#include <9pm/u.h>
#include <9pm/libc.h>
#include <9pm/fcall.h>
#include <9pm/ns.h>

void
validstat(uchar *s, int n)
{
	int m;
	char buf[64];

	if(statcheck(s, n) < 0)
		error("bad stat entry");
	/* verify that name entry is acceptable */
	s += STATFIXLEN - 4*BIT16SZ;	/* location of first string */
	/*
	 * s now points at count for first string.
	 * if it's too long, let the server decide; this is
	 * only for his protection anyway. otherwise
	 * we'd have to allocate and waserror.
	 */
	m = GBIT16(s);
	s += BIT16SZ;
	if(m+1 > sizeof buf)
		return;
	memmove(buf, s, m);
	buf[m] = '\0';
	/* name could be '/' */
	if(strcmp(buf, "/") != 0)
		validname(buf, 0);
}

/*
 * Rewrite channel type and dev for in-flight data to
 * reflect local values.  These entries are known to be
 * the first two in the Dir encoding after the count.
 */
void
mntdirfix(uchar *dirbuf, Mnt *mnt)
{
	uint r;

	r = mnt->dev->dc;
	dirbuf += BIT16SZ;	/* skip count */
	PBIT16(dirbuf, r);
	dirbuf += BIT16SZ;
	PBIT32(dirbuf, mnt->devid);
}

static char isfrog[256]={
	/*NUL*/	1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1,
	/*DLE*/	1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1,
	/*0x20*/	0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 1,	/* 0x2F = '/' */
	/*0x30*/	0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0,
	/*0x40*/	0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0,
	/*0x50*/	0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0,
	/*0x60*/	0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0,
	/*0x70*/	0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 1,	/* 0x7F = rubout */
};

/*
 * Check that the name
 *  a) is in valid memory (no-op here)
 *  b) is shorter than 2^16 bytes, so it can fit in a 9P string field.
 *  c) contains no frogs.
 * The first byte is known to be addressible by the requester, so the
 * routine works for kernel and user memory both.
 * The parameter slashok flags whether a slash character is an error
 * or a valid character.
 */
void
validname(char *name, int slashok)
{
	char *ename;
	int c;
	Rune r;

	ename = memchr(name, 0, (1<<16));

	if(ename==nil || ename-name>=(1<<16))
		error("name too long");

	while(*name){
		/* all characters above '~' are ok */
		c = *(uchar*)name;
		if(c >= Runeself)
			name += chartorune(&r, name);
		else{
			if(isfrog[c])
				if(!slashok || c!='/')
					error("bad character in file name");
			name++;
		}
	}
}

void
mntdirreadfix(uchar *p, int n, Mnt *mnt)
{
	int dirlen;
	uchar *e;

	for(e = &p[n]; p+BIT16SZ < e; p += dirlen){
		dirlen = BIT16SZ+GBIT16(p);
		if(p+dirlen > e)
			break;
		validstat(p, dirlen);
		mntdirfix(p, mnt);
	}
	if(p != e)
		error("bad directory entry in directory read");
}