/*	$NetBSD: ustarfs.c,v 1.37 2019/11/21 21:45:34 mrg Exp $	*/

/* [Notice revision 2.2]
 * Copyright (c) 1997, 1998 Avalon Computer Systems, Inc.
 * All rights reserved.
 *
 * Author: Ross Harvey
 *
 * Redistribution and use in source and binary forms, with or without
 * modification, are permitted provided that the following conditions
 * are met:
 * 1. Redistributions of source code must retain the above copyright and
 *    author notice, this list of conditions, and the following disclaimer.
 * 2. Redistributions in binary form must reproduce the above copyright
 *    notice, this list of conditions and the following disclaimer in the
 *    documentation and/or other materials provided with the distribution.
 * 3. Neither the name of Avalon Computer Systems, Inc. nor the names of
 *    its contributors may be used to endorse or promote products derived
 *    from this software without specific prior written permission.
 * 4. This copyright will be assigned to The NetBSD Foundation on
 *    1/1/2000 unless these terms (including possibly the assignment
 *    date) are updated in writing by Avalon prior to the latest specified
 *    assignment date.
 *
 * THIS SOFTWARE IS PROVIDED BY AVALON COMPUTER SYSTEMS, INC. AND CONTRIBUTORS
 * ``AS IS'' AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED
 * TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR
 * PURPOSE ARE DISCLAIMED.  IN NO EVENT SHALL AVALON OR THE CONTRIBUTORS
 * BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
 * CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF
 * SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
 * INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN
 * CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
 * ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
 * POSSIBILITY OF SUCH DAMAGE.
 */


/*
 ******************************* USTAR FS *******************************
 */

/*
 * Implement an ROFS with an 8K boot area followed by ustar-format data.
 * The point: minimal FS overhead, and it's easy (well, `possible') to
 * split files over multiple volumes.
 *
 * XXX - TODO LIST
 * --- - ---- ----
 * XXX - tag volume numbers and verify that the correct volume is
 *       inserted after volume swaps.
 *
 * XXX - stop hardwiring FS metadata for floppies...embed it in a file,
 * 	 file name, or something. (Remember __SYMDEF? :-)
 *
 * XXX Does not currently implement:
 * XXX
 * XXX LIBSA_NO_FS_CLOSE
 * XXX LIBSA_NO_FS_SEEK
 * XXX LIBSA_NO_FS_WRITE
 * XXX LIBSA_NO_FS_SYMLINK (does this even make sense?)
 * XXX LIBSA_FS_SINGLECOMPONENT
 */

#ifdef _STANDALONE
#include <lib/libkern/libkern.h>
#else
#include <string.h>
#endif
#include "stand.h"
#include "ustarfs.h"

#define	BBSIZE	8192
#define	USTAR_NAME_BLOCK 512

/*
 * Virtual offset: relative to start of ustar archive
 * Logical offset: volume-relative
 * Physical offset: the usual meaning
 */

/* virtual offset to volume number */

#define	vda2vn(_v,_volsize) ((_v) / (_volsize))

/* conversions between the three different levels of disk addresses */

#define	vda2lda(_v,_volsize) ((_v) % (_volsize))
#define	lda2vda(_v,_volsize,_volnumber) ((_v) + (_volsize) * (_volnumber))

#define	lda2pda(_lda) ((_lda) + ustarfs_mode_offset)
#define	pda2lda(_pda) ((_pda) - ustarfs_mode_offset)
/*
 * Change this to off_t if you want to support big volumes. If we only use
 * ustarfs on floppies it can stay int for libsa code density.
 *
 * It needs to be signed.
 */
typedef	int ustoffs;

typedef struct ustar_struct {
	char	ust_name[100],
		ust_mode[8],
		ust_uid[8],
		ust_gid[8],
		ust_size[12],
		ust_misc[12 + 8 + 1 + 100],
		ust_magic[6],
	/* there is more, but we don't care */
		ust_pad[1];	/* make it aligned */
} ustar_t;

/*
 * We buffer one even cylinder of data...it's actually only really one
 * cyl on a 1.44M floppy, but on other devices it's fast enough with any
 * kind of block buffering, so we optimize for the slowest device.
 */

#ifndef USTAR_SECT_PER_CYL
#define USTAR_SECT_PER_CYL	(18 * 2)
#endif

typedef struct ust_active_struct {
	ustar_t	uas_active;
	char	uas_1cyl[USTAR_SECT_PER_CYL * 512];
	ustoffs	uas_volsize;		/* XXX this is hardwired now */
	ustoffs	uas_windowbase;		/* relative to volume 0 */
	ustoffs	uas_filestart;		/* relative to volume 0 */
	ustoffs	uas_fseek;		/* relative to file */
	ustoffs	uas_filesize;		/* relative to volume 0 */
	int	uas_init_window;	/* data present in window */
	int	uas_init_fs;		/* ust FS actually found */
	int	uas_volzerosig;		/* ID volume 0 by signature */
	int	uas_sigdone;		/* did sig already */
	int	uas_offset;		/* amount of cylinder below lba 0 */
} ust_active_t;

static const char formatid[] = "USTARFS",
                  metaname[] = "USTAR.volsize.";

static const int ustarfs_mode_offset = BBSIZE;

static int checksig(ust_active_t *);
static int convert(const char *, int, int);
static int get_volume(struct open_file *, int);
static void setwindow(ust_active_t *, ustoffs, ustoffs);
static int real_fs_cylinder_read(struct open_file *, ustoffs, int);
static int ustarfs_cylinder_read(struct open_file *, ustoffs, int);
static void ustarfs_sscanf(const char *, const char *, int *);
static int read512block(struct open_file *, ustoffs, char block[512]);
static int init_volzero_sig(struct open_file *);

#ifdef HAVE_CHANGEDISK_HOOK
/*
 * Called when the next volume is prompted.
 * Machine dependent code can eject the medium etc.
 * The new medium must be ready when this hook returns.
 */
void changedisk_hook(struct open_file *);
#endif

static int
convert(const char *f, int base, int fw)
{
	int	i, c, result = 0;

	while(fw > 0 && *f == ' ') {
		--fw;
		++f;
	}
	for(i = 0; i < fw; ++i) {
		c = f[i];
		if ('0' <= c && c < '0' + base) {
			c -= '0';
			result = result * base + c;
		} else	break;
	}
	return result;
}

static void
ustarfs_sscanf(const char *s, const char *f, int *xi)
{

	*xi = convert(s, 8, convert(f + 1, 10, 99));
}

static int
ustarfs_cylinder_read(struct open_file *f, ustoffs seek2, int forcelabel)
{
	int i, e;

	for (i = 0; i < 3; ++i) {
		e = real_fs_cylinder_read(f, seek2, forcelabel);
		if (e == 0)
			return 0;
	}
	return e;
}

static int
real_fs_cylinder_read(struct open_file *f, ustoffs seek2, int forcelabel)
{
	int i;
	int e = 0;	/* XXX work around gcc warning */
	ustoffs	lda;
	char *xferbase;
	ust_active_t *ustf;
	size_t xferrqst, xfercount;

	ustf = f->f_fsdata;
	xferrqst = sizeof ustf->uas_1cyl;
	xferbase = ustf->uas_1cyl;
	lda = pda2lda(seek2);
	if (lda < 0) {
		lda = -lda;
		ustf->uas_offset = lda;
		/*
		 * don't read the label unless we have to. (Preserve
		 * sequential block access so tape boot works.)
		 */
		if (!forcelabel) {
			memset(xferbase, 0, lda);
			xferrqst -= lda;
			xferbase += lda;
			seek2    += lda;
		}
	} else {
		ustf->uas_offset = 0;
	}
	while(xferrqst > 0) {
#if !defined(LIBSA_NO_TWIDDLE)
		twiddle();
#endif
		for (i = 0; i < 3; ++i) {
			e = DEV_STRATEGY(f->f_dev)(f->f_devdata, F_READ,
			    seek2 / 512, xferrqst, xferbase, &xfercount);
			if (e == 0)
				break;
			printf("@");
		}
		if (e)
			break;
		if (xfercount != xferrqst)
			printf("Warning, unexpected short transfer %d/%d\n",
				(int)xfercount, (int)xferrqst);
		xferrqst -= xfercount;
		xferbase += xfercount;
		seek2    += xfercount;
	}
	return e;
}

static int
checksig(ust_active_t *ustf)
{
	int	i, rcs;

	for(i = rcs = 0; i < (int)(sizeof ustf->uas_1cyl); ++i)
		rcs += ustf->uas_1cyl[i];
	return rcs;
}

static int
get_volume(struct open_file *f, int vn)
{
	int	e, needvolume, havevolume;
	ust_active_t *ustf;

	ustf = f->f_fsdata;
	havevolume = vda2vn(ustf->uas_windowbase, ustf->uas_volsize);
	needvolume = vn;
	while(havevolume != needvolume) {
		printf("\nPlease ");
		if (havevolume >= 0)
			printf("remove disk %d, ", havevolume + 1);
		printf("insert disk %d, and press return...",
			needvolume + 1);
#ifdef HAVE_CHANGEDISK_HOOK
		changedisk_hook(f);
#else
		for (;;) {
			int c = getchar();
			if ((c == '\n') || (c == '\r'))
				break;
		}
#endif
		printf("\n");
		e = ustarfs_cylinder_read(f, 0, needvolume != 0);
		if (e)
			return e;
		if(strncmp(formatid, ustf->uas_1cyl, strlen(formatid))) {
			/* no magic, might be OK if we want volume 0 */
			if (ustf->uas_volzerosig == checksig(ustf)) {
				havevolume = 0;
				continue;
			}
			printf("Disk is not from the volume set?!\n");
			havevolume = -2;
			continue;
		}
		ustarfs_sscanf(ustf->uas_1cyl + strlen(formatid), "%9o",
			&havevolume);
		--havevolume;
	}
	return 0;
}

static void
setwindow(ust_active_t *ustf, ustoffs pda, ustoffs vda)
{
	ustf->uas_windowbase = lda2vda(pda2lda(pda), ustf->uas_volsize,
	                                vda2vn(vda, ustf->uas_volsize))
	                     + ustf->uas_offset;
	ustf->uas_init_window = 1;
}

static int
read512block(struct open_file *f, ustoffs vda, char block[512])
{
	ustoffs pda;
	ssize_t	e;
	int	dienow;
	ust_active_t *ustf;

	dienow = 0;
	ustf = f->f_fsdata;

	/*
	 * if (vda in window)
	 * 	copy out and return data
	 * if (vda is on some other disk)
	 * 	do disk swap
	 * get physical disk address
	 * round down to cylinder boundary
	 * read cylinder
	 * set window (in vda space) and try again
	 * [ there is an implicit assumption that windowbase always identifies
	 *    the current volume, even if initwindow == 0. This way, a
	 *    windowbase of 0 causes the initial volume to be disk 0 ]
	 */
tryagain:
	if(ustf->uas_init_window
	&& ustf->uas_windowbase <= vda && vda <
	   ustf->uas_windowbase +
	     (int)(sizeof ustf->uas_1cyl) - ustf->uas_offset) {
		memcpy(block, ustf->uas_1cyl
				+ (vda - ustf->uas_windowbase)
				+ ustf->uas_offset, 512);
		return 0;
	}
	if (dienow++)
		panic("ustarfs read512block");
	ustf->uas_init_window = 0;
	e = get_volume(f, vda2vn(vda, ustf->uas_volsize));
	if (e)
		return e;
	pda = lda2pda(vda2lda(vda, ustf->uas_volsize));
	pda-= pda % sizeof ustf->uas_1cyl;
	e = ustarfs_cylinder_read(f, pda, 0);
	if (e)
		return e;
	setwindow(ustf, pda, vda);
	goto tryagain;
}

static int
init_volzero_sig(struct open_file *f)
{
	int e;
	ust_active_t *ustf;

	ustf = f->f_fsdata;
	if (!ustf->uas_sigdone) {
		e = ustarfs_cylinder_read(f, 0, 0);
		if (e)
			return e;
		ustf->uas_volzerosig = checksig(ustf);
		setwindow(ustf, 0, 0);
	}
	return 0;
}

/*
 * XXX Hack alert.  GCC 8.3 mis-compiles this function and calls
 * strncmp() with the wrong second pointer, as seen in PR#54703.
 *
 * Until the real cause is located, work around it by using -O1
 * for this function.
 */
#if defined(__i386__) && !defined(__clang__)
__attribute__((__optimize__("O1")))
#endif
__compactcall int
ustarfs_open(const char *path, struct open_file *f)
{
	ust_active_t *ustf;
	ustoffs offset;
	char	block[512];
	int	filesize;
	int	e, e2;
	int	newvolblocks;

	if (*path == '/')
		++path;
	f->f_fsdata = ustf = alloc(sizeof *ustf);
	memset(ustf, 0, sizeof *ustf);
	offset = 0;
	/* default to 2880 sector floppy */
	ustf->uas_volsize = 80 * 2 * 18 * 512 - lda2pda(0);
	ustf->uas_fseek = 0;
	e = init_volzero_sig(f);
	if (e)
		return e;
	e2 = EINVAL;
	for(;;) {
		ustf->uas_filestart = offset;
		e = read512block(f, offset, block);
		if (e)
			break;
		memcpy(&ustf->uas_active, block, sizeof ustf->uas_active);
		if(strncmp(ustf->uas_active.ust_magic, "ustar", 5)) {
			e = e2;
			break;
		}
		e2 = ENOENT;	/* it must be an actual ustarfs */
		ustf->uas_init_fs = 1;
		/* if volume metadata is found, use it */
		if(strncmp(ustf->uas_active.ust_name, metaname,
		    strlen(metaname)) == 0) {
			ustarfs_sscanf(ustf->uas_active.ust_name
				+ strlen(metaname), "%99o", &newvolblocks);
			ustf->uas_volsize = newvolblocks * 512
					  - lda2pda(0);
		}
		ustarfs_sscanf(ustf->uas_active.ust_size,"%12o",&filesize);
		if(strncmp(ustf->uas_active.ust_name, path,
		    sizeof ustf->uas_active.ust_name) == 0) {
			ustf->uas_filesize = filesize;
			break;
		}
		offset += USTAR_NAME_BLOCK + filesize;
		filesize %= 512;
		if (filesize)
			offset += 512 - filesize;
	}
	if (e) {
		dealloc(ustf, sizeof *ustf);
		f->f_fsdata = 0;
	}
	return e;
}

#ifndef LIBSA_NO_FS_WRITE
__compactcall int
ustarfs_write(struct open_file *f, void *start, size_t size, size_t *resid)
{

	return EROFS;
}
#endif /* !LIBSA_NO_FS_WRITE */

#ifndef LIBSA_NO_FS_SEEK
__compactcall off_t
ustarfs_seek(struct open_file *f, off_t offs, int whence)
{
	ust_active_t *ustf;

	ustf = f->f_fsdata;
	switch (whence) {
	case SEEK_SET:
		ustf->uas_fseek = offs;
		break;
	case SEEK_CUR:
		ustf->uas_fseek += offs;
		break;
	case SEEK_END:
		ustf->uas_fseek = ustf->uas_filesize - offs;
		break;
	default:
		return -1;
	}
	return ustf->uas_fseek;
}
#endif /* !LIBSA_NO_FS_SEEK */

__compactcall int
ustarfs_read(struct open_file *f, void *start, size_t size, size_t *resid)
{
	ust_active_t *ustf;
	int	e;
	char	*space512;
	int	blkoffs;
	int	readoffs;
	int	bufferoffset;
	size_t	seg;
	size_t	infile;
	size_t	inbuffer;

	e = 0;
	space512 = alloc(512);
	ustf = f->f_fsdata;
	while(size != 0) {
		if (ustf->uas_fseek >= ustf->uas_filesize)
			break;
		bufferoffset = ustf->uas_fseek % 512;
		blkoffs  = ustf->uas_fseek - bufferoffset;
		readoffs = ustf->uas_filestart + 512 + blkoffs;
		e = read512block(f, readoffs, space512);
		if (e)
			break;
		seg = size;
		inbuffer = 512 - bufferoffset;
		if (inbuffer < seg)
			seg = inbuffer;
		infile = ustf->uas_filesize - ustf->uas_fseek;
		if (infile < seg)
			seg = infile;
		memcpy(start, space512 + bufferoffset, seg);
		ustf->uas_fseek += seg;
		start = (char *)start + seg;
		size -= seg;
	}
	if (resid)
		*resid = size;
	dealloc(space512, 512);
	return e;
}

__compactcall int
ustarfs_stat(struct open_file *f, struct stat *sb)
{
	int	mode, uid, gid;
	ust_active_t *ustf;

	if (f == NULL)
		return EINVAL;
	ustf = f->f_fsdata;
	memset(sb, 0, sizeof *sb);
	ustarfs_sscanf(ustf->uas_active.ust_mode, "%8o", &mode);
	ustarfs_sscanf(ustf->uas_active.ust_uid, "%8o", &uid);
	ustarfs_sscanf(ustf->uas_active.ust_gid, "%8o", &gid);
	sb->st_mode = mode;
	sb->st_uid  = uid;
	sb->st_gid  = gid;
	sb->st_size = ustf->uas_filesize;
	return 0;
}


#if defined(LIBSA_ENABLE_LS_OP)
#include "ls.h"
__compactcall void
ustarfs_ls(struct open_file *f, const char *pattern)
{
	lsunsup("ustarfs");
	return;
}
#endif

#ifndef LIBSA_NO_FS_CLOSE
__compactcall int
ustarfs_close(struct open_file *f)
{
	if (f == NULL || f->f_fsdata == NULL)
		return EINVAL;
	dealloc(f->f_fsdata, sizeof(ust_active_t));
	f->f_fsdata = 0;
	return 0;
}
#endif /* !LIBSA_NO_FS_CLOSE */