g_get_application_name ()

const gchar *
g_get_application_name (void);

Gets a human-readable name for the application, as set by g_set_application_name(). This name should be localized if possible, and is intended for display to the user. Contrast with g_get_prgname(), which gets a non-localized name. If g_set_application_name() has not been called, returns the result of g_get_prgname() (which may be NULL if g_set_prgname() has also not been called).

Since 2.2

g_set_application_name ()

void
g_set_application_name (const gchar *application_name);

Sets a human-readable name for the application. This name should be localized if possible, and is intended for display to the user. Contrast with g_set_prgname(), which sets a non-localized name. g_set_prgname() will be called automatically by gtk_init(), but g_set_application_name() will not.

Note that for thread safety reasons, this function can only be called once.

The application name will be used in contexts such as error messages, or when displaying an application's name in the task list.

Since 2.2

g_get_prgname ()

const gchar *
g_get_prgname (void);

Gets the name of the program. This name should not be localized, in contrast to g_get_application_name().

If you are using GDK or GTK+ the program name is set in gdk_init(), which is called by gtk_init(). The program name is found by taking the last component of argv [0].

g_set_prgname ()

void
g_set_prgname (const gchar *prgname);

Sets the name of the program. This name should not be localized, in contrast to g_set_application_name().

Note that for thread-safety reasons this function can only be called once.

g_get_environ ()

gchar **
g_get_environ (void);

Gets the list of environment variables for the current process.

The list is NULL terminated and each item in the list is of the form 'NAME=VALUE'.

This is equivalent to direct access to the 'environ' global variable, except portable.

The return value is freshly allocated and it should be freed with g_strfreev() when it is no longer needed.

Since 2.28

g_environ_getenv ()

const gchar *
g_environ_getenv (gchar **envp,
                  const gchar *variable);

Returns the value of the environment variable variable in the provided list envp .

Since 2.32

g_environ_setenv ()

gchar **
g_environ_setenv (gchar **envp,
                  const gchar *variable,
                  const gchar *value,
                  gboolean overwrite);

Sets the environment variable variable in the provided list envp to value .

Since 2.32

g_environ_unsetenv ()

gchar **
g_environ_unsetenv (gchar **envp,
                    const gchar *variable);

Removes the environment variable variable from the provided environment envp .

Since 2.32

g_getenv ()

const gchar *
g_getenv (const gchar *variable);

Returns the value of an environment variable.

The name and value are in the GLib file name encoding. On UNIX, this means the actual bytes which might or might not be in some consistent character set and encoding. On Windows, it is in UTF-8. On Windows, in case the environment variable's value contains references to other environment variables, they are expanded.

g_setenv ()

gboolean
g_setenv (const gchar *variable,
          const gchar *value,
          gboolean overwrite);

Sets an environment variable. 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.

Note that on some systems, when variables are overwritten, the memory used for the previous variables and its value isn't reclaimed.

You should be mindful of the fact that environment variable handling in UNIX is not thread-safe, and your program may crash if one thread calls g_setenv() while another thread is calling getenv(). (And note that many functions, such as gettext(), call getenv() internally.) This function is only safe to use at the very start of your program, before creating any other threads (or creating objects that create worker threads of their own).

If you need to set up the environment for a child process, you can use g_get_environ() to get an environment array, modify that with g_environ_setenv() and g_environ_unsetenv(), and then pass that array directly to execvpe(), g_spawn_async(), or the like.

Since 2.4

g_unsetenv ()

void
g_unsetenv (const gchar *variable);

Removes an environment variable from the environment.

Note that on some systems, when variables are overwritten, the memory used for the previous variables and its value isn't reclaimed.

You should be mindful of the fact that environment variable handling in UNIX is not thread-safe, and your program may crash if one thread calls g_unsetenv() while another thread is calling getenv(). (And note that many functions, such as gettext(), call getenv() internally.) This function is only safe to use at the very start of your program, before creating any other threads (or creating objects that create worker threads of their own).

If you need to set up the environment for a child process, you can use g_get_environ() to get an environment array, modify that with g_environ_setenv() and g_environ_unsetenv(), and then pass that array directly to execvpe(), g_spawn_async(), or the like.

Since 2.4

g_listenv ()

gchar **
g_listenv (void);

Gets the names of all variables set in the environment.

Programs that want to be portable to Windows should typically use this function and g_getenv() instead of using the environ array from the C library directly. On Windows, the strings in the environ array are in system codepage encoding, while in most of the typical use cases for environment variables in GLib-using programs you want the UTF-8 encoding that this function and g_getenv() provide.

Since 2.8

g_get_user_name ()

const gchar *
g_get_user_name (void);

Gets the user name of the current user. The encoding of the returned string is system-defined. On UNIX, it might be the preferred file name encoding, or something else, and there is no guarantee that it is even consistent on a machine. On Windows, it is always UTF-8.

g_get_real_name ()

const gchar *
g_get_real_name (void);

Gets the real name of the user. This usually comes from the user's entry in the passwd file. The encoding of the returned string is system-defined. (On Windows, it is, however, always UTF-8.) If the real user name cannot be determined, the string "Unknown" is returned.

g_get_user_cache_dir ()

const gchar *
g_get_user_cache_dir (void);

Returns a base directory in which to store non-essential, cached data specific to particular user.

On UNIX platforms this is determined using the mechanisms described in the XDG Base Directory Specification. In this case the directory retrieved will be XDG_CACHE_HOME.

On Windows is the directory that serves as a common repository for temporary Internet files. A typical path is C:\Documents and Settings\username\Local Settings\Temporary Internet Files. See documentation for CSIDL_INTERNET_CACHE.

Since 2.6

g_get_user_data_dir ()

const gchar *
g_get_user_data_dir (void);

Returns a base directory in which to access application data such as icons that is customized for a particular user.

On UNIX platforms this is determined using the mechanisms described in the XDG Base Directory Specification. In this case the directory retrieved will be XDG_DATA_HOME.

On Windows this is the folder to use for local (as opposed to roaming) application data. See documentation for CSIDL_LOCAL_APPDATA. Note that on Windows it thus is the same as what g_get_user_config_dir() returns.

Since 2.6

g_get_user_config_dir ()

const gchar *
g_get_user_config_dir (void);

Returns a base directory in which to store user-specific application configuration information such as user preferences and settings.

On UNIX platforms this is determined using the mechanisms described in the XDG Base Directory Specification. In this case the directory retrieved will be XDG_CONFIG_HOME.

On Windows this is the folder to use for local (as opposed to roaming) application data. See documentation for CSIDL_LOCAL_APPDATA. Note that on Windows it thus is the same as what g_get_user_data_dir() returns.

Since 2.6

g_get_user_runtime_dir ()

const gchar *
g_get_user_runtime_dir (void);

Returns a directory that is unique to the current user on the local system.

On UNIX platforms this is determined using the mechanisms described in the XDG Base Directory Specification. This is the directory specified in the XDG_RUNTIME_DIR environment variable. In the case that this variable is not set, GLib will issue a warning message to stderr and return the value of g_get_user_cache_dir().

On Windows this is the folder to use for local (as opposed to roaming) application data. See documentation for CSIDL_LOCAL_APPDATA. Note that on Windows it thus is the same as what g_get_user_config_dir() returns.

Since 2.28

g_get_user_special_dir ()

const gchar *
g_get_user_special_dir (GUserDirectory directory);

Returns the full path of a special directory using its logical id.

On UNIX this is done using the XDG special user directories. For compatibility with existing practise, G_USER_DIRECTORY_DESKTOP falls back to $HOME/Desktop when XDG special user directories have not been set up.

Depending on the platform, the user might be able to change the path of the special directory without requiring the session to restart; GLib will not reflect any change once the special directories are loaded.

Since 2.14

g_get_system_data_dirs ()

const gchar * const *
g_get_system_data_dirs (void);

Returns an ordered list of base directories in which to access system-wide application data.

On UNIX platforms this is determined using the mechanisms described in the XDG Base Directory Specification In this case the list of directories retrieved will be XDG_DATA_DIRS.

On Windows the first elements in the list are the Application Data and Documents folders for All Users. (These can be determined only on Windows 2000 or later and are not present in the list on other Windows versions.) See documentation for CSIDL_COMMON_APPDATA and CSIDL_COMMON_DOCUMENTS.

Then follows the "share" subfolder in the installation folder for the package containing the DLL that calls this function, if it can be determined.

Finally the list contains the "share" subfolder in the installation folder for GLib, and in the installation folder for the package the application's .exe file belongs to.

The installation folders above are determined by looking up the folder where the module (DLL or EXE) in question is located. If the folder's name is "bin", its parent is used, otherwise the folder itself.

Note that on Windows the returned list can vary depending on where this function is called.

Since 2.6

g_get_system_config_dirs ()

const gchar * const *
g_get_system_config_dirs (void);

Returns an ordered list of base directories in which to access system-wide configuration information.

On UNIX platforms this is determined using the mechanisms described in the XDG Base Directory Specification. In this case the list of directories retrieved will be XDG_CONFIG_DIRS.

On Windows is the directory that contains application data for all users. A typical path is C:\Documents and Settings\All Users\Application Data. This folder is used for application data that is not user specific. For example, an application can store a spell-check dictionary, a database of clip art, or a log file in the CSIDL_COMMON_APPDATA folder. This information will not roam and is available to anyone using the computer.

Since 2.6

g_reload_user_special_dirs_cache ()

void
g_reload_user_special_dirs_cache (void);

Resets the cache used for g_get_user_special_dir(), so that the latest on-disk version is used. Call this only if you just changed the data on disk yourself.

Due to threadsafety issues this may cause leaking of strings that were previously returned from g_get_user_special_dir() that can't be freed. We ensure to only leak the data for the directories that actually changed value though.

Since 2.22

g_get_host_name ()

const gchar *
g_get_host_name (void);

Return a name for the machine.

The returned name is not necessarily a fully-qualified domain name, or even present in DNS or some other name service at all. It need not even be unique on your local network or site, but usually it is. Callers should not rely on the return value having any specific properties like uniqueness for security purposes. Even if the name of the machine is changed while an application is running, the return value from this function does not change. The returned string is owned by GLib and should not be modified or freed. If no name can be determined, a default fixed string "localhost" is returned.

Since 2.8

g_get_home_dir ()

const gchar *
g_get_home_dir (void);

Gets the current user's home directory.

As with most UNIX tools, this function will return the value of the HOME environment variable if it is set to an existing absolute path name, falling back to the passwd file in the case that it is unset.

If the path given in HOME is non-absolute, does not exist, or is not a directory, the result is undefined.

Before version 2.36 this function would ignore the HOME environment variable, taking the value from the passwd database instead. This was changed to increase the compatibility of GLib with other programs (and the XDG basedir specification) and to increase testability of programs based on GLib (by making it easier to run them from test frameworks).

If your program has a strong requirement for either the new or the old behaviour (and if you don't wish to increase your GLib dependency to ensure that the new behaviour is in effect) then you should either directly check the HOME environment variable yourself or unset it before calling any functions in GLib.

When the pre-2.36 behaviour was in effect, Debian provided the <envar>G_HOME</envar> environment variable for testing and development purposes. This is now unnecessary as <envar>HOME</envar> can be used directly, but is retained for compatibility. It is deprecated and will be removed in a future release.

g_get_tmp_dir ()

const gchar *
g_get_tmp_dir (void);

Gets the directory to use for temporary files.

On UNIX, this is taken from the TMPDIR environment variable. If the variable is not set, P_tmpdir is used, as defined by the system C library. Failing that, a hard-coded default of "/tmp" is returned.

On Windows, the TEMP environment variable is used, with the root directory of the Windows installation (eg: "C:\") used as a default.

The encoding of the returned string is system-defined. On Windows, it is always UTF-8. The return value is never NULL or the empty string.

g_get_current_dir ()

gchar *
g_get_current_dir (void);

Gets the current directory.

The returned string should be freed when no longer needed. The encoding of the returned string is system defined. On Windows, it is always UTF-8.

Since GLib 2.40, this function will return the value of the "PWD" environment variable if it is set and it happens to be the same as the current directory. This can make a difference in the case that the current directory is the target of a symbolic link.

g_basename ()

const gchar *
g_basename (const gchar *file_name);

Gets the name of the file without any leading directory components. It returns a pointer into the given file name string.

g_path_is_absolute ()

gboolean
g_path_is_absolute (const gchar *file_name);

Returns TRUE if the given file_name is an absolute file name. Note that this is a somewhat vague concept on Windows.

On POSIX systems, an absolute file name is well-defined. It always starts from the single root directory. For example "/usr/local".

On Windows, the concepts of current drive and drive-specific current directory introduce vagueness. This function interprets as an absolute file name one that either begins with a directory separator such as "\Users\tml" or begins with the root on a drive, for example "C:\Windows". The first case also includes UNC paths such as "\myserver\docs\foo". In all cases, either slashes or backslashes are accepted.

Note that a file name relative to the current drive root does not truly specify a file uniquely over time and across processes, as the current drive is a per-process value and can be changed.

File names relative the current directory on some specific drive, such as "D:foo/bar", are not interpreted as absolute by this function, but they obviously are not relative to the normal current directory as returned by getcwd() or g_get_current_dir() either. Such paths should be avoided, or need to be handled using Windows-specific code.

g_path_skip_root ()

const gchar *
g_path_skip_root (const gchar *file_name);

Returns a pointer into file_name after the root component, i.e. after the "/" in UNIX or "C:\" under Windows. If file_name is not an absolute path it returns NULL.

g_path_get_basename ()

gchar *
g_path_get_basename (const gchar *file_name);

Gets the last component of the filename.

If file_name ends with a directory separator it gets the component before the last slash. If file_name consists only of directory separators (and on Windows, possibly a drive letter), a single separator is returned. If file_name is empty, it gets ".".

g_path_get_dirname ()

gchar *
g_path_get_dirname (const gchar *file_name);

Gets the directory components of a file name.

If the file name has no directory components "." is returned. The returned string should be freed when no longer needed.

g_build_filename ()

gchar *
g_build_filename (const gchar *first_element,
                  ...);

Creates a filename from a series of elements using the correct separator for filenames.

On Unix, this function behaves identically to g_build_path (G_DIR_SEPARATOR_S, first_element, ....).

On Windows, it takes into account that either the backslash (\ or slash (/) can be used as separator in filenames, but otherwise behaves as on UNIX. When file pathname separators need to be inserted, the one that last previously occurred in the parameters (reading from left to right) is used.

No attempt is made to force the resulting filename to be an absolute path. If the first element is a relative path, the result will be a relative path.

g_build_filenamev ()

gchar *
g_build_filenamev (gchar **args);

Behaves exactly like g_build_filename(), but takes the path elements as a string array, instead of varargs. This function is mainly meant for language bindings.

Since 2.8

g_build_path ()

gchar *
g_build_path (const gchar *separator,
              const gchar *first_element,
              ...);

Creates a path from a series of elements using separator as the separator between elements. At the boundary between two elements, any trailing occurrences of separator in the first element, or leading occurrences of separator in the second element are removed and exactly one copy of the separator is inserted.

Empty elements are ignored.

The number of leading copies of the separator on the result is the same as the number of leading copies of the separator on the first non-empty element.

The number of trailing copies of the separator on the result is the same as the number of trailing copies of the separator on the last non-empty element. (Determination of the number of trailing copies is done without stripping leading copies, so if the separator is ABA, then ABABA has 1 trailing copy.)

However, if there is only a single non-empty element, and there are no characters in that element not part of the leading or trailing separators, then the result is exactly the original value of that element.

Other than for determination of the number of leading and trailing copies of the separator, elements consisting only of copies of the separator are ignored.

g_build_pathv ()

gchar *
g_build_pathv (const gchar *separator,
               gchar **args);

Behaves exactly like g_build_path(), but takes the path elements as a string array, instead of varargs. This function is mainly meant for language bindings.

Since 2.8

g_format_size ()

gchar *
g_format_size (guint64 size);

Formats a size (for example the size of a file) into a human readable string. Sizes are rounded to the nearest size prefix (kB, MB, GB) and are displayed rounded to the nearest tenth. E.g. the file size 3292528 bytes will be converted into the string "3.2 MB".

The prefix units base is 1000 (i.e. 1 kB is 1000 bytes).

This string should be freed with g_free() when not needed any longer.

See g_format_size_full() for more options about how the size might be formatted.

Since 2.30

g_format_size_full ()

gchar *
g_format_size_full (guint64 size,
                    GFormatSizeFlags flags);

Formats a size.

This function is similar to g_format_size() but allows for flags that modify the output. See GFormatSizeFlags.

Since 2.30

g_format_size_for_display ()

gchar *
g_format_size_for_display (goffset size);

Formats a size (for example the size of a file) into a human readable string. Sizes are rounded to the nearest size prefix (KB, MB, GB) and are displayed rounded to the nearest tenth. E.g. the file size 3292528 bytes will be converted into the string "3.1 MB".

The prefix units base is 1024 (i.e. 1 KB is 1024 bytes).

This string should be freed with g_free() when not needed any longer.

Since 2.16

g_find_program_in_path ()

gchar *
g_find_program_in_path (const gchar *program);

Locates the first executable named program in the user's path, in the same way that execvp() would locate it. Returns an allocated string with the absolute path name, or NULL if the program is not found in the path. If program is already an absolute path, returns a copy of program if program exists and is executable, and NULL otherwise.

On Windows, if program does not have a file type suffix, tries with the suffixes .exe, .cmd, .bat and .com, and the suffixes in the PATHEXT environment variable.

On Windows, it looks for the file in the same way as CreateProcess() would. This means first in the directory where the executing program was loaded from, then in the current directory, then in the Windows 32-bit system directory, then in the Windows directory, and finally in the directories in the PATH environment variable. If the program is found, the return value contains the full name including the type suffix.

g_bit_nth_lsf ()

gint
g_bit_nth_lsf (gulong mask,
               gint nth_bit);

Find the position of the first bit set in mask , searching from (but not including) nth_bit upwards. Bits are numbered from 0 (least significant) to sizeof(gulong) * 8 - 1 (31 or 63, usually). To start searching from the 0th bit, set nth_bit to -1.

g_bit_nth_msf ()

gint
g_bit_nth_msf (gulong mask,
               gint nth_bit);

Find the position of the first bit set in mask , searching from (but not including) nth_bit downwards. Bits are numbered from 0 (least significant) to sizeof(gulong) * 8 - 1 (31 or 63, usually). To start searching from the last bit, set nth_bit to -1 or GLIB_SIZEOF_LONG * 8.

g_bit_storage ()

guint
g_bit_storage (gulong number);

Gets the number of bits used to hold number , e.g. if number is 4, 3 bits are needed.

g_spaced_primes_closest ()

guint
g_spaced_primes_closest (guint num);

Gets the smallest prime number from a built-in array of primes which is larger than num . This is used within GLib to calculate the optimum size of a GHashTable.

The built-in array of primes ranges from 11 to 13845163 such that each prime is approximately 1.5-2 times the previous prime.

g_atexit ()

void
g_atexit (GVoidFunc func);

Specifies a function to be called at normal program termination.

Since GLib 2.8.2, on Windows g_atexit() actually is a preprocessor macro that maps to a call to the atexit() function in the C library. This means that in case the code that calls g_atexit(), i.e. atexit(), is in a DLL, the function will be called when the DLL is detached from the program. This typically makes more sense than that the function is called when the GLib DLL is detached, which happened earlier when g_atexit() was a function in the GLib DLL.

The behaviour of atexit() in the context of dynamically loaded modules is not formally specified and varies wildly.

On POSIX systems, calling g_atexit() (or atexit()) in a dynamically loaded module which is unloaded before the program terminates might well cause a crash at program exit.

Some POSIX systems implement atexit() like Windows, and have each dynamically loaded module maintain an own atexit chain that is called when the module is unloaded.

On other POSIX systems, before a dynamically loaded module is unloaded, the registered atexit functions (if any) residing in that module are called, regardless where the code that registered them resided. This is presumably the most robust approach.

As can be seen from the above, for portability it's best to avoid calling g_atexit() (or atexit()) except in the main executable of a program.

g_parse_debug_string ()

guint
g_parse_debug_string (const gchar *string,
                      const GDebugKey *keys,
                      guint nkeys);

Parses a string containing debugging options into a guint containing bit flags. This is used within GDK and GTK+ to parse the debug options passed on the command line or through environment variables.

If string is equal to "all", all flags are set. Any flags specified along with "all" in string are inverted; thus, "all,foo,bar" or "foo,bar,all" sets all flags except those corresponding to "foo" and "bar".

If string is equal to "help", all the available keys in keys are printed out to standard error.

GVoidFunc ()

void
(*GVoidFunc) (void);

Declares a type of function which takes no arguments and has no return value. It is used to specify the type function passed to g_atexit().

GFreeFunc ()

void
(*GFreeFunc) (gpointer data);

Declares a type of function which takes an arbitrary data pointer argument and has no return value. It is not currently used in GLib or GTK+.

g_qsort_with_data ()

void
g_qsort_with_data (gconstpointer pbase,
                   gint total_elems,
                   gsize size,
                   GCompareDataFunc compare_func,
                   gpointer user_data);

This is just like the standard C qsort() function, but the comparison routine accepts a user data argument.

This is guaranteed to be a stable sort since version 2.32.

g_nullify_pointer ()

void
g_nullify_pointer (gpointer *nullify_location);

Set the pointer at the specified location to NULL.

enum GUserDirectory

These are logical ids for special directories which are defined depending on the platform used. You should use g_get_user_special_dir() to retrieve the full path associated to the logical id.

The GUserDirectory enumeration can be extended at later date. Not every platform has a directory for every logical id in this enumeration.

Since 2.14

g_dirname

#define             g_dirname

Gets the directory components of a file name.

If the file name has no directory components "." is returned. The returned string should be freed when no longer needed.

enum GFormatSizeFlags

Flags to modify the format of the string returned by g_format_size_full().

struct GDebugKey

struct GDebugKey {
  const gchar *key;
  guint	       value;
};

Associates a string with a bit flag. Used in g_parse_debug_string().