1 <refentry id="glib-running" revision="17 Jan 2002">
3 <refentrytitle>Running GLib Applications</refentrytitle>
4 <manvolnum>3</manvolnum>
5 <refmiscinfo>GLib Library</refmiscinfo>
9 <refname>Running GLib Applications</refname>
11 How to run and debug your GLib application
16 <title>Running and debugging GLib Applications</title>
19 <title>Environment variables</title>
22 GLib inspects a few of environment variables in addition to standard
23 variables like <envar>LANG</envar>, <envar>PATH</envar> or <envar>HOME</envar>.
26 <formalpara id="G_FILENAME_ENCODING">
27 <title><envar>G_FILENAME_ENCODING</envar></title>
30 This environment variable can be set to a comma-separated list of character
31 set names. GLib assumes that filenames are encoded in the first character
32 set from that list rather than in UTF-8. The special token "@locale" can be
33 used to specify the character set for the current locale.
37 <formalpara id="G_BROKEN_FILENAMES">
38 <title><envar>G_BROKEN_FILENAMES</envar></title>
41 If this environment variable is set, GLib assumes that filenames are in
42 the locale encoding rather than in UTF-8. G_FILENAME_ENCODING takes
43 priority over G_BROKEN_FILENAMES.
47 <formalpara id="G_MESSAGES_PREFIXED">
48 <title><envar>G_MESSAGES_PREFIXED</envar></title>
51 A list of log levels for which messages should be prefixed by the
52 program name and PID of the application. The default is to prefix
53 everything except <literal>G_LOG_LEVEL_MESSAGE</literal> and <literal>G_LOG_LEVEL_INFO</literal>.
57 <formalpara id="G_DEBUG">
58 <title><envar>G_DEBUG</envar></title>
60 If GLib has been configured with <option>--enable-debug=yes</option>,
61 this variable can be set to a list of debug options, which cause GLib
62 to print out different types of debugging information.
65 <term>fatal_warnings</term>
66 <listitem><para>Causes GLib to abort the program at the first call
67 to <link linkend="g-warning">g_warning</link>() or
68 <link linkend="g-critical">g_critical</link>(). This option is
69 special in that it doesn't require GLib to be configured with
70 debugging support.</para>
74 <term>fatal_criticals</term>
75 <listitem><para>Causes GLib to abort the program at the first call
76 to <link linkend="g-critical">g_critical</link>(). This option is
77 special in that it doesn't require GLib to be configured with
78 debugging support.</para>
82 <term>gc-friendly</term>
85 Newly allocated memory that isn't directly initialized, as well
86 as memory being freed will be reset to 0. The point here is to
87 allow memory checkers and similar programs that use bohem GC alike
88 algorithms to produce more accurate results.
89 This option is special in that it doesn't require GLib to be
90 configured with debugging support.
95 <term>resident-modules</term>
98 All modules loaded by GModule will be made resident. This can be useful
99 for tracking memory leaks in modules which are later unloaded; but it can
100 also hide bugs where code is accessed after the module would have normally
102 This option is special in that it doesn't require GLib to be
103 configured with debugging support.
108 <term>bind-now-modules</term>
111 All modules loaded by GModule will bind their symbols at load time, even
112 when the code uses %G_MODULE_BIND_LAZY.
113 This option is special in that it doesn't require GLib to be
114 configured with debugging support.
122 <formalpara id="G_SLICE">
123 <title><envar>G_SLICE</envar></title>
125 This environment variable allows reconfiguration of the GSlice
129 <term>always-malloc</term>
132 This will cause all slices allocated through g_slice_alloc() and
133 released by g_slice_free1() to be actually allocated via direct
134 calls to g_malloc() and g_free().
135 This is most useful for memory checkers and similar programs that
136 use Bohem GC alike algorithms to produce more accurate results.
137 It can also be in conjunction with debugging features of the system's
138 malloc implementation such as glibc's MALLOC_CHECK_=2 to debug
139 erroneous slice allocation code, allthough <term>debug-blocks</term>
140 usually is a better suited debugging tool.
145 <term>debug-blocks</term>
148 Using this option (present since GLib-2.13) engages extra code
149 which performs sanity checks on the released memory slices.
150 Invalid slice adresses or slice sizes will be reported and lead to
152 This option should only be used in debugging scenarios, because it
153 significantly degrades GSlice performance. Extra per slice memory
154 is requied to do the necessary bookeeping, and multi-thread scalability
155 is given up to perform global slice validation.
156 This option is mostly useful in scenarios where program crashes are encountered
157 while GSlice is in use, but crashes cannot be reproduced with G_SLICE=always-malloc.
158 A potential cause for such a situation that will be caught by G_SLICE=debug-blocks
161 void *slist = g_slist_alloc(); // void* gives up type-safety
162 g_list_free (slist); // corruption: sizeof (GSList) != sizeof (GList)
171 <formalpara id="G_RANDOM_VERSION">
172 <title><envar>G_RANDOM_VERSION</envar></title>
175 If this environment variable is set to '2.0', the outdated
176 pseudo-random number seeding and generation algorithms from
177 GLib-2.0 are used instead of the new better ones. Use the GLib-2.0
178 algorithms only if you have sequences of numbers generated with
179 Glib-2.0 that you need to reproduce exactly.
183 <formalpara id="LIBCHARSET_ALIAS_DIR">
184 <title><envar>LIBCHARSET_ALIAS_DIR</envar></title>
187 Allows to specify a nonstandard location for the
188 <filename>charset.aliases</filename> file that is used by the
189 character set conversion routines. The default location is the
190 <replaceable>libdir</replaceable> specified at compilation time.
194 <formalpara id="G_WIN32_PRETEND_WIN9X">
195 <title><envar>G_WIN32_PRETEND_WIN9X</envar></title>
198 Setting this variable to any value forces g_win32_get_windows_version()
199 to return a version code for Windows 9x. This is mainly an internal
200 debugging aid for GTK+ and GLib developers, to be able to check the
201 code paths for Windows 9x.
207 <refsect2 id="setlocale">
208 <title>Locale</title>
211 A number of interfaces in GLib depend on the current locale in which
212 an application is running. Therefore, most GLib-using applications should
213 call <function>setlocale (LC_ALL, "")</function> to set up the current
218 <title>Traps and traces</title>
221 <indexterm><primary>g_trap_free_size</primary></indexterm>
222 <indexterm><primary>g_trap_realloc_size</primary></indexterm>
223 <indexterm><primary>g_trap_malloc_size</primary></indexterm>
224 Some code portions contain trap variables that can be set during debugging
225 time if GLib has been configured with <option>--enable-debug=yes</option>.
226 Such traps lead to immediate code halts to examine the current program state
231 Currently, the following trap variables exist:
233 static volatile gulong g_trap_free_size;
234 static volatile gulong g_trap_realloc_size;
235 static volatile gulong g_trap_malloc_size;
237 If set to a size > 0, <link linkend="g-free">g_free</link>(),
238 <link linkend="g-realloc">g_realloc</link>() and
239 <link linkend="g-malloc">g_malloc</link>() will be intercepted if the size
240 matches the size of the corresponding memory block. This will only work with
241 <literal>g_mem_set_vtable (glib_mem_profiler_table)</literal> upon startup
242 though, because memory profiling is required to match on the memory block sizes.
245 Note that many modern debuggers support conditional breakpoints, which achieve
246 pretty much the same. E.g. in gdb, you can do
249 condition 1 n_bytes == 20
251 to break only on g_malloc() calls where the size of the allocated memory block