xref: /haiku/src/add-ons/kernel/file_systems/shared/DeviceOpener.cpp (revision d72239d23d37436ce8e7e230056136a858c0ec79)

/*
 * Copyright 2008-2010, Axel Dörfler, axeld@pinc-software.de.
 * All rights reserved. Distributed under the terms of the MIT License.
 */


#include "system_dependencies.h"
#include "file_systems/DeviceOpener.h"


DeviceOpener::DeviceOpener(const char* device, int mode)
	:
	fBlockCache(NULL)
{
	Open(device, mode);
}


DeviceOpener::DeviceOpener(int fd, int mode)
	:
	fBlockCache(NULL)
{
	Open(fd, mode);
}


DeviceOpener::~DeviceOpener()
{
	if (fDevice >= 0){
		RemoveCache(false);
		close(fDevice);
	}
}


int
DeviceOpener::Open(const char* device, int mode)
{
	fDevice = open(device, mode | O_NOCACHE);
	if (fDevice < 0)
		fDevice = errno;

	if (fDevice < 0 && _IsReadWrite(mode)) {
		return Open(device, O_RDONLY | O_NOCACHE);
	}

	if (fDevice >= 0) {
		fMode = mode;
		if (_IsReadWrite(mode)) {
			device_geometry geometry;
			if (!ioctl(fDevice, B_GET_GEOMETRY, &geometry,
						sizeof(device_geometry)))
			{
				if (geometry.read_only) {
					close(fDevice);
					return Open(device, O_RDONLY | O_NOCACHE);
				}
			}
		}
	}
	return fDevice;
}


int
DeviceOpener::Open(int fd, int mode)
{
	fDevice = dup(fd);
	if (fDevice < 0)
		return errno;

	fMode = mode;

	return fDevice;
}


void*
DeviceOpener::InitCache(off_t numBlocks, uint32 blockSize)
{
	return fBlockCache = block_cache_create(fDevice, numBlocks, blockSize,
		IsReadOnly());
}


void
DeviceOpener::RemoveCache(bool allowWrites)
{
	if (fBlockCache == NULL)
		return;

	block_cache_delete(fBlockCache, allowWrites);
	fBlockCache = NULL;
}


void
DeviceOpener::Keep()
{
	fDevice = -1;
}


status_t
DeviceOpener::GetSize(off_t* _size, uint32* _blockSize)
{
	device_geometry geometry;
	if (ioctl(fDevice, B_GET_GEOMETRY, &geometry,
				sizeof(device_geometry)) < 0) {
		// maybe it's just a file
		struct stat stat;
		if (fstat(fDevice, &stat) < 0)
			return B_ERROR;

		if (_size)
			*_size = stat.st_size;
		if (_blockSize)	// that shouldn't cause us any problems
			*_blockSize = 512;

		return B_OK;
	}

	if (_size) {
		*_size = 1ULL * geometry.head_count * geometry.cylinder_count
			* geometry.sectors_per_track * geometry.bytes_per_sector;
	}
	if (_blockSize)
		*_blockSize = geometry.bytes_per_sector;

	return B_OK;
}