh;			/* ending head */
	uchar	ends;			/* ending sector */
	uchar	endc;			/* ending cylinder */
	uchar	xlba[4];		/* starting LBA from beginning of disc or ext. partition */
	uchar	xsize[4];		/* size in sectors */
};

enum {
	Active		= 0x80,		/* partition is active */
	Primary		= 0x01,		/* internal flag */

	TypeBB		= 0xFF,

	TypeEMPTY	= 0x00,
	TypeFAT12	= 0x01,
	TypeXENIX	= 0x02,		/* root */
	TypeXENIXUSR	= 0x03,		/* usr */
	TypeFAT16	= 0x04,
	TypeEXTENDED	= 0x05,
	TypeFATHUGE	= 0x06,
	TypeHPFS	= 0x07,
	TypeAIXBOOT	= 0x08,
	TypeAIXDATA	= 0x09,
	TypeOS2BOOT	= 0x0A,		/* OS/2 Boot Manager */
	TypeFAT32	= 0x0B,		/* FAT 32 */
	TypeFAT32LBA	= 0x0C,		/* FAT 32 needing LBA support */
	TypeFAT16X	= 0x0E,		/* FAT 16 needing LBA support */
	TypeEXTHUGE	= 0x0F,		/* FAT 32 extended partition */
	TypeUNFORMATTED	= 0x16,		/* unformatted primary partition (OS/2 FDISK)? */
	TypeHPFS2	= 0x17,
	TypeIBMRecovery = 0x1C,		/* really hidden fat */
	TypeCPM0	= 0x52,
	TypeDMDDO	= 0x54,		/* Disk Manager Dynamic Disk Overlay */
	TypeGB		= 0x56,		/* ???? */
	TypeSPEEDSTOR	= 0x61,
	TypeSYSV386	= 0x63,		/* also HURD? */
	TypeNETWARE	= 0x64,
	TypePCIX	= 0x75,
	TypeMINIX13	= 0x80,		/* Minix v1.3 and below */
	TypeMINIX	= 0x81,		/* Minix v1.5+ */
	TypeLINUXSWAP	= 0x82,
	TypeLINUX	= 0x83,
	TypeLINUXEXT	= 0x85,
	TypeAMOEBA	= 0x93,
	TypeAMOEBABB	= 0x94,
	TypeBSD386	= 0xA5,
	TypeBSDI	= 0xB7,
	TypeBSDISWAP	= 0xB8,
	TypeOTHER	= 0xDA,
	TypeCPM		= 0xDB,
	TypeDellRecovery= 0xDE,
	TypeSPEEDSTOR12	= 0xE1,
	TypeSPEEDSTOR16	= 0xE4,
	TypeLANSTEP	= 0xFE,

	Type9		= 0x39,

	Toffset		= 446,		/* offset of partition table in sector */
	Magic0		= 0x55,
	Magic1		= 0xAA,
};

struct Table {
	Tentry	entry[NTentry];
	uchar	magic[2];
};

struct Type {
	char *desc;
	char *name;
};

struct Dospart {
	Part;
	Tentry;

	u32int	lba;
	u32int	size;
	int		primary;
};

struct Recover {
	Table	table;
	ulong	lba;
};

static Type types[256] = {
	[TypeEMPTY]		{ "EMPTY", "" },
	[TypeFAT12]		{ "FAT12", "dos" },
	[TypeFAT16]		{ "FAT16", "dos" },
	[TypeFAT32]		{ "FAT32", "dos" },
	[TypeFAT32LBA]		{ "FAT32LBA", "dos" },
	[TypeFAT16X]		{ "FAT16X", "dos" },
	[TypeEXTHUGE]		{ "EXTHUGE", "" },
	[TypeIBMRecovery]	{ "IBMRECOVERY", "ibm" },
	[TypeEXTENDED]		{ "EXTENDED", "" },
	[TypeFATHUGE]		{ "FATHUGE", "dos" },
	[TypeBB]		{ "BB", "bb" },

	[TypeXENIX]		{ "XENIX", "xenix" },
	[TypeXENIXUSR]		{ "XENIX USR", "xenixusr" },
	[TypeHPFS]		{ "HPFS", "ntfs" },
	[TypeAIXBOOT]		{ "AIXBOOT", "aixboot" },
	[TypeAIXDATA]		{ "AIXDATA", "aixdata" },
	[TypeOS2BOOT]		{ "OS/2BOOT", "os2boot" },
	[TypeUNFORMATTED]	{ "UNFORMATTED", "" },
	[TypeHPFS2]		{ "HPFS2", "hpfs2" },
	[TypeCPM0]		{ "CPM0", "cpm0" },
	[TypeDMDDO]		{ "DMDDO", "dmdd0" },
	[TypeGB]		{ "GB", "gb" },
	[TypeSPEEDSTOR]		{ "SPEEDSTOR", "speedstor" },
	[TypeSYSV386]		{ "SYSV386", "sysv386" },
	[TypeNETWARE]		{ "NETWARE", "netware" },
	[TypePCIX]		{ "PCIX", "pcix" },
	[TypeMINIX13]		{ "MINIXV1.3", "minix13" },
	[TypeMINIX]		{ "MINIXV1.5", "minix15" },
	[TypeLINUXSWAP]		{ "LINUXSWAP", "linuxswap" },
	[TypeLINUX]		{ "LINUX", "linux" },
	[TypeLINUXEXT]		{ "LINUXEXTENDED", "" },
	[TypeAMOEBA]		{ "AMOEBA", "amoeba" },
	[TypeAMOEBABB]		{ "AMOEBABB", "amoebaboot" },
	[TypeBSD386]		{ "BSD386", "bsd386" },
	[TypeBSDI]		{ "BSDI", "bsdi" },
	[TypeBSDISWAP]		{ "BSDISWAP", "bsdiswap" },
	[TypeOTHER]		{ "OTHER", "other" },
	[TypeCPM]		{ "CPM", "cpm" },
	[TypeDellRecovery]	{ "DELLRECOVERY", "dell" },
	[TypeSPEEDSTOR12]	{ "SPEEDSTOR12", "speedstor" },
	[TypeSPEEDSTOR16]	{ "SPEEDSTOR16", "speedstor" },
	[TypeLANSTEP]		{ "LANSTEP", "lanstep" },

	[Type9]			{ "PLAN9", "plan9" },
};

static Dospart	part[Mpart];
static int		npart;

static char*
typestr0(int type)
{
	static char buf[100];

	sprint(buf, "type %d", type);
	if(type < 0 || type >= 256)
		return buf;
	if(types[type].desc == nil)
		return buf;
	return types[type].desc;
}

static u32int
getle32(void* v)
{
	uchar *p;

	p = v;
	return (p[3]<<24)|(p[2]<<16)|(p[1]<<8)|p[0];
}

static void
putle32(void* v, u32int i)
{
	uchar *p;

	p = v;
	p[0] = i;
	p[1] = i>>8;
	p[2] = i>>16;
	p[3] = i>>24;
}

static void
diskread(Disk *disk, void *data, int ndata, u32int sec, u32int off)
{
	if(seek(disk->fd, (vlong)sec*disk->secsize+off, 0) != (vlong)sec*disk->secsize+off)
		sysfatal("diskread seek %lud.%lud: %r", (ulong)sec, (ulong)off);
	if(readn(disk->fd, data, ndata) != ndata)
		sysfatal("diskread %lud at %lud.%lud: %r", (ulong)ndata, (ulong)sec, (ulong)off);
}

static int
diskwrite(Disk *disk, void *data, int ndata, u32int sec, u32int off)
{
	written = 1;
	if(seek(disk->wfd, (vlong)sec*disk->secsize+off, 0) != (vlong)sec*disk->secsize+off)
		goto Error;
	if(write(disk->wfd, data, ndata) != ndata)
		goto Error;
	return 0;

Error:
	fprint(2, "write %d bytes at %lud.%lud failed: %r\n", ndata, (ulong)sec, (ulong)off);
	return -1;
}

static Dospart*
mkpart(char *name, int primary, u32int lba, u32int size, Tentry *t)
{
	static int n;
	Dospart *p;

	p = emalloc(sizeof(*p));
	if(name)
		p->name = estrdup(name);
	else{
		p->name = emalloc(20);
		sprint(p->name, "%c%d", primary ? 'p' : 's', ++n);
	}

	if(t)
		p->Tentry = *t;
	else
		memset(&p->Tentry, 0, sizeof(Tentry));

	p->changed = 0;
	p->start = lba/sec2cyl;
	p->end = (lba+size)/sec2cyl;
	p->ctlstart = lba;
	p->ctlend = lba+size;
	p->lba = lba;
	p->size = size;
	p->primary = primary;
	return p;
}

/*
 * Recovery takes care of remembering what the various tables
 * looked like when we started, attempting to restore them when
 * we are finished.
 */
static Recover	*rtab;
static int		nrtab;

static void
addrecover(Table t, ulong lba)
{
	if((nrtab%8) == 0) {
		rtab = realloc(rtab, (nrtab+8)*sizeof(rtab[0]));
		if(rtab == nil)
			sysfatal("out of memory");
	}
	rtab[nrtab] = (Recover){t, lba};
	nrtab++;
}

static void
recover(Edit *edit)
{
	int err, i, ctlfd;
	vlong offset;

	err = 0;
	for(i=0; i<nrtab; i++)
		if(diskwrite(edit->disk, &rtab[i].table, sizeof(Table), rtab[i].lba, Toffset) < 0)
			err = 1;
	if(err) {
		fprint(2, "warning: some writes failed during restoration of old partition tables\n");
		exits("inconsistent");
	} else {
		fprint(2, "restored old partition tables\n");
	}

	ctlfd = edit->disk->ctlfd;
	offset = edit->disk->offset;
	if(ctlfd >= 0){
		for(i=0; i<edit->npart; i++)
			if(edit->part[i]->ctlname && fprint(ctlfd, "delpart %s", edit->part[i]->ctlname)<0)
				fprint(2, "delpart failed: %s: %r", edit->part[i]->ctlname);
		for(i=0; i<edit->nctlpart; i++)
			if(edit->part[i]->name && fprint(ctlfd, "delpart %s", edit->ctlpart[i]->name)<0)
				fprint(2, "delpart failed: %s: %r", edit->ctlpart[i]->name);
		for(i=0; i<edit->nctlpart; i++){
			if(fprint(ctlfd, "part %s %lld %lld", edit->ctlpart[i]->name,
				edit->ctlpart[i]->start+offset, edit->ctlpart[i]->end+offset) < 0){
				fprint(2, "restored disk partition table but not kernel; reboot\n");
				exits("inconsistent");
			}
		}
	}
	exits("restored");

}

/*
 * Read the partition table (including extended partition tables)
 * from the disk into the part array.
 */
static void
rdpart(Edit *edit, ulong lba, ulong xbase)
{
	char *err;
	Table table;
	Tentry *tp, *ep;
	Dospart *p;

	if(xbase == 0)
		xbase = lba;

	diskread(edit->disk, &table, sizeof table, mbroffset+lba, Toffset);
	addrecover(table, mbroffset+lba);

	if(table.magic[0] != Magic0 || table.magic[1] != Magic1) {
		assert(lba != 0);
		return;
	}

	for(tp=table.entry, ep=tp+NTentry; tp<ep && npart < Mpart; tp++) {
		switch(tp->type) {
		case TypeEMPTY:
			break;
		case TypeEXTENDED:
		case TypeEXTHUGE:
		case TypeLINUXEXT:
			rdpart(edit, xbase+getle32(tp->xlba), xbase);
			break;
		default:
			p = mkpart(nil, lba==0, lba+getle32(tp->xlba), getle32(tp->xsize), tp);
			if(err = addpart(edit, p))
				fprint(2, "adding partition: %s\n", err);
			break;
		}
	}
}

static void
blankpart(Edit *edit)
{
	edit->changed = 1;
}

static void
findmbr(Edit *edit)
{
	Table table;
	Tentry *tp;

	diskread(edit->disk, &table, sizeof(Table), 0, Toffset);
	if(table.magic[0] != Magic0 || table.magic[1] != Magic1)
		sysfatal("did not find master boot record");

	for(tp = table.entry; tp < &table.entry[NTentry]; tp++)
		if(tp->type == TypeDMDDO)
			mbroffset = edit->disk->s;
}

static int
haveroom(Edit *edit, int primary, vlong start)
{
	int i, lastsec, n;
	Dospart *p, *q;
	ulong pend, qstart;

	if(primary) {
		/*
		 * must be open primary slot.
		 * primary slots are taken by primary partitions
		 * and runs of secondary partitions.
		 */
		n = 0;
		lastsec = 0;
		for(i=0; i<edit->npart; i++) {
			p = (Dospart*)edit->part[i];
			if(p->primary)
				n++, lastsec=0;
			else if(!lastsec)
				n++, lastsec=1;
		}