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UNIX-specific utilities and integrationUNIX-specific utilities and integration — pipes, signal handling |
Functions
Description
Most of GLib is intended to be portable; in contrast, this set of functions is designed for programs which explicitly target UNIX, or are using it to build higher level abstractions which would be conditionally compiled if the platform matches G_OS_UNIX.
To use these functions, you must explicitly include the "glib-unix.h" header.
Functions
G_UNIX_ERROR
#define G_UNIX_ERROR (g_unix_error_quark())
Error domain for API in the g_unix_ namespace. Note that there is no
exported enumeration mapping errno
. Instead, all functions ensure that
errno
is relevant. The code for all G_UNIX_ERROR is always 0, and the
error message is always generated via g_strerror()
.
It is expected that most code will not look at errno
from these APIs.
Important cases where one would want to differentiate between errors are
already covered by existing cross-platform GLib API, such as e.g. GFile
wrapping ENOENT
. However, it is provided for completeness, at least.
g_unix_open_pipe ()
gboolean g_unix_open_pipe (gint *fds
,gint flags
,GError **error
);
Similar to the UNIX pipe()
call, but on modern systems like Linux
uses the pipe2()
system call, which atomically creates a pipe with
the configured flags. The only supported flag currently is
FD_CLOEXEC
. If for example you want to configure O_NONBLOCK
, that
must still be done separately with fcntl()
.
This function does not take O_CLOEXEC
, it takes FD_CLOEXEC
as if
for fcntl()
; these are different on Linux/glibc.
Parameters
fds |
Array of two integers |
|
flags |
Bitfield of file descriptor flags, as for |
|
error |
a GError |
Since 2.30
g_unix_set_fd_nonblocking ()
gboolean g_unix_set_fd_nonblocking (gint fd
,gboolean nonblock
,GError **error
);
Control the non-blocking state of the given file descriptor,
according to nonblock
. On most systems this uses O_NONBLOCK
, but
on some older ones may use O_NDELAY
.
Since 2.30
g_unix_signal_add ()
guint g_unix_signal_add (gint signum
,GSourceFunc handler
,gpointer user_data
);
A convenience function for g_unix_signal_source_new()
, which
attaches to the default GMainContext. You can remove the watch
using g_source_remove()
.
Since 2.30
g_unix_signal_add_full ()
guint g_unix_signal_add_full (gint priority
,gint signum
,GSourceFunc handler
,gpointer user_data
,GDestroyNotify notify
);
A convenience function for g_unix_signal_source_new()
, which
attaches to the default GMainContext. You can remove the watch
using g_source_remove()
.
Parameters
priority |
the priority of the signal source. Typically this will be in the range between G_PRIORITY_DEFAULT and G_PRIORITY_HIGH. |
|
signum |
Signal number |
|
handler |
Callback |
|
user_data |
Data for |
|
notify |
GDestroyNotify for |
Since 2.30
g_unix_signal_source_new ()
GSource *
g_unix_signal_source_new (gint signum
);
Create a GSource that will be dispatched upon delivery of the UNIX
signal signum
. In GLib versions before 2.36, only SIGHUP
, SIGINT
,
SIGTERM
can be monitored. In GLib 2.36, SIGUSR1
and SIGUSR2
were added.
Note that unlike the UNIX default, all sources which have created a
watch will be dispatched, regardless of which underlying thread
invoked g_unix_signal_source_new()
.
For example, an effective use of this function is to handle SIGTERM
cleanly; flushing any outstanding files, and then calling
g_main_loop_quit()
. It is not safe to do any of this a regular
UNIX signal handler; your handler may be invoked while malloc()
or
another library function is running, causing reentrancy if you
attempt to use it from the handler. None of the GLib/GObject API
is safe against this kind of reentrancy.
The interaction of this source when combined with native UNIX
functions like sigprocmask()
is not defined.
The source will not initially be associated with any GMainContext
and must be added to one with g_source_attach()
before it will be
executed.
Since 2.30
GUnixFDSourceFunc ()
gboolean (*GUnixFDSourceFunc) (gint fd
,GIOCondition condition
,gpointer user_data
);
The type of functions to be called when a UNIX fd watch source triggers.
Parameters
fd |
the fd that triggered the event |
|
condition |
the IO conditions reported on |
|
user_data |
user data passed to |
g_unix_fd_add ()
guint g_unix_fd_add (gint fd
,GIOCondition condition
,GUnixFDSourceFunc function
,gpointer user_data
);
Sets a function to be called when the IO condition, as specified by
condition
becomes true for fd
.
function
will be called when the specified IO condition becomes
TRUE
. The function is expected to clear whatever event caused the
IO condition to become true and return TRUE
in order to be notified
when it happens again. If function
returns FALSE
then the watch
will be cancelled.
The return value of this function can be passed to g_source_remove()
to cancel the watch at any time that it exists.
The source will never close the fd -- you must do it yourself.
Parameters
fd |
a file descriptor |
|
condition |
IO conditions to watch for on |
|
function |
a GPollFDFunc |
|
user_data |
data to pass to |
Since 2.36
g_unix_fd_add_full ()
guint g_unix_fd_add_full (gint priority
,gint fd
,GIOCondition condition
,GUnixFDSourceFunc function
,gpointer user_data
,GDestroyNotify notify
);
Sets a function to be called when the IO condition, as specified by
condition
becomes true for fd
.
This is the same as g_unix_fd_add()
, except that it allows you to
specify a non-default priority and a provide a GDestroyNotify for
user_data
.
Parameters
priority |
the priority of the source |
|
fd |
a file descriptor |
|
condition |
IO conditions to watch for on |
|
function |
||
user_data |
data to pass to |
|
notify |
function to call when the idle is removed, or |
Since 2.36
g_unix_fd_source_new ()
GSource * g_unix_fd_source_new (gint fd
,GIOCondition condition
);
Creates a GSource to watch for a particular IO condition on a file descriptor.
The source will never close the fd -- you must do it yourself.
Since 2.36