harvey/sys/src/libufs/block.c

/*
 * Copyright (c) 2002 Juli Mallett.  All rights reserved.
 *
 * This software was written by Juli Mallett <jmallett@FreeBSD.org> for the
 * FreeBSD project.  Redistribution and use in source and binary forms, with
 * or without modification, are permitted provided that the following
 * conditions are met:
 *
 * 1. Redistribution of source code must retain the above copyright notice,
 *    this list of conditions and the following disclaimer.
 * 2. Redistribution 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.
 *
 * THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``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 THE AUTHOR 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.
 */

#include <u.h>
#include <libc.h>

#include <ufs/libufsdat.h>
#include <ufs/dinode.h>
#include <ufs/fs.h>
#include <ufs/libufs.h>

int32_t
bread(Uufsd *disk, ufs2_daddr_t blockno, void *data, size_t size)
{
	void *p2;
	int32_t cnt;

	libufserror(disk, nil);

	p2 = data;
	/*
	 * XXX: various disk controllers require alignment of our buffer
	 * XXX: which is stricter than struct alignment.
	 * XXX: Bounce the buffer if not 64 byte aligned.
	 * XXX: this can be removed if/when the kernel is fixed
	 */
	if (((intptr_t)data) & 0x3f) {
		p2 = malloc(size);
		if (p2 == nil) {
			libufserror(disk, "allocate bounce buffer");
			goto fail;
		}
	}
	cnt = pread(disk->d_fd, p2, size, (off_t)(blockno * disk->d_bsize));
	if (cnt == -1) {
		libufserror(disk, "read error from block device");
		goto fail;
	}
	if (cnt == 0) {
		libufserror(disk, "end of file from block device");
		goto fail;
	}
	if ((size_t)cnt != size) {
		libufserror(disk, "short read or read error from block device");
		goto fail;
	}
	if (p2 != data) {
		memcpy(data, p2, size);
		free(p2);
	}
	return (cnt);
fail:	memset(data, 0, size);
	if (p2 != data) {
		free(p2);
	}
	return (-1);
}

int32_t
bwrite(Uufsd *disk, ufs2_daddr_t blockno, const void *data, size_t size)
{
	int32_t cnt;
	int rv;
	void *p2 = nil;

	libufserror(disk, nil);

	rv = ufs_disk_write(disk);
	if (rv == -1) {
		libufserror(disk, "failed to open disk for writing");
		return (-1);
	}

	/*
	 * XXX: various disk controllers require alignment of our buffer
	 * XXX: which is stricter than struct alignment.
	 * XXX: Bounce the buffer if not 64 byte aligned.
	 * XXX: this can be removed if/when the kernel is fixed
	 */
	if (((intptr_t)data) & 0x3f) {
		p2 = malloc(size);
		if (p2 == nil) {
			libufserror(disk, "allocate bounce buffer");
			return (-1);
		}
		memcpy(p2, data, size);
		data = p2;
	}
	cnt = pwrite(disk->d_fd, data, size, (off_t)(blockno * disk->d_bsize));
	if (p2 != nil)
		free(p2);
	if (cnt == -1) {
		libufserror(disk, "write error to block device");
		return (-1);
	}
	if ((size_t)cnt != size) {
		libufserror(disk, "short write to block device");
		return (-1);
	}

	return (cnt);
}

static int
berase_helper(Uufsd *disk, ufs2_daddr_t blockno, ufs2_daddr_t size)
{
	char *zero_chunk;
	off_t offset, zero_chunk_size, pwrite_size;
	int rv;

	offset = blockno * disk->d_bsize;
	zero_chunk_size = 65536 * disk->d_bsize;
	zero_chunk = calloc(1, zero_chunk_size);
	if (zero_chunk == nil) {
		libufserror(disk, "failed to allocate memory");
		return (-1);
	}
	while (size > 0) { 
		pwrite_size = size;
		if (pwrite_size > zero_chunk_size)
			pwrite_size = zero_chunk_size;
		rv = pwrite(disk->d_fd, zero_chunk, pwrite_size, offset);
		if (rv == -1) {
			libufserror(disk, "failed writing to disk");
			break;
		}
		size -= rv;
		offset += rv;
		rv = 0;
	}
	free(zero_chunk);
	return (rv);
}

int
berase(Uufsd *disk, ufs2_daddr_t blockno, ufs2_daddr_t size)
{
	int rv;

	libufserror(disk, nil);
	rv = ufs_disk_write(disk);
	if (rv == -1) {
		libufserror(disk, "failed to open disk for writing");
		return(rv);
	}
	return (berase_helper(disk, blockno, size));
}

/*
 * Trace steps through libufs, to be used at entry and erroneous return.
 */
void
libufserror(Uufsd *u, const char *str)
{
	if (str != nil)
		perror(str);
	if (u != nil)
		u->d_error = str;
}