part.c

操作系统源代码

	if (device < 0) {
		/* No device open?  Then try to read first. */
		event('r', op);
		if (device < 0) return;
	}

	near= op;
	dist= -1;

	for (op2= world; op2 != nil; op2= op2->next) {
		if (op2 == op || !(op2->flags & OF_MOD)) continue;

		dr= abs(op2->row - op->row);
		dc= abs(op2->col - op->col);

		d2= 25*dr*dr + dc*dc;
		if (op2->row != op->row && op2->col != op->col) d2+= 1000;

		switch (ev) {
		case 'h':	/* Left */
			if (op2->col >= op->col) d2= -1;
			break;
		case 'j':	/* Down */
			if (op2->row <= op->row) d2= -1;
			break;
		case 'k':	/* Up */
			if (op2->row >= op->row) d2= -1;
			break;
		case 'l':	/* Right */
			if (op2->col <= op->col) d2= -1;
			break;
		case 'H':	/* Home */
			if (op2->type == O_DEV) d2= 0;
		}
		if (d2 < dist) { near= op2; dist= d2; }
	}
	if (near != op) event(E_LEAVE, op);
	event(E_ENTER, near);
}

void m_updown(int ev, object_t *op)
/* Move a partition table entry up or down. */
{
	int i, j;
	struct part_entry tmp;
	int tmpx;

	if (ev != ctrl('K') && ev != ctrl('J')) return;
	if (op->entry == nil) return;

	i= op->entry - table;
	if (ev == ctrl('K')) {
		if (i <= 1) return;
		j= i-1;
	} else {
		if (i >= NR_PARTITIONS) return;
		j= i+1;
	}

	tmp= table[i]; table[i]= table[j]; table[j]= tmp;
	tmpx= existing[i]; existing[i]= existing[j]; existing[j]= tmpx;
	sort();
	dirty= 1;
	event(ev == ctrl('K') ? 'k' : 'j', op);
}

void m_enter(int ev, object_t *op)
/* We've moved onto this object. */
{
	if (ev != E_ENTER && ev != ' ' && ev != '<' && ev != '>' && ev != 'X')
		return;
	curobj= op;
	typing= 0;
	magic= 0;
}

void m_leave(int ev, object_t *op)
/* About to leave this object. */
{
	if (ev != E_LEAVE) return;
}

int within(unsigned *var, unsigned low, unsigned value, unsigned high)
/* Only set *var to value if it looks reasonable. */
{
	if (low <= value && value <= high) {
		*var= value;
		return 1;
	} else
		return 0;
}

int lwithin(unsigned long *var, unsigned long low, unsigned long value,
							unsigned long high)
{
	if (low <= value && value <= high) {
		*var= value;
		return 1;
	} else
		return 0;
}

int nextdevice(object_t *op, int delta)
/* Select the next or previous device from the device list. */
{
	dev_t rdev;

	if (offset != 0) return 0;
	if (dirty) event(E_WRITE, op);
	if (dirty) return 0;

	if (device >= 0) {
		(void) close(device);
		device= -1;
	}
	recompute0();

	rdev= curdev->rdev;
	if (delta < 0) {
		do
			curdev= curdev->prev;
		while (delta < -1 && major(curdev->rdev) == major(rdev)
			&& curdev->rdev < rdev);
	} else {
		do
			curdev= curdev->next;
		while (delta > 1 && major(curdev->rdev) == major(rdev)
			&& curdev->rdev > rdev);
	}
	return 1;
}

void check_ind(struct part_entry *pe)
/* If there are no other partitions then make this new one active. */
{
	struct part_entry *pe2;

	if (pe->sysind != NO_PART) return;

	for (pe2= table + 1; pe2 < table + 1 + NR_PARTITIONS; pe2++)
		if (pe2->sysind != NO_PART || pe2->bootind & ACTIVE_FLAG) break;

	if (pe2 == table + 1 + NR_PARTITIONS) pe->bootind= ACTIVE_FLAG;
}

int check_existing(struct part_entry *pe)
/* Check and if not ask if an existing partition may be modified. */
{
	static int expert= 0;
	int c;

	if (expert || pe == nil || !existing[pe - table]) return 1;

	stat_start(1);
	putstr("Do you wish to modify existing partitions? (y/n) ");
	fflush(stdout);
	while ((c= getchar()) != 'y' && c != 'n') {}
	putchr(c);
	stat_end(3);
	return (expert= (c == 'y'));
}

void m_modify(int ev, object_t *op)
/* Increment, decrement, set, or toggle the value of an object, using
 * arithmetic tricks the author doesn't understand either.
 */
{
	object_t *op2;
	struct part_entry *pe= op->entry;
	int mul, delta;
	unsigned level= 1;
	unsigned long surplus;
	int radix= op->type == O_TYPHEX ? 0x10 : 10;
	unsigned long t;

	if (device < 0 && op->type != O_DEV) return;

	switch (ev) {
	case '-':
		mul= radix; delta= -1; typing= 0;
		break;
	case '+':
		mul= radix; delta= 1; typing= 0;
		break;
	case '\b':
		if (!typing) return;
		mul= 1; delta= 0;
		break;
	case '\r':
		typing= 0;
		return;
	default:
		if ('0' <= ev && ev <= '9')
			delta= ev - '0';
		else
		if (radix == 0x10 && 'a' <= ev && ev <= 'f')
			delta= ev - 'a' + 10;
		else
		if (radix == 0x10 && 'A' <= ev && ev <= 'F')
			delta= ev - 'A' + 10;
		else
			return;

		mul= typing ? radix*radix : 0;
		typing= 1;
	}
	magic= 0;

	if (!check_existing(pe)) return;

	switch (op->type) {
	case O_DEV:
		if (ev != '-' && ev != '+') return;
		if (!nextdevice(op, delta)) return;
		break;
	case O_CYL:
		if (!within(&cylinders, 1,
			cylinders * mul / radix + delta, 1024)) return;
		recompute0();
		break;
	case O_HEAD:
		if (!within(&heads, 1, heads * mul / radix + delta, 255))
			return;
		recompute0();
		break;
	case O_SEC:
		if (!within(&sectors, 1, sectors * mul / radix + delta, 63))
			return;
		recompute0();
		break;
	case O_NUM:
		if (ev != '-' && ev != '+') return;
		for (op2= world; op2 != nil; op2= op2->next) {
			if (op2->type == O_NUM && ev == '+')
				op2->entry->bootind= 0;
		}
		op->entry->bootind= ev == '+' ? ACTIVE_FLAG : 0;
		break;
	case O_TYPHEX:
		check_ind(pe);
		pe->sysind= pe->sysind * mul / radix + delta;
		break;
	case O_TYPTXT:
		if (ev != '-' && ev != '+') return;
		check_ind(pe);
		pe->sysind= round_sysind(pe->sysind, delta);
		break;
	case O_SCYL:
		level= heads;
	case O_SHEAD:
		level*= sectors;
	case O_SSEC:
		if (op->type != O_SCYL && ev != '-' && ev != '+') return;
	case O_BASE:
		if (pe->sysind == NO_PART) memset(pe, 0, sizeof(*pe));
		t= pe->lowsec;
		surplus= t % level;
		if (!lwithin(&t, 0L,
			(t / level * mul / radix + delta) * level + surplus,
			MAXSIZE)) return;
		if (howend == LAST || op->type != O_BASE)
			pe->size-= t - pe->lowsec;
		pe->lowsec= t;
		check_ind(pe);
		if (pe->sysind == NO_PART) pe->sysind= MINIX_PART;
		break;
	case O_LCYL:
		level= heads;
	case O_LHEAD:
		level*= sectors;
	case O_LSEC:
		if (op->type != O_LCYL && ev != '-' && ev != '+') return;

		if (pe->sysind == NO_PART) memset(pe, 0, sizeof(*pe));
		t= pe->lowsec + pe->size - 1 + level;
		surplus= t % level - mul / radix * level;
		if (!lwithin(&t, 0L,
			(t / level * mul / radix + delta) * level + surplus,
			MAXSIZE)) return;
		pe->size= t - pe->lowsec + 1;
		check_ind(pe);
		if (pe->sysind == NO_PART) pe->sysind= MINIX_PART;
		break;
	case O_KB:
		level= 2;
		if (mul == 0) pe->size= 0;	/* new value, no surplus */
	case O_SIZE:
		if (pe->sysind == NO_PART) {
			if (op->type == O_KB || howend == SIZE) {
				/* First let loose magic to set the base. */
				event('m', op);
				magic= 0;
				pe->size= 0;
				event(ev, op);
				return;
			}
			memset(pe, 0, sizeof(*pe));
		}
		t= (op->type == O_KB || howend == SIZE) ? pe->size
						: pe->lowsec + pe->size - 1;
		surplus= t % level;
		if (!lwithin(&t, 0L,
			(t / level * mul / radix + delta) * level + surplus,
			MAXSIZE)) return;
		pe->size= (op->type == O_KB || howend == SIZE) ? t :
							t - pe->lowsec + 1;
		check_ind(pe);
		if (pe->sysind == NO_PART) pe->sysind= MINIX_PART;
		break;
	default:
		return;
	}

	/* The order among the entries may have changed. */
	sort();
	dirty= 1;
}

unsigned long spell[3 + 4 * (1+NR_PARTITIONS)];
int nspells;
objtype_t touching;

void newspell(unsigned long charm)
/* Add a new spell, descending order for the base, ascending for the size. */
{
	int i, j;

	if (charm - table[0].lowsec > table[0].size) return;

	for (i= 0; i < nspells; i++) {
		if (charm == spell[i]) return;	/* duplicate */

		if (touching == O_BASE) {
			if (charm == table[0].lowsec + table[0].size) return;
			if ((spell[0] - charm) < (spell[0] - spell[i])) break;
		} else {
			if (charm == table[0].lowsec) return;
			if ((charm - spell[0]) < (spell[i] - spell[0])) break;
		}
	}
	for (j= ++nspells; j > i; j--) spell[j]= spell[j-1];
	spell[i]= charm;
}

void m_magic(int ev, object_t *op)
/* Apply magic onto a base or size number. */
{
	struct part_entry *pe= op->entry, *pe2;
	int rough= (offset != 0 && extbase == 0);

	if (ev != 'm' || device < 0) return;
	typing= 0;

	if (!check_existing(pe)) return;

	if (magic == 0) {
		/* See what magic we can let loose on this value. */
		nspells= 1;

		/* First spell, the current value. */
		switch (op->type) {
		case O_SCYL:
		case O_SHEAD:	/* Start of partition. */
		case O_SSEC:
		case O_BASE:
			touching= O_BASE;
			spell[0]= pe->lowsec;
			break;
		case O_LCYL:
		case O_LHEAD:
		case O_LSEC:	/* End of partition. */
		case O_KB:
		case O_SIZE:
			touching= O_SIZE;
			spell[0]= pe->lowsec + pe->size;
			break;
		default:
			return;
		}
		if (pe->sysind == NO_PART) {
			memset(pe, 0, sizeof(*pe));
			check_ind(pe);
			pe->sysind= MINIX_PART;
			spell[0]= 0;
			if (touching == O_SIZE) {
				/* First let loose magic on the base. */
				object_t *op2;

				for (op2= world; op2 != nil; op2= op2->next) {
					if (op2->row == op->row &&
							op2->type == O_BASE) {
						event('m', op2);
					}
				}
				magic= 0;
				event('m', op);
				return;
			}
		}
		/* Avoid the first sector on the device. */
		if (spell[0] == table[0].lowsec) newspell(spell[0] + 1);

		/* Further interesting values are the the bases of other
		 * partitions or their ends.
		 */
		for (pe2= table; pe2 < table + 1 + NR_PARTITIONS; pe2++) {
			if (pe2 == pe || pe2->sysind == NO_PART) continue;
			if (pe2->lowsec == table[0].lowsec)
				newspell(table[0].lowsec + 1);
			else
				newspell(pe2->lowsec);
			newspell(pe2->lowsec + pe2->size);
			if (touching == O_BASE && howend == SIZE) {
				newspell(pe2->lowsec - pe->size);
				newspell(pe2->lowsec + pe2->size - pe->size);
			}
			if (pe2->lowsec % sectors != 0) rough= 1;
		}
		/* Present values rounded up to the next cylinder unless
		 * the table is already a mess.  Use "start + 1 track" instead
		 * of "start + 1 cylinder".  Also add the end of the last
		 * cylinder.
		 */
		if (!rough) {
			unsigned long n= spell[0];
			if (n == table[0].lowsec) n++;
			n= (n + sectors - 1) / sectors * sectors;
			if (n != table[0].lowsec + sectors)
				n= (n + secpcyl - 1) / secpcyl * secpcyl;
			newspell(n);
			if (touching == O_SIZE)
				newspell(table[0].size / secpcyl * secpcyl);
		}
	}
	/* Magic has been applied, a spell needs to be chosen. */

	if (++magic == nspells) magic= 0;

	if (touching == O_BASE) {
		if (howend == LAST) pe->size-= spell[magic] - pe->lowsec;
		pe->lowsec= spell[magic];
	} else
		pe->size= spell[magic] - pe->lowsec;

	/* The order among the entries may have changed. */
	sort();
	dirty= 1;
}

typedef struct diving {
	struct diving	*up;
	struct part_entry  old0;
	char		*oldsubname;
	char		oldpart[6];
	parttype_t	oldparttype;
	unsigned long	oldoffset;
	unsigned long	oldextbase;
} diving_t;

diving_t *diving= nil;

void m_in(int ev, object_t *op)
/* Go down into a primary or extended partition. */
{
	diving_t *newdiv;
	struct part_entry *pe= op->entry, ext;
	int n;

	if (ev != '>' || device < 0 || pe == nil || pe == &table[0]
		|| (!(pe->sysind == MINIX_PART && offset == 0)
					&& pe->sysind != EXT_PART)
		|| pe->size == 0) return;

	ext= *pe;
	if (extbase != 0) ext.size= extbase + extsize - ext.lowsec;

	if (dirty) event(E_WRITE, op);
	if (dirty) return;
	if (device >= 0) { close(device); device= -1; }

	newdiv= alloc(sizeof(*newdiv));
	newdiv->old0= table[0];
	newdiv->oldsubname= curdev->subname;
	strcpy(newdiv->oldpart, curdev->part);
	newdiv->oldparttype= curdev->parttype;
	newdiv->oldoffset= offset;
	newdiv->oldextbase= extbase;
	newdiv->up= diving;
	diving= newdiv;

	table[0]= ext;

	n= strlen(diving->oldsubname);
	curdev->subname= alloc((n + 3) * sizeof(curdev->subname[0]));
	strcpy(curdev->subname, diving->oldsubname);
	curdev->subname[n++]= ':';
	curdev->subname[n++]= '0' + (pe - table);
	curdev->subname[n]= 0;

	if (curdev->parttype != DUNNO) curdev->parttype--;
	offset= ext.lowsec;
	if (ext.sysind == EXT_PART && extbase == 0) {
		extbase= ext.lowsec;
		extsize= ext.size;
		curdev->parttype= DUNNO;
	}
	if (curdev->parttype == SUBPART) {
		n= strlen(curdev->part);
		if (n == 5) { strcpy(curdev->part, curdev->part + 1); n--; }
		curdev->part[n-1] += sort_index[pe - table];
	}

	submerged= 1;
	event('r', op);
}

void m_out(int ev, object_t *op)
/* Go up from an extended or subpartition table to its enclosing. */
{
	diving_t *olddiv;