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/*
* Copyright (c) 2020, the SerenityOS developers.
* Copyright (c) 2021, Andreas Kling <kling@serenityos.org>
*
* SPDX-License-Identifier: BSD-2-Clause
*/
#pragma once
#include <AK/Types.h>
#include <AK/Userspace.h>
#include <Kernel/API/POSIX/errno.h>
#include <Kernel/Memory/MemoryManager.h>
#include <Kernel/StdLib.h>
#include <Kernel/UnixTypes.h>
namespace Kernel {
class [[nodiscard]] UserOrKernelBuffer {
public:
UserOrKernelBuffer() = delete;
static UserOrKernelBuffer for_kernel_buffer(u8* kernel_buffer)
{
VERIFY(!kernel_buffer || !Memory::is_user_address(VirtualAddress(kernel_buffer)));
return UserOrKernelBuffer(kernel_buffer);
}
static ErrorOr<UserOrKernelBuffer> for_user_buffer(u8* user_buffer, size_t size)
{
if (user_buffer && !Memory::is_user_range(VirtualAddress(user_buffer), size))
return Error::from_errno(EFAULT);
return UserOrKernelBuffer(user_buffer);
}
template<typename UserspaceType>
static ErrorOr<UserOrKernelBuffer> for_user_buffer(UserspaceType userspace, size_t size)
{
if (!Memory::is_user_range(VirtualAddress(userspace.unsafe_userspace_ptr()), size))
return Error::from_errno(EFAULT);
return UserOrKernelBuffer(const_cast<u8*>((const u8*)userspace.unsafe_userspace_ptr()));
}
[[nodiscard]] bool is_kernel_buffer() const;
[[nodiscard]] const void* user_or_kernel_ptr() const { return m_buffer; }
[[nodiscard]] UserOrKernelBuffer offset(size_t offset) const
{
if (!m_buffer)
return *this;
UserOrKernelBuffer offset_buffer = *this;
offset_buffer.m_buffer += offset;
VERIFY(offset_buffer.is_kernel_buffer() == is_kernel_buffer());
return offset_buffer;
}
ErrorOr<NonnullOwnPtr<KString>> try_copy_into_kstring(size_t) const;
ErrorOr<void> write(const void* src, size_t offset, size_t len);
ErrorOr<void> write(const void* src, size_t len)
{
return write(src, 0, len);
}
ErrorOr<void> write(ReadonlyBytes bytes)
{
return write(bytes.data(), bytes.size());
}
ErrorOr<void> read(void* dest, size_t offset, size_t len) const;
ErrorOr<void> read(void* dest, size_t len) const
{
return read(dest, 0, len);
}
ErrorOr<void> read(Bytes bytes) const
{
return read(bytes.data(), bytes.size());
}
ErrorOr<void> memset(int value, size_t offset, size_t len);
ErrorOr<void> memset(int value, size_t len)
{
return memset(value, 0, len);
}
template<size_t BUFFER_BYTES, typename F>
ErrorOr<size_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
Bytes bytes { m_buffer + offset, len };
return f(bytes);
}
// 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);
Bytes bytes { buffer, to_copy };
ErrorOr<size_t> copied_or_error = f(bytes);
if (copied_or_error.is_error())
return copied_or_error.release_error();
auto copied = copied_or_error.release_value();
VERIFY(copied <= to_copy);
TRY(write(buffer, nwritten, copied));
nwritten += copied;
if (copied < to_copy)
break;
}
return nwritten;
}
template<size_t BUFFER_BYTES, typename F>
ErrorOr<size_t> write_buffered(size_t len, F f)
{
return write_buffered<BUFFER_BYTES, F>(0, len, f);
}
template<size_t BUFFER_BYTES, typename F>
ErrorOr<size_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);
TRY(read(buffer, nread, to_copy));
ReadonlyBytes read_only_bytes { buffer, to_copy };
ErrorOr<size_t> copied_or_error = f(read_only_bytes);
if (copied_or_error.is_error())
return copied_or_error.release_error();
auto copied = copied_or_error.release_value();
VERIFY(copied <= to_copy);
nread += copied;
if (copied < to_copy)
break;
}
return nread;
}
template<size_t BUFFER_BYTES, typename F>
ErrorOr<size_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;
};
}
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