diff --git a/docs/reference/gio/overview.md b/docs/reference/gio/overview.md index f75ea0439..89859f490 100644 --- a/docs/reference/gio/overview.md +++ b/docs/reference/gio/overview.md @@ -17,7 +17,7 @@ right level in the library stack, as well as other generally useful APIs for desktop applications (such as networking and D-Bus support). The goal is to overcome the shortcomings of GnomeVFS and provide an API that is so good that developers prefer it over raw POSIX calls. Among other things -that means using GObject. It also means not cloning the POSIX API, but +that means using [class@GObject.Object]. It also means not cloning the POSIX API, but providing higher-level, document-centric interfaces. The abstract file system model of GIO consists of a number of interfaces and @@ -71,11 +71,11 @@ There is a framework for storing and retrieving application settings: : stores and retrieves application settings There is support for network programming, including connectivity monitoring, -name resolution, lowlevel socket APIs and highlevel client and server helper +name resolution, low-level socket APIs and high-level client and server helper classes: [class@Gio.Socket] -: lowlevel platform independent socket object +: low-level platform independent socket object [class@Gio.Resolver] : asynchronous and cancellable DNS resolver @@ -123,14 +123,15 @@ which spawn further mount daemons for each individual connection. The GIO model of I/O is stateful: if an application establishes e.g. a SFTP connection to a server, it becomes available to all applications in the -session; the user does not have to enter his password over and over again. +session; the user does not have to enter their password over and over again. One of the big advantages of putting the VFS in the GLib layer is that GTK -can directly use it, e.g. in the filechooser. +can directly use it, e.g. in the file chooser. ## Writing GIO applications -The information in the GLib documentation about writing GLib applications is +The information in the GLib documentation about +[writing GLib applications](https://docs.gtk.org/glib/programming.html) is generally applicable when writing GIO applications. ### Threads @@ -153,7 +154,7 @@ dispatched, such as input and redraw handlers for the application’s UI. This can cause the application to ‘freeze’ until I/O completes. A few self-contained groups of functions, such as code generated by -gdbus-codegen, use a different convention: functions are asynchronous +[`gdbus-codegen`](gdbus-codegen.html), use a different convention: functions are asynchronous default, and it is the synchronous version which has a `_sync` suffix. Aside from naming differences, they should be treated the same way as functions following the normal convention above. @@ -187,10 +188,10 @@ a new user account), there are various ways in which you can go about this: executing the operation. [polkit](https://www.freedesktop.org/software/polkit/docs/latest/polkit.8.html) is a framework that allows this. -- Use a small helper that is executed with elevated privileges via pkexec. +- Use a small helper that is executed with elevated privileges via `pkexec`. [`pkexec`](https://www.freedesktop.org/software/polkit/docs/latest/pkexec.1.html) is a small program launcher that is part of polkit. -- Use a small helper that is executed with elevated privileges by being suid +- Use a small helper that is executed with elevated privileges by being SUID root. None of these approaches is the clear winner, they all have their advantages @@ -204,13 +205,13 @@ excellent book on this topic, When using GIO in code that runs with elevated privileges, you have to be careful. GIO has extension points whose implementations get loaded from modules (executable code in shared objects), which could allow an attacker -to sneak his own code into your application by tricking it into loading the +to sneak their own code into your application by tricking it into loading the code as a module. However, GIO will never load modules from your home directory except when explicitly asked to do so via an environment variable. -In most cases, your helper program should be so small that you don't need +In most cases, your helper program should be so small that you don’t need GIO, whose APIs are largely designed to support full-blown desktop -applications. If you can't resist the convenience of these APIs, here are +applications. If you can’t resist the convenience of these APIs, here are some steps you should take: - Clear the environment, e.g. using the `clearenv()` function. David Wheeler @@ -221,7 +222,7 @@ some steps you should take: GIO. In particular, `PATH` (used to locate binaries), `GIO_EXTRA_MODULES` (used to locate loadable modules) and `DBUS_{SYSTEM,SESSION}_BUS_ADDRESS` (used to locate the D-Bus system and session bus) are important. -- Don't use GVfs, by setting `GIO_USE_VFS=local` in the environment. The +- Don’t use GVfs, by setting `GIO_USE_VFS=local` in the environment. The reason to avoid GVfs in security-sensitive programs is that it uses many libraries which have not necessarily been audited for security problems. Gvfs is also heavily distributed and relies on a session bus to be @@ -231,10 +232,11 @@ some steps you should take: GIO comes with a `gio-2.0.pc` file that you should use together with pkg-config to obtain the necessary information about header files and -libraries. See the pkg-config man page or the GLib documentation for more +libraries. See the [pkg-config man page](man:pkg-config(1)) or the +[GLib documentation](https://docs.gtk.org/glib/compiling.html) for more information on how to use pkg-config to compile your application. -If you are using GIO on UNIX-like systems, you may want to use UNIX-specific +If you are using GIO on Unix-like systems, you may want to use Unix-specific GIO interfaces such as `GUnixInputStream`, `GUnixOutputStream`, `GUnixMount` or `GDesktopAppInfo`. To do so, use the `gio-unix-2.0.pc` file as well as `gio-2.0.pc` (or, in GIR namespace terms, `GioUnix-2.0` as well as `Gio-2.0`). @@ -253,9 +255,9 @@ GIO inspects a few environment variables in addition to the ones used by GLib. - `GIO_USE_VFS`. This environment variable can be set to the name of a GVfs implementation to override the default for debugging purposes. The GVfs implementation for local files that is included in GIO has the name - "local", the implementation in the gvfs module has the name "gvfs". Most - commonly, system software will set this to "local" to avoid having `GFile` - APIs perform unnecessary D-Bus calls. The special value help can be used + `local`, the implementation in the GVfs module has the name `gvfs`. Most + commonly, system software will set this to `local` to avoid having [iface@Gio.File] + APIs perform unnecessary D-Bus calls. The special value `help` can be used to print a list of available implementations to standard output. The following environment variables are only useful for debugging GIO itself @@ -263,23 +265,38 @@ or modules that it loads. They should not be set in a production environment. - `GIO_USE_FILE_MONITOR`. This variable can be set to the name of a - GFileMonitor implementation to override the default for debugging - purposes. The GFileMonitor implementation for local files that is included - in GIO on Linux has the name "inotify", others that are built are built as - modules (depending on the platform) are called "fam" and "fen". The - special value help can be used to print a list of available + [class@Gio.FileMonitor] implementation to override the default for debugging + purposes. The [class@Gio.FileMonitor] implementation for local files that is included + in GIO on Linux has the name `inotify`, others that are built are built as + modules (depending on the platform) are called `kqueue` and `win32`. The + special value `help` can be used to print a list of available implementations to standard output. - `GIO_USE_VOLUME_MONITOR`. This variable can be set to the name of a - GVolumeMonitor implementation to override the default for debugging - purposes. The GVolumeMonitor implementation for local files that is - included in GIO has the name "unix", the udisks2-based implementation in - the gvfs module has the name "udisks2". The special value help can be used + [class@Gio.VolumeMonitor] implementation to override the default for debugging + purposes. The [class@Gio.VolumeMonitor] implementation for local files that is + included in GIO has the name `unix`, the udisks2-based implementation in + the GVfs module has the name `udisks2`. The special value `help` can be used to print a list of available implementations to standard output. -- `GIO_USE_TLS`. This variable can be set to the name of a GTlsBackend +- `GIO_USE_MEMORY_MONITOR`. This variable can be set to the name of a + [iface@Gio.MemoryMonitor] implementation to override the default for debugging + purposes. The available implementations included in GIO have the names + `dbus`, `portal` and `win32`. The special value `help` can be used + to print a list of available implementations to standard output. +- `GIO_USE_NETWORK_MONITOR`. This variable can be set to the name of a + [iface@Gio.NetworkMonitor] implementation to override the default for debugging + purposes. The available implementations included in GIO have the names + `netlink`, `networkmanager` and `portal`. The special value `help` can + be used to print a list of available implementations to standard output. +- `GIO_USE_POWER_PROFILE_MONITOR`. This variable can be set to the name of a + [iface@Gio.PowerProfileMonitor] implementation to override the default for debugging + purposes. The available implementations included in GIO have the names + `dbus` and `portal`. The special value `help` can be used to print a list + of available implementations to standard output. +- `GIO_USE_TLS`. This variable can be set to the name of a [iface@Gio.TlsBackend] implementation to override the default for debugging purposes. GIO does - not include a GTlsBackend implementation, the gnutls-based implementation - in the glib-networking module has the name "gnutls". The special value - help can be used to print a list of available implementations to standard + not include a [iface@Gio.TlsBackend] implementation — the GnuTLS-based implementation + in the glib-networking module has the name `gnutls`. The special value + `help` can be used to print a list of available implementations to standard output. - `GIO_USE_PORTALS`. This variable can be set to override detection of portals and force them to be used to provide various bits of GIO functionality, for @@ -287,21 +304,26 @@ environment. - `GIO_MODULE_DIR`. When this environment variable is set to a path, GIO will load modules from this alternate directory instead of the directory built into GIO. This is useful when running tests, for example. This - environment variable is ignored when running in a setuid program. + environment variable is ignored when running in a SUID program. - `GIO_EXTRA_MODULES`. When this environment variable is set to a path, or a set of paths separated by a colon, GIO will attempt to load additional modules from within the path. This environment variable is ignored when - running in a setuid program. + running in a SUID program. +- `GNOTIFICATION_BACKEND`. This variable can be set to the name of a + `GNotificationBackend` implementation to override the default for debugging + purposes. The implementations that are included in GIO have the names + `freedesktop`, `cocoa`, `gtk` and `portal`. The special value `help` can + be used to print a list of available implementations to standard output. - `GSETTINGS_BACKEND`. This variable can be set to the name of a - GSettingsBackend implementation to override the default for debugging + [class@Gio.SettingsBackend] implementation to override the default for debugging purposes. The memory-based implementation that is included in GIO has the - name "memory", the one in dconf has the name "dconf". The special value - help can be used to print a list of available implementations to standard + name `memory`, the one in dconf has the name `dconf`. The special value + `help` can be used to print a list of available implementations to standard output. - `GSETTINGS_SCHEMA_DIR`. This variable can be set to the names of - directories to consider when looking for compiled schemas for GSettings, + directories to consider when looking for compiled schemas for [class@Gio.Settings], in addition to the `glib-2.0/schemas` subdirectories of the XDG system - data dirs. To specify multiple directories, use `G_SEARCHPATH_SEPARATOR_S` + data directories. To specify multiple directories, use `G_SEARCHPATH_SEPARATOR_S` as a separator. - `DBUS_SYSTEM_BUS_ADDRESS`. This variable is consulted to find the address of the D-Bus system bus. For the format of D-Bus addresses, see the @@ -312,32 +334,32 @@ environment. address of the D-Bus session bus. Setting this variable overrides platform-specific ways of determining the session bus address. - `DBUS_STARTER_BUS_TYPE`. This variable is consulted to find out the - 'starter' bus for an application that has been started via D-Bus - activation. The possible values are 'system' or 'session'. + ‘starter’ bus for an application that has been started via D-Bus + activation. The possible values are `system` or `session`. - `G_DBUS_DEBUG`. This variable can be set to a list of debug options, which cause GLib to print out different types of debugging information when using the D-Bus routines. - - `transport`: Show IO activity (e.g. reads and writes) + - `transport`: Show I/O activity (e.g. reads and writes) - `message`: Show all sent and received D-Bus messages - `payload`: Show payload for all sent and received D-Bus messages (implies message) - - `call`: Trace `g_dbus_connection_call()` and - `g_dbus_connection_call_sync()` API usage + - `call`: Trace [method@Gio.DBusConnection.call] and + [method@Gio.DBusConnection.call_sync] API usage - `signal`: Show when a D-Bus signal is received - `incoming`: Show when an incoming D-Bus method call is received - - `return`: Show when a reply is returned via the GDBusMethodInvocation API - - `emission`: Trace `g_dbus_connection_emit_signal()` API usage + - `return`: Show when a reply is returned via the [class@Gio.DBusMethodInvocation] API + - `emission`: Trace [method@Gio.DBusConnection.emit_signal] API usage - `authentication`: Show information about connection authentication - `address`: Show information about D-Bus address lookups and autolaunching - `all`: Turn on all debug options - `help`: Print a list of supported options to the standard output - `G_DBUS_COOKIE_SHA1_KEYRING_DIR`. Can be used to override the directory used to store the keyring used in the `DBUS_COOKIE_SHA1` authentication - mechanism. Normally the directory used is `.dbus-keyrings` in the user's + mechanism. Normally the directory used is `.dbus-keyrings` in the user’s home directory. - `G_DBUS_COOKIE_SHA1_KEYRING_DIR_IGNORE_PERMISSION`. If set, the permissions of the directory used to store the keyring used in the - `DBUS_COOKIE_SHA1` authentication mechanism won't be checked. Normally the + `DBUS_COOKIE_SHA1` authentication mechanism won’t be checked. Normally the directory must be readable only by the user. ## Extending GIO @@ -351,58 +373,77 @@ see [`struct@Gio.IOExtensionPoint`]. The following extension points are currently defined by GIO: - `G_VFS_EXTENSION_POINT_NAME`. Allows to override the functionality of the - GVfs class. Implementations of this extension point must be derived from - GVfs. GIO uses the implementation with the highest priority that is - active, see `g_vfs_is_active()`. GIO implements this extension point for + [class@Gio.Vfs] class. Implementations of this extension point must be derived from + [class@Gio.Vfs]. GIO uses the implementation with the highest priority that is + active, see [method@Gio.Vfs.is_active]. GIO implements this extension point for local files, gvfs contains an implementation that supports all the backends in gvfs. - `G_VOLUME_MONITOR_EXTENSION_POINT_NAME`. Allows to add more volume monitors. Implementations of this extension point must be derived from - GVolumeMonitor. GIO uses all registered extensions. gvfs contains an - implementation that works together with the GVfs implementation in gvfs. + [class@Gio.VolumeMonitor]. GIO uses all registered extensions. gvfs contains an + implementation that works together with the [class@Gio.Vfs] implementation in gvfs. - `G_NATIVE_VOLUME_MONITOR_EXTENSION_POINT_NAME`. Allows to override the - 'native' volume monitor. Implementations of this extension point must be - derived from GNativeVolumeMonitor. GIO uses the implementation with the - highest priority that is supported, as determined by the `is_supported()` - vfunc in GVolumeMonitorClass. GIO implements this extension point for + ‘native’ volume monitor. Implementations of this extension point must be + derived from [class@Gio.NativeVolumeMonitor]. GIO uses the implementation with the + highest priority that is supported, as determined by + `GVolumeMonitorClass.is_supported()`. GIO implements this extension point for local mounts, gvfs contains a udisks2-based implementation. - `G_LOCAL_FILE_MONITOR_EXTENSION_POINT_NAME`. Allows to override the file monitor implementation for local files. Implementations of this extension - point must be derived from GLocalFileMonitor. GIO uses the implementation - with the highest priority that is supported, as determined by the - `is_supported()` vfunc in GLocalFileMonitorClass. GIO uses this extension - point internally, to switch between its fam-based and inotify-based file + point must be derived from `GLocalFileMonitor`. GIO uses the implementation + with the highest priority that is supported, as determined by + `GLocalFileMonitorClass.is_supported()`. GIO uses this extension + point internally, to switch between its poll-based and inotify-based file monitoring implementations. - `G_LOCAL_DIRECTORY_MONITOR_EXTENSION_POINT_NAME`. Allows to override the directory monitor implementation for local files. Implementations of this - extension point must be derived from GLocalDirectoryMonitor. GIO uses the + extension point must be derived from `GLocalDirectoryMonitor`. GIO uses the implementation with the highest priority that is supported, as determined - by the `is_supported()` vfunc in GLocalDirectoryMonitorClass. GIO uses - this extension point internally, to switch between its fam-based and + by `GLocalDirectoryMonitorClass.is_supported()`. GIO uses + this extension point internally, to switch between its poll-based and inotify-based directory monitoring implementations. - `G_DESKTOP_APP_INFO_LOOKUP_EXTENSION_POINT_NAME`. Unix-only. Allows to provide a way to associate default handlers with URI schemes. Implementations of this extension point must implement the - GDesktopAppInfoLookup interface. GIO uses the implementation with the + `GDesktopAppInfoLookup` interface. GIO uses the implementation with the highest priority. This extension point has been discontinued in GLib 2.28. It is still available to keep API and ABI stability, but GIO is no longer - using it for default handlers. Instead, the mime handler mechanism is - used, together with x-scheme-handler pseudo-mimetypes. + using it for default handlers. Instead, the MIME handler mechanism is + used, together with `x-scheme-handler` pseudo-MIME-types. +- `G_NOTIFICATION_BACKEND_EXTENSION_POINT_NAME`. Allows to provide an + alternative implementation for sending notifications. Implementations of + this extension point must derive from the `GNotificationBackend` type. GIO + contains implementations based on the freedesktop notification D-Bus + interface, the macOS Cocoa API, the gnome-shell D-Bus API, and the desktop + portal for this functionality. - `G_SETTINGS_BACKEND_EXTENSION_POINT_NAME`. Allows to provide an - alternative storage for GSettings. Implementations of this extension point - must derive from the GSettingsBackend type. GIO contains a keyfile-based + alternative storage for [class@Gio.Settings]. Implementations of this extension point + must derive from the [class@Gio.SettingsBackend] type. GIO contains a keyfile-based implementation of this extension point, another one is provided by dconf. - `G_PROXY_EXTENSION_POINT_NAME`. Allows to provide implementations for network proxying. Implementations of this extension point must provide the - GProxy interface, and must be named after the network protocol they are + [iface@Gio.Proxy] interface, and must be named after the network protocol they are proxying. glib-networking contains an implementation of this extension point based on libproxy. - `G_TLS_BACKEND_EXTENSION_POINT_NAME`. Allows to provide implementations for TLS support. Implementations of this extension point must implement - the GTlsBackend interface. glib-networking contains an implementation of + the [iface@Gio.TlsBackend] interface. glib-networking contains an implementation of this extension point. - `G_NETWORK_MONITOR_EXTENSION_POINT_NAME`. Allows to provide implementations for network connectivity monitoring. Implementations of - this extension point must implement the GNetworkMonitorInterface - interface. GIO contains an implementation of this extension point that is - using the netlink interface of the Linux kernel. + this extension point must implement the [iface@Gio.NetworkMonitor] + interface. GIO contains implementations of this extension point that use + the netlink interface of the Linux kernel, the NetworkManager D-Bus interface + and the desktop portal for this functionality. +- `G_MEMORY_MONITOR_EXTENSION_POINT_NAME`. Allows to provide + implementations for memory usage monitoring. Implementations of this + extension point must implement the [iface@Gio.MemoryMonitor] interface. + GIO contains implementations of this extension point that use the + `org.freedesktop.LowMemoryMonitor` D-Bus interface, the Windows API and + the desktop portal for this functionality. +- `G_POWER_PROFILE_MONITOR_EXTENSION_POINT_NAME`. Allows to provide + implementations for power usage monitoring. Implementations of this + extension point must implement the [iface@Gio.PowerProfileMonitor] interface. + GIO contains implementations of this extension point that use the + `net.hadess.PowerProfiles` D-Bus interface and the desktop portal for + this functionality.