Subversion Repositories planix.SVN

#include <u.h>

#include <libc.h>

#include <bio.h>

#include <libsec.h>

#include "iso9660.h"

/*

 * Add the requisite path tables to the CD image.

 * They get put on the end once everything else is done.

 * We use the path table itself as a queue in the breadth-first

 * traversal of the tree.  

 *

 * The only problem with this is that the path table does not

 * store the lengths of the directories.  So we keep an explicit

 * map in an array in memory.

 */

enum {

	Big,

	Little

};

static void

Crdpath(Cdimg *cd, Cpath *p)

{

	p->namelen = Cgetc(cd);

	if(p->namelen == 0) {

		Crseek(cd, (Croffset(cd)+Blocksize-1)/Blocksize * Blocksize);

		p->namelen = Cgetc(cd);

		assert(p->namelen != 0);

	}

	p->xlen = Cgetc(cd);

	assert(p->xlen == 0);	/* sanity, might not be true if we start using the extended fields */

	Cread(cd, p->dloc, 4);

	Cread(cd, p->parent, 2);

	p->name[0] = '\0';

	Crseek(cd, Croffset(cd)+p->namelen+p->xlen+(p->namelen&1));	/* skip name, ext data */

}

static void

writepath(Cdimg *cd, Cdir *c, int parent, int size)

{

/*

	DO NOT UNCOMMENT THIS CODE.

	This commented-out code is here only so that no one comes

	along and adds it later.

	The ISO 9660 spec is silent about whether path table entries

	need to be padded so that they never cross block boundaries.

	It would be reasonable to assume that they are like every other

	data structure in the bloody spec; this code pads them out.

	Empirically, though, they're NOT padded.  Windows NT and

	derivatives are the only known current operating systems

	that actually read these things.

	int l;

	l = 1+1+4+2+c->namelen;

	if(Cwoffset(cd)/Blocksize != (Cwoffset(cd)+l)/Blocksize)

		Cpadblock(cd);

*/

	Cputc(cd, c->namelen);

	Cputc(cd, 0);

	Cwrite(cd, c->dloc + (size==Little ? 0 : 4), 4);

	(size==Little ? Cputnl : Cputnm)(cd, parent, 2);

	Cwrite(cd, c->name, c->namelen);

	if(c->namelen & 1)

		Cputc(cd, 0);

}

static ulong*

addlength(ulong *a, ulong x, int n)

{

	if(n%128==0)

		a = erealloc(a, (n+128)*sizeof a[0]);

	a[n] = x;

	return a;

}

static ulong

writepathtable(Cdimg *cd, ulong vdblock, int size)

{

	int rp, wp;

	uchar buf[Blocksize];

	ulong bk, i, *len, n;

	uvlong start, end, rdoff;

	Cdir *c;

	Cpath p;

	Creadblock(cd, buf, vdblock, Blocksize);

	c = (Cdir*)(buf + offsetof(Cvoldesc, rootdir[0]));

	rp = 0;

	wp = 0;

	len = nil;

	start = (vlong)cd->nextblock * Blocksize;

	Cwseek(cd, start);

	Crseek(cd, start);

	writepath(cd, c, 1, size);

	len = addlength(len, little(c->dlen, 4), wp);

	wp++;

	while(rp < wp) {

		Crdpath(cd, &p);

		n = (len[rp]+Blocksize-1)/Blocksize;

		rp++;

		bk = (size==Big ? big : little)(p.dloc, 4);

		rdoff = Croffset(cd);

		for(i=0; i<n; i++) {

			Creadblock(cd, buf, bk+i, Blocksize);

			c = (Cdir*)buf;

			if(i != 0 && c->namelen == 1 && c->name[0] == '\0')

				break;	/* hit another directory; stop */

			while(c->len && c->namelen &&

			    (uchar*)c + c->len < buf + Blocksize) {

				if(c->flags & 0x02 &&

				    (c->namelen > 1 || c->name[0] > '\001')) {

					/* directory */

					writepath(cd, c, rp, size);

					len = addlength(len, little(c->dlen, 4), wp);

					wp++;

				}

				c = (Cdir*)((uchar*)c+c->len);

			}

		}

		Crseek(cd, rdoff);

	}

	end = Cwoffset(cd);

	Cpadblock(cd);

	return end-start;

}

static void

writepathtablepair(Cdimg *cd, ulong vdblock)

{

	ulong bloc, lloc, sz, sz2;

	lloc = cd->nextblock;

	sz = writepathtable(cd, vdblock, Little);

	bloc = cd->nextblock;

	sz2 = writepathtable(cd, vdblock, Big);

	assert(sz == sz2);

	setpathtable(cd, vdblock, sz, lloc, bloc);

}

void

writepathtables(Cdimg *cd)

{

	cd->pathblock = cd->nextblock;

	writepathtablepair(cd, cd->iso9660pvd);

	if(cd->flags & CDjoliet)

		writepathtablepair(cd, cd->jolietsvd);

}