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GDBusError

GDBusError — Mapping D-Bus errors to and from GError

Types and Values

Includes

#include <gio/gio.h>

Description

All facilities that return errors from remote methods (such as g_dbus_connection_call_sync()) use GError to represent both D-Bus errors (e.g. errors returned from the other peer) and locally in-process generated errors.

To check if a returned GError is an error from a remote peer, use g_dbus_error_is_remote_error(). To get the actual D-Bus error name, use g_dbus_error_get_remote_error(). Before presenting an error, always use g_dbus_error_strip_remote_error().

In addition, facilities used to return errors to a remote peer also use GError. See g_dbus_method_invocation_return_error() for discussion about how the D-Bus error name is set.

Applications can associate a GError error domain with a set of D-Bus errors in order to automatically map from D-Bus errors to GError and back. This is typically done in the function returning the GQuark for the error domain:

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// foo-bar-error.h:

#define FOO_BAR_ERROR (foo_bar_error_quark ())
GQuark foo_bar_error_quark (void);

typedef enum
{
  FOO_BAR_ERROR_FAILED,
  FOO_BAR_ERROR_ANOTHER_ERROR,
  FOO_BAR_ERROR_SOME_THIRD_ERROR,
  FOO_BAR_N_ERRORS / *< skip >* /
} FooBarError;

// foo-bar-error.c:

static const GDBusErrorEntry foo_bar_error_entries[] =
{
  {FOO_BAR_ERROR_FAILED,           "org.project.Foo.Bar.Error.Failed"},
  {FOO_BAR_ERROR_ANOTHER_ERROR,    "org.project.Foo.Bar.Error.AnotherError"},
  {FOO_BAR_ERROR_SOME_THIRD_ERROR, "org.project.Foo.Bar.Error.SomeThirdError"},
};

// Ensure that every error code has an associated D-Bus error name
G_STATIC_ASSERT (G_N_ELEMENTS (foo_bar_error_entries) == FOO_BAR_N_ERRORS);

GQuark
foo_bar_error_quark (void)
{
  static volatile gsize quark_volatile = 0;
  g_dbus_error_register_error_domain ("foo-bar-error-quark",
                                      &quark_volatile,
                                      foo_bar_error_entries,
                                      G_N_ELEMENTS (foo_bar_error_entries));
  return (GQuark) quark_volatile;
}

With this setup, a D-Bus peer can transparently pass e.g. FOO_BAR_ERROR_ANOTHER_ERROR and other peers will see the D-Bus error name org.project.Foo.Bar.Error.AnotherError.

If the other peer is using GDBus, and has registered the association with g_dbus_error_register_error_domain() in advance (e.g. by invoking the FOO_BAR_ERROR quark generation itself in the previous example) the peer will see also FOO_BAR_ERROR_ANOTHER_ERROR instead of G_IO_ERROR_DBUS_ERROR. Note that GDBus clients can still recover org.project.Foo.Bar.Error.AnotherError using g_dbus_error_get_remote_error().

Note that errors in the G_DBUS_ERROR error domain is intended only for returning errors from a remote message bus process. Errors generated locally in-process by e.g. GDBusConnection is from the G_IO_ERROR domain.

Functions

g_dbus_error_is_remote_error ()

gboolean
g_dbus_error_is_remote_error (const GError *error);

Checks if error represents an error received via D-Bus from a remote peer. If so, use g_dbus_error_get_remote_error() to get the name of the error.

Parameters

error

A GError.

 

Returns

TRUE if error represents an error from a remote peer, FALSE otherwise.

Since: 2.26


g_dbus_error_get_remote_error ()

gchar *
g_dbus_error_get_remote_error (const GError *error);

Gets the D-Bus error name used for error , if any.

This function is guaranteed to return a D-Bus error name for all GErrors returned from functions handling remote method calls (e.g. g_dbus_connection_call_finish()) unless g_dbus_error_strip_remote_error() has been used on error .

Parameters

error

a GError

 

Returns

an allocated string or NULL if the D-Bus error name could not be found. Free with g_free().

Since: 2.26


g_dbus_error_strip_remote_error ()

gboolean
g_dbus_error_strip_remote_error (GError *error);

Looks for extra information in the error message used to recover the D-Bus error name and strips it if found. If stripped, the message field in error will correspond exactly to what was received on the wire.

This is typically used when presenting errors to the end user.

Parameters

error

A GError.

 

Returns

TRUE if information was stripped, FALSE otherwise.

Since: 2.26


g_dbus_error_register_error_domain ()

void
g_dbus_error_register_error_domain (const gchar *error_domain_quark_name,
                                    volatile gsize *quark_volatile,
                                    const GDBusErrorEntry *entries,
                                    guint num_entries);

Helper function for associating a GError error domain with D-Bus error names.

Parameters

error_domain_quark_name

The error domain name.

 

quark_volatile

A pointer where to store the GQuark.

 

entries

A pointer to num_entries GDBusErrorEntry struct items.

 

num_entries

Number of items to register.

 

Since: 2.26


g_dbus_error_register_error ()

gboolean
g_dbus_error_register_error (GQuark error_domain,
                             gint error_code,
                             const gchar *dbus_error_name);

Creates an association to map between dbus_error_name and GErrors specified by error_domain and error_code .

This is typically done in the routine that returns the GQuark for an error domain.

Parameters

error_domain

A GQuark for a error domain.

 

error_code

An error code.

 

dbus_error_name

A D-Bus error name.

 

Returns

TRUE if the association was created, FALSE if it already exists.

Since: 2.26


g_dbus_error_unregister_error ()

gboolean
g_dbus_error_unregister_error (GQuark error_domain,
                               gint error_code,
                               const gchar *dbus_error_name);

Destroys an association previously set up with g_dbus_error_register_error().

Parameters

error_domain

A GQuark for a error domain.

 

error_code

An error code.

 

dbus_error_name

A D-Bus error name.

 

Returns

TRUE if the association was destroyed, FALSE if it wasn't found.

Since: 2.26


g_dbus_error_new_for_dbus_error ()

GError *
g_dbus_error_new_for_dbus_error (const gchar *dbus_error_name,
                                 const gchar *dbus_error_message);

Creates a GError based on the contents of dbus_error_name and dbus_error_message .

Errors registered with g_dbus_error_register_error() will be looked up using dbus_error_name and if a match is found, the error domain and code is used. Applications can use g_dbus_error_get_remote_error() to recover dbus_error_name .

If a match against a registered error is not found and the D-Bus error name is in a form as returned by g_dbus_error_encode_gerror() the error domain and code encoded in the name is used to create the GError. Also, dbus_error_name is added to the error message such that it can be recovered with g_dbus_error_get_remote_error().

Otherwise, a GError with the error code G_IO_ERROR_DBUS_ERROR in the G_IO_ERROR error domain is returned. Also, dbus_error_name is added to the error message such that it can be recovered with g_dbus_error_get_remote_error().

In all three cases, dbus_error_name can always be recovered from the returned GError using the g_dbus_error_get_remote_error() function (unless g_dbus_error_strip_remote_error() hasn't been used on the returned error).

This function is typically only used in object mappings to prepare GError instances for applications. Regular applications should not use it.

Parameters

dbus_error_name

D-Bus error name.

 

dbus_error_message

D-Bus error message.

 

Returns

An allocated GError. Free with g_error_free().

Since: 2.26


g_dbus_error_set_dbus_error ()

void
g_dbus_error_set_dbus_error (GError **error,
                             const gchar *dbus_error_name,
                             const gchar *dbus_error_message,
                             const gchar *format,
                             ...);

Does nothing if error is NULL. Otherwise sets *error to a new GError created with g_dbus_error_new_for_dbus_error() with dbus_error_message prepend with format (unless NULL).

Parameters

error

A pointer to a GError or NULL.

 

dbus_error_name

D-Bus error name.

 

dbus_error_message

D-Bus error message.

 

format

printf()-style format to prepend to dbus_error_message or NULL.

[nullable]

...

Arguments for format .

 

Since: 2.26


g_dbus_error_set_dbus_error_valist ()

void
g_dbus_error_set_dbus_error_valist (GError **error,
                                    const gchar *dbus_error_name,
                                    const gchar *dbus_error_message,
                                    const gchar *format,
                                    va_list var_args);

Like g_dbus_error_set_dbus_error() but intended for language bindings.

Parameters

error

A pointer to a GError or NULL.

 

dbus_error_name

D-Bus error name.

 

dbus_error_message

D-Bus error message.

 

format

printf()-style format to prepend to dbus_error_message or NULL.

[nullable]

var_args

Arguments for format .

 

Since: 2.26


g_dbus_error_encode_gerror ()

gchar *
g_dbus_error_encode_gerror (const GError *error);

Creates a D-Bus error name to use for error . If error matches a registered error (cf. g_dbus_error_register_error()), the corresponding D-Bus error name will be returned.

Otherwise the a name of the form org.gtk.GDBus.UnmappedGError.Quark._ESCAPED_QUARK_NAME.Code_ERROR_CODE will be used. This allows other GDBus applications to map the error on the wire back to a GError using g_dbus_error_new_for_dbus_error().

This function is typically only used in object mappings to put a GError on the wire. Regular applications should not use it.

Parameters

error

A GError.

 

Returns

A D-Bus error name (never NULL). Free with g_free().

Since: 2.26

Types and Values

enum GDBusError

Error codes for the G_DBUS_ERROR error domain.

Members

G_DBUS_ERROR_FAILED

A generic error; "something went wrong" - see the error message for more.

 

G_DBUS_ERROR_NO_MEMORY

There was not enough memory to complete an operation.

 

G_DBUS_ERROR_SERVICE_UNKNOWN

The bus doesn't know how to launch a service to supply the bus name you wanted.

 

G_DBUS_ERROR_NAME_HAS_NO_OWNER

The bus name you referenced doesn't exist (i.e. no application owns it).

 

G_DBUS_ERROR_NO_REPLY

No reply to a message expecting one, usually means a timeout occurred.

 

G_DBUS_ERROR_IO_ERROR

Something went wrong reading or writing to a socket, for example.

 

G_DBUS_ERROR_BAD_ADDRESS

A D-Bus bus address was malformed.

 

G_DBUS_ERROR_NOT_SUPPORTED

Requested operation isn't supported (like ENOSYS on UNIX).

 

G_DBUS_ERROR_LIMITS_EXCEEDED

Some limited resource is exhausted.

 

G_DBUS_ERROR_ACCESS_DENIED

Security restrictions don't allow doing what you're trying to do.

 

G_DBUS_ERROR_AUTH_FAILED

Authentication didn't work.

 

G_DBUS_ERROR_NO_SERVER

Unable to connect to server (probably caused by ECONNREFUSED on a socket).

 

G_DBUS_ERROR_TIMEOUT

Certain timeout errors, possibly ETIMEDOUT on a socket. Note that G_DBUS_ERROR_NO_REPLY is used for message reply timeouts. Warning: this is confusingly-named given that G_DBUS_ERROR_TIMED_OUT also exists. We can't fix it for compatibility reasons so just be careful.

 

G_DBUS_ERROR_NO_NETWORK

No network access (probably ENETUNREACH on a socket).

 

G_DBUS_ERROR_ADDRESS_IN_USE

Can't bind a socket since its address is in use (i.e. EADDRINUSE).

 

G_DBUS_ERROR_DISCONNECTED

The connection is disconnected and you're trying to use it.

 

G_DBUS_ERROR_INVALID_ARGS

Invalid arguments passed to a method call.

 

G_DBUS_ERROR_FILE_NOT_FOUND

Missing file.

 

G_DBUS_ERROR_FILE_EXISTS

Existing file and the operation you're using does not silently overwrite.

 

G_DBUS_ERROR_UNKNOWN_METHOD

Method name you invoked isn't known by the object you invoked it on.

 

G_DBUS_ERROR_TIMED_OUT

Certain timeout errors, e.g. while starting a service. Warning: this is confusingly-named given that G_DBUS_ERROR_TIMEOUT also exists. We can't fix it for compatibility reasons so just be careful.

 

G_DBUS_ERROR_MATCH_RULE_NOT_FOUND

Tried to remove or modify a match rule that didn't exist.

 

G_DBUS_ERROR_MATCH_RULE_INVALID

The match rule isn't syntactically valid.

 

G_DBUS_ERROR_SPAWN_EXEC_FAILED

While starting a new process, the exec() call failed.

 

G_DBUS_ERROR_SPAWN_FORK_FAILED

While starting a new process, the fork() call failed.

 

G_DBUS_ERROR_SPAWN_CHILD_EXITED

While starting a new process, the child exited with a status code.

 

G_DBUS_ERROR_SPAWN_CHILD_SIGNALED

While starting a new process, the child exited on a signal.

 

G_DBUS_ERROR_SPAWN_FAILED

While starting a new process, something went wrong.

 

G_DBUS_ERROR_SPAWN_SETUP_FAILED

We failed to setup the environment correctly.

 

G_DBUS_ERROR_SPAWN_CONFIG_INVALID

We failed to setup the config parser correctly.

 

G_DBUS_ERROR_SPAWN_SERVICE_INVALID

Bus name was not valid.

 

G_DBUS_ERROR_SPAWN_SERVICE_NOT_FOUND

Service file not found in system-services directory.

 

G_DBUS_ERROR_SPAWN_PERMISSIONS_INVALID

Permissions are incorrect on the setuid helper.

 

G_DBUS_ERROR_SPAWN_FILE_INVALID

Service file invalid (Name, User or Exec missing).

 

G_DBUS_ERROR_SPAWN_NO_MEMORY

Tried to get a UNIX process ID and it wasn't available.

 

G_DBUS_ERROR_UNIX_PROCESS_ID_UNKNOWN

Tried to get a UNIX process ID and it wasn't available.

 

G_DBUS_ERROR_INVALID_SIGNATURE

A type signature is not valid.

 

G_DBUS_ERROR_INVALID_FILE_CONTENT

A file contains invalid syntax or is otherwise broken.

 

G_DBUS_ERROR_SELINUX_SECURITY_CONTEXT_UNKNOWN

Asked for SELinux security context and it wasn't available.

 

G_DBUS_ERROR_ADT_AUDIT_DATA_UNKNOWN

Asked for ADT audit data and it wasn't available.

 

G_DBUS_ERROR_OBJECT_PATH_IN_USE

There's already an object with the requested object path.

 

G_DBUS_ERROR_UNKNOWN_OBJECT

Object you invoked a method on isn't known. Since 2.42

 

G_DBUS_ERROR_UNKNOWN_INTERFACE

Interface you invoked a method on isn't known by the object. Since 2.42

 

G_DBUS_ERROR_UNKNOWN_PROPERTY

Property you tried to access isn't known by the object. Since 2.42

 

G_DBUS_ERROR_PROPERTY_READ_ONLY

Property you tried to set is read-only. Since 2.42

 

Since: 2.26


G_DBUS_ERROR

#define G_DBUS_ERROR g_dbus_error_quark()

Error domain for errors generated by a remote message bus. Errors in this domain will be from the GDBusError enumeration. See GError for more information on error domains.

Note that errors in this error domain is intended only for returning errors from a remote message bus process. Errors generated locally in-process by e.g. GDBusConnection is from the G_IO_ERROR domain.

Since: 2.26


GDBusErrorEntry

typedef struct {
  gint         error_code;
  const gchar *dbus_error_name;
} GDBusErrorEntry;

Struct used in g_dbus_error_register_error_domain().

Members

gint error_code;

An error code.

 

const gchar *dbus_error_name;

The D-Bus error name to associate with error_code .

 

Since: 2.26

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