qemu/util/oslib-win32.c
Daniel P. Berrange 57cb38b383 osdep: add qemu_fork() wrapper for safely handling signals
When using regular fork() the child process of course inherits
all the parents' signal handlers. If the child then proceeds
to close() any open file descriptors, it may break some of those
registered signal handlers. The child generally does not want to
ever run any of the signal handlers that the parent may have
installed in the short time before it exec's. The parent may also
have blocked various signals which the child process will want
enabled.

This introduces a wrapper qemu_fork() that takes care to sanitize
signal handling across fork. Before forking it blocks all signals
in the parent thread. After fork returns, the parent unblocks the
signals and carries on as usual. The child, however, resets all the
signal handlers back to their defaults before it unblocks signals.
The child process can now exec the binary in a "clean" signal
environment.

Signed-off-by: Daniel P. Berrange <berrange@redhat.com>
2015-10-20 14:40:49 +01:00

507 lines
14 KiB
C

/*
* os-win32.c
*
* Copyright (c) 2003-2008 Fabrice Bellard
* Copyright (c) 2010 Red Hat, Inc.
*
* QEMU library functions for win32 which are shared between QEMU and
* the QEMU tools.
*
* Permission is hereby granted, free of charge, to any person obtaining a copy
* of this software and associated documentation files (the "Software"), to deal
* in the Software without restriction, including without limitation the rights
* to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
* copies of the Software, and to permit persons to whom the Software is
* furnished to do so, subject to the following conditions:
*
* The above copyright notice and this permission notice shall be included in
* all copies or substantial portions of the Software.
*
* THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
* IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
* FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL
* THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
* LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
* OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
* THE SOFTWARE.
*
* The implementation of g_poll (functions poll_rest, g_poll) at the end of
* this file are based on code from GNOME glib-2 and use a different license,
* see the license comment there.
*/
#include <windows.h>
#include <glib.h>
#include <stdlib.h>
#include "config-host.h"
#include "sysemu/sysemu.h"
#include "qemu/main-loop.h"
#include "trace.h"
#include "qemu/sockets.h"
/* this must come after including "trace.h" */
#include <shlobj.h>
void *qemu_oom_check(void *ptr)
{
if (ptr == NULL) {
fprintf(stderr, "Failed to allocate memory: %lu\n", GetLastError());
abort();
}
return ptr;
}
void *qemu_try_memalign(size_t alignment, size_t size)
{
void *ptr;
if (!size) {
abort();
}
ptr = VirtualAlloc(NULL, size, MEM_COMMIT, PAGE_READWRITE);
trace_qemu_memalign(alignment, size, ptr);
return ptr;
}
void *qemu_memalign(size_t alignment, size_t size)
{
return qemu_oom_check(qemu_try_memalign(alignment, size));
}
void *qemu_anon_ram_alloc(size_t size, uint64_t *align)
{
void *ptr;
/* FIXME: this is not exactly optimal solution since VirtualAlloc
has 64Kb granularity, but at least it guarantees us that the
memory is page aligned. */
ptr = VirtualAlloc(NULL, size, MEM_COMMIT, PAGE_READWRITE);
trace_qemu_anon_ram_alloc(size, ptr);
return ptr;
}
void qemu_vfree(void *ptr)
{
trace_qemu_vfree(ptr);
if (ptr) {
VirtualFree(ptr, 0, MEM_RELEASE);
}
}
void qemu_anon_ram_free(void *ptr, size_t size)
{
trace_qemu_anon_ram_free(ptr, size);
if (ptr) {
VirtualFree(ptr, 0, MEM_RELEASE);
}
}
#ifndef CONFIG_LOCALTIME_R
/* FIXME: add proper locking */
struct tm *gmtime_r(const time_t *timep, struct tm *result)
{
struct tm *p = gmtime(timep);
memset(result, 0, sizeof(*result));
if (p) {
*result = *p;
p = result;
}
return p;
}
/* FIXME: add proper locking */
struct tm *localtime_r(const time_t *timep, struct tm *result)
{
struct tm *p = localtime(timep);
memset(result, 0, sizeof(*result));
if (p) {
*result = *p;
p = result;
}
return p;
}
#endif /* CONFIG_LOCALTIME_R */
void qemu_set_block(int fd)
{
unsigned long opt = 0;
WSAEventSelect(fd, NULL, 0);
ioctlsocket(fd, FIONBIO, &opt);
}
void qemu_set_nonblock(int fd)
{
unsigned long opt = 1;
ioctlsocket(fd, FIONBIO, &opt);
qemu_fd_register(fd);
}
int socket_set_fast_reuse(int fd)
{
/* Enabling the reuse of an endpoint that was used by a socket still in
* TIME_WAIT state is usually performed by setting SO_REUSEADDR. On Windows
* fast reuse is the default and SO_REUSEADDR does strange things. So we
* don't have to do anything here. More info can be found at:
* http://msdn.microsoft.com/en-us/library/windows/desktop/ms740621.aspx */
return 0;
}
int inet_aton(const char *cp, struct in_addr *ia)
{
uint32_t addr = inet_addr(cp);
if (addr == 0xffffffff) {
return 0;
}
ia->s_addr = addr;
return 1;
}
void qemu_set_cloexec(int fd)
{
}
/* Offset between 1/1/1601 and 1/1/1970 in 100 nanosec units */
#define _W32_FT_OFFSET (116444736000000000ULL)
int qemu_gettimeofday(qemu_timeval *tp)
{
union {
unsigned long long ns100; /*time since 1 Jan 1601 in 100ns units */
FILETIME ft;
} _now;
if(tp) {
GetSystemTimeAsFileTime (&_now.ft);
tp->tv_usec=(long)((_now.ns100 / 10ULL) % 1000000ULL );
tp->tv_sec= (long)((_now.ns100 - _W32_FT_OFFSET) / 10000000ULL);
}
/* Always return 0 as per Open Group Base Specifications Issue 6.
Do not set errno on error. */
return 0;
}
int qemu_get_thread_id(void)
{
return GetCurrentThreadId();
}
char *
qemu_get_local_state_pathname(const char *relative_pathname)
{
HRESULT result;
char base_path[MAX_PATH+1] = "";
result = SHGetFolderPath(NULL, CSIDL_COMMON_APPDATA, NULL,
/* SHGFP_TYPE_CURRENT */ 0, base_path);
if (result != S_OK) {
/* misconfigured environment */
g_critical("CSIDL_COMMON_APPDATA unavailable: %ld", (long)result);
abort();
}
return g_strdup_printf("%s" G_DIR_SEPARATOR_S "%s", base_path,
relative_pathname);
}
void qemu_set_tty_echo(int fd, bool echo)
{
HANDLE handle = (HANDLE)_get_osfhandle(fd);
DWORD dwMode = 0;
if (handle == INVALID_HANDLE_VALUE) {
return;
}
GetConsoleMode(handle, &dwMode);
if (echo) {
SetConsoleMode(handle, dwMode | ENABLE_ECHO_INPUT | ENABLE_LINE_INPUT);
} else {
SetConsoleMode(handle,
dwMode & ~(ENABLE_ECHO_INPUT | ENABLE_LINE_INPUT));
}
}
static char exec_dir[PATH_MAX];
void qemu_init_exec_dir(const char *argv0)
{
char *p;
char buf[MAX_PATH];
DWORD len;
len = GetModuleFileName(NULL, buf, sizeof(buf) - 1);
if (len == 0) {
return;
}
buf[len] = 0;
p = buf + len - 1;
while (p != buf && *p != '\\') {
p--;
}
*p = 0;
if (access(buf, R_OK) == 0) {
pstrcpy(exec_dir, sizeof(exec_dir), buf);
}
}
char *qemu_get_exec_dir(void)
{
return g_strdup(exec_dir);
}
/*
* The original implementation of g_poll from glib has a problem on Windows
* when using timeouts < 10 ms.
*
* Whenever g_poll is called with timeout < 10 ms, it does a quick poll instead
* of wait. This causes significant performance degradation of QEMU.
*
* The following code is a copy of the original code from glib/gpoll.c
* (glib commit 20f4d1820b8d4d0fc4447188e33efffd6d4a88d8 from 2014-02-19).
* Some debug code was removed and the code was reformatted.
* All other code modifications are marked with 'QEMU'.
*/
/*
* gpoll.c: poll(2) abstraction
* Copyright 1998 Owen Taylor
* Copyright 2008 Red Hat, Inc.
*
* This library is free software; you can redistribute it and/or
* modify it under the terms of the GNU Lesser General Public
* License as published by the Free Software Foundation; either
* version 2 of the License, or (at your option) any later version.
*
* This library 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
* Lesser General Public License for more details.
*
* You should have received a copy of the GNU Lesser General Public
* License along with this library; if not, see <http://www.gnu.org/licenses/>.
*/
static int poll_rest(gboolean poll_msgs, HANDLE *handles, gint nhandles,
GPollFD *fds, guint nfds, gint timeout)
{
DWORD ready;
GPollFD *f;
int recursed_result;
if (poll_msgs) {
/* Wait for either messages or handles
* -> Use MsgWaitForMultipleObjectsEx
*/
ready = MsgWaitForMultipleObjectsEx(nhandles, handles, timeout,
QS_ALLINPUT, MWMO_ALERTABLE);
if (ready == WAIT_FAILED) {
gchar *emsg = g_win32_error_message(GetLastError());
g_warning("MsgWaitForMultipleObjectsEx failed: %s", emsg);
g_free(emsg);
}
} else if (nhandles == 0) {
/* No handles to wait for, just the timeout */
if (timeout == INFINITE) {
ready = WAIT_FAILED;
} else {
SleepEx(timeout, TRUE);
ready = WAIT_TIMEOUT;
}
} else {
/* Wait for just handles
* -> Use WaitForMultipleObjectsEx
*/
ready =
WaitForMultipleObjectsEx(nhandles, handles, FALSE, timeout, TRUE);
if (ready == WAIT_FAILED) {
gchar *emsg = g_win32_error_message(GetLastError());
g_warning("WaitForMultipleObjectsEx failed: %s", emsg);
g_free(emsg);
}
}
if (ready == WAIT_FAILED) {
return -1;
} else if (ready == WAIT_TIMEOUT || ready == WAIT_IO_COMPLETION) {
return 0;
} else if (poll_msgs && ready == WAIT_OBJECT_0 + nhandles) {
for (f = fds; f < &fds[nfds]; ++f) {
if (f->fd == G_WIN32_MSG_HANDLE && f->events & G_IO_IN) {
f->revents |= G_IO_IN;
}
}
/* If we have a timeout, or no handles to poll, be satisfied
* with just noticing we have messages waiting.
*/
if (timeout != 0 || nhandles == 0) {
return 1;
}
/* If no timeout and handles to poll, recurse to poll them,
* too.
*/
recursed_result = poll_rest(FALSE, handles, nhandles, fds, nfds, 0);
return (recursed_result == -1) ? -1 : 1 + recursed_result;
} else if (/* QEMU: removed the following unneeded statement which causes
* a compiler warning: ready >= WAIT_OBJECT_0 && */
ready < WAIT_OBJECT_0 + nhandles) {
for (f = fds; f < &fds[nfds]; ++f) {
if ((HANDLE) f->fd == handles[ready - WAIT_OBJECT_0]) {
f->revents = f->events;
}
}
/* If no timeout and polling several handles, recurse to poll
* the rest of them.
*/
if (timeout == 0 && nhandles > 1) {
/* Remove the handle that fired */
int i;
if (ready < nhandles - 1) {
for (i = ready - WAIT_OBJECT_0 + 1; i < nhandles; i++) {
handles[i-1] = handles[i];
}
}
nhandles--;
recursed_result = poll_rest(FALSE, handles, nhandles, fds, nfds, 0);
return (recursed_result == -1) ? -1 : 1 + recursed_result;
}
return 1;
}
return 0;
}
gint g_poll(GPollFD *fds, guint nfds, gint timeout)
{
HANDLE handles[MAXIMUM_WAIT_OBJECTS];
gboolean poll_msgs = FALSE;
GPollFD *f;
gint nhandles = 0;
int retval;
for (f = fds; f < &fds[nfds]; ++f) {
if (f->fd == G_WIN32_MSG_HANDLE && (f->events & G_IO_IN)) {
poll_msgs = TRUE;
} else if (f->fd > 0) {
/* Don't add the same handle several times into the array, as
* docs say that is not allowed, even if it actually does seem
* to work.
*/
gint i;
for (i = 0; i < nhandles; i++) {
if (handles[i] == (HANDLE) f->fd) {
break;
}
}
if (i == nhandles) {
if (nhandles == MAXIMUM_WAIT_OBJECTS) {
g_warning("Too many handles to wait for!\n");
break;
} else {
handles[nhandles++] = (HANDLE) f->fd;
}
}
}
}
for (f = fds; f < &fds[nfds]; ++f) {
f->revents = 0;
}
if (timeout == -1) {
timeout = INFINITE;
}
/* Polling for several things? */
if (nhandles > 1 || (nhandles > 0 && poll_msgs)) {
/* First check if one or several of them are immediately
* available
*/
retval = poll_rest(poll_msgs, handles, nhandles, fds, nfds, 0);
/* If not, and we have a significant timeout, poll again with
* timeout then. Note that this will return indication for only
* one event, or only for messages. We ignore timeouts less than
* ten milliseconds as they are mostly pointless on Windows, the
* MsgWaitForMultipleObjectsEx() call will timeout right away
* anyway.
*
* Modification for QEMU: replaced timeout >= 10 by timeout > 0.
*/
if (retval == 0 && (timeout == INFINITE || timeout > 0)) {
retval = poll_rest(poll_msgs, handles, nhandles,
fds, nfds, timeout);
}
} else {
/* Just polling for one thing, so no need to check first if
* available immediately
*/
retval = poll_rest(poll_msgs, handles, nhandles, fds, nfds, timeout);
}
if (retval == -1) {
for (f = fds; f < &fds[nfds]; ++f) {
f->revents = 0;
}
}
return retval;
}
size_t getpagesize(void)
{
SYSTEM_INFO system_info;
GetSystemInfo(&system_info);
return system_info.dwPageSize;
}
void os_mem_prealloc(int fd, char *area, size_t memory)
{
int i;
size_t pagesize = getpagesize();
memory = (memory + pagesize - 1) & -pagesize;
for (i = 0; i < memory / pagesize; i++) {
memset(area + pagesize * i, 0, 1);
}
}
/* XXX: put correct support for win32 */
int qemu_read_password(char *buf, int buf_size)
{
int c, i;
printf("Password: ");
fflush(stdout);
i = 0;
for (;;) {
c = getchar();
if (c < 0) {
buf[i] = '\0';
return -1;
} else if (c == '\n') {
break;
} else if (i < (buf_size - 1)) {
buf[i++] = c;
}
}
buf[i] = '\0';
return 0;
}
pid_t qemu_fork(Error **errp)
{
errno = ENOSYS;
error_setg_errno(errp, errno,
"cannot fork child process");
return -1;
}