1 package ExtUtils::Liblist;
5 our $VERSION = '6.53_02';
8 require ExtUtils::Liblist::Kid;
9 our @ISA = qw(ExtUtils::Liblist::Kid File::Spec);
11 # Backwards compatibility with old interface.
13 goto &ExtUtils::Liblist::Kid::ext;
20 my @out = grep /$rex/, readdir DIR;
29 ExtUtils::Liblist - determine libraries to use and how to use them
33 require ExtUtils::Liblist;
35 $MM->ext($potential_libs, $verbose, $need_names);
37 # Usually you can get away with:
38 ExtUtils::Liblist->ext($potential_libs, $verbose, $need_names)
42 This utility takes a list of libraries in the form C<-llib1 -llib2
43 -llib3> and returns lines suitable for inclusion in an extension
44 Makefile. Extra library paths may be included with the form
45 C<-L/another/path> this will affect the searches for all subsequent
48 It returns an array of four or five scalar values: EXTRALIBS,
49 BSLOADLIBS, LDLOADLIBS, LD_RUN_PATH, and, optionally, a reference to
50 the array of the filenames of actual libraries. Some of these don't
51 mean anything unless on Unix. See the details about those platform
52 specifics below. The list of the filenames is returned only if
53 $need_names argument is true.
55 Dependent libraries can be linked in one of three ways:
59 =item * For static extensions
61 by the ld command when the perl binary is linked with the extension
62 library. See EXTRALIBS below.
64 =item * For dynamic extensions at build/link time
66 by the ld command when the shared object is built/linked. See
69 =item * For dynamic extensions at load time
71 by the DynaLoader when the shared object is loaded. See BSLOADLIBS
78 List of libraries that need to be linked with when linking a perl
79 binary which includes this extension. Only those libraries that
80 actually exist are included. These are written to a file and used
83 =head2 LDLOADLIBS and LD_RUN_PATH
85 List of those libraries which can or must be linked into the shared
86 library when created using ld. These may be static or dynamic
87 libraries. LD_RUN_PATH is a colon separated list of the directories
88 in LDLOADLIBS. It is passed as an environment variable to the process
89 that links the shared library.
93 List of those libraries that are needed but can be linked in
94 dynamically at run time on this platform. SunOS/Solaris does not need
95 this because ld records the information (from LDLOADLIBS) into the
96 object file. This list is used to create a .bs (bootstrap) file.
100 This module deals with a lot of system dependencies and has quite a
101 few architecture specific C<if>s in the code.
103 =head2 VMS implementation
105 The version of ext() which is executed under VMS differs from the
106 Unix-OS/2 version in several respects:
112 Input library and path specifications are accepted with or without the
113 C<-l> and C<-L> prefixes used by Unix linkers. If neither prefix is
114 present, a token is considered a directory to search if it is in fact
115 a directory, and a library to search for otherwise. Authors who wish
116 their extensions to be portable to Unix or OS/2 should use the Unix
117 prefixes, since the Unix-OS/2 version of ext() requires them.
121 Wherever possible, shareable images are preferred to object libraries,
122 and object libraries to plain object files. In accordance with VMS
123 naming conventions, ext() looks for files named I<lib>shr and I<lib>rtl;
124 it also looks for I<lib>lib and libI<lib> to accommodate Unix conventions
125 used in some ported software.
129 For each library that is found, an appropriate directive for a linker options
130 file is generated. The return values are space-separated strings of
131 these directives, rather than elements used on the linker command line.
135 LDLOADLIBS contains both the libraries found based on C<$potential_libs> and
136 the CRTLs, if any, specified in Config.pm. EXTRALIBS contains just those
137 libraries found based on C<$potential_libs>. BSLOADLIBS and LD_RUN_PATH
142 In addition, an attempt is made to recognize several common Unix library
143 names, and filter them out or convert them to their VMS equivalents, as
146 In general, the VMS version of ext() should properly handle input from
147 extensions originally designed for a Unix or VMS environment. If you
148 encounter problems, or discover cases where the search could be improved,
151 =head2 Win32 implementation
153 The version of ext() which is executed under Win32 differs from the
154 Unix-OS/2 version in several respects:
160 If C<$potential_libs> is empty, the return value will be empty.
161 Otherwise, the libraries specified by C<$Config{perllibs}> (see Config.pm)
162 will be appended to the list of C<$potential_libs>. The libraries
163 will be searched for in the directories specified in C<$potential_libs>,
164 C<$Config{libpth}>, and in C<$Config{installarchlib}/CORE>.
165 For each library that is found, a space-separated list of fully qualified
166 library pathnames is generated.
170 Input library and path specifications are accepted with or without the
171 C<-l> and C<-L> prefixes used by Unix linkers.
173 An entry of the form C<-La:\foo> specifies the C<a:\foo> directory to look
174 for the libraries that follow.
176 An entry of the form C<-lfoo> specifies the library C<foo>, which may be
177 spelled differently depending on what kind of compiler you are using. If
178 you are using GCC, it gets translated to C<libfoo.a>, but for other win32
179 compilers, it becomes C<foo.lib>. If no files are found by those translated
180 names, one more attempt is made to find them using either C<foo.a> or
181 C<libfoo.lib>, depending on whether GCC or some other win32 compiler is
182 being used, respectively.
184 If neither the C<-L> or C<-l> prefix is present in an entry, the entry is
185 considered a directory to search if it is in fact a directory, and a
186 library to search for otherwise. The C<$Config{lib_ext}> suffix will
187 be appended to any entries that are not directories and don't already have
190 Note that the C<-L> and C<-l> prefixes are B<not required>, but authors
191 who wish their extensions to be portable to Unix or OS/2 should use the
192 prefixes, since the Unix-OS/2 version of ext() requires them.
196 Entries cannot be plain object files, as many Win32 compilers will
197 not handle object files in the place of libraries.
201 Entries in C<$potential_libs> beginning with a colon and followed by
202 alphanumeric characters are treated as flags. Unknown flags will be ignored.
204 An entry that matches C</:nodefault/i> disables the appending of default
205 libraries found in C<$Config{perllibs}> (this should be only needed very rarely).
207 An entry that matches C</:nosearch/i> disables all searching for
208 the libraries specified after it. Translation of C<-Lfoo> and
209 C<-lfoo> still happens as appropriate (depending on compiler being used,
210 as reflected by C<$Config{cc}>), but the entries are not verified to be
211 valid files or directories.
213 An entry that matches C</:search/i> reenables searching for
214 the libraries specified after it. You can put it at the end to
215 enable searching for default libraries specified by C<$Config{perllibs}>.
219 The libraries specified may be a mixture of static libraries and
220 import libraries (to link with DLLs). Since both kinds are used
221 pretty transparently on the Win32 platform, we do not attempt to
222 distinguish between them.
226 LDLOADLIBS and EXTRALIBS are always identical under Win32, and BSLOADLIBS
227 and LD_RUN_PATH are always empty (this may change in future).
231 You must make sure that any paths and path components are properly
232 surrounded with double-quotes if they contain spaces. For example,
233 C<$potential_libs> could be (literally):
235 "-Lc:\Program Files\vc\lib" msvcrt.lib "la test\foo bar.lib"
237 Note how the first and last entries are protected by quotes in order
238 to protect the spaces.
242 Since this module is most often used only indirectly from extension
243 C<Makefile.PL> files, here is an example C<Makefile.PL> entry to add
244 a library to the build process for an extension:
248 When using GCC, that entry specifies that MakeMaker should first look
249 for C<libgl.a> (followed by C<gl.a>) in all the locations specified by
252 When using a compiler other than GCC, the above entry will search for
253 C<gl.lib> (followed by C<libgl.lib>).
255 If the library happens to be in a location not in C<$Config{libpth}>,
258 LIBS => ['-Lc:\gllibs -lgl']
260 Here is a less often used example:
262 LIBS => ['-lgl', ':nosearch -Ld:\mesalibs -lmesa -luser32']
264 This specifies a search for library C<gl> as before. If that search
265 fails to find the library, it looks at the next item in the list. The
266 C<:nosearch> flag will prevent searching for the libraries that follow,
267 so it simply returns the value as C<-Ld:\mesalibs -lmesa -luser32>,
268 since GCC can use that value as is with its linker.
270 When using the Visual C compiler, the second item is returned as
271 C<-libpath:d:\mesalibs mesa.lib user32.lib>.
273 When using the Borland compiler, the second item is returned as
274 C<-Ld:\mesalibs mesa.lib user32.lib>, and MakeMaker takes care of
275 moving the C<-Ld:\mesalibs> to the correct place in the linker
283 L<ExtUtils::MakeMaker>