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GSubprocess: New class for spawning child processes

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There are a number of nice things this class brings:

0) Has a race-free termination API on all platforms (on UNIX, calls to
   kill() and waitpid() are coordinated as not to cause problems).
1) Operates in terms of G{Input,Output}Stream, not file descriptors
2) Standard GIO-style async API for wait() with cancellation
3) Makes some simple cases easy, like synchronously spawning a
   process with an argument list
4) Makes hard cases possible, like asynchronously running a process
   with stdout/stderr merged, output directly to a file path

Much rewriting and code review from Ryan Lortie <desrt@desrt.ca>

https://bugzilla.gnome.org/show_bug.cgi?id=672102
This commit is contained in:
Colin Walters
2012-05-17 14:37:17 -04:00
committed by Ryan Lortie
parent e30bbca667
commit 5b48dc40cc
17 changed files with 3963 additions and 60 deletions
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718
gio/gsubprocesslauncher.c Normal file
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@@ -0,0 +1,718 @@
/* GIO - GLib Input, Output and Streaming Library
*
* Copyright © 2012 Red Hat, Inc.
* Copyright © 2012-2013 Canonical Limited
*
* This program is free software: you can redistribute it and/or modify
* it under the terms of the GNU Lesser General Public License as published
* by the Free Software Foundation; either version 2 of the licence or (at
* your option) any later version.
*
* See the included COPYING file for more information.
*
* Authors: Colin Walters <walters@verbum.org>
* Ryan Lortie <desrt@desrt.ca>
*/
/**
* SECTION:gsubprocess
* @title: GSubprocess Launcher
* @short_description: Environment options for launching a child process
*
* 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.
*
* Since: 2.40
*/
#define ALL_STDIN_FLAGS (G_SUBPROCESS_FLAGS_STDIN_PIPE | \
G_SUBPROCESS_FLAGS_STDIN_INHERIT)
#define ALL_STDOUT_FLAGS (G_SUBPROCESS_FLAGS_STDOUT_PIPE | \
G_SUBPROCESS_FLAGS_STDOUT_SILENCE)
#define ALL_STDERR_FLAGS (G_SUBPROCESS_FLAGS_STDERR_PIPE | \
G_SUBPROCESS_FLAGS_STDERR_SILENCE | \
G_SUBPROCESS_FLAGS_STDERR_MERGE)
#include "config.h"
#include "gsubprocesslauncher-private.h"
#include "gioenumtypes.h"
#include "gsubprocess.h"
#include "ginitable.h"
#ifdef G_OS_UNIX
#include <unistd.h>
#include <fcntl.h>
#endif
typedef GObjectClass GSubprocessLauncherClass;
G_DEFINE_TYPE (GSubprocessLauncher, g_subprocess_launcher, G_TYPE_OBJECT);
static gboolean
verify_disposition (const gchar *stream_name,
GSubprocessFlags filtered_flags,
gint fd,
const gchar *filename)
{
guint n_bits;
if (!filtered_flags)
n_bits = 0;
else if (((filtered_flags - 1) & filtered_flags) == 0)
n_bits = 1;
else
n_bits = 2; /* ...or more */
if (n_bits + (fd >= 0) + (filename != NULL) > 1)
{
GString *err;
err = g_string_new (NULL);
if (n_bits)
{
GFlagsClass *class;
GFlagsValue *value;
class = g_type_class_peek (G_TYPE_SUBPROCESS_FLAGS);
while ((value = g_flags_get_first_value (class, filtered_flags)))
{
g_string_append_printf (err, " %s", value->value_name);
filtered_flags &= value->value;
}
g_type_class_unref (class);
}
if (fd >= 0)
g_string_append_printf (err, " g_subprocess_launcher_take_%s_fd()", stream_name);
if (filename)
g_string_append_printf (err, " g_subprocess_launcher_set_%s_file_path()", stream_name);
g_critical ("You may specify at most one disposition for the %s stream, but you specified:%s.",
stream_name, err->str);
g_string_free (err, TRUE);
return FALSE;
}
return TRUE;
}
static gboolean
verify_flags (GSubprocessFlags flags)
{
return verify_disposition ("stdin", flags & ALL_STDIN_FLAGS, -1, NULL) &&
verify_disposition ("stdout", flags & ALL_STDOUT_FLAGS, -1, NULL) &&
verify_disposition ("stderr", flags & ALL_STDERR_FLAGS, -1, NULL);
}
static void
g_subprocess_launcher_set_property (GObject *object, guint prop_id,
const GValue *value, GParamSpec *pspec)
{
GSubprocessLauncher *launcher = G_SUBPROCESS_LAUNCHER (object);
g_assert (prop_id == 1);
if (verify_flags (g_value_get_flags (value)))
launcher->flags = g_value_get_flags (value);
}
static void
g_subprocess_launcher_finalize (GObject *object)
{
GSubprocessLauncher *self = G_SUBPROCESS_LAUNCHER (object);
g_strfreev (self->envp);
g_free (self->cwd);
#ifdef G_OS_UNIX
g_free (self->stdin_path);
g_free (self->stdout_path);
g_free (self->stderr_path);
if (self->stdin_fd != -1)
close (self->stdin_fd);
if (self->stdout_fd != -1)
close (self->stdout_fd);
if (self->stderr_fd != -1)
close (self->stderr_fd);
g_clear_pointer (&self->basic_fd_assignments, g_array_unref);
g_clear_pointer (&self->needdup_fd_assignments, g_array_unref);
#endif
if (self->child_setup_destroy_notify)
(* self->child_setup_destroy_notify) (self->child_setup_user_data);
G_OBJECT_CLASS (g_subprocess_launcher_parent_class)->finalize (object);
}
static void
g_subprocess_launcher_init (GSubprocessLauncher *self)
{
self->envp = g_listenv ();
self->stdin_fd = -1;
self->stdout_fd = -1;
self->stderr_fd = -1;
#ifdef G_OS_UNIX
self->basic_fd_assignments = g_array_new (FALSE, 0, sizeof (int));
self->needdup_fd_assignments = g_array_new (FALSE, 0, sizeof (int));
#endif
}
static void
g_subprocess_launcher_class_init (GSubprocessLauncherClass *class)
{
GObjectClass *gobject_class = G_OBJECT_CLASS (class);
gobject_class->set_property = g_subprocess_launcher_set_property;
gobject_class->finalize = g_subprocess_launcher_finalize;
g_object_class_install_property (gobject_class, 1,
g_param_spec_flags ("flags", "Flags", "GSubprocessFlags for launched processes",
G_TYPE_SUBPROCESS_FLAGS, 0, G_PARAM_WRITABLE |
G_PARAM_STATIC_STRINGS | G_PARAM_CONSTRUCT_ONLY));
}
/**
* g_subprocess_launcher_new:
*
* 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.
*
* Since: 2.40
**/
GSubprocessLauncher *
g_subprocess_launcher_new (GSubprocessFlags flags)
{
if (!verify_flags (flags))
return NULL;
return g_object_new (G_TYPE_SUBPROCESS_LAUNCHER,
"flags", flags,
NULL);
}
/**
* g_subprocess_launcher_set_environ:
* @self: a #GSubprocess
* @environ: the replacement environment
*
* 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.
*
* All strings in this array are expected to be in the GLib file name
* encoding. On UNIX, this means that they can be arbitrary byte
* strings. On Windows, they should be in UTF-8.
*
* Since: 2.40
**/
void
g_subprocess_launcher_set_environ (GSubprocessLauncher *self,
gchar **environ)
{
g_strfreev (self->envp);
self->envp = g_strdupv (environ);
}
/**
* g_subprocess_launcher_setenv:
* @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
*
* Sets the environment variable @variable in the environment of
* processes launched from this launcher.
*
* Both the variable's name and value should be in the GLib file name
* encoding. On UNIX, this means that they can be arbitrary byte
* strings. On Windows, they should be in UTF-8.
*
*
* Since: 2.40
**/
void
g_subprocess_launcher_setenv (GSubprocessLauncher *self,
const gchar *variable,
const gchar *value,
gboolean overwrite)
{
self->envp = g_environ_setenv (self->envp, variable, value, overwrite);
}
/**
* g_subprocess_launcher_unsetsenv:
* @self: a #GSubprocess
* @variable: the environment variable to unset, must not contain '='
*
* Removes the environment variable @variable from the environment of
* processes launched from this launcher.
*
* The variable name should be in the GLib file name encoding. On UNIX,
* this means that they can be arbitrary byte strings. On Windows, they
* should be in UTF-8.
*
* Since: 2.40
**/
void
g_subprocess_launcher_unsetenv (GSubprocessLauncher *self,
const gchar *variable)
{
self->envp = g_environ_unsetenv (self->envp, variable);
}
/**
* g_subprocess_launcher_getenv:
* @self: a #GSubprocess
* @variable: the environment variable to get
*
* Returns the value of the environment variable @variable in the
* environment of processes launched from this launcher.
*
* The returned string is in the GLib file name encoding. On UNIX, this
* means that it can be an arbitrary byte string. On Windows, it will
* be UTF-8.
*
* Returns: the value of the environment variable, %NULL if unset
*
* Since: 2.40
**/
const gchar *
g_subprocess_launcher_getenv (GSubprocessLauncher *self,
const gchar *variable)
{
return g_environ_getenv (self->envp, variable);
}
/**
* g_subprocess_launcher_set_cwd:
* @self: a #GSubprocess
* @cwd: the cwd for launched processes
*
* 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.
*
* Since: 2.40
**/
void
g_subprocess_launcher_set_cwd (GSubprocessLauncher *self,
const gchar *cwd)
{
g_free (self->cwd);
self->cwd = g_strdup (cwd);
}
/**
* g_subprocess_launcher_set_flags:
* @self: a #GSubprocessLauncher
* @flags: #GSubprocessFlags
*
* 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().
*
* Since: 2.40
**/
void
g_subprocess_launcher_set_flags (GSubprocessLauncher *self,
GSubprocessFlags flags)
{
if (verify_disposition ("stdin", flags & ALL_STDIN_FLAGS, self->stdin_fd, self->stdin_path) &&
verify_disposition ("stdout", flags & ALL_STDOUT_FLAGS, self->stdout_fd, self->stdout_path) &&
verify_disposition ("stderr", flags & ALL_STDERR_FLAGS, self->stderr_fd, self->stderr_path))
self->flags = flags;
}
#ifdef G_OS_UNIX
static void
assign_fd (gint *fd_ptr, gint fd)
{
gint flags;
if (*fd_ptr != -1)
close (*fd_ptr);
*fd_ptr = fd;
if (fd != -1)
{
/* best effort */
flags = fcntl (fd, F_GETFD);
if (~flags & FD_CLOEXEC)
fcntl (fd, F_SETFD, flags | FD_CLOEXEC);
}
}
/**
* g_subprocess_launcher_set_stdin_file_path:
* @self: a #GSubprocessLauncher
* @path: a filename or %NULL
*
* 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.
*
* Since: 2.40
**/
void
g_subprocess_launcher_set_stdin_file_path (GSubprocessLauncher *self,
const gchar *path)
{
if (verify_disposition ("stdin", self->flags & ALL_STDIN_FLAGS, self->stdin_fd, path))
{
g_free (self->stdin_path);
self->stdin_path = g_strdup (path);
}
}
/**
* g_subprocess_launcher_take_stdin_fd:
* @self: a #GSubprocessLauncher
* @fd: a file descriptor, or -1
*
* 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.
*
* Since: 2.40
**/
void
g_subprocess_launcher_take_stdin_fd (GSubprocessLauncher *self,
gint fd)
{
if (verify_disposition ("stdin", self->flags & ALL_STDIN_FLAGS, fd, self->stdin_path))
assign_fd (&self->stdin_fd, fd);
}
/**
* g_subprocess_launcher_set_stdout_file_path:
* @self: a #GSubprocessLauncher
* @path: a filename or %NULL
*
* 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.
*
* Since: 2.40
**/
void
g_subprocess_launcher_set_stdout_file_path (GSubprocessLauncher *self,
const gchar *path)
{
if (verify_disposition ("stdout", self->flags & ALL_STDOUT_FLAGS, self->stdout_fd, path))
{
g_free (self->stdout_path);
self->stdout_path = g_strdup (path);
}
}
/**
* g_subprocess_launcher_take_stdout_fd:
* @self: a #GSubprocessLauncher
* @fd: a file descriptor, or -1
*
* 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.
*
* Since: 2.40
**/
void
g_subprocess_launcher_take_stdout_fd (GSubprocessLauncher *self,
gint fd)
{
if (verify_disposition ("stdout", self->flags & ALL_STDOUT_FLAGS, fd, self->stdout_path))
assign_fd (&self->stdout_fd, fd);
}
/**
* g_subprocess_launcher_set_stderr_file_path:
* @self: a #GSubprocessLauncher
* @path: a filename or %NULL
*
* 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.
*
* Since: 2.40
**/
void
g_subprocess_launcher_set_stderr_file_path (GSubprocessLauncher *self,
const gchar *path)
{
if (verify_disposition ("stderr", self->flags & ALL_STDERR_FLAGS, self->stderr_fd, path))
{
g_free (self->stderr_path);
self->stderr_path = g_strdup (path);
}
}
/**
* g_subprocess_launcher_take_stderr_fd:
* @self: a #GSubprocessLauncher
* @fd: a file descriptor, or -1
*
* 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.
*
* Since: 2.40
**/
void
g_subprocess_launcher_take_stderr_fd (GSubprocessLauncher *self,
gint fd)
{
if (verify_disposition ("stderr", self->flags & ALL_STDERR_FLAGS, fd, self->stderr_path))
assign_fd (&self->stderr_fd, fd);
}
/**
* g_subprocess_launcher_pass_fd:
* @self: a #GSubprocessLauncher
* @source_fd: File descriptor in parent process
* @target_fd: Target descriptor for child process
*
* Pass an arbitrary file descriptor from parent process to
* the child. 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.
*/
void
g_subprocess_launcher_pass_fd (GSubprocessLauncher *self,
gint source_fd,
gint target_fd)
{
if (source_fd == target_fd)
{
g_array_append_val (self->basic_fd_assignments, source_fd);
}
else
{
g_array_append_val (self->needdup_fd_assignments, source_fd);
g_array_append_val (self->needdup_fd_assignments, target_fd);
}
}
/**
* g_subprocess_launcher_set_child_setup:
* @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
*
* 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.
*
* Since: 2.40
**/
void
g_subprocess_launcher_set_child_setup (GSubprocessLauncher *self,
GSpawnChildSetupFunc child_setup,
gpointer user_data,
GDestroyNotify destroy_notify)
{
if (self->child_setup_destroy_notify)
(* self->child_setup_destroy_notify) (self->child_setup_user_data);
self->child_setup_func = child_setup;
self->child_setup_user_data = user_data;
self->child_setup_destroy_notify = destroy_notify;
}
#endif
/**
* g_subprocess_launcher_spawn:
* @self: a #GSubprocessLauncher
* @error: Error
* @argv0: Command line arguments
* @...: Continued arguments, %NULL terminated
*
* A convenience helper for creating a #GSubprocess given a provided
* varargs list of arguments.
*
* Since: 2.40
* Returns: (transfer full): A new #GSubprocess, or %NULL on error (and @error will be set)
**/
GSubprocess *
g_subprocess_launcher_spawn (GSubprocessLauncher *launcher,
GError **error,
const gchar *argv0,
...)
{
GSubprocess *result;
GPtrArray *args;
const gchar *arg;
va_list ap;
g_return_val_if_fail (argv0 != NULL && argv0[0] != '\0', NULL);
g_return_val_if_fail (error == NULL || *error == NULL, NULL);
args = g_ptr_array_new ();
va_start (ap, argv0);
g_ptr_array_add (args, (gchar *) argv0);
while ((arg = va_arg (ap, const gchar *)))
g_ptr_array_add (args, (gchar *) arg);
result = g_subprocess_launcher_spawnv (launcher, (const gchar * const *) args->pdata, error);
g_ptr_array_free (args, TRUE);
return result;
}
/**
* g_subprocess_launcher_spawnv:
* @self: a #GSubprocessLauncher
* @argv: Command line arguments
* @error: Error
*
* A convenience helper for creating a #GSubprocess given a provided
* array of arguments.
*
* Since: 2.40
* Returns: (transfer full): A new #GSubprocess, or %NULL on error (and @error will be set)
**/
GSubprocess *
g_subprocess_launcher_spawnv (GSubprocessLauncher *launcher,
const gchar * const *argv,
GError **error)
{
GSubprocess *subprocess;
g_return_val_if_fail (argv != NULL && argv[0] != NULL && argv[0][0] != '\0', NULL);
subprocess = g_object_new (G_TYPE_SUBPROCESS,
"argv", argv,
"flags", launcher->flags,
NULL);
g_subprocess_set_launcher (subprocess, launcher);
if (!g_initable_init (G_INITABLE (subprocess), NULL, error))
{
g_object_unref (subprocess);
return NULL;
}
return subprocess;
}