ladybird/Kernel/UserOrKernelBuffer.h

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/*
* Copyright (c) 2020, the SerenityOS developers.
* All rights reserved.
*
* 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 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.
*
* THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS 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 THE COPYRIGHT HOLDER OR 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.
*/
#pragma once
#include <AK/String.h>
#include <AK/Types.h>
#include <AK/Userspace.h>
#include <Kernel/StdLib.h>
#include <Kernel/UnixTypes.h>
#include <Kernel/VM/MemoryManager.h>
#include <LibC/errno_numbers.h>
namespace Kernel {
class UserOrKernelBuffer {
public:
UserOrKernelBuffer() = delete;
static UserOrKernelBuffer for_kernel_buffer(u8* kernel_buffer)
{
ASSERT(!kernel_buffer || !is_user_address(VirtualAddress(kernel_buffer)));
return UserOrKernelBuffer(kernel_buffer);
}
static Optional<UserOrKernelBuffer> for_user_buffer(u8* user_buffer, size_t size)
{
if (user_buffer && !is_user_range(VirtualAddress(user_buffer), size))
return {};
return UserOrKernelBuffer(user_buffer);
}
template<typename UserspaceType>
static Optional<UserOrKernelBuffer> for_user_buffer(UserspaceType userspace, size_t size)
{
if (!is_user_range(VirtualAddress(userspace.unsafe_userspace_ptr()), size))
return {};
return UserOrKernelBuffer(const_cast<u8*>((const u8*)userspace.unsafe_userspace_ptr()));
}
bool is_kernel_buffer() const;
const void* user_or_kernel_ptr() const { return m_buffer; }
UserOrKernelBuffer offset(ssize_t offset) const
{
if (!m_buffer)
return *this;
UserOrKernelBuffer offset_buffer = *this;
offset_buffer.m_buffer += offset;
ASSERT(offset_buffer.is_kernel_buffer() == is_kernel_buffer());
return offset_buffer;
}
String copy_into_string(size_t size) const;
[[nodiscard]] bool write(const void* src, size_t offset, size_t len);
[[nodiscard]] bool write(const void* src, size_t len)
{
return write(src, 0, len);
}
[[nodiscard]] bool write(ReadonlyBytes bytes)
{
return write(bytes.data(), bytes.size());
}
[[nodiscard]] bool read(void* dest, size_t offset, size_t len) const;
[[nodiscard]] bool read(void* dest, size_t len) const
{
return read(dest, 0, len);
}
[[nodiscard]] bool read(Bytes bytes) const
{
return read(bytes.data(), bytes.size());
}
[[nodiscard]] bool memset(int value, size_t offset, size_t len);
[[nodiscard]] bool memset(int value, size_t len)
{
return memset(value, 0, len);
}
template<size_t BUFFER_BYTES, typename F>
[[nodiscard]] ssize_t write_buffered(size_t offset, size_t len, F f)
{
if (!m_buffer)
return -EFAULT;
if (is_kernel_buffer()) {
// We're transferring directly to a kernel buffer, bypass
return f(m_buffer + offset, len);
}
// The purpose of using a buffer on the stack is that we can
// avoid a bunch of small (e.g. 1-byte) copy_to_user calls
u8 buffer[BUFFER_BYTES];
size_t nwritten = 0;
while (nwritten < len) {
auto to_copy = min(sizeof(buffer), len - nwritten);
ssize_t copied = f(buffer, to_copy);
if (copied < 0)
return copied;
ASSERT((size_t)copied <= to_copy);
if (!write(buffer, nwritten, (size_t)copied))
return -EFAULT;
nwritten += (size_t)copied;
if ((size_t)copied < to_copy)
break;
}
return (ssize_t)nwritten;
}
template<size_t BUFFER_BYTES, typename F>
[[nodiscard]] ssize_t write_buffered(size_t len, F f)
{
return write_buffered<BUFFER_BYTES, F>(0, len, f);
}
template<size_t BUFFER_BYTES, typename F>
[[nodiscard]] ssize_t read_buffered(size_t offset, size_t len, F f) const
{
if (!m_buffer)
return -EFAULT;
if (is_kernel_buffer()) {
// We're transferring directly from a kernel buffer, bypass
return f(m_buffer + offset, len);
}
// The purpose of using a buffer on the stack is that we can
// avoid a bunch of small (e.g. 1-byte) copy_from_user calls
u8 buffer[BUFFER_BYTES];
size_t nread = 0;
while (nread < len) {
auto to_copy = min(sizeof(buffer), len - nread);
if (!read(buffer, nread, to_copy))
return -EFAULT;
ssize_t copied = f(buffer, to_copy);
if (copied < 0)
return copied;
ASSERT((size_t)copied <= to_copy);
nread += (size_t)copied;
if ((size_t)copied < to_copy)
break;
}
return nread;
}
template<size_t BUFFER_BYTES, typename F>
[[nodiscard]] ssize_t read_buffered(size_t len, F f) const
{
return read_buffered<BUFFER_BYTES, F>(0, len, f);
}
private:
explicit UserOrKernelBuffer(u8* buffer)
: m_buffer(buffer)
{
}
u8* m_buffer;
};
}