transmission/libtransmission/subprocess-win32.cc

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/*
* This file Copyright (C) 2011-2017 Mnemosyne LLC
*
* It may be used under the GNU GPL versions 2 or 3
* or any future license endorsed by Mnemosyne LLC.
*
*/
#include <algorithm>
#include <climits>
#include <cstdlib>
#include <cstring>
#include <cwchar>
#include <windows.h>
#include "transmission.h"
#include "error.h"
#include "subprocess.h"
#include "tr-assert.h"
#include "utils.h"
enum tr_app_type
{
TR_APP_TYPE_EXE,
TR_APP_TYPE_BATCH
};
static void set_system_error(tr_error** error, DWORD code, char const* what)
{
if (error == nullptr)
{
return;
}
char* message = tr_win32_format_message(code);
if (message == nullptr)
{
message = tr_strdup_printf("Unknown error: 0x%08lx", code);
}
if (what == nullptr)
{
tr_error_set_literal(error, code, message);
}
else
{
tr_error_set(error, code, "%s failed: %s", what, message);
}
tr_free(message);
}
static void append_to_env_block(wchar_t** env_block, size_t* env_block_len, wchar_t const* part, size_t part_len)
{
*env_block = tr_renew(wchar_t, *env_block, *env_block_len + part_len + 1);
wmemcpy(*env_block + *env_block_len, part, part_len);
*env_block_len += part_len;
}
static bool parse_env_block_part(wchar_t const* part, size_t* full_len, size_t* name_len)
{
TR_ASSERT(part != nullptr);
auto const* const equals_pos = wcschr(part, L'=');
if (equals_pos == nullptr)
{
/* Invalid part */
return false;
}
ptrdiff_t const my_name_len = equals_pos - part;
if (my_name_len > SIZE_MAX)
{
/* Invalid part */
return false;
}
if (full_len != nullptr)
{
/* Includes terminating '\0' */
*full_len = wcslen(part) + 1;
}
if (name_len != nullptr)
{
*name_len = (size_t)my_name_len;
}
return true;
}
static int compare_wide_strings_ci(wchar_t const* lhs, size_t lhs_len, wchar_t const* rhs, size_t rhs_len)
{
int diff = wcsnicmp(lhs, rhs, std::min(lhs_len, rhs_len));
if (diff == 0)
{
diff = lhs_len < rhs_len ? -1 : (lhs_len > rhs_len ? 1 : 0);
}
return diff;
}
static int compare_env_part_names(void const* vlhs, void const* vrhs)
{
int ret = 0;
auto const* const* const lhs = reinterpret_cast<wchar_t const* const*>(vlhs);
auto const* const* const rhs = reinterpret_cast<wchar_t const* const*>(vrhs);
size_t lhs_part_len;
size_t lhs_name_len;
if (parse_env_block_part(*lhs, &lhs_part_len, &lhs_name_len))
{
size_t rhs_part_len;
size_t rhs_name_len;
if (parse_env_block_part(*rhs, &rhs_part_len, &rhs_name_len))
{
ret = compare_wide_strings_ci(*lhs, lhs_name_len, *rhs, rhs_name_len);
}
}
return ret;
}
static wchar_t** to_wide_env(char const* const* env)
{
if (env == nullptr || env[0] == nullptr)
{
return nullptr;
}
size_t part_count = 0;
while (env[part_count] != nullptr)
{
++part_count;
}
wchar_t** wide_env = tr_new(wchar_t*, part_count + 1);
for (size_t i = 0; i < part_count; ++i)
{
wide_env[i] = tr_win32_utf8_to_native(env[i], -1);
}
wide_env[part_count] = nullptr;
/* "The sort is case-insensitive, Unicode order, without regard to locale" (c) MSDN */
qsort(wide_env, part_count, sizeof(wchar_t*), &compare_env_part_names);
return wide_env;
}
static bool create_env_block(char const* const* env, wchar_t** env_block, tr_error** error)
{
wchar_t** wide_env = to_wide_env(env);
if (wide_env == nullptr)
{
*env_block = nullptr;
return true;
}
wchar_t* const old_env_block = GetEnvironmentStringsW();
if (old_env_block == nullptr)
{
set_system_error(error, GetLastError(), "Call to GetEnvironmentStrings()");
return false;
}
*env_block = nullptr;
wchar_t const* old_part = old_env_block;
size_t env_block_len = 0;
for (size_t i = 0; wide_env[i] != nullptr; ++i)
{
wchar_t const* const part = wide_env[i];
size_t part_len;
size_t name_len;
if (!parse_env_block_part(part, &part_len, &name_len))
{
continue;
}
while (*old_part != L'\0')
{
size_t old_part_len;
size_t old_name_len;
if (!parse_env_block_part(old_part, &old_part_len, &old_name_len))
{
continue;
}
int const name_diff = compare_wide_strings_ci(old_part, old_name_len, part, name_len);
if (name_diff < 0)
{
append_to_env_block(env_block, &env_block_len, old_part, old_part_len);
}
if (name_diff <= 0)
{
old_part += old_part_len;
}
if (name_diff >= 0)
{
break;
}
}
append_to_env_block(env_block, &env_block_len, part, part_len);
}
while (*old_part != L'\0')
{
size_t old_part_len;
if (!parse_env_block_part(old_part, &old_part_len, nullptr))
{
continue;
}
append_to_env_block(env_block, &env_block_len, old_part, old_part_len);
old_part += old_part_len;
}
(*env_block)[env_block_len] = '\0';
FreeEnvironmentStringsW(old_env_block);
tr_free_ptrv((void* const*)wide_env);
tr_free(wide_env);
return true;
}
static void append_argument(char** arguments, char const* argument)
{
size_t arguments_len = *arguments != nullptr ? strlen(*arguments) : 0u;
size_t const argument_len = strlen(argument);
if (arguments_len > 0)
{
(*arguments)[arguments_len++] = ' ';
}
if (!tr_str_is_empty(argument) && strpbrk(argument, " \t\n\v\"") == nullptr)
{
*arguments = tr_renew(char, *arguments, arguments_len + argument_len + 2);
strcpy(*arguments + arguments_len, argument);
return;
}
*arguments = tr_renew(char, *arguments, arguments_len + argument_len * 2 + 4);
char* dst = *arguments + arguments_len;
*(dst++) = '"';
for (char const* src = argument; *src != '\0';)
{
size_t backslash_count = 0;
while (*src == '\\')
{
++backslash_count;
++src;
}
switch (*src)
{
case '\0':
backslash_count = backslash_count * 2;
break;
case '"':
backslash_count = backslash_count * 2 + 1;
break;
}
if (backslash_count != 0)
{
memset(dst, '\\', backslash_count);
dst += backslash_count;
}
if (*src != '\0')
{
*(dst++) = *(src++);
}
}
*(dst++) = '"';
*(dst++) = '\0';
}
static bool contains_batch_metachars(char const* text)
{
/* First part - chars explicitly documented by `cmd.exe /?` as "special" */
return strpbrk(
text,
"&<>()@^|"
"%!^\"") != nullptr;
}
static enum tr_app_type get_app_type(char const* app)
{
if (tr_str_has_suffix(app, ".cmd") || tr_str_has_suffix(app, ".bat"))
{
return TR_APP_TYPE_BATCH;
}
/* TODO: Support other types? */
return TR_APP_TYPE_EXE;
}
static void append_app_launcher_arguments(enum tr_app_type app_type, char** args)
{
switch (app_type)
{
case TR_APP_TYPE_EXE:
break;
case TR_APP_TYPE_BATCH:
append_argument(args, "cmd.exe");
append_argument(args, "/d");
append_argument(args, "/e:off");
append_argument(args, "/v:off");
append_argument(args, "/s");
append_argument(args, "/c");
break;
default:
TR_ASSERT_MSG(false, "unsupported application type %d", (int)app_type);
break;
}
}
static bool construct_cmd_line(char const* const* cmd, wchar_t** cmd_line)
{
enum tr_app_type const app_type = get_app_type(cmd[0]);
char* args = nullptr;
size_t arg_count = 0;
bool ret = false;
append_app_launcher_arguments(app_type, &args);
for (size_t i = 0; cmd[i] != nullptr; ++i)
{
if (app_type == TR_APP_TYPE_BATCH && i > 0 && contains_batch_metachars(cmd[i]))
{
/* FIXME: My attempts to escape them one or another way didn't lead to anything good so far */
goto cleanup;
}
append_argument(&args, cmd[i]);
++arg_count;
}
*cmd_line = args != nullptr ? tr_win32_utf8_to_native(args, -1) : nullptr;
ret = true;
cleanup:
tr_free(args);
return ret;
}
bool tr_spawn_async(char* const* cmd, char* const* env, char const* work_dir, tr_error** error)
{
wchar_t* env_block = nullptr;
if (!create_env_block(env, &env_block, error))
{
return false;
}
wchar_t* cmd_line;
if (!construct_cmd_line(cmd, &cmd_line))
{
set_system_error(error, ERROR_INVALID_PARAMETER, "Constructing command line");
return false;
}
wchar_t* current_dir = work_dir != nullptr ? tr_win32_utf8_to_native(work_dir, -1) : nullptr;
auto si = STARTUPINFOW{};
si.cb = sizeof(si);
si.dwFlags = STARTF_USESHOWWINDOW;
si.wShowWindow = SW_HIDE;
PROCESS_INFORMATION pi;
bool const ret = CreateProcessW(
nullptr,
cmd_line,
nullptr,
nullptr,
FALSE,
NORMAL_PRIORITY_CLASS | CREATE_UNICODE_ENVIRONMENT | CREATE_NO_WINDOW | CREATE_DEFAULT_ERROR_MODE,
env_block,
current_dir,
&si,
&pi);
if (ret)
{
CloseHandle(pi.hThread);
CloseHandle(pi.hProcess);
}
else
{
set_system_error(error, GetLastError(), "Call to CreateProcess()");
}
tr_free(current_dir);
tr_free(cmd_line);
tr_free(env_block);
return ret;
}