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/* Copyright (c) 2010, 2025, Oracle and/or its affiliates.
This program is free software; you can redistribute it and/or modify
it under the terms of the GNU General Public License, version 2.0,
as published by the Free Software Foundation.
This program is designed to work with certain software (including
but not limited to OpenSSL) that is licensed under separate terms,
as designated in a particular file or component or in included license
documentation. The authors of MySQL hereby grant you an additional
permission to link the program and your derivative works with the
separately licensed software that they have either included with
the program or referenced in the documentation.
This program is distributed in the hope that it will be useful,
but WITHOUT ANY WARRANTY; without even the implied warranty of
MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
GNU General Public License, version 2.0, for more details.
You should have received a copy of the GNU General Public License
along with this program; if not, write to the Free Software
Foundation, Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA */
#include "vio_priv.h"
#include "my_byteorder.h"
#include "my_dbug.h"
#include "my_shm_defaults.h"
size_t vio_read_shared_memory(Vio *vio, uchar *buf, size_t size) {
size_t length;
size_t remain_local;
uchar *current_position;
HANDLE events[2];
DWORD timeout;
DBUG_TRACE;
remain_local = size;
current_position = buf;
timeout = vio->read_timeout >= 0 ? vio->read_timeout : INFINITE;
events[0] = vio->event_server_wrote;
events[1] = vio->event_conn_closed;
do {
if (vio->shared_memory_remain == 0) {
DWORD wait_status;
wait_status = WaitForMultipleObjects(array_elements(events), events,
false, timeout);
/*
WaitForMultipleObjects can return next values:
WAIT_OBJECT_0+0 - event from vio->event_server_wrote
WAIT_OBJECT_0+1 - event from vio->event_conn_closed.
We can't read anything
WAIT_ABANDONED_0 and WAIT_TIMEOUT - fail. We can't read anything
*/
if (wait_status != WAIT_OBJECT_0) {
/*
If wait_status is WAIT_TIMEOUT, set error code to indicate a
timeout error. If vio->event_conn_closed was set, use an EOF
condition (return value of zero) to indicate that the operation
has been aborted.
*/
if (wait_status == WAIT_TIMEOUT)
SetLastError(SOCKET_ETIMEDOUT);
else if (wait_status == (WAIT_OBJECT_0 + 1))
return 0;
return -1;
}
vio->shared_memory_pos = vio->handle_map;
vio->shared_memory_remain = uint4korr(vio->shared_memory_pos);
vio->shared_memory_pos += 4;
}
length = size;
if (vio->shared_memory_remain < length) length = vio->shared_memory_remain;
if (length > remain_local) length = remain_local;
memcpy(current_position, vio->shared_memory_pos, length);
vio->shared_memory_remain -= length;
vio->shared_memory_pos += length;
current_position += length;
remain_local -= length;
if (!vio->shared_memory_remain) {
if (!SetEvent(vio->event_client_read)) return -1;
}
} while (remain_local);
length = size;
return length;
}
size_t vio_write_shared_memory(Vio *vio, const uchar *buf, size_t size) {
size_t length, remain, sz;
HANDLE pos;
const uchar *current_position;
HANDLE events[2];
DWORD timeout;
DBUG_TRACE;
remain = size;
current_position = buf;
timeout = vio->write_timeout >= 0 ? vio->write_timeout : INFINITE;
events[0] = vio->event_server_read;
events[1] = vio->event_conn_closed;
while (remain != 0) {
DWORD wait_status;
wait_status =
WaitForMultipleObjects(array_elements(events), events, false, timeout);
if (wait_status != WAIT_OBJECT_0) {
/* Set error code to indicate a timeout error or disconnect. */
if (wait_status == WAIT_TIMEOUT)
SetLastError(SOCKET_ETIMEDOUT);
else
SetLastError(ERROR_GRACEFUL_DISCONNECT);
return (size_t)-1;
}
sz = (remain > shared_memory_buffer_length ? shared_memory_buffer_length
: remain);
int4store(vio->handle_map, (uint32)sz);
pos = vio->handle_map + 4;
memcpy(pos, current_position, sz);
remain -= sz;
current_position += sz;
if (!SetEvent(vio->event_client_wrote)) return (size_t)-1;
}
length = size;
return length;
}
bool vio_is_connected_shared_memory(Vio *vio) {
return (WaitForSingleObject(vio->event_conn_closed, 0) != WAIT_OBJECT_0);
}
void vio_delete_shared_memory(Vio *vio) {
DBUG_TRACE;
if (!vio) return;
if (vio->inactive == false) vio->vioshutdown(vio);
/*
Close all handlers. UnmapViewOfFile and CloseHandle return non-zero
result if they are success.
*/
if (UnmapViewOfFile(vio->handle_map) == 0)
DBUG_PRINT("vio_error", ("UnmapViewOfFile() failed"));
if (CloseHandle(vio->event_server_wrote) == 0)
DBUG_PRINT("vio_error", ("CloseHandle(vio->esw) failed"));
if (CloseHandle(vio->event_server_read) == 0)
DBUG_PRINT("vio_error", ("CloseHandle(vio->esr) failed"));
if (CloseHandle(vio->event_client_wrote) == 0)
DBUG_PRINT("vio_error", ("CloseHandle(vio->ecw) failed"));
if (CloseHandle(vio->event_client_read) == 0)
DBUG_PRINT("vio_error", ("CloseHandle(vio->ecr) failed"));
if (CloseHandle(vio->handle_file_map) == 0)
DBUG_PRINT("vio_error", ("CloseHandle(vio->hfm) failed"));
if (CloseHandle(vio->event_conn_closed) == 0)
DBUG_PRINT("vio_error", ("CloseHandle(vio->ecc) failed"));
vio_delete(vio);
}
/*
When "kill connection xx" is executed on an arbitrary thread it calls
THD::shutdown_active_vio() on the THD referred to by xx. Since the
thread serving the connection xx might be in the middle of a vio_read
or vio_write, we cannot unmap the shared memory here.
Therefore we here just signal the connection_closed event and give
the thread servicing connection xx a chance to gracefully exit.
All handles are closed and the VIO is cleaned up when vio_delete() is
called and this completes the vio cleanup operation in its entirety.
*/
int vio_shutdown_shared_memory(Vio *vio) {
DBUG_TRACE;
if (vio->inactive == false) {
/*
Set event_conn_closed for notification of both client and server that
connection is closed
*/
SetEvent(vio->event_conn_closed);
}
vio->inactive = true;
vio->mysql_socket = MYSQL_INVALID_SOCKET;
return 0;
}
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