mpv/osdep/subprocess-win.c

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/*
* This file is part of mpv.
*
* mpv is free software; you can redistribute it and/or modify
* it under the terms of the GNU General Public License as published by
* the Free Software Foundation; either version 2 of the License, or
* (at your option) any later version.
*
* mpv 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 for more details.
*
* You should have received a copy of the GNU General Public License along
* with mpv. If not, see <http://www.gnu.org/licenses/>.
*/
#include <windows.h>
#include <string.h>
#include "osdep/subprocess.h"
#include "osdep/io.h"
#include "osdep/atomics.h"
#include "talloc.h"
#include "common/common.h"
#include "stream/stream.h"
#include "misc/bstr.h"
static void write_arg(bstr *cmdline, char *arg)
{
// If the string doesn't have characters that need to be escaped, it's best
// to leave it alone for the sake of Windows programs that don't process
// quoted args correctly.
if (!strpbrk(arg, " \t\"")) {
bstr_xappend(NULL, cmdline, bstr0(arg));
return;
}
// If there are characters that need to be escaped, write a quoted string
bstr_xappend(NULL, cmdline, bstr0("\""));
// Escape the argument. To match the behavior of CommandLineToArgvW,
// backslashes are only escaped if they appear before a quote or the end of
// the string.
int num_slashes = 0;
for (int pos = 0; arg[pos]; pos++) {
switch (arg[pos]) {
case '\\':
// Count backslashes that appear in a row
num_slashes++;
break;
case '"':
bstr_xappend(NULL, cmdline, (struct bstr){arg, pos});
// Double preceding slashes
for (int i = 0; i < num_slashes; i++)
bstr_xappend(NULL, cmdline, bstr0("\\"));
// Escape the following quote
bstr_xappend(NULL, cmdline, bstr0("\\"));
arg += pos;
pos = 0;
num_slashes = 0;
break;
default:
num_slashes = 0;
}
}
// Write the rest of the argument
bstr_xappend(NULL, cmdline, bstr0(arg));
// Double slashes that appear at the end of the string
for (int i = 0; i < num_slashes; i++)
bstr_xappend(NULL, cmdline, bstr0("\\"));
bstr_xappend(NULL, cmdline, bstr0("\""));
}
// Convert an array of arguments to a properly escaped command-line string
static wchar_t *write_cmdline(void *ctx, char **argv)
{
// argv[0] should always be quoted. Otherwise, arguments may be interpreted
// as part of the program name. Also, it can't contain escape sequences.
bstr cmdline = {0};
bstr_xappend_asprintf(NULL, &cmdline, "\"%s\"", argv[0]);
for (int i = 1; argv[i]; i++) {
bstr_xappend(NULL, &cmdline, bstr0(" "));
write_arg(&cmdline, argv[i]);
}
wchar_t *wcmdline = mp_from_utf8(ctx, cmdline.start);
talloc_free(cmdline.start);
return wcmdline;
}
static int create_overlapped_pipe(HANDLE *read, HANDLE *write)
{
static atomic_ulong counter = ATOMIC_VAR_INIT(0);
// Generate pipe name
unsigned long id = atomic_fetch_add(&counter, 1);
unsigned pid = GetCurrentProcessId();
wchar_t buf[36];
swprintf(buf, sizeof(buf), L"\\\\?\\pipe\\mpv-anon-%08x-%08lx", pid, id);
// The function for creating anonymous pipes (CreatePipe) can't create
// overlapped pipes, so instead, use a named pipe with a unique name
*read = CreateNamedPipeW(buf, PIPE_ACCESS_INBOUND |
FILE_FLAG_FIRST_PIPE_INSTANCE | FILE_FLAG_OVERLAPPED,
PIPE_TYPE_BYTE | PIPE_WAIT, 1, 0, 4096, 0, NULL);
if (*read == INVALID_HANDLE_VALUE)
goto error;
// Open the write end of the pipe as a synchronous handle
*write = CreateFileW(buf, GENERIC_WRITE, 0, NULL, OPEN_EXISTING,
FILE_ATTRIBUTE_NORMAL, NULL);
if (*write == INVALID_HANDLE_VALUE)
goto error;
return 0;
error:
*read = *write = INVALID_HANDLE_VALUE;
return -1;
}
static void delete_handle_list(void *p)
{
LPPROC_THREAD_ATTRIBUTE_LIST list = p;
VOID (WINAPI *pDeleteProcThreadAttributeList)(LPPROC_THREAD_ATTRIBUTE_LIST);
HMODULE kernel32 = GetModuleHandleW(L"kernel32.dll");
pDeleteProcThreadAttributeList =
(VOID (WINAPI*)(LPPROC_THREAD_ATTRIBUTE_LIST))
GetProcAddress(kernel32, "DeleteProcThreadAttributeList");
if (pDeleteProcThreadAttributeList)
pDeleteProcThreadAttributeList(list);
}
// Create a PROC_THREAD_ATTRIBUTE_LIST that specifies exactly which handles are
// inherited by the subprocess
static LPPROC_THREAD_ATTRIBUTE_LIST create_handle_list(void *ctx,
HANDLE *handles, int num)
{
WINBOOL (WINAPI *pInitializeProcThreadAttributeList)(
LPPROC_THREAD_ATTRIBUTE_LIST, DWORD, DWORD, PSIZE_T);
WINBOOL (WINAPI *pUpdateProcThreadAttribute)(LPPROC_THREAD_ATTRIBUTE_LIST,
DWORD, DWORD_PTR, PVOID, SIZE_T, PVOID, PSIZE_T);
// Load Windows Vista functions, if available
HMODULE kernel32 = GetModuleHandleW(L"kernel32.dll");
pInitializeProcThreadAttributeList =
(WINBOOL (WINAPI*)(LPPROC_THREAD_ATTRIBUTE_LIST, DWORD, DWORD, PSIZE_T))
GetProcAddress(kernel32, "InitializeProcThreadAttributeList");
pUpdateProcThreadAttribute =
(WINBOOL (WINAPI*)(LPPROC_THREAD_ATTRIBUTE_LIST, DWORD, DWORD_PTR,
PVOID, SIZE_T, PVOID, PSIZE_T))
GetProcAddress(kernel32, "UpdateProcThreadAttribute");
if (!pInitializeProcThreadAttributeList || !pUpdateProcThreadAttribute)
return NULL;
// Get required attribute list size
SIZE_T size = 0;
if (!pInitializeProcThreadAttributeList(NULL, 1, 0, &size)) {
if (GetLastError() != ERROR_INSUFFICIENT_BUFFER)
return NULL;
}
// Allocate attribute list
LPPROC_THREAD_ATTRIBUTE_LIST list = talloc_size(ctx, size);
if (!pInitializeProcThreadAttributeList(list, 1, 0, &size))
goto error;
talloc_set_destructor(list, delete_handle_list);
if (!pUpdateProcThreadAttribute(list, 0, PROC_THREAD_ATTRIBUTE_HANDLE_LIST,
handles, num * sizeof(HANDLE), NULL, NULL))
goto error;
return list;
error:
talloc_free(list);
return NULL;
}
// Helper method similar to sparse_poll, skips NULL handles
static int sparse_wait(HANDLE *handles, unsigned num_handles)
{
unsigned w_num_handles = 0;
HANDLE w_handles[num_handles];
int map[num_handles];
for (unsigned i = 0; i < num_handles; i++) {
if (!handles[i])
continue;
w_handles[w_num_handles] = handles[i];
map[w_num_handles] = i;
w_num_handles++;
}
if (w_num_handles == 0)
return -1;
DWORD i = WaitForMultipleObjects(w_num_handles, w_handles, FALSE, INFINITE);
i -= WAIT_OBJECT_0;
if (i >= w_num_handles)
return -1;
return map[i];
}
// Wrapper for ReadFile that treats ERROR_IO_PENDING as success
static int async_read(HANDLE file, void *buf, unsigned size, OVERLAPPED* ol)
{
if (!ReadFile(file, buf, size, NULL, ol))
return (GetLastError() == ERROR_IO_PENDING) ? 0 : -1;
return 0;
}
static void write_none(void *ctx, char *data, size_t size)
{
}
int mp_subprocess(char **args, struct mp_cancel *cancel, void *ctx,
subprocess_read_cb on_stdout, subprocess_read_cb on_stderr,
char **error)
{
wchar_t *tmp = talloc_new(NULL);
int status = -1;
struct {
HANDLE read;
HANDLE write;
OVERLAPPED ol;
char buf[4096];
subprocess_read_cb read_cb;
} pipes[2] = {
{ .read_cb = on_stdout ? on_stdout : write_none },
{ .read_cb = on_stderr ? on_stderr : write_none },
};
// If the function exits before CreateProcess, there was an init error
*error = "init";
for (int i = 0; i < 2; i++) {
pipes[i].ol.hEvent = CreateEventW(NULL, TRUE, FALSE, NULL);
if (!pipes[i].ol.hEvent)
goto done;
if (create_overlapped_pipe(&pipes[i].read, &pipes[i].write))
goto done;
if (!SetHandleInformation(pipes[i].write, HANDLE_FLAG_INHERIT,
HANDLE_FLAG_INHERIT))
goto done;
}
// Convert the args array to a UTF-16 Windows command-line string
wchar_t *cmdline = write_cmdline(tmp, args);
DWORD flags = CREATE_UNICODE_ENVIRONMENT;
PROCESS_INFORMATION pi = {0};
STARTUPINFOEXW si = {
.StartupInfo = {
.cb = sizeof(si),
.dwFlags = STARTF_USESTDHANDLES,
.hStdInput = NULL,
.hStdOutput = pipes[0].write,
.hStdError = pipes[1].write,
},
// Specify which handles are inherited by the subprocess. If this isn't
// specified, the subprocess inherits all inheritable handles, which
// could include handles created by other threads. See:
// http://blogs.msdn.com/b/oldnewthing/archive/2011/12/16/10248328.aspx
.lpAttributeList = create_handle_list(tmp,
(HANDLE[]){ pipes[0].write, pipes[1].write }, 2),
};
// PROC_THREAD_ATTRIBUTE_LISTs are only supported in Vista and up. If not
// supported, create_handle_list will return NULL.
if (si.lpAttributeList)
flags |= EXTENDED_STARTUPINFO_PRESENT;
// If we have a console, the subprocess will automatically attach to it so
// it can receive Ctrl+C events. If we don't have a console, prevent the
// subprocess from creating its own console window by specifying
// CREATE_NO_WINDOW. GetConsoleCP() can be used to reliably determine if we
// have a console or not (Cygwin uses it too.)
if (!GetConsoleCP())
flags |= CREATE_NO_WINDOW;
if (!CreateProcessW(NULL, cmdline, NULL, NULL, TRUE, flags, NULL, NULL,
&si.StartupInfo, &pi))
goto done;
talloc_free(cmdline);
talloc_free(si.lpAttributeList);
CloseHandle(pi.hThread);
// Init is finished
*error = NULL;
// List of handles to watch with sparse_wait
HANDLE handles[] = { pipes[0].ol.hEvent, pipes[1].ol.hEvent, pi.hProcess,
cancel ? mp_cancel_get_event(cancel) : NULL };
for (int i = 0; i < 2; i++) {
// Close our copy of the write end of the pipes
CloseHandle(pipes[i].write);
pipes[i].write = NULL;
// Do the first read operation on each pipe
if (async_read(pipes[i].read, pipes[i].buf, 4096, &pipes[i].ol)) {
CloseHandle(pipes[i].read);
handles[i] = pipes[i].read = NULL;
}
}
DWORD r;
DWORD exit_code;
while (pipes[0].read || pipes[1].read || pi.hProcess) {
int i = sparse_wait(handles, MP_ARRAY_SIZE(handles));
switch (i) {
case 0:
case 1:
// Complete the read operation on the pipe
if (!GetOverlappedResult(pipes[i].read, &pipes[i].ol, &r, TRUE)) {
CloseHandle(pipes[i].read);
handles[i] = pipes[i].read = NULL;
break;
}
pipes[i].read_cb(ctx, pipes[i].buf, r);
// Begin the next read operation on the pipe
if (async_read(pipes[i].read, pipes[i].buf, 4096, &pipes[i].ol)) {
CloseHandle(pipes[i].read);
handles[i] = pipes[i].read = NULL;
}
break;
case 2:
GetExitCodeProcess(pi.hProcess, &exit_code);
status = exit_code;
CloseHandle(pi.hProcess);
handles[i] = pi.hProcess = NULL;
break;
case 3:
if (pi.hProcess) {
TerminateProcess(pi.hProcess, 1);
*error = "killed";
goto done;
}
break;
default:
goto done;
}
}
done:
for (int i = 0; i < 2; i++) {
if (pipes[i].read) {
// Cancel any pending I/O (if the process was killed)
CancelIo(pipes[i].read);
GetOverlappedResult(pipes[i].read, &pipes[i].ol, &r, TRUE);
CloseHandle(pipes[i].read);
}
if (pipes[i].write) CloseHandle(pipes[i].write);
if (pipes[i].ol.hEvent) CloseHandle(pipes[i].ol.hEvent);
}
if (pi.hProcess) CloseHandle(pi.hProcess);
talloc_free(tmp);
return status;
}