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/*
* Contains code taken from Flatpak.
*
* Copyright © 2014-2019 Red Hat, Inc
* Copyright © 2017-2019 Collabora Ltd.
*
* SPDX-License-Identifier: LGPL-2.1-or-later
*
* 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 2.1 of the License, or (at your option) any later version.
*
* This library is distributed in the hope that it will be useful,
* but WITHOUT ANY WARRANTY; without even the implied warranty of
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
* Lesser General Public License for more details.
*
* You should have received a copy of the GNU Lesser General Public
* License along with this library. If not, see <http://www.gnu.org/licenses/>.
*/
#include "utils.h"
#include <ftw.h>
#include <sys/prctl.h>
#include <sys/signalfd.h>
#include <sys/types.h>
#include <sys/wait.h>
#include <glib/gstdio.h>
#include <gio/gio.h>
#include "glib-backports.h"
#include "flatpak-bwrap-private.h"
#include "flatpak-utils-base-private.h"
#include "flatpak-utils-private.h"
static void
child_setup_cb (gpointer user_data)
{
flatpak_close_fds_workaround (3);
}
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/**
* pv_avoid_gvfs:
*
* Disable gvfs. This function must be called from main() before
* starting any threads.
*/
void
pv_avoid_gvfs (void)
{
g_autofree gchar *old_env = NULL;
/* avoid gvfs (http://bugzilla.gnome.org/show_bug.cgi?id=526454) */
old_env = g_strdup (g_getenv ("GIO_USE_VFS"));
g_setenv ("GIO_USE_VFS", "local", TRUE);
g_vfs_get_default ();
if (old_env)
g_setenv ("GIO_USE_VFS", old_env, TRUE);
else
g_unsetenv ("GIO_USE_VFS");
}
/**
* pv_envp_cmp:
* @p1: a `const char * const *`
* @p2: a `const char * const *`
*
* Compare two environment variables, given as pointers to pointers
* to the actual `KEY=value` string.
*
* In particular this is suitable for sorting a #GStrv using `qsort`.
*
* Returns: negative, 0 or positive if `*p1` compares before, equal to
* or after `*p2`
*/
int
pv_envp_cmp (const void *p1,
const void *p2)
{
const char * const * s1 = p1;
const char * const * s2 = p2;
size_t l1 = strlen (*s1);
size_t l2 = strlen (*s2);
size_t min;
const char *tmp;
int ret;
tmp = strchr (*s1, '=');
if (tmp != NULL)
l1 = tmp - *s1;
tmp = strchr (*s2, '=');
if (tmp != NULL)
l2 = tmp - *s2;
min = MIN (l1, l2);
ret = strncmp (*s1, *s2, min);
/* If they differ before the first '=' (if any) in either s1 or s2,
* then they are certainly different */
if (ret != 0)
return ret;
ret = strcmp (*s1, *s2);
/* If they do not differ at all, then they are equal */
if (ret == 0)
return ret;
/* FOO < FOO=..., and FOO < FOOBAR */
if ((*s1)[min] == '\0')
return -1;
/* FOO=... > FOO, and FOOBAR > FOO */
if ((*s2)[min] == '\0')
return 1;
/* FOO= < FOOBAR */
if ((*s1)[min] == '=' && (*s2)[min] != '=')
/* FOOBAR > FOO= */
if ((*s2)[min] == '=' && (*s1)[min] != '=')
/* Fall back to plain string comparison */
return ret;
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}
/**
* pv_get_current_dirs:
* @cwd_p: (out) (transfer full) (optional): Used to return the
* current physical working directory, equivalent to `$(pwd -P)`
* in a shell
* @cwd_l: (out) (transfer full) (optional): Used to return the
* current logical working directory, equivalent to `$(pwd -L)`
* in a shell
*
* Return the physical and/or logical working directory.
*
* Equivalent to `$(pwd -L)` in a shell.
*/
void
pv_get_current_dirs (gchar **cwd_p,
gchar **cwd_l)
{
g_autofree gchar *cwd = NULL;
const gchar *pwd;
g_return_if_fail (cwd_p == NULL || *cwd_p == NULL);
g_return_if_fail (cwd_l == NULL || *cwd_l == NULL);
cwd = g_get_current_dir ();
if (cwd_p != NULL)
*cwd_p = flatpak_canonicalize_filename (cwd);
if (cwd_l != NULL)
{
pwd = g_getenv ("PWD");
if (pwd != NULL && pv_is_same_file (pwd, cwd))
*cwd_l = g_strdup (pwd);
else
*cwd_l = g_strdup (cwd);
}
}
/**
* pv_is_same_file:
* @a: a path
* @b: a path
*
* Returns: %TRUE if a and b are names for the same inode.
*/
gboolean
pv_is_same_file (const gchar *a,
const gchar *b)
{
GStatBuf a_buffer, b_buffer;
g_return_val_if_fail (a != NULL, FALSE);
g_return_val_if_fail (b != NULL, FALSE);
if (strcmp (a, b) == 0)
return TRUE;
return (stat (a, &a_buffer) == 0
&& stat (b, &b_buffer) == 0
&& a_buffer.st_dev == b_buffer.st_dev
&& a_buffer.st_ino == b_buffer.st_ino);
}
void
pv_search_path_append (GString *search_path,
const gchar *item)
{
g_return_if_fail (search_path != NULL);
if (item == NULL || item[0] == '\0')
return;
if (search_path->len != 0)
g_string_append (search_path, ":");
g_string_append (search_path, item);
}
gchar *
pv_capture_output (const char * const * argv,
GError **error)
{
gsize len;
gint wait_status;
g_autofree gchar *output = NULL;
g_autofree gchar *errors = NULL;
gsize i;
g_autoptr(GString) command = g_string_new ("");
g_return_val_if_fail (argv != NULL, NULL);
g_return_val_if_fail (argv[0] != NULL, NULL);
g_return_val_if_fail (error == NULL || *error == NULL, FALSE);
for (i = 0; argv[i] != NULL; i++)
{
g_autofree gchar *quoted = g_shell_quote (argv[i]);
g_string_append_printf (command, " %s", quoted);
}
g_debug ("run:%s", command->str);
/* We use LEAVE_DESCRIPTORS_OPEN to work around a deadlock in older GLib,
* see flatpak_close_fds_workaround */
if (!g_spawn_sync (NULL, /* cwd */
(char **) argv,
NULL, /* env */
(G_SPAWN_SEARCH_PATH |
G_SPAWN_LEAVE_DESCRIPTORS_OPEN),
child_setup_cb, NULL,
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&output,
&errors,
&wait_status,
error))
return NULL;
g_printerr ("%s", errors);
if (!g_spawn_check_exit_status (wait_status, error))
return NULL;
len = strlen (output);
/* Emulate shell $() */
if (len > 0 && output[len - 1] == '\n')
output[len - 1] = '\0';
g_debug ("-> %s", output);
return g_steal_pointer (&output);
}
/*
* Returns: (transfer none): The first key in @table in iteration order,
* or %NULL if @table is empty.
*/
gpointer
pv_hash_table_get_arbitrary_key (GHashTable *table)
{
GHashTableIter iter;
gpointer key = NULL;
g_hash_table_iter_init (&iter, table);
if (g_hash_table_iter_next (&iter, &key, NULL))
return key;
else
return NULL;
}
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static gint
ftw_remove (const gchar *path,
const struct stat *sb,
gint typeflags,
struct FTW *ftwbuf)
{
if (remove (path) < 0)
return -1;
return 0;
}
/*
* @directory: (type filename): The directory to remove.
*
* Recursively delete @directory within the same file system and
* without following symbolic links.
*
* Returns: %TRUE if the removal was successful
*/
gboolean
pv_rm_rf (const char *directory)
{
g_return_val_if_fail (directory != NULL, FALSE);
if (nftw (directory, ftw_remove, 10, FTW_DEPTH|FTW_MOUNT|FTW_PHYS) < 0)
return FALSE;
return TRUE;
}
gboolean
pv_boolean_environment (const gchar *name,
gboolean def)
{
const gchar *value = g_getenv (name);
if (g_strcmp0 (value, "1") == 0)
return TRUE;
if (g_strcmp0 (value, "") == 0 || g_strcmp0 (value, "0") == 0)
return FALSE;
if (value != NULL)
g_warning ("Unrecognised value \"%s\" for $%s", value, name);
return def;
}
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/**
* pv_divert_stdout_to_stderr:
* @error: Used to raise an error on failure
*
* Duplicate file descriptors so that functions that would write to
* `stdout` instead write to a copy of the original `stderr`. Return
* a file handle that can be used to print structured output to the
* original `stdout`.
*
* Returns: (transfer full): A libc file handle for the original `stdout`,
* or %NULL on error. Free with `fclose()`.
*/
FILE *
pv_divert_stdout_to_stderr (GError **error)
{
g_autoptr(FILE) original_stdout = NULL;
glnx_autofd int original_stdout_fd = -1;
int flags;
g_return_val_if_fail (error == NULL || *error == NULL, FALSE);
/* Duplicate the original stdout so that we still have a way to write
* machine-readable output. */
original_stdout_fd = dup (STDOUT_FILENO);
if (original_stdout_fd < 0)
return glnx_null_throw_errno_prefix (error,
"Unable to duplicate fd %d",
STDOUT_FILENO);
flags = fcntl (original_stdout_fd, F_GETFD, 0);
if (flags < 0)
return glnx_null_throw_errno_prefix (error,
"Unable to get flags of new fd");
fcntl (original_stdout_fd, F_SETFD, flags|FD_CLOEXEC);
/* If something like g_debug writes to stdout, make it come out of
* our original stderr. */
if (dup2 (STDERR_FILENO, STDOUT_FILENO) != STDOUT_FILENO)
return glnx_null_throw_errno_prefix (error,
"Unable to make fd %d a copy of fd %d",
STDOUT_FILENO, STDERR_FILENO);
original_stdout = fdopen (original_stdout_fd, "w");
if (original_stdout == NULL)
return glnx_null_throw_errno_prefix (error,
"Unable to create a stdio wrapper for fd %d",
original_stdout_fd);
else
original_stdout_fd = -1; /* ownership taken, do not close */
return g_steal_pointer (&original_stdout);
}
/**
* pv_async_signal_safe_error:
* @message: A human-readable message
* @exit_status: Call `_exit` with this status
*
* Exit with a fatal error, like g_error(), but async-signal-safe
* (see signal-safety(7)).
*/
void
pv_async_signal_safe_error (const char *message,
int exit_status)
{
if (write (2, message, strlen (message)) < 0)
{
/* Ignore - there's nothing we can do about it anyway - but
* suppress -Wunused-result. */
}
_exit (exit_status);
}
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#define PROC_SYS_KERNEL_RANDOM_UUID "/proc/sys/kernel/random/uuid"
/**
* pv_get_random_uuid:
* @error: Used to raise an error on failure
*
* Return a random UUID (RFC 4122 version 4) as a string.
* It is a 128-bit quantity, with 122 bits of entropy, and 6 fixed bits
* indicating the "variant" (type, 0b10) and "version" (subtype, 0b0100).
*
* Returns: (transfer full): A random UUID, or %NULL on error
*/
gchar *
pv_get_random_uuid (GError **error)
{
g_autofree gchar *contents = NULL;
if (!g_file_get_contents (PROC_SYS_KERNEL_RANDOM_UUID,
&contents, NULL, error))
return NULL;
g_strchomp (contents); /* delete trailing newline */
/* Format: xxxxxxxx-xxxx-xxxx-xxxx-xxxxxxxxxxxx */
if (strlen (contents) != 36)
return glnx_null_throw (error, "%s not in expected format",
PROC_SYS_KERNEL_RANDOM_UUID);
return g_steal_pointer (&contents);
}
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/**
* pv_wait_for_child_processes:
* @main_process: process for which we will report wait-status;
* zero or negative if there is no main process
* @wait_status_out: (out): Used to store the wait status of `@main_process`,
* as if from `wait()`, on success
* @error: Used to raise an error on failure
*
* Wait for child processes of this process to exit, until the @main_process
* has exited. If there is no main process, wait until there are no child
* processes at all.
*
* If the process is a subreaper (`PR_SET_CHILD_SUBREAPER`),
* indirect child processes whose parents have exited will be reparented
* to it, so this will have the effect of waiting for all descendants.
*
* If @main_process is positive, return when @main_process has exited.
* Child processes that exited before @main_process will also have been
* "reaped", but child processes that exit after @main_process will not
* (use `pv_wait_for_child_processes (0, &error)` to resume waiting).
*
* If @main_process is zero or negative, wait for all child processes
* to exit.
*
* This function cannot be called in a process that is using
* g_child_watch_source_new() or similar functions, because it waits
* for all child processes regardless of their process IDs, and that is
* incompatible with waiting for individual child processes.
*
* Returns: %TRUE when @main_process has exited, or if @main_process
* is zero or negative and all child processes have exited
*/
gboolean
pv_wait_for_child_processes (pid_t main_process,
int *wait_status_out,
GError **error)
{
if (wait_status_out != NULL)
*wait_status_out = -1;
while (1)
{
int wait_status = -1;
pid_t died = wait (&wait_status);
if (died < 0)
{
if (errno == EINTR)
{
continue;
}
else if (errno == ECHILD)
{
g_debug ("No more child processes");
break;
}
else
{
return glnx_throw_errno_prefix (error, "wait");
}
}
g_debug ("Child %lld exited with wait status %d",
(long long) died, wait_status);
if (died == main_process)
{
if (wait_status_out != NULL)
*wait_status_out = wait_status;
return TRUE;
}
}
if (main_process > 0)
{
g_set_error (error, G_IO_ERROR, G_IO_ERROR_NOT_FOUND,
"Process %lld was not seen to exit",
(long long) main_process);
return FALSE;
}
return TRUE;
}
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typedef struct
{
GError *error;
GMainContext *context;
GSource *wait_source;
GSource *kill_source;
GSource *sigchld_source;
gchar *children_file;
/* GINT_TO_POINTER (pid) => arbitrary */
GHashTable *sent_sigterm;
/* GINT_TO_POINTER (pid) => arbitrary */
GHashTable *sent_sigkill;
/* Scratch space to build temporary strings */
GString *buffer;
/* 0, SIGTERM or SIGKILL */
int sending_signal;
/* Nonzero if wait_source has been attached to context */
guint wait_source_id;
guint kill_source_id;
guint sigchld_source_id;
/* TRUE if we reach a point where we have no more child processes. */
gboolean finished;
} TerminationData;
/*
* Free everything in @data.
*/
static void
termination_data_clear (TerminationData *data)
{
if (data->wait_source_id != 0)
{
g_source_destroy (data->wait_source);
data->wait_source_id = 0;
}
if (data->kill_source_id != 0)
{
g_source_destroy (data->kill_source);
data->kill_source_id = 0;
}
if (data->sigchld_source_id != 0)
{
g_source_destroy (data->sigchld_source);
data->sigchld_source_id = 0;
}
if (data->wait_source != NULL)
g_source_unref (g_steal_pointer (&data->wait_source));
if (data->kill_source != NULL)
g_source_unref (g_steal_pointer (&data->kill_source));
if (data->sigchld_source != NULL)
g_source_unref (g_steal_pointer (&data->sigchld_source));
g_clear_pointer (&data->children_file, g_free);
g_clear_pointer (&data->context, g_main_context_unref);
g_clear_error (&data->error);
g_clear_pointer (&data->sent_sigterm, g_hash_table_unref);
g_clear_pointer (&data->sent_sigkill, g_hash_table_unref);
if (data->buffer != NULL)
g_string_free (g_steal_pointer (&data->buffer), TRUE);
}
G_DEFINE_AUTO_CLEANUP_CLEAR_FUNC (TerminationData, termination_data_clear)
/*
* Do whatever the next step for pv_terminate_all_child_processes() is.
*
* First, reap child processes that already exited, without blocking.
*
* Then, act according to the phase we are in:
* - before wait_period: do nothing
* - after wait_period but before grace_period: send SIGTERM
* - after wait_period and grace_period: send SIGKILL
*/
static void
termination_data_refresh (TerminationData *data)
{
g_autofree gchar *contents = NULL;
gboolean has_child = FALSE;
const char *p;
char *endptr;
if (data->error != NULL)
return;
g_debug ("Checking for child processes");
while (1)
{
int wait_status = -1;
pid_t died = waitpid (-1, &wait_status, WNOHANG);
if (died < 0)
{
if (errno == EINTR)
{
continue;
}
else if (errno == ECHILD)
{
/* No child processes at all. We'll double-check this
* a bit later. */
break;
}
else
{
glnx_throw_errno_prefix (&data->error, "wait");
return;
}
}
else if (died == 0)
{
/* No more child processes have exited, but at least one is
* still running. */
break;
}
/* This process has gone away, so remove any record that we have
* sent it signals. If the pid is reused, we'll want to send
* the same signals again. */
g_debug ("Process %d exited", died);
g_hash_table_remove (data->sent_sigkill, GINT_TO_POINTER (died));
g_hash_table_remove (data->sent_sigterm, GINT_TO_POINTER (died));
}
/* See whether we have any remaining children. These could be direct
* child processes, or they could be children we adopted because
* their parent was one of our descendants and has exited, leaving the
* child to be reparented to us (their (great)*grandparent) because we
* are a subreaper. */
if (!g_file_get_contents (data->children_file, &contents, NULL, &data->error))
return;
g_debug ("Child tasks: %s", contents);
for (p = contents;
p != NULL && *p != '\0';
p = endptr)
{
guint64 maybe_child;
int child;
GHashTable *already;
while (*p != '\0' && g_ascii_isspace (*p))
p++;
if (*p == '\0')
break;
maybe_child = g_ascii_strtoull (p, &endptr, 10);
if (*endptr != '\0' && !g_ascii_isspace (*endptr))
{
glnx_throw (&data->error, "Non-numeric string found in %s: %s",
data->children_file, p);
return;
}
if (maybe_child > G_MAXINT)
{
glnx_throw (&data->error, "Out-of-range number found in %s: %s",
data->children_file, p);
return;
}
child = (int) maybe_child;
g_string_printf (data->buffer, "/proc/%d", child);
/* If the task is just a thread, it won't have a /proc/%d directory
* in its own right. We don't kill threads, only processes. */
if (!g_file_test (data->buffer->str, G_FILE_TEST_IS_DIR))
{
g_debug ("Task %d is a thread, not a process", child);
continue;
}
has_child = TRUE;
if (data->sending_signal == 0)
break;
else if (data->sending_signal == SIGKILL)
already = data->sent_sigkill;
else
already = data->sent_sigterm;
if (!g_hash_table_contains (already, GINT_TO_POINTER (child)))
{
g_debug ("Sending signal %d to process %d",
data->sending_signal, child);
g_hash_table_add (already, GINT_TO_POINTER (child));
if (kill (child, data->sending_signal) < 0)
g_warning ("Unable to send signal %d to process %d: %s",
data->sending_signal, child, g_strerror (errno));
/* In case the child is stopped, wake it up to receive the signal */
if (kill (child, SIGCONT) < 0)
g_warning ("Unable to send SIGCONT to process %d: %s",
child, g_strerror (errno));
/* When the child terminates, we will get SIGCHLD and come
* back to here. */
}
}
if (!has_child)
data->finished = TRUE;
}
/*
* Move from wait period to grace period: start sending SIGTERM to
* child processes.
*/
static gboolean
start_sending_sigterm (gpointer user_data)
{
TerminationData *data = user_data;
g_debug ("Wait period finished, starting to send SIGTERM...");
if (data->sending_signal == 0)
data->sending_signal = SIGTERM;
termination_data_refresh (data);
data->wait_source_id = 0;
return G_SOURCE_REMOVE;
}
/*
* End of grace period: start sending SIGKILL to child processes.
*/
static gboolean
start_sending_sigkill (gpointer user_data)
{
TerminationData *data = user_data;
g_debug ("Grace period finished, starting to send SIGKILL...");
data->sending_signal = SIGKILL;
termination_data_refresh (data);
data->kill_source_id = 0;
return G_SOURCE_REMOVE;
}
/*
* Called when at least one child process has exited, resulting in
* SIGCHLD to this process.
*/
static gboolean
sigchld_cb (int sfd,
G_GNUC_UNUSED GIOCondition condition,
gpointer user_data)
{
TerminationData *data = user_data;
struct signalfd_siginfo info;
ssize_t size;
size = read (sfd, &info, sizeof (info));
if (size < 0)
{
if (errno != EINTR && errno != EAGAIN)
g_warning ("Unable to read struct signalfd_siginfo: %s",
g_strerror (errno));
}
else if (size != sizeof (info))
{
g_warning ("Expected struct signalfd_siginfo of size %"
G_GSIZE_FORMAT ", got %" G_GSSIZE_FORMAT,
sizeof (info), size);
}
g_debug ("One or more child processes exited");
termination_data_refresh (data);
return G_SOURCE_CONTINUE;
}
/**
* pv_terminate_all_child_processes:
* @wait_period: If greater than 0, wait this many microseconds before
* sending `SIGTERM`
* @grace_period: If greater than 0, after @wait_period plus this many
* microseconds, use `SIGKILL` instead of `SIGTERM`. If 0, proceed
* directly to sending `SIGKILL`.
* @error: Used to raise an error on failure
*
* Make sure all child processes are terminated.
*
* If a child process catches `SIGTERM` but does not exit promptly and
* does not pass the signal on to its descendants, note that its
* descendant processes are not guaranteed to be terminated gracefully
* with `SIGTERM`; they might only receive `SIGKILL`.
*
* Return when all child processes have exited or when an error has
* occurred.
*
* This function cannot be called in a process that is using
* g_child_watch_source_new() or similar functions.
*
* The process must be a subreaper, and must have `SIGCHLD` blocked.
*
* Returns: %TRUE on success.
*/
gboolean
pv_terminate_all_child_processes (GTimeSpan wait_period,
GTimeSpan grace_period,
GError **error)
{
g_auto(TerminationData) data = {};
sigset_t mask;
int is_subreaper = -1;
glnx_autofd int sfd = -1;
if (prctl (PR_GET_CHILD_SUBREAPER, (unsigned long) &is_subreaper, 0, 0, 0) != 0)
return glnx_throw_errno_prefix (error, "prctl PR_GET_CHILD_SUBREAPER");
if (is_subreaper != 1)
return glnx_throw (error, "Process is not a subreaper");
sigemptyset (&mask);
if (pthread_sigmask (SIG_BLOCK, NULL, &mask) != 0)
return glnx_throw_errno_prefix (error, "pthread_sigmask");
if (!sigismember (&mask, SIGCHLD))
return glnx_throw (error, "Process has not blocked SIGCHLD");
data.children_file = g_strdup_printf ("/proc/%d/task/%d/children",
getpid (), getpid ());
data.context = g_main_context_new ();
data.sent_sigterm = g_hash_table_new (NULL, NULL);
data.sent_sigkill = g_hash_table_new (NULL, NULL);
data.buffer = g_string_new ("/proc/2345678901");
if (wait_period > 0 && grace_period > 0)
{
data.wait_source = g_timeout_source_new (wait_period / G_TIME_SPAN_MILLISECOND);
g_source_set_callback (data.wait_source, start_sending_sigterm,
&data, NULL);
data.wait_source_id = g_source_attach (data.wait_source, data.context);
}
else if (grace_period > 0)
{
start_sending_sigterm (&data);
}
if (wait_period + grace_period > 0)
{
data.kill_source = g_timeout_source_new ((wait_period + grace_period) / G_TIME_SPAN_MILLISECOND);
g_source_set_callback (data.kill_source, start_sending_sigkill,
&data, NULL);
data.kill_source_id = g_source_attach (data.kill_source, data.context);
}
else
{
start_sending_sigkill (&data);
}
sigemptyset (&mask);
sigaddset (&mask, SIGCHLD);
sfd = signalfd (-1, &mask, SFD_NONBLOCK | SFD_CLOEXEC);
if (sfd < 0)
return glnx_throw_errno_prefix (error, "signalfd");
data.sigchld_source = g_unix_fd_source_new (sfd, G_IO_IN);
g_source_set_callback (data.sigchld_source,
(GSourceFunc) G_CALLBACK (sigchld_cb), &data, NULL);
data.sigchld_source_id = g_source_attach (data.sigchld_source, data.context);
termination_data_refresh (&data);
while (data.error == NULL
&& !data.finished
&& (data.wait_source_id != 0
|| data.kill_source_id != 0
|| data.sigchld_source_id != 0))
g_main_context_iteration (data.context, TRUE);
if (data.error != NULL)
{
g_propagate_error (error, g_steal_pointer (&data.error));
return FALSE;
}
return TRUE;
}