SDL/src/process/windows/SDL_windowsprocess.c

/*
  Simple DirectMedia Layer
  Copyright (C) 1997-2025 Sam Lantinga <slouken@libsdl.org>

  This software is provided 'as-is', without any express or implied
  warranty.  In no event will the authors be held liable for any damages
  arising from the use of this software.

  Permission is granted to anyone to use this software for any purpose,
  including commercial applications, and to alter it and redistribute it
  freely, subject to the following restrictions:

  1. The origin of this software must not be misrepresented; you must not
     claim that you wrote the original software. If you use this software
     in a product, an acknowledgment in the product documentation would be
     appreciated but is not required.
  2. Altered source versions must be plainly marked as such, and must not be
     misrepresented as being the original software.
  3. This notice may not be removed or altered from any source distribution.
*/
#include "SDL_internal.h"

#ifdef SDL_PROCESS_WINDOWS

#include "../../core/windows/SDL_windows.h"
#include "../SDL_sysprocess.h"
#include "../../io/SDL_iostream_c.h"

#define READ_END 0
#define WRITE_END 1

struct SDL_ProcessData {
    PROCESS_INFORMATION process_information;
};

static void CleanupStream(void *userdata, void *value)
{
    SDL_Process *process = (SDL_Process *)value;
    const char *property = (const char *)userdata;

    SDL_ClearProperty(process->props, property);
}

static bool SetupStream(SDL_Process *process, HANDLE handle, const char *mode, const char *property)
{
    SDL_IOStream *io = SDL_IOFromHandle(handle, mode, true);
    if (!io) {
        return false;
    }

    SDL_SetPointerPropertyWithCleanup(SDL_GetIOProperties(io), "SDL.internal.process", process, CleanupStream, (void *)property);
    SDL_SetPointerProperty(process->props, property, io);
    return true;
}

static bool SetupRedirect(SDL_PropertiesID props, const char *property, HANDLE *result)
{
    SDL_IOStream *io = (SDL_IOStream *)SDL_GetPointerProperty(props, property, NULL);
    if (!io) {
        SDL_SetError("%s is not set", property);
        return false;
    }

    HANDLE handle = (HANDLE)SDL_GetPointerProperty(SDL_GetIOProperties(io), SDL_PROP_IOSTREAM_WINDOWS_HANDLE_POINTER, INVALID_HANDLE_VALUE);
    if (handle == INVALID_HANDLE_VALUE) {
        SDL_SetError("%s doesn't have SDL_PROP_IOSTREAM_WINDOWS_HANDLE_POINTER available", property);
        return false;
    }

    if (!DuplicateHandle(GetCurrentProcess(), handle,
                         GetCurrentProcess(), result,
                         0, TRUE, DUPLICATE_SAME_ACCESS)) {
        WIN_SetError("DuplicateHandle()");
        return false;
    }

    if (GetFileType(*result) == FILE_TYPE_PIPE) {
        DWORD wait_mode = PIPE_WAIT;
        if (!SetNamedPipeHandleState(*result, &wait_mode, NULL, NULL)) {
            WIN_SetError("SetNamedPipeHandleState()");
            return false;
        }
    }
    return true;
}

static bool is_batch_file_path(const char *path) {
    size_t len_path = SDL_strlen(path);
    if (len_path < 4) {
        return false;
    }
    if (SDL_strcasecmp(path + len_path - 4, ".bat") == 0 || SDL_strcasecmp(path + len_path - 4, ".cmd") == 0) {
        return true;
    }
    return false;
}

static bool join_arguments(const char * const *args, LPWSTR *args_out)
{
    size_t len;
    int i;
    size_t i_out;
    char *result;
    bool batch_file = is_batch_file_path(args[0]);

    len = 0;
    for (i = 0; args[i]; i++) {
        const char *a = args[i];

        /* two double quotes to surround an argument with */
        len += 2;

        for (; *a; a++) {
            switch (*a) {
            case '"':
                len += 2;
                break;
            case '\\':
                /* only escape backslashes that precede a double quote */
                len += (a[1] == '"' || a[1] == '\0') ? 2 : 1;
                break;
            case ' ':
            case '^':
            case '&':
            case '|':
            case '<':
            case '>':
                if (batch_file) {
                    len += 2;
                } else {
                    len += 1;
                }
                break;
            default:
                len += 1;
                break;
            }
        }
        /* space separator or final '\0' */
        len += 1;
    }

    result = SDL_malloc(len);
    if (!result) {
        *args_out = NULL;
        return false;
    }

    i_out = 0;
    for (i = 0; args[i]; i++) {
        const char *a = args[i];

        result[i_out++] = '"';
        for (; *a; a++) {
            switch (*a) {
            case '"':
                if (batch_file) {
                    result[i_out++] = '"';
                } else {
                    result[i_out++] = '\\';
                }
                result[i_out++] = *a;
                break;
            case '\\':
                result[i_out++] = *a;
                if (a[1] == '"' || a[1] == '\0') {
                    result[i_out++] = *a;
                }
                break;
            case ' ':
                if (batch_file) {
                    result[i_out++] = '^';
                }
                result[i_out++] = *a;
                break;
            case '^':
            case '&':
            case '|':
            case '<':
            case '>':
                if (batch_file) {
                    result[i_out++] = '^';
                }
                result[i_out++] = *a;
                break;
            default:
                result[i_out++] = *a;
                break;
            }
        }
        result[i_out++] = '"';
        result[i_out++] = ' ';
    }
    SDL_assert(i_out == len);
    result[len - 1] = '\0';

    *args_out = (LPWSTR)SDL_iconv_string("UTF-16LE", "UTF-8", (const char *)result, len);
    SDL_free(result);
    if (!args_out) {
        return false;
    }
    return true;
}

static bool join_env(char **env, LPWSTR *env_out)
{
    size_t len;
    char **var;
    char *result;

    len = 0;
    for (var = env; *var; var++) {
        len += SDL_strlen(*var) + 1;
    }
    result = SDL_malloc(len + 1);
    if (!result) {
        return false;
    }

    len = 0;
    for (var = env; *var; var++) {
        size_t l = SDL_strlen(*var);
        SDL_memcpy(result + len, *var, l);
        result[len + l] = '\0';
        len += l + 1;
    }
    result[len] = '\0';

    *env_out = (LPWSTR)SDL_iconv_string("UTF-16LE", "UTF-8", (const char *)result, len);
    SDL_free(result);
    if (!*env_out) {
        return false;
    }
    return true;
}

bool SDL_SYS_CreateProcessWithProperties(SDL_Process *process, SDL_PropertiesID props)
{
    const char * const *args = SDL_GetPointerProperty(props, SDL_PROP_PROCESS_CREATE_ARGS_POINTER, NULL);
    SDL_Environment *env = SDL_GetPointerProperty(props, SDL_PROP_PROCESS_CREATE_ENVIRONMENT_POINTER, SDL_GetEnvironment());
    char **envp = NULL;
    SDL_ProcessIO stdin_option = (SDL_ProcessIO)SDL_GetNumberProperty(props, SDL_PROP_PROCESS_CREATE_STDIN_NUMBER, SDL_PROCESS_STDIO_NULL);
    SDL_ProcessIO stdout_option = (SDL_ProcessIO)SDL_GetNumberProperty(props, SDL_PROP_PROCESS_CREATE_STDOUT_NUMBER, SDL_PROCESS_STDIO_INHERITED);
    SDL_ProcessIO stderr_option = (SDL_ProcessIO)SDL_GetNumberProperty(props, SDL_PROP_PROCESS_CREATE_STDERR_NUMBER, SDL_PROCESS_STDIO_INHERITED);
    bool redirect_stderr = SDL_GetBooleanProperty(props, SDL_PROP_PROCESS_CREATE_STDERR_TO_STDOUT_BOOLEAN, false) &&
                           !SDL_HasProperty(props, SDL_PROP_PROCESS_CREATE_STDERR_NUMBER);
    LPWSTR createprocess_cmdline = NULL;
    LPWSTR createprocess_env = NULL;
    STARTUPINFOW startup_info;
    DWORD creation_flags;
    SECURITY_ATTRIBUTES security_attributes;
    HANDLE stdin_pipe[2] = { INVALID_HANDLE_VALUE, INVALID_HANDLE_VALUE };
    HANDLE stdout_pipe[2] = { INVALID_HANDLE_VALUE, INVALID_HANDLE_VALUE };
    HANDLE stderr_pipe[2] = { INVALID_HANDLE_VALUE, INVALID_HANDLE_VALUE };
    DWORD pipe_mode = PIPE_NOWAIT;
    bool result = false;

    // Keep the malloc() before exec() so that an OOM won't run a process at all
    envp = SDL_GetEnvironmentVariables(env);
    if (!envp) {
        return false;
    }

    SDL_ProcessData *data = SDL_calloc(1, sizeof(*data));
    if (!data) {
        SDL_free(envp);
        return false;
    }
    process->internal = data;
    data->process_information.hProcess = INVALID_HANDLE_VALUE;
    data->process_information.hThread = INVALID_HANDLE_VALUE;

    creation_flags = CREATE_UNICODE_ENVIRONMENT;

    SDL_zero(startup_info);
    startup_info.cb = sizeof(startup_info);
    startup_info.dwFlags |= STARTF_USESTDHANDLES;
    startup_info.hStdInput = INVALID_HANDLE_VALUE;
    startup_info.hStdOutput = INVALID_HANDLE_VALUE;
    startup_info.hStdError = INVALID_HANDLE_VALUE;

    SDL_zero(security_attributes);
    security_attributes.nLength = sizeof(SECURITY_ATTRIBUTES);
    security_attributes.bInheritHandle = TRUE;
    security_attributes.lpSecurityDescriptor = NULL;

    if (!join_arguments(args, &createprocess_cmdline)) {
        goto done;
    }

    if (!join_env(envp, &createprocess_env)) {
        goto done;
    }

    // Background processes don't have access to the terminal
    // This isn't necessary on Windows, but we keep the same behavior as the POSIX implementation.
    if (process->background) {
        if (stdin_option == SDL_PROCESS_STDIO_INHERITED) {
            stdin_option = SDL_PROCESS_STDIO_NULL;
        }
        if (stdout_option == SDL_PROCESS_STDIO_INHERITED) {
            stdout_option = SDL_PROCESS_STDIO_NULL;
        }
        if (stderr_option == SDL_PROCESS_STDIO_INHERITED) {
            stderr_option = SDL_PROCESS_STDIO_NULL;
        }
        creation_flags |= CREATE_NO_WINDOW;
    }

    switch (stdin_option) {
    case SDL_PROCESS_STDIO_REDIRECT:
        if (!SetupRedirect(props, SDL_PROP_PROCESS_CREATE_STDIN_POINTER, &startup_info.hStdInput)) {
            goto done;
        }
        break;
    case SDL_PROCESS_STDIO_APP:
        if (!CreatePipe(&stdin_pipe[READ_END], &stdin_pipe[WRITE_END], &security_attributes, 0)) {
            stdin_pipe[READ_END] = INVALID_HANDLE_VALUE;
            stdin_pipe[WRITE_END] = INVALID_HANDLE_VALUE;
            goto done;
        }
        if (!SetNamedPipeHandleState(stdin_pipe[WRITE_END], &pipe_mode, NULL, NULL)) {
            WIN_SetError("SetNamedPipeHandleState()");
            goto done;
        }
        if (!SetHandleInformation(stdin_pipe[WRITE_END], HANDLE_FLAG_INHERIT, 0) ) {
            WIN_SetError("SetHandleInformation()");
            goto done;
        }
        startup_info.hStdInput = stdin_pipe[READ_END];
        break;
    case SDL_PROCESS_STDIO_NULL:
        startup_info.hStdInput = CreateFile(TEXT("\\\\.\\NUL"), GENERIC_ALL, 0, &security_attributes, OPEN_EXISTING, 0, NULL);
        break;
    case SDL_PROCESS_STDIO_INHERITED:
    default:
        if (!DuplicateHandle(GetCurrentProcess(), GetStdHandle(STD_INPUT_HANDLE),
                             GetCurrentProcess(), &startup_info.hStdInput,
                             0, TRUE, DUPLICATE_SAME_ACCESS)) {
            startup_info.hStdInput = INVALID_HANDLE_VALUE;
            WIN_SetError("DuplicateHandle()");
            goto done;
        }
        break;
    }

    switch (stdout_option) {
    case SDL_PROCESS_STDIO_REDIRECT:
        if (!SetupRedirect(props, SDL_PROP_PROCESS_CREATE_STDOUT_POINTER, &startup_info.hStdOutput)) {
            goto done;
        }
        break;
    case SDL_PROCESS_STDIO_APP:
        if (!CreatePipe(&stdout_pipe[READ_END], &stdout_pipe[WRITE_END], &security_attributes, 0)) {
            stdout_pipe[READ_END] = INVALID_HANDLE_VALUE;
            stdout_pipe[WRITE_END] = INVALID_HANDLE_VALUE;
            goto done;
        }
        if (!SetNamedPipeHandleState(stdout_pipe[READ_END], &pipe_mode, NULL, NULL)) {
            WIN_SetError("SetNamedPipeHandleState()");
            goto done;
        }
        if (!SetHandleInformation(stdout_pipe[READ_END], HANDLE_FLAG_INHERIT, 0) ) {
            WIN_SetError("SetHandleInformation()");
            goto done;
        }
        startup_info.hStdOutput = stdout_pipe[WRITE_END];
        break;
    case SDL_PROCESS_STDIO_NULL:
        startup_info.hStdOutput = CreateFile(TEXT("\\\\.\\NUL"), GENERIC_ALL, 0, &security_attributes, OPEN_EXISTING, 0, NULL);
        break;
    case SDL_PROCESS_STDIO_INHERITED:
    default:
        if (!DuplicateHandle(GetCurrentProcess(), GetStdHandle(STD_OUTPUT_HANDLE),
                             GetCurrentProcess(), &startup_info.hStdOutput,
                             0, TRUE, DUPLICATE_SAME_ACCESS)) {
            startup_info.hStdOutput = INVALID_HANDLE_VALUE;
            WIN_SetError("DuplicateHandle()");
            goto done;
        }
        break;
    }

    if (redirect_stderr) {
        if (!DuplicateHandle(GetCurrentProcess(), startup_info.hStdOutput,
                             GetCurrentProcess(), &startup_info.hStdError,
                             0, TRUE, DUPLICATE_SAME_ACCESS)) {
            startup_info.hStdError = INVALID_HANDLE_VALUE;
            WIN_SetError("DuplicateHandle()");
            goto done;
        }
    } else {
        switch (stderr_option) {
        case SDL_PROCESS_STDIO_REDIRECT:
            if (!SetupRedirect(props, SDL_PROP_PROCESS_CREATE_STDERR_POINTER, &startup_info.hStdError)) {
                goto done;
            }
            break;
        case SDL_PROCESS_STDIO_APP:
            if (!CreatePipe(&stderr_pipe[READ_END], &stderr_pipe[WRITE_END], &security_attributes, 0)) {
                stderr_pipe[READ_END] = INVALID_HANDLE_VALUE;
                stderr_pipe[WRITE_END] = INVALID_HANDLE_VALUE;
                goto done;
            }
            if (!SetNamedPipeHandleState(stderr_pipe[READ_END], &pipe_mode, NULL, NULL)) {
                WIN_SetError("SetNamedPipeHandleState()");
                goto done;
            }
            if (!SetHandleInformation(stderr_pipe[READ_END], HANDLE_FLAG_INHERIT, 0) ) {
                WIN_SetError("SetHandleInformation()");
                goto done;
            }
            startup_info.hStdError = stderr_pipe[WRITE_END];
            break;
        case SDL_PROCESS_STDIO_NULL:
            startup_info.hStdError = CreateFile(TEXT("\\\\.\\NUL"), GENERIC_ALL, 0, &security_attributes, OPEN_EXISTING, 0, NULL);
            break;
        case SDL_PROCESS_STDIO_INHERITED:
        default:
            if (!DuplicateHandle(GetCurrentProcess(), GetStdHandle(STD_ERROR_HANDLE),
                                 GetCurrentProcess(), &startup_info.hStdError,
                                 0, TRUE, DUPLICATE_SAME_ACCESS)) {
                startup_info.hStdError = INVALID_HANDLE_VALUE;
                WIN_SetError("DuplicateHandle()");
                goto done;
            }
            break;
        }
    }

    if (!CreateProcessW(NULL, createprocess_cmdline, NULL, NULL, TRUE, creation_flags, createprocess_env, NULL, &startup_info, &data->process_information)) {
        WIN_SetError("CreateProcess");
        goto done;
    }

    SDL_SetNumberProperty(process->props, SDL_PROP_PROCESS_PID_NUMBER, data->process_information.dwProcessId);

    if (stdin_option == SDL_PROCESS_STDIO_APP) {
        if (!SetupStream(process, stdin_pipe[WRITE_END], "wb", SDL_PROP_PROCESS_STDIN_POINTER)) {
            CloseHandle(stdin_pipe[WRITE_END]);
            stdin_pipe[WRITE_END] = INVALID_HANDLE_VALUE;
        }
    }
    if (stdout_option == SDL_PROCESS_STDIO_APP) {
        if (!SetupStream(process, stdout_pipe[READ_END], "rb", SDL_PROP_PROCESS_STDOUT_POINTER)) {
            CloseHandle(stdout_pipe[READ_END]);
            stdout_pipe[READ_END] = INVALID_HANDLE_VALUE;
        }
    }
    if (stderr_option == SDL_PROCESS_STDIO_APP) {
        if (!SetupStream(process, stderr_pipe[READ_END], "rb", SDL_PROP_PROCESS_STDERR_POINTER)) {
            CloseHandle(stderr_pipe[READ_END]);
            stderr_pipe[READ_END] = INVALID_HANDLE_VALUE;
        }
    }

    result = true;

done:
    if (startup_info.hStdInput != INVALID_HANDLE_VALUE &&
        startup_info.hStdInput != stdin_pipe[READ_END]) {
        CloseHandle(startup_info.hStdInput);
    }
    if (startup_info.hStdOutput != INVALID_HANDLE_VALUE &&
        startup_info.hStdOutput != stdout_pipe[WRITE_END]) {
        CloseHandle(startup_info.hStdOutput);
    }
    if (startup_info.hStdError != INVALID_HANDLE_VALUE &&
        startup_info.hStdError != stderr_pipe[WRITE_END]) {
        CloseHandle(startup_info.hStdError);
    }
    if (stdin_pipe[READ_END] != INVALID_HANDLE_VALUE) {
        CloseHandle(stdin_pipe[READ_END]);
    }
    if (stdout_pipe[WRITE_END] != INVALID_HANDLE_VALUE) {
        CloseHandle(stdout_pipe[WRITE_END]);
    }
    if (stderr_pipe[WRITE_END] != INVALID_HANDLE_VALUE) {
        CloseHandle(stderr_pipe[WRITE_END]);
    }
    SDL_free(createprocess_cmdline);
    SDL_free(createprocess_env);
    SDL_free(envp);

    if (!result) {
        if (stdin_pipe[WRITE_END] != INVALID_HANDLE_VALUE) {
            CloseHandle(stdin_pipe[WRITE_END]);
        }
        if (stdout_pipe[READ_END] != INVALID_HANDLE_VALUE) {
            CloseHandle(stdout_pipe[READ_END]);
        }
        if (stderr_pipe[READ_END] != INVALID_HANDLE_VALUE) {
            CloseHandle(stderr_pipe[READ_END]);
        }
    }
    return result;
}

bool SDL_SYS_KillProcess(SDL_Process *process, bool force)
{
    if (!TerminateProcess(process->internal->process_information.hProcess, 1)) {
        return WIN_SetError("TerminateProcess failed");
    }
    return true;
}

bool SDL_SYS_WaitProcess(SDL_Process *process, bool block, int *exitcode)
{
    DWORD result;

    result = WaitForSingleObject(process->internal->process_information.hProcess, block ? INFINITE : 0);

    if (result == WAIT_OBJECT_0) {
        DWORD rc;
        if (!GetExitCodeProcess(process->internal->process_information.hProcess, &rc)) {
            return WIN_SetError("GetExitCodeProcess");
        }
        if (exitcode) {
            *exitcode = (int)rc;
        }
        return true;
    } else if (result == WAIT_FAILED) {
        return WIN_SetError("WaitForSingleObject(hProcess) returned WAIT_FAILED");
    } else {
        SDL_ClearError();
        return false;
    }
}

void SDL_SYS_DestroyProcess(SDL_Process *process)
{
    SDL_ProcessData *data = process->internal;
    SDL_IOStream *io;

    io = (SDL_IOStream *)SDL_GetPointerProperty(process->props, SDL_PROP_PROCESS_STDIN_POINTER, NULL);
    if (io) {
        SDL_CloseIO(io);
    }
    io = (SDL_IOStream *)SDL_GetPointerProperty(process->props, SDL_PROP_PROCESS_STDERR_POINTER, NULL);
    if (io) {
        SDL_CloseIO(io);
    }
    io = (SDL_IOStream *)SDL_GetPointerProperty(process->props, SDL_PROP_PROCESS_STDOUT_POINTER, NULL);
    if (io) {
        SDL_CloseIO(io);
    }
    if (data) {
        if (data->process_information.hThread != INVALID_HANDLE_VALUE) {
            CloseHandle(data->process_information.hThread);
        }
        if (data->process_information.hProcess != INVALID_HANDLE_VALUE) {
            CloseHandle(data->process_information.hProcess);
        }
    }
    SDL_free(data);
}

#endif // SDL_PROCESS_WINDOWS