Struct gio::Subprocess

#[repr(transparent)]
pub struct Subprocess { /* private fields */ }

Subprocess allows the creation of and interaction with child processes.

Processes can be communicated with using standard GIO-style APIs (ie: InputStream, OutputStream). There are GIO-style APIs to wait for process termination (ie: cancellable and with an asynchronous variant).

There is an API to force a process to terminate, as well as a race-free API for sending UNIX signals to a subprocess.

One major advantage that GIO brings over the core GLib library is comprehensive API for asynchronous I/O, such OutputStreamExt::splice_async(). This makes GSubprocess significantly more powerful and flexible than equivalent APIs in some other languages such as the subprocess.py included with Python. For example, using Subprocess one could create two child processes, reading standard output from the first, processing it, and writing to the input stream of the second, all without blocking the main loop.

A powerful communicate() API is provided similar to the communicate() method of subprocess.py. This enables very easy interaction with a subprocess that has been opened with pipes.

Subprocess defaults to tight control over the file descriptors open in the child process, avoiding dangling-fd issues that are caused by a simple fork()/exec(). The only open file descriptors in the spawned process are ones that were explicitly specified by the Subprocess API (unless SubprocessFlags::INHERIT_FDS was specified).

Subprocess will quickly reap all child processes as they exit, avoiding “zombie processes” remaining around for long periods of time. wait() can be used to wait for this to happen, but it will happen even without the call being explicitly made.

As a matter of principle, Subprocess has no API that accepts shell-style space-separated strings. It will, however, match the typical shell behaviour of searching the PATH for executables that do not contain a directory separator in their name. By default, the PATH of the current process is used. You can specify SubprocessFlags::SEARCH_PATH_FROM_ENVP to use the PATH of the launcher environment instead.

Subprocess attempts to have a very simple API for most uses (ie: spawning a subprocess with arguments and support for most typical kinds of input and output redirection). See g_subprocess_new(). The SubprocessLauncher API is provided for more complicated cases (advanced types of redirection, environment variable manipulation, change of working directory, child setup functions, etc).

A typical use of Subprocess will involve calling g_subprocess_new(), followed by wait_async() or wait(). After the process exits, the status can be checked using functions such as has_exited() (which are similar to the familiar WIFEXITED-style POSIX macros).

Implements

glib::ObjectExt, InitableExt

Implementations

impl Subprocess

pub fn communicate_utf8_async<R: FnOnce(Result<(Option<GString>, Option<GString>), Error>) + 'static, C: IsA<Cancellable>>(
    &self,
    stdin_buf: Option<String>,
    cancellable: Option<&C>,
    callback: R
)

Asynchronous version of communicate_utf8(). Complete invocation with g_subprocess_communicate_utf8_finish().

stdin_buf

Input data, or None

cancellable

Cancellable

callback

Callback

pub fn communicate_utf8_future(
    &self,
    stdin_buf: Option<String>
) -> Pin<Box<dyn Future<Output = Result<(Option<GString>, Option<GString>), Error>> + 'static>>

impl Subprocess

pub fn newv(
    argv: &[&OsStr],
    flags: SubprocessFlags
) -> Result<Subprocess, Error>

Create a new process with the given flags and argument list.

The argument list is expected to be None-terminated.

argv

commandline arguments for the subprocess

flags

flags that define the behaviour of the subprocess

Returns

A newly created Subprocess, or None on error (and error will be set)

pub fn communicate(
    &self,
    stdin_buf: Option<&Bytes>,
    cancellable: Option<&impl IsA<Cancellable>>
) -> Result<(Option<Bytes>, Option<Bytes>), Error>

Communicate with the subprocess until it terminates, and all input and output has been completed.

If stdin_buf is given, the subprocess must have been created with SubprocessFlags::STDIN_PIPE. The given data is fed to the stdin of the subprocess and the pipe is closed (ie: EOF).

At the same time (as not to cause blocking when dealing with large amounts of data), if SubprocessFlags::STDOUT_PIPE or SubprocessFlags::STDERR_PIPE were used, reads from those streams. The data that was read is returned in stdout and/or the stderr.

If the subprocess was created with SubprocessFlags::STDOUT_PIPE, stdout_buf will contain the data read from stdout. Otherwise, for subprocesses not created with SubprocessFlags::STDOUT_PIPE, stdout_buf will be set to None. Similar provisions apply to stderr_buf and SubprocessFlags::STDERR_PIPE.

As usual, any output variable may be given as None to ignore it.

If you desire the stdout and stderr data to be interleaved, create the subprocess with SubprocessFlags::STDOUT_PIPE and SubprocessFlags::STDERR_MERGE. The merged result will be returned in stdout_buf and stderr_buf will be set to None.

In case of any error (including cancellation), false will be returned with error set. Some or all of the stdin data may have been written. Any stdout or stderr data that has been read will be discarded. None of the out variables (aside from error) will have been set to anything in particular and should not be inspected.

In the case that true is returned, the subprocess has exited and the exit status inspection APIs (eg: has_exited(), exit_status()) may be used.

You should not attempt to use any of the subprocess pipes after starting this function, since they may be left in strange states, even if the operation was cancelled. You should especially not attempt to interact with the pipes while the operation is in progress (either from another thread or if using the asynchronous version).

stdin_buf

data to send to the stdin of the subprocess, or None

cancellable

a Cancellable

Returns

true if successful

stdout_buf

data read from the subprocess stdout

stderr_buf

data read from the subprocess stderr

pub fn communicate_async<P: FnOnce(Result<(Option<Bytes>, Option<Bytes>), Error>) + 'static>(
    &self,
    stdin_buf: Option<&Bytes>,
    cancellable: Option<&impl IsA<Cancellable>>,
    callback: P
)

Asynchronous version of communicate(). Complete invocation with g_subprocess_communicate_finish().

stdin_buf

Input data, or None

cancellable

Cancellable

callback

Callback

pub fn communicate_future(
    &self,
    stdin_buf: Option<&Bytes>
) -> Pin<Box_<dyn Future<Output = Result<(Option<Bytes>, Option<Bytes>), Error>> + 'static>>

pub fn communicate_utf8(
    &self,
    stdin_buf: Option<&str>,
    cancellable: Option<&impl IsA<Cancellable>>
) -> Result<(Option<GString>, Option<GString>), Error>

Like communicate(), but validates the output of the process as UTF-8, and returns it as a regular NUL terminated string.

On error, stdout_buf and stderr_buf will be set to undefined values and should not be used.

stdin_buf

data to send to the stdin of the subprocess, or None

cancellable

a Cancellable

Returns

stdout_buf

data read from the subprocess stdout

stderr_buf

data read from the subprocess stderr

pub fn force_exit(&self)

Use an operating-system specific method to attempt an immediate, forceful termination of the process. There is no mechanism to determine whether or not the request itself was successful; however, you can use wait() to monitor the status of the process after calling this function.

On Unix, this function sends SIGKILL.

pub fn exit_status(&self) -> i32

Check the exit status of the subprocess, given that it exited normally. This is the value passed to the exit() system call or the return value from main.

This is equivalent to the system WEXITSTATUS macro.

It is an error to call this function before wait() and unless has_exited() returned true.

Returns

the exit status

pub fn identifier(&self) -> Option<GString>

On UNIX, returns the process ID as a decimal string. On Windows, returns the result of GetProcessId() also as a string. If the subprocess has terminated, this will return None.

Returns

the subprocess identifier, or None if the subprocess has terminated

pub fn has_exited(&self) -> bool

Check if the given subprocess exited normally (ie: by way of exit() or return from main()).

This is equivalent to the system WIFEXITED macro.

It is an error to call this function before wait() has returned.

Returns

true if the case of a normal exit

pub fn has_signaled(&self) -> bool

Check if the given subprocess terminated in response to a signal.

This is equivalent to the system WIFSIGNALED macro.

It is an error to call this function before wait() has returned.

Returns

true if the case of termination due to a signal

pub fn status(&self) -> i32

Gets the raw status code of the process, as from waitpid().

This value has no particular meaning, but it can be used with the macros defined by the system headers such as WIFEXITED. It can also be used with g_spawn_check_wait_status().

It is more likely that you want to use has_exited() followed by exit_status().

It is an error to call this function before wait() has returned.

Returns

the (meaningless) waitpid() exit status from the kernel

pub fn stderr_pipe(&self) -> Option<InputStream>

Gets the InputStream from which to read the stderr output of self.

The process must have been created with SubprocessFlags::STDERR_PIPE, otherwise None will be returned.

Returns

the stderr pipe

pub fn stdin_pipe(&self) -> Option<OutputStream>

Gets the OutputStream that you can write to in order to give data to the stdin of self.

The process must have been created with SubprocessFlags::STDIN_PIPE and not SubprocessFlags::STDIN_INHERIT, otherwise None will be returned.

Returns

the stdout pipe

pub fn stdout_pipe(&self) -> Option<InputStream>

Gets the InputStream from which to read the stdout output of self.

The process must have been created with SubprocessFlags::STDOUT_PIPE, otherwise None will be returned.

Returns

the stdout pipe

pub fn is_successful(&self) -> bool

Checks if the process was “successful”. A process is considered successful if it exited cleanly with an exit status of 0, either by way of the exit() system call or return from main().

It is an error to call this function before wait() has returned.

Returns

true if the process exited cleanly with a exit status of 0

pub fn term_sig(&self) -> i32

Get the signal number that caused the subprocess to terminate, given that it terminated due to a signal.

This is equivalent to the system WTERMSIG macro.

It is an error to call this function before wait() and unless has_signaled() returned true.

Returns

the signal causing termination

pub fn send_signal(&self, signal_num: i32)

Available on non-Windows only.

Sends the UNIX signal signal_num to the subprocess, if it is still running.

This API is race-free. If the subprocess has terminated, it will not be signalled.

This API is not available on Windows.

signal_num

the signal number to send

pub fn wait(
    &self,
    cancellable: Option<&impl IsA<Cancellable>>
) -> Result<(), Error>

Synchronously wait for the subprocess to terminate.

After the process terminates you can query its exit status with functions such as has_exited() and exit_status().

This function does not fail in the case of the subprocess having abnormal termination. See wait_check() for that.

Cancelling cancellable doesn’t kill the subprocess. Call force_exit() if it is desirable.

cancellable

a Cancellable

Returns

true on success, false if cancellable was cancelled

pub fn wait_async<P: FnOnce(Result<(), Error>) + 'static>(
    &self,
    cancellable: Option<&impl IsA<Cancellable>>,
    callback: P
)

Wait for the subprocess to terminate.

This is the asynchronous version of wait().

cancellable

a Cancellable, or None

callback

a GAsyncReadyCallback to call when the operation is complete

pub fn wait_future(
    &self
) -> Pin<Box_<dyn Future<Output = Result<(), Error>> + 'static>>

pub fn wait_check(
    &self,
    cancellable: Option<&impl IsA<Cancellable>>
) -> Result<(), Error>

Combines wait() with g_spawn_check_wait_status().

cancellable

a Cancellable

Returns

true on success, false if process exited abnormally, or cancellable was cancelled

pub fn wait_check_async<P: FnOnce(Result<(), Error>) + 'static>(
    &self,
    cancellable: Option<&impl IsA<Cancellable>>,
    callback: P
)

Combines wait_async() with g_spawn_check_wait_status().

This is the asynchronous version of wait_check().

cancellable

a Cancellable, or None

callback

a GAsyncReadyCallback to call when the operation is complete

pub fn wait_check_future(
    &self
) -> Pin<Box_<dyn Future<Output = Result<(), Error>> + 'static>>

Trait Implementations

impl Clone for Subprocess

fn clone(&self) -> Self

Returns a copy of the value.

fn clone_from(&mut self, source: &Self)

Performs copy-assignment from source.

impl Debug for Subprocess

fn fmt(&self, f: &mut Formatter<'_>) -> Result

Formats the value using the given formatter.

impl Display for Subprocess

fn fmt(&self, f: &mut Formatter<'_>) -> Result

Formats the value using the given formatter.

impl Hash for Subprocess

fn hash<H>(&self, state: &mut H) where
    H: Hasher, 

Feeds this value into the given Hasher.

fn hash_slice<H>(data: &[Self], state: &mut H) where
    H: Hasher, 

Feeds a slice of this type into the given Hasher.

impl Ord for Subprocess

fn cmp(&self, other: &Self) -> Ordering

This method returns an Ordering between self and other.

fn max(self, other: Self) -> Self

Compares and returns the maximum of two values.

fn min(self, other: Self) -> Self

Compares and returns the minimum of two values.

fn clamp(self, min: Self, max: Self) -> Self

Restrict a value to a certain interval.

impl ParentClassIs for Subprocess

type Parent = Object

impl<OT: ObjectType> PartialEq<OT> for Subprocess

fn eq(&self, other: &OT) -> bool

This method tests for self and other values to be equal, and is used by ==.

fn ne(&self, other: &Rhs) -> bool

This method tests for !=.

impl<OT: ObjectType> PartialOrd<OT> for Subprocess

fn partial_cmp(&self, other: &OT) -> Option<Ordering>

This method returns an ordering between self and other values if one exists.

fn lt(&self, other: &Rhs) -> bool

This method tests less than (for self and other) and is used by the < operator.

fn le(&self, other: &Rhs) -> bool

This method tests less than or equal to (for self and other) and is used by the <= operator.

fn gt(&self, other: &Rhs) -> bool

This method tests greater than (for self and other) and is used by the > operator.

fn ge(&self, other: &Rhs) -> bool

This method tests greater than or equal to (for self and other) and is used by the >= operator.

impl StaticType for Subprocess

fn static_type() -> Type

Returns the type identifier of Self.

impl Eq for Subprocess

impl IsA<Initable> for Subprocess