GSubprocess Launcher

GSubprocess Launcher — Environment options for launching a child process

Properties

GSubprocessFlags flags Write / Construct Only

Types and Values

Object Hierarchy

    GObject
    ╰── GSubprocessLauncher

Includes

#include <gio/gio.h>

Description

This class contains a set of options for launching child processes, such as where its standard input and output will be directed, the argument list, the environment, and more.

While the GSubprocess class has high level functions covering popular cases, use of this class allows access to more advanced options. It can also be used to launch multiple subprocesses with a similar configuration.

Functions

g_subprocess_launcher_new ()

GSubprocessLauncher *
g_subprocess_launcher_new (GSubprocessFlags flags);

Creates a new GSubprocessLauncher.

The launcher is created with the default options. A copy of the environment of the calling process is made at the time of this call and will be used as the environment that the process is launched in.

Parameters

flags

GSubprocessFlags

 

Since: 2.40


g_subprocess_launcher_spawn ()

GSubprocess *
g_subprocess_launcher_spawn (GSubprocessLauncher *self,
                             GError **error,
                             const gchar *argv0,
                             ...);

Creates a GSubprocess given a provided varargs list of arguments.

Parameters

self

a GSubprocessLauncher

 

error

Error

 

argv0

Command line arguments

 

...

Continued arguments, NULL terminated

 

Returns

A new GSubprocess, or NULL on error (and error will be set).

[transfer full]

Since: 2.40


g_subprocess_launcher_spawnv ()

GSubprocess *
g_subprocess_launcher_spawnv (GSubprocessLauncher *self,
                              const gchar * const *argv,
                              GError **error);

Creates a GSubprocess given a provided array of arguments.

Parameters

self

a GSubprocessLauncher

 

argv

Command line arguments.

[array zero-terminated=1][element-type utf8]

error

Error

 

Returns

A new GSubprocess, or NULL on error (and error will be set).

[transfer full]

Since: 2.40


g_subprocess_launcher_set_environ ()

void
g_subprocess_launcher_set_environ (GSubprocessLauncher *self,
                                   gchar **env);

Replace the entire environment of processes launched from this launcher with the given 'environ' variable.

Typically you will build this variable by using g_listenv() to copy the process 'environ' and using the functions g_environ_setenv(), g_environ_unsetenv(), etc.

As an alternative, you can use g_subprocess_launcher_setenv(), g_subprocess_launcher_unsetenv(), etc.

Pass NULL to inherit the parent process' environment. Pass an empty array to set an empty environment.

On UNIX, all strings in this array can be arbitrary byte strings. On Windows, they should be in UTF-8.

Parameters

self

a GSubprocess

 

env

the replacement environment.

[array zero-terminated=1]

Since: 2.40


g_subprocess_launcher_setenv ()

void
g_subprocess_launcher_setenv (GSubprocessLauncher *self,
                              const gchar *variable,
                              const gchar *value,
                              gboolean overwrite);

Sets the environment variable variable in the environment of processes launched from this launcher.

On UNIX, both the variable's name and value can be arbitrary byte strings, except that the variable's name cannot contain '='. On Windows, they should be in UTF-8.

Parameters

self

a GSubprocess

 

variable

the environment variable to set, must not contain '='

 

value

the new value for the variable

 

overwrite

whether to change the variable if it already exists

 

Since: 2.40


g_subprocess_launcher_unsetenv ()

void
g_subprocess_launcher_unsetenv (GSubprocessLauncher *self,
                                const gchar *variable);

Removes the environment variable variable from the environment of processes launched from this launcher.

On UNIX, the variable's name can be an arbitrary byte string not containing '='. On Windows, it should be in UTF-8.

Parameters

self

a GSubprocess

 

variable

the environment variable to unset, must not contain '='

 

Since: 2.40


g_subprocess_launcher_getenv ()

const gchar *
g_subprocess_launcher_getenv (GSubprocessLauncher *self,
                              const gchar *variable);

Returns the value of the environment variable variable in the environment of processes launched from this launcher.

On UNIX, the returned string can be an arbitrary byte string. On Windows, it will be UTF-8.

Parameters

self

a GSubprocess

 

variable

the environment variable to get

 

Returns

the value of the environment variable, NULL if unset

Since: 2.40


g_subprocess_launcher_set_cwd ()

void
g_subprocess_launcher_set_cwd (GSubprocessLauncher *self,
                               const gchar *cwd);

Sets the current working directory that processes will be launched with.

By default processes are launched with the current working directory of the launching process at the time of launch.

Parameters

self

a GSubprocess

 

cwd

the cwd for launched processes.

[type filename]

Since: 2.40


g_subprocess_launcher_set_flags ()

void
g_subprocess_launcher_set_flags (GSubprocessLauncher *self,
                                 GSubprocessFlags flags);

Sets the flags on the launcher.

The default flags are G_SUBPROCESS_FLAGS_NONE.

You may not set flags that specify conflicting options for how to handle a particular stdio stream (eg: specifying both G_SUBPROCESS_FLAGS_STDIN_PIPE and G_SUBPROCESS_FLAGS_STDIN_INHERIT).

You may also not set a flag that conflicts with a previous call to a function like g_subprocess_launcher_set_stdin_file_path() or g_subprocess_launcher_take_stdout_fd().

Parameters

Since: 2.40


g_subprocess_launcher_set_stdin_file_path ()

void
g_subprocess_launcher_set_stdin_file_path
                               (GSubprocessLauncher *self,
                                const gchar *path);

Sets the file path to use as the stdin for spawned processes.

If path is NULL then any previously given path is unset.

The file must exist or spawning the process will fail.

You may not set a stdin file path if a stdin fd is already set or if the launcher flags contain any flags directing stdin elsewhere.

This feature is only available on UNIX.

Parameters

self

a GSubprocessLauncher

 

path

(type filename) (nullable: a filename or NULL

 

Since: 2.40


g_subprocess_launcher_take_stdin_fd ()

void
g_subprocess_launcher_take_stdin_fd (GSubprocessLauncher *self,
                                     gint fd);

Sets the file descriptor to use as the stdin for spawned processes.

If fd is -1 then any previously given fd is unset.

Note that if your intention is to have the stdin of the calling process inherited by the child then G_SUBPROCESS_FLAGS_STDIN_INHERIT is a better way to go about doing that.

The passed fd is noted but will not be touched in the current process. It is therefore necessary that it be kept open by the caller until the subprocess is spawned. The file descriptor will also not be explicitly closed on the child side, so it must be marked O_CLOEXEC if that's what you want.

You may not set a stdin fd if a stdin file path is already set or if the launcher flags contain any flags directing stdin elsewhere.

This feature is only available on UNIX.

Parameters

self

a GSubprocessLauncher

 

fd

a file descriptor, or -1

 

Since: 2.40


g_subprocess_launcher_set_stdout_file_path ()

void
g_subprocess_launcher_set_stdout_file_path
                               (GSubprocessLauncher *self,
                                const gchar *path);

Sets the file path to use as the stdout for spawned processes.

If path is NULL then any previously given path is unset.

The file will be created or truncated when the process is spawned, as would be the case if using '>' at the shell.

You may not set a stdout file path if a stdout fd is already set or if the launcher flags contain any flags directing stdout elsewhere.

This feature is only available on UNIX.

Parameters

self

a GSubprocessLauncher

 

path

a filename or NULL.

[type filename][nullable]

Since: 2.40


g_subprocess_launcher_take_stdout_fd ()

void
g_subprocess_launcher_take_stdout_fd (GSubprocessLauncher *self,
                                      gint fd);

Sets the file descriptor to use as the stdout for spawned processes.

If fd is -1 then any previously given fd is unset.

Note that the default behaviour is to pass stdout through to the stdout of the parent process.

The passed fd is noted but will not be touched in the current process. It is therefore necessary that it be kept open by the caller until the subprocess is spawned. The file descriptor will also not be explicitly closed on the child side, so it must be marked O_CLOEXEC if that's what you want.

You may not set a stdout fd if a stdout file path is already set or if the launcher flags contain any flags directing stdout elsewhere.

This feature is only available on UNIX.

Parameters

self

a GSubprocessLauncher

 

fd

a file descriptor, or -1

 

Since: 2.40


g_subprocess_launcher_set_stderr_file_path ()

void
g_subprocess_launcher_set_stderr_file_path
                               (GSubprocessLauncher *self,
                                const gchar *path);

Sets the file path to use as the stderr for spawned processes.

If path is NULL then any previously given path is unset.

The file will be created or truncated when the process is spawned, as would be the case if using '2>' at the shell.

If you want to send both stdout and stderr to the same file then use G_SUBPROCESS_FLAGS_STDERR_MERGE.

You may not set a stderr file path if a stderr fd is already set or if the launcher flags contain any flags directing stderr elsewhere.

This feature is only available on UNIX.

Parameters

self

a GSubprocessLauncher

 

path

a filename or NULL.

[type filename][nullable]

Since: 2.40


g_subprocess_launcher_take_stderr_fd ()

void
g_subprocess_launcher_take_stderr_fd (GSubprocessLauncher *self,
                                      gint fd);

Sets the file descriptor to use as the stderr for spawned processes.

If fd is -1 then any previously given fd is unset.

Note that the default behaviour is to pass stderr through to the stderr of the parent process.

The passed fd belongs to the GSubprocessLauncher. It will be automatically closed when the launcher is finalized. The file descriptor will also be closed on the child side when executing the spawned process.

You may not set a stderr fd if a stderr file path is already set or if the launcher flags contain any flags directing stderr elsewhere.

This feature is only available on UNIX.

Parameters

self

a GSubprocessLauncher

 

fd

a file descriptor, or -1

 

Since: 2.40


g_subprocess_launcher_take_fd ()

void
g_subprocess_launcher_take_fd (GSubprocessLauncher *self,
                               gint source_fd,
                               gint target_fd);

Transfer an arbitrary file descriptor from parent process to the child. This function takes "ownership" of the fd; it will be closed in the parent when self is freed.

By default, all file descriptors from the parent will be closed. This function allows you to create (for example) a custom pipe() or socketpair() before launching the process, and choose the target descriptor in the child.

An example use case is GNUPG, which has a command line argument --passphrase-fd providing a file descriptor number where it expects the passphrase to be written.

Parameters

self

a GSubprocessLauncher

 

source_fd

File descriptor in parent process

 

target_fd

Target descriptor for child process

 

g_subprocess_launcher_set_child_setup ()

void
g_subprocess_launcher_set_child_setup (GSubprocessLauncher *self,
                                       GSpawnChildSetupFunc child_setup,
                                       gpointer user_data,
                                       GDestroyNotify destroy_notify);

Sets up a child setup function.

The child setup function will be called after fork() but before exec() on the child's side.

destroy_notify will not be automatically called on the child's side of the fork(). It will only be called when the last reference on the GSubprocessLauncher is dropped or when a new child setup function is given.

NULL can be given as child_setup to disable the functionality.

Child setup functions are only available on UNIX.

Parameters

self

a GSubprocessLauncher

 

child_setup

a GSpawnChildSetupFunc to use as the child setup function

 

user_data

user data for child_setup

 

destroy_notify

a GDestroyNotify for user_data

 

Since: 2.40

Types and Values

GSubprocessLauncher

typedef struct _GSubprocessLauncher GSubprocessLauncher;

Options for launching a child process.

Since: 2.40

Property Details

The “flags” property

  “flags”                    GSubprocessFlags

GSubprocessFlags for launched processes.

Flags: Write / Construct Only