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Diffstat (limited to 'src/lib/process/process_win32.c')
| -rw-r--r-- | src/lib/process/process_win32.c | 1105 |
1 files changed, 1105 insertions, 0 deletions
diff --git a/src/lib/process/process_win32.c b/src/lib/process/process_win32.c new file mode 100644 index 0000000000..8683e17fc2 --- /dev/null +++ b/src/lib/process/process_win32.c @@ -0,0 +1,1105 @@ +/* Copyright (c) 2003, Roger Dingledine + * Copyright (c) 2004-2006, Roger Dingledine, Nick Mathewson. + * Copyright (c) 2007-2020, The Tor Project, Inc. */ +/* See LICENSE for licensing information */ + +/** + * \file process_win32.c + * \brief Module for working with Windows processes. + **/ + +#define PROCESS_WIN32_PRIVATE +#include "lib/intmath/cmp.h" +#include "lib/buf/buffers.h" +#include "lib/net/buffers_net.h" +#include "lib/container/smartlist.h" +#include "lib/log/log.h" +#include "lib/log/util_bug.h" +#include "lib/log/win32err.h" +#include "lib/process/process.h" +#include "lib/process/process_win32.h" +#include "lib/process/env.h" + +#ifdef HAVE_SYS_TIME_H +#include <sys/time.h> +#endif + +#ifdef HAVE_STRING_H +#include <string.h> +#endif + +#ifdef _WIN32 + +/** The size of our intermediate buffers. */ +#define BUFFER_SIZE (1024) + +/** Timer that ticks once a second and calls the process_win32_timer_callback() + * function. */ +static periodic_timer_t *periodic_timer; + +/** Structure to represent the state around the pipe HANDLE. + * + * This structure is used to store state about a given HANDLE, including + * whether we have reached end of file, its intermediate buffers, and how much + * data that is available in the intermediate buffer. */ +struct process_win32_handle_t { + /** Standard out pipe handle. */ + HANDLE pipe; + + /** True iff we have reached EOF from the pipe. */ + bool reached_eof; + + /** How much data is available in buffer. */ + size_t data_available; + + /** Intermediate buffer for ReadFileEx() and WriteFileEx(). */ + char buffer[BUFFER_SIZE]; + + /** Overlapped structure for ReadFileEx() and WriteFileEx(). */ + OVERLAPPED overlapped; + + /** Are we waiting for another I/O operation to complete? */ + bool busy; +}; + +/** Structure to represent the Windows specific implementation details of this + * Process backend. + * + * This structure is attached to <b>process_t</b> (see process.h) and is + * reachable from <b>process_t</b> via the <b>process_get_win32_process()</b> + * method. */ +struct process_win32_t { + /** Standard in state. */ + process_win32_handle_t stdin_handle; + + /** Standard out state. */ + process_win32_handle_t stdout_handle; + + /** Standard error state. */ + process_win32_handle_t stderr_handle; + + /** Process Information. */ + PROCESS_INFORMATION process_information; +}; + +/** Create a new <b>process_win32_t</b>. + * + * This function constructs a new <b>process_win32_t</b> and initializes the + * default values. */ +process_win32_t * +process_win32_new(void) +{ + process_win32_t *win32_process; + win32_process = tor_malloc_zero(sizeof(process_win32_t)); + + win32_process->stdin_handle.pipe = INVALID_HANDLE_VALUE; + win32_process->stdout_handle.pipe = INVALID_HANDLE_VALUE; + win32_process->stderr_handle.pipe = INVALID_HANDLE_VALUE; + + return win32_process; +} + +/** Free a given <b>process_win32_t</b>. + * + * This function deinitializes and frees up the resources allocated for the + * given <b>process_win32_t</b>. */ +void +process_win32_free_(process_win32_t *win32_process) +{ + if (! win32_process) + return; + + /* Cleanup our handles. */ + process_win32_cleanup_handle(&win32_process->stdin_handle); + process_win32_cleanup_handle(&win32_process->stdout_handle); + process_win32_cleanup_handle(&win32_process->stderr_handle); + + tor_free(win32_process); +} + +/** Initialize the Windows backend of the Process subsystem. */ +void +process_win32_init(void) +{ + /* We don't start the periodic timer here because it makes no sense to have + * the timer running until we have some processes that benefits from the + * timer timer ticks. */ +} + +/** Deinitialize the Windows backend of the Process subsystem. */ +void +process_win32_deinit(void) +{ + /* Stop our timer, but only if it's running. */ + if (process_win32_timer_running()) + process_win32_timer_stop(); +} + +/** Execute the given process. This function is responsible for setting up + * named pipes for I/O between the child process and the Tor process. Returns + * <b>PROCESS_STATUS_RUNNING</b> upon success. */ +process_status_t +process_win32_exec(process_t *process) +{ + tor_assert(process); + + process_win32_t *win32_process = process_get_win32_process(process); + + HANDLE stdout_pipe_read = NULL; + HANDLE stdout_pipe_write = NULL; + HANDLE stderr_pipe_read = NULL; + HANDLE stderr_pipe_write = NULL; + HANDLE stdin_pipe_read = NULL; + HANDLE stdin_pipe_write = NULL; + BOOL ret = FALSE; + + /* Setup our security attributes. */ + SECURITY_ATTRIBUTES security_attributes; + security_attributes.nLength = sizeof(security_attributes); + security_attributes.bInheritHandle = TRUE; + /* FIXME: should we set explicit security attributes? + * (See Ticket #2046, comment 5) */ + security_attributes.lpSecurityDescriptor = NULL; + + /* Create our standard out pipe. */ + if (! process_win32_create_pipe(&stdout_pipe_read, + &stdout_pipe_write, + &security_attributes, + PROCESS_WIN32_PIPE_TYPE_READER)) { + return PROCESS_STATUS_ERROR; + } + + /* Create our standard error pipe. */ + if (! process_win32_create_pipe(&stderr_pipe_read, + &stderr_pipe_write, + &security_attributes, + PROCESS_WIN32_PIPE_TYPE_READER)) { + return PROCESS_STATUS_ERROR; + } + + /* Create out standard in pipe. */ + if (! process_win32_create_pipe(&stdin_pipe_read, + &stdin_pipe_write, + &security_attributes, + PROCESS_WIN32_PIPE_TYPE_WRITER)) { + return PROCESS_STATUS_ERROR; + } + + /* Configure startup info for our child process. */ + STARTUPINFOA startup_info; + + memset(&startup_info, 0, sizeof(startup_info)); + startup_info.cb = sizeof(startup_info); + startup_info.hStdError = stderr_pipe_write; + startup_info.hStdOutput = stdout_pipe_write; + startup_info.hStdInput = stdin_pipe_read; + startup_info.dwFlags |= STARTF_USESTDHANDLES; + + /* Create the env value for our new process. */ + process_environment_t *env = process_get_environment(process); + + /* Create the argv value for our new process. */ + char **argv = process_get_argv(process); + + /* Windows expects argv to be a whitespace delimited string, so join argv up + */ + char *joined_argv = tor_join_win_cmdline((const char **)argv); + + /* Create the child process */ + ret = CreateProcessA(NULL, + joined_argv, + NULL, + NULL, + TRUE, + CREATE_NO_WINDOW, + env->windows_environment_block[0] == '\0' ? + NULL : env->windows_environment_block, + NULL, + &startup_info, + &win32_process->process_information); + + tor_free(argv); + tor_free(joined_argv); + process_environment_free(env); + + if (! ret) { + log_warn(LD_PROCESS, "CreateProcessA() failed: %s", + format_win32_error(GetLastError())); + + /* Cleanup our handles. */ + CloseHandle(stdout_pipe_read); + CloseHandle(stdout_pipe_write); + CloseHandle(stderr_pipe_read); + CloseHandle(stderr_pipe_write); + CloseHandle(stdin_pipe_read); + CloseHandle(stdin_pipe_write); + + /* In the Unix backend, we do not get an error in the Tor process when a + * child process fails to spawn its target executable since we need to + * first do the fork() call in the Tor process and then the child process + * is responsible for doing the call to execve(). + * + * This means that the user of the process_exec() API must check for + * whether it returns PROCESS_STATUS_ERROR, which will rarely happen on + * Unix, but will happen for error cases on Windows where it does not + * happen on Unix. For example: when the target executable does not exist + * on the file system. + * + * To have somewhat feature compatibility between the Unix and the Windows + * backend, we here notify the process_t owner that the process have exited + * (even though it never managed to run) to ensure that the exit callback + * is executed. + */ + process_notify_event_exit(process, 0); + + return PROCESS_STATUS_ERROR; + } + + /* TODO: Should we close hProcess and hThread in + * process_handle->process_information? */ + win32_process->stdout_handle.pipe = stdout_pipe_read; + win32_process->stderr_handle.pipe = stderr_pipe_read; + win32_process->stdin_handle.pipe = stdin_pipe_write; + + /* Close our ends of the pipes that is now owned by the child process. */ + CloseHandle(stdout_pipe_write); + CloseHandle(stderr_pipe_write); + CloseHandle(stdin_pipe_read); + + /* Used by the callback functions from ReadFileEx() and WriteFileEx() such + * that we can figure out which process_t that was responsible for the event. + * + * Warning, here be dragons: + * + * MSDN says that the hEvent member of the overlapped structure is unused + * for ReadFileEx() and WriteFileEx, which allows us to store a pointer to + * our process state there. + */ + win32_process->stdout_handle.overlapped.hEvent = (HANDLE)process; + win32_process->stderr_handle.overlapped.hEvent = (HANDLE)process; + win32_process->stdin_handle.overlapped.hEvent = (HANDLE)process; + + /* Start our timer if it is not already running. */ + if (! process_win32_timer_running()) + process_win32_timer_start(); + + /* We use Windows Extended I/O functions, so our completion callbacks are + * called automatically for us when there is data to read. Because of this + * we start the read of standard out and error right away. */ + process_notify_event_stdout(process); + process_notify_event_stderr(process); + + return PROCESS_STATUS_RUNNING; +} + +/** Terminate the given process. Returns true on success, otherwise false. */ +bool +process_win32_terminate(process_t *process) +{ + tor_assert(process); + + process_win32_t *win32_process = process_get_win32_process(process); + + /* Terminate our process. */ + BOOL ret; + + ret = TerminateProcess(win32_process->process_information.hProcess, 0); + + if (! ret) { + log_warn(LD_PROCESS, "TerminateProcess() failed: %s", + format_win32_error(GetLastError())); + return false; + } + + /* Cleanup our handles. */ + process_win32_cleanup_handle(&win32_process->stdin_handle); + process_win32_cleanup_handle(&win32_process->stdout_handle); + process_win32_cleanup_handle(&win32_process->stderr_handle); + + return true; +} + +/** Returns the unique process identifier for the given <b>process</b>. */ +process_pid_t +process_win32_get_pid(process_t *process) +{ + tor_assert(process); + + process_win32_t *win32_process = process_get_win32_process(process); + return (process_pid_t)win32_process->process_information.dwProcessId; +} + +/** Schedule an async write of the data found in <b>buffer</b> for the given + * process. This function runs an async write operation of the content of + * buffer, if we are not already waiting for a pending I/O request. Returns the + * number of bytes that Windows will hopefully write for us in the background. + * */ +int +process_win32_write(struct process_t *process, buf_t *buffer) +{ + tor_assert(process); + tor_assert(buffer); + + process_win32_t *win32_process = process_get_win32_process(process); + BOOL ret = FALSE; + DWORD error_code = 0; + const size_t buffer_size = buf_datalen(buffer); + + /* Windows is still writing our buffer. */ + if (win32_process->stdin_handle.busy) + return 0; + + /* Nothing for us to do right now. */ + if (buffer_size == 0) + return 0; + + /* We have reached end of file already? */ + if (BUG(win32_process->stdin_handle.reached_eof)) + return 0; + + /* Figure out how much data we should read. */ + const size_t write_size = MIN(buffer_size, + sizeof(win32_process->stdin_handle.buffer)); + + /* Read data from the process_t buffer into our intermediate buffer. */ + buf_get_bytes(buffer, win32_process->stdin_handle.buffer, write_size); + + /* Because of the slightly weird API for WriteFileEx() we must set this to 0 + * before we call WriteFileEx() because WriteFileEx() does not reset the last + * error itself when it's succesful. See comment below after the call to + * GetLastError(). */ + SetLastError(0); + + /* Schedule our write. */ + ret = WriteFileEx(win32_process->stdin_handle.pipe, + win32_process->stdin_handle.buffer, + write_size, + &win32_process->stdin_handle.overlapped, + process_win32_stdin_write_done); + + if (! ret) { + error_code = GetLastError(); + + /* No need to log at warning level for these two. */ + if (error_code == ERROR_HANDLE_EOF || error_code == ERROR_BROKEN_PIPE) { + log_debug(LD_PROCESS, "WriteFileEx() returned EOF from pipe: %s", + format_win32_error(error_code)); + } else { + log_warn(LD_PROCESS, "WriteFileEx() failed: %s", + format_win32_error(error_code)); + } + + win32_process->stdin_handle.reached_eof = true; + return 0; + } + + /* Here be dragons: According to MSDN's documentation for WriteFileEx() we + * should check GetLastError() after a call to WriteFileEx() even though the + * `ret` return value was successful. If everything is good, GetLastError() + * returns `ERROR_SUCCESS` and nothing happens. + * + * XXX(ahf): I have not managed to trigger this code while stress-testing + * this code. */ + error_code = GetLastError(); + + if (error_code != ERROR_SUCCESS) { + /* LCOV_EXCL_START */ + log_warn(LD_PROCESS, "WriteFileEx() failed after returning success: %s", + format_win32_error(error_code)); + win32_process->stdin_handle.reached_eof = true; + return 0; + /* LCOV_EXCL_STOP */ + } + + /* This cast should be safe since our buffer can maximum be BUFFER_SIZE + * large. */ + return (int)write_size; +} + +/** This function is called from the Process subsystem whenever the Windows + * backend says it has data ready. This function also ensures that we are + * starting a new background read from the standard output of the child process + * and asks Windows to call process_win32_stdout_read_done() when that + * operation is finished. Returns the number of bytes moved into <b>buffer</b>. + * */ +int +process_win32_read_stdout(struct process_t *process, buf_t *buffer) +{ + tor_assert(process); + tor_assert(buffer); + + process_win32_t *win32_process = process_get_win32_process(process); + + return process_win32_read_from_handle(&win32_process->stdout_handle, + buffer, + process_win32_stdout_read_done); +} + +/** This function is called from the Process subsystem whenever the Windows + * backend says it has data ready. This function also ensures that we are + * starting a new background read from the standard error of the child process + * and asks Windows to call process_win32_stderr_read_done() when that + * operation is finished. Returns the number of bytes moved into <b>buffer</b>. + * */ +int +process_win32_read_stderr(struct process_t *process, buf_t *buffer) +{ + tor_assert(process); + tor_assert(buffer); + + process_win32_t *win32_process = process_get_win32_process(process); + + return process_win32_read_from_handle(&win32_process->stderr_handle, + buffer, + process_win32_stderr_read_done); +} + +/** This function is responsible for moving the Tor process into what Microsoft + * calls an "alertable" state. Once the process is in an alertable state the + * Windows kernel will notify us when our background I/O requests have finished + * and the callbacks will be executed. */ +void +process_win32_trigger_completion_callbacks(void) +{ + DWORD ret; + + /* The call to SleepEx(dwMilliseconds, dwAlertable) makes the process sleep + * for dwMilliseconds and if dwAlertable is set to TRUE it will also cause + * the process to enter alertable state, where the Windows kernel will notify + * us about completed I/O requests from ReadFileEx() and WriteFileEX(), which + * will cause our completion callbacks to be executed. + * + * This function returns 0 if the time interval expired or WAIT_IO_COMPLETION + * if one or more I/O callbacks were executed. */ + ret = SleepEx(0, TRUE); + + /* Warn us if the function returned something we did not anticipate. */ + if (ret != 0 && ret != WAIT_IO_COMPLETION) { + log_warn(LD_PROCESS, "SleepEx() returned %lu", ret); + } +} + +/** Start the periodic timer which is reponsible for checking whether processes + * are still alive and to make sure that the Tor process is periodically being + * moved into an alertable state. */ +void +process_win32_timer_start(void) +{ + /* Make sure we never start our timer if it's already running. */ + if (BUG(process_win32_timer_running())) + return; + + /* Wake up once a second. */ + static const struct timeval interval = {1, 0}; + + log_info(LD_PROCESS, "Starting Windows Process I/O timer"); + periodic_timer = periodic_timer_new(tor_libevent_get_base(), + &interval, + process_win32_timer_callback, + NULL); +} + +/** Stops the periodic timer. */ +void +process_win32_timer_stop(void) +{ + if (BUG(periodic_timer == NULL)) + return; + + log_info(LD_PROCESS, "Stopping Windows Process I/O timer"); + periodic_timer_free(periodic_timer); +} + +/** Returns true iff the periodic timer is running. */ +bool +process_win32_timer_running(void) +{ + return periodic_timer != NULL; +} + +/** This function is called whenever the periodic_timer ticks. The function is + * responsible for moving the Tor process into an alertable state once a second + * and checking for whether our child processes have terminated since the last + * tick. */ +STATIC void +process_win32_timer_callback(periodic_timer_t *timer, void *data) +{ + tor_assert(timer == periodic_timer); + tor_assert(data == NULL); + + /* Move the process into an alertable state. */ + process_win32_trigger_completion_callbacks(); + + /* Check if our processes are still alive. */ + + /* Since the call to process_win32_timer_test_process() might call + * process_notify_event_exit() which again might call process_free() which + * updates the list of processes returned by process_get_all_processes() it + * is important here that we make sure to not touch the list of processes if + * the call to process_win32_timer_test_process() returns true. */ + bool done; + + do { + const smartlist_t *processes = process_get_all_processes(); + done = true; + + SMARTLIST_FOREACH_BEGIN(processes, process_t *, process) { + /* If process_win32_timer_test_process() returns true, it means that + * smartlist_remove() might have been called on the list returned by + * process_get_all_processes(). We start the loop over again until we + * have a succesful run over the entire list where the list was not + * modified. */ + if (process_win32_timer_test_process(process)) { + done = false; + break; + } + } SMARTLIST_FOREACH_END(process); + } while (! done); +} + +/** Test whether a given process is still alive. Notify the Process subsystem + * if our process have died. Returns true iff the given process have + * terminated. */ +STATIC bool +process_win32_timer_test_process(process_t *process) +{ + tor_assert(process); + + /* No need to look at processes that don't claim they are running. */ + if (process_get_status(process) != PROCESS_STATUS_RUNNING) + return false; + + process_win32_t *win32_process = process_get_win32_process(process); + BOOL ret = FALSE; + DWORD exit_code = 0; + + /* Sometimes the Windows kernel wont give us the EOF/Broken Pipe error + * message until some time after the process have actually terminated. We + * make sure that our ReadFileEx() calls for the process have *all* returned + * and both standard out and error have been marked as EOF before we try to + * see if the process terminated. + * + * This ensures that we *never* call the exit callback of the `process_t`, + * which potentially ends up calling `process_free()` on our `process_t`, + * before all data have been received from the process. + * + * We do NOT have a check here for whether standard in reached EOF since + * standard in's WriteFileEx() function is only called on-demand when we have + * something to write and is thus usually not awaiting to finish any + * operations. If we WriteFileEx() to a file that has terminated we'll simply + * get an error from ReadFileEx() or its completion routine and move on with + * life. */ + if (! win32_process->stdout_handle.reached_eof) + return false; + + if (! win32_process->stderr_handle.reached_eof) + return false; + + /* We start by testing whether our process is still running. */ + ret = GetExitCodeProcess(win32_process->process_information.hProcess, + &exit_code); + + if (! ret) { + log_warn(LD_PROCESS, "GetExitCodeProcess() failed: %s", + format_win32_error(GetLastError())); + return false; + } + + /* Notify our process_t that our process have terminated. Since our + * exit_callback might decide to process_free() our process handle it is very + * important that we do not touch the process_t after the call to + * process_notify_event_exit(). */ + if (exit_code != STILL_ACTIVE) { + process_notify_event_exit(process, exit_code); + return true; + } + + return false; +} + +/** Create a new overlapped named pipe. This function creates a new connected, + * named, pipe in <b>*read_pipe</b> and <b>*write_pipe</b> if the function is + * succesful. Returns true on sucess, false on failure. */ +STATIC bool +process_win32_create_pipe(HANDLE *read_pipe, + HANDLE *write_pipe, + SECURITY_ATTRIBUTES *attributes, + process_win32_pipe_type_t pipe_type) +{ + tor_assert(read_pipe); + tor_assert(write_pipe); + tor_assert(attributes); + + BOOL ret = FALSE; + + /* Buffer size. */ + const size_t size = 4096; + + /* Our additional read/write modes that depends on which pipe type we are + * creating. */ + DWORD read_mode = 0; + DWORD write_mode = 0; + + /* Generate the unique pipe name. */ + char pipe_name[MAX_PATH]; + static DWORD process_id = 0; + static DWORD counter = 0; + + if (process_id == 0) + process_id = GetCurrentProcessId(); + + tor_snprintf(pipe_name, sizeof(pipe_name), + "\\\\.\\Pipe\\Tor-Process-Pipe-%lu-%lu", + process_id, counter++); + + /* Only one of our handles can be overlapped. */ + switch (pipe_type) { + case PROCESS_WIN32_PIPE_TYPE_READER: + read_mode = FILE_FLAG_OVERLAPPED; + break; + case PROCESS_WIN32_PIPE_TYPE_WRITER: + write_mode = FILE_FLAG_OVERLAPPED; + break; + default: + /* LCOV_EXCL_START */ + tor_assert_nonfatal_unreached_once(); + /* LCOV_EXCL_STOP */ + } + + /* Setup our read and write handles. */ + HANDLE read_handle; + HANDLE write_handle; + + /* Create our named pipe. */ + read_handle = CreateNamedPipeA(pipe_name, + (PIPE_ACCESS_INBOUND|read_mode), + (PIPE_TYPE_BYTE|PIPE_WAIT), + 1, + size, + size, + 1000, + attributes); + + if (read_handle == INVALID_HANDLE_VALUE) { + log_warn(LD_PROCESS, "CreateNamedPipeA() failed: %s", + format_win32_error(GetLastError())); + return false; + } + + /* Create our file in the pipe namespace. */ + write_handle = CreateFileA(pipe_name, + GENERIC_WRITE, + 0, + attributes, + OPEN_EXISTING, + (FILE_ATTRIBUTE_NORMAL|write_mode), + NULL); + + if (write_handle == INVALID_HANDLE_VALUE) { + log_warn(LD_PROCESS, "CreateFileA() failed: %s", + format_win32_error(GetLastError())); + + CloseHandle(read_handle); + + return false; + } + + /* Set the inherit flag for our pipe. */ + switch (pipe_type) { + case PROCESS_WIN32_PIPE_TYPE_READER: + ret = SetHandleInformation(read_handle, HANDLE_FLAG_INHERIT, 0); + break; + case PROCESS_WIN32_PIPE_TYPE_WRITER: + ret = SetHandleInformation(write_handle, HANDLE_FLAG_INHERIT, 0); + break; + default: + /* LCOV_EXCL_START */ + tor_assert_nonfatal_unreached_once(); + /* LCOV_EXCL_STOP */ + } + + if (! ret) { + log_warn(LD_PROCESS, "SetHandleInformation() failed: %s", + format_win32_error(GetLastError())); + + CloseHandle(read_handle); + CloseHandle(write_handle); + + return false; + } + + /* Everything is good. */ + *read_pipe = read_handle; + *write_pipe = write_handle; + + return true; +} + +/** Cleanup a given <b>handle</b>. */ +STATIC void +process_win32_cleanup_handle(process_win32_handle_t *handle) +{ + tor_assert(handle); + +#if 0 + BOOL ret; + DWORD error_code; + + /* Cancel any pending I/O requests: This means that instead of getting + * ERROR_BROKEN_PIPE we get ERROR_OPERATION_ABORTED, but it doesn't seem + * like this is needed. */ + ret = CancelIo(handle->pipe); + + if (! ret) { + error_code = GetLastError(); + + /* There was no pending I/O requests for our handle. */ + if (error_code != ERROR_NOT_FOUND) { + log_warn(LD_PROCESS, "CancelIo() failed: %s", + format_win32_error(error_code)); + } + } +#endif /* 0 */ + + /* Close our handle. */ + if (handle->pipe != INVALID_HANDLE_VALUE) { + CloseHandle(handle->pipe); + handle->pipe = INVALID_HANDLE_VALUE; + handle->reached_eof = true; + } +} + +/** This function is called when ReadFileEx() completes its background read + * from the child process's standard output. We notify the Process subsystem if + * there is data available for it to read from us. */ +STATIC VOID WINAPI +process_win32_stdout_read_done(DWORD error_code, + DWORD byte_count, + LPOVERLAPPED overlapped) +{ + tor_assert(overlapped); + tor_assert(overlapped->hEvent); + + /* Extract our process_t from the hEvent member of OVERLAPPED. */ + process_t *process = (process_t *)overlapped->hEvent; + process_win32_t *win32_process = process_get_win32_process(process); + + if (process_win32_handle_read_completion(&win32_process->stdout_handle, + error_code, + byte_count)) { + /* Schedule our next read. */ + process_notify_event_stdout(process); + } +} + +/** This function is called when ReadFileEx() completes its background read + * from the child process's standard error. We notify the Process subsystem if + * there is data available for it to read from us. */ +STATIC VOID WINAPI +process_win32_stderr_read_done(DWORD error_code, + DWORD byte_count, + LPOVERLAPPED overlapped) +{ + tor_assert(overlapped); + tor_assert(overlapped->hEvent); + + /* Extract our process_t from the hEvent member of OVERLAPPED. */ + process_t *process = (process_t *)overlapped->hEvent; + process_win32_t *win32_process = process_get_win32_process(process); + + if (process_win32_handle_read_completion(&win32_process->stderr_handle, + error_code, + byte_count)) { + /* Schedule our next read. */ + process_notify_event_stderr(process); + } +} + +/** This function is called when WriteFileEx() completes its background write + * to the child process's standard input. We notify the Process subsystem that + * it can write data to us again. */ +STATIC VOID WINAPI +process_win32_stdin_write_done(DWORD error_code, + DWORD byte_count, + LPOVERLAPPED overlapped) +{ + tor_assert(overlapped); + tor_assert(overlapped->hEvent); + + (void)byte_count; + + process_t *process = (process_t *)overlapped->hEvent; + process_win32_t *win32_process = process_get_win32_process(process); + + /* Mark our handle as not having any outstanding I/O requests. */ + win32_process->stdin_handle.busy = false; + + /* Check if we have been asked to write to the handle that have been marked + * as having reached EOF. */ + if (BUG(win32_process->stdin_handle.reached_eof)) + return; + + if (error_code == 0) { + /** Our data have been succesfully written. Clear our state and schedule + * the next write. */ + win32_process->stdin_handle.data_available = 0; + memset(win32_process->stdin_handle.buffer, 0, + sizeof(win32_process->stdin_handle.buffer)); + + /* Schedule the next write. */ + process_notify_event_stdin(process); + } else if (error_code == ERROR_HANDLE_EOF || + error_code == ERROR_BROKEN_PIPE) { + /* Our WriteFileEx() call was succesful, but we reached the end of our + * file. We mark our handle as having reached EOF and returns. */ + tor_assert(byte_count == 0); + + win32_process->stdin_handle.reached_eof = true; + } else { + /* An error happened: We warn the user and mark our handle as having + * reached EOF */ + log_warn(LD_PROCESS, + "Error in I/O completion routine from WriteFileEx(): %s", + format_win32_error(error_code)); + win32_process->stdin_handle.reached_eof = true; + } +} + +/** This function reads data from the given <b>handle</b>'s internal buffer and + * moves it into the given <b>buffer</b>. Additionally, we start the next + * ReadFileEx() background operation with the given <b>callback</b> as + * completion callback. Returns the number of bytes written to the buffer. */ +STATIC int +process_win32_read_from_handle(process_win32_handle_t *handle, + buf_t *buffer, + LPOVERLAPPED_COMPLETION_ROUTINE callback) +{ + tor_assert(handle); + tor_assert(buffer); + tor_assert(callback); + + BOOL ret = FALSE; + int bytes_available = 0; + DWORD error_code = 0; + + /* We already have a request to read data that isn't complete yet. */ + if (BUG(handle->busy)) + return 0; + + /* Check if we have been asked to read from a handle that have already told + * us that we have reached the end of the file. */ + if (BUG(handle->reached_eof)) + return 0; + + /* This cast should be safe since our buffer can be at maximum up to + * BUFFER_SIZE in size. */ + bytes_available = (int)handle->data_available; + + if (handle->data_available > 0) { + /* Read data from our intermediate buffer into the process_t buffer. */ + buf_add(buffer, handle->buffer, handle->data_available); + + /* Reset our read state. */ + handle->data_available = 0; + memset(handle->buffer, 0, sizeof(handle->buffer)); + } + + /* Because of the slightly weird API for ReadFileEx() we must set this to 0 + * before we call ReadFileEx() because ReadFileEx() does not reset the last + * error itself when it's succesful. See comment below after the call to + * GetLastError(). */ + SetLastError(0); + + /* Ask the Windows kernel to read data from our pipe into our buffer and call + * the callback function when it is done. */ + ret = ReadFileEx(handle->pipe, + handle->buffer, + sizeof(handle->buffer), + &handle->overlapped, + callback); + + if (! ret) { + error_code = GetLastError(); + + /* No need to log at warning level for these two. */ + if (error_code == ERROR_HANDLE_EOF || error_code == ERROR_BROKEN_PIPE) { + log_debug(LD_PROCESS, "ReadFileEx() returned EOF from pipe: %s", + format_win32_error(error_code)); + } else { + log_warn(LD_PROCESS, "ReadFileEx() failed: %s", + format_win32_error(error_code)); + } + + handle->reached_eof = true; + return bytes_available; + } + + /* Here be dragons: According to MSDN's documentation for ReadFileEx() we + * should check GetLastError() after a call to ReadFileEx() even though the + * `ret` return value was successful. If everything is good, GetLastError() + * returns `ERROR_SUCCESS` and nothing happens. + * + * XXX(ahf): I have not managed to trigger this code while stress-testing + * this code. */ + error_code = GetLastError(); + + if (error_code != ERROR_SUCCESS) { + /* LCOV_EXCL_START */ + log_warn(LD_PROCESS, "ReadFileEx() failed after returning success: %s", + format_win32_error(error_code)); + handle->reached_eof = true; + return bytes_available; + /* LCOV_EXCL_STOP */ + } + + /* We mark our handle as having a pending I/O request. */ + handle->busy = true; + + return bytes_available; +} + +/** This function checks the callback values from ReadFileEx() in + * <b>error_code</b> and <b>byte_count</b> if we have read data. Returns true + * iff our caller should request more data from ReadFileEx(). */ +STATIC bool +process_win32_handle_read_completion(process_win32_handle_t *handle, + DWORD error_code, + DWORD byte_count) +{ + tor_assert(handle); + + /* Mark our handle as not having any outstanding I/O requests. */ + handle->busy = false; + + if (error_code == 0) { + /* Our ReadFileEx() call was succesful and there is data for us. */ + + /* This cast should be safe since byte_count should never be larger than + * BUFFER_SIZE. */ + tor_assert(byte_count <= BUFFER_SIZE); + handle->data_available = (size_t)byte_count; + + /* Tell our caller to schedule the next read. */ + return true; + } else if (error_code == ERROR_HANDLE_EOF || + error_code == ERROR_BROKEN_PIPE) { + /* Our ReadFileEx() finished, but we reached the end of our file. We mark + * our handle as having reached EOF and returns. */ + tor_assert(byte_count == 0); + + handle->reached_eof = true; + } else { + /* An error happened: We warn the user and mark our handle as having + * reached EOF */ + log_warn(LD_PROCESS, + "Error in I/O completion routine from ReadFileEx(): %s", + format_win32_error(error_code)); + + handle->reached_eof = true; + } + + /* Our caller should NOT schedule the next read. */ + return false; +} + +/** Format a single argument for being put on a Windows command line. + * Returns a newly allocated string */ +STATIC char * +format_win_cmdline_argument(const char *arg) +{ + char *formatted_arg; + char need_quotes; + const char *c; + int i; + int bs_counter = 0; + /* Backslash we can point to when one is inserted into the string */ + const char backslash = '\\'; + + /* Smartlist of *char */ + smartlist_t *arg_chars; + arg_chars = smartlist_new(); + + /* Quote string if it contains whitespace or is empty */ + need_quotes = (strchr(arg, ' ') || strchr(arg, '\t') || '\0' == arg[0]); + + /* Build up smartlist of *chars */ + for (c=arg; *c != '\0'; c++) { + if ('"' == *c) { + /* Double up backslashes preceding a quote */ + for (i=0; i<(bs_counter*2); i++) + smartlist_add(arg_chars, (void*)&backslash); + bs_counter = 0; + /* Escape the quote */ + smartlist_add(arg_chars, (void*)&backslash); + smartlist_add(arg_chars, (void*)c); + } else if ('\\' == *c) { + /* Count backslashes until we know whether to double up */ + bs_counter++; + } else { + /* Don't double up slashes preceding a non-quote */ + for (i=0; i<bs_counter; i++) + smartlist_add(arg_chars, (void*)&backslash); + bs_counter = 0; + smartlist_add(arg_chars, (void*)c); + } + } + /* Don't double up trailing backslashes */ + for (i=0; i<bs_counter; i++) + smartlist_add(arg_chars, (void*)&backslash); + + /* Allocate space for argument, quotes (if needed), and terminator */ + const size_t formatted_arg_len = smartlist_len(arg_chars) + + (need_quotes ? 2 : 0) + 1; + formatted_arg = tor_malloc_zero(formatted_arg_len); + + /* Add leading quote */ + i=0; + if (need_quotes) + formatted_arg[i++] = '"'; + + /* Add characters */ + SMARTLIST_FOREACH(arg_chars, char*, ch, + { + formatted_arg[i++] = *ch; + }); + + /* Add trailing quote */ + if (need_quotes) + formatted_arg[i++] = '"'; + formatted_arg[i] = '\0'; + + smartlist_free(arg_chars); + return formatted_arg; +} + +/** Format a command line for use on Windows, which takes the command as a + * string rather than string array. Follows the rules from "Parsing C++ + * Command-Line Arguments" in MSDN. Algorithm based on list2cmdline in the + * Python subprocess module. Returns a newly allocated string */ +STATIC char * +tor_join_win_cmdline(const char *argv[]) +{ + smartlist_t *argv_list; + char *joined_argv; + int i; + + /* Format each argument and put the result in a smartlist */ + argv_list = smartlist_new(); + for (i=0; argv[i] != NULL; i++) { + smartlist_add(argv_list, (void *)format_win_cmdline_argument(argv[i])); + } + + /* Join the arguments with whitespace */ + joined_argv = smartlist_join_strings(argv_list, " ", 0, NULL); + + /* Free the newly allocated arguments, and the smartlist */ + SMARTLIST_FOREACH(argv_list, char *, arg, + { + tor_free(arg); + }); + smartlist_free(argv_list); + + return joined_argv; +} + +#endif /* defined(_WIN32) */ |