1 package ExtUtils::Liblist;
5 use vars qw($VERSION @ISA);
9 require ExtUtils::Liblist::Kid;
10 @ISA = qw(ExtUtils::Liblist::Kid File::Spec);
12 # Backwards compatibility with old interface.
14 goto &ExtUtils::Liblist::Kid::ext;
21 my @out = grep /$rex/, readdir DIR;
30 ExtUtils::Liblist - determine libraries to use and how to use them
34 require ExtUtils::Liblist;
36 $MM->ext($potential_libs, $verbose, $need_names);
38 # Usually you can get away with:
39 ExtUtils::Liblist->ext($potential_libs, $verbose, $need_names)
43 This utility takes a list of libraries in the form C<-llib1 -llib2
44 -llib3> and returns lines suitable for inclusion in an extension
45 Makefile. Extra library paths may be included with the form
46 C<-L/another/path> this will affect the searches for all subsequent
49 It returns an array of four or five scalar values: EXTRALIBS,
50 BSLOADLIBS, LDLOADLIBS, LD_RUN_PATH, and, optionally, a reference to
51 the array of the filenames of actual libraries. Some of these don't
52 mean anything unless on Unix. See the details about those platform
53 specifics below. The list of the filenames is returned only if
54 $need_names argument is true.
56 Dependent libraries can be linked in one of three ways:
60 =item * For static extensions
62 by the ld command when the perl binary is linked with the extension
63 library. See EXTRALIBS below.
65 =item * For dynamic extensions at build/link time
67 by the ld command when the shared object is built/linked. See
70 =item * For dynamic extensions at load time
72 by the DynaLoader when the shared object is loaded. See BSLOADLIBS
79 List of libraries that need to be linked with when linking a perl
80 binary which includes this extension. Only those libraries that
81 actually exist are included. These are written to a file and used
84 =head2 LDLOADLIBS and LD_RUN_PATH
86 List of those libraries which can or must be linked into the shared
87 library when created using ld. These may be static or dynamic
88 libraries. LD_RUN_PATH is a colon separated list of the directories
89 in LDLOADLIBS. It is passed as an environment variable to the process
90 that links the shared library.
94 List of those libraries that are needed but can be linked in
95 dynamically at run time on this platform. SunOS/Solaris does not need
96 this because ld records the information (from LDLOADLIBS) into the
97 object file. This list is used to create a .bs (bootstrap) file.
101 This module deals with a lot of system dependencies and has quite a
102 few architecture specific C<if>s in the code.
104 =head2 VMS implementation
106 The version of ext() which is executed under VMS differs from the
107 Unix-OS/2 version in several respects:
113 Input library and path specifications are accepted with or without the
114 C<-l> and C<-L> prefixes used by Unix linkers. If neither prefix is
115 present, a token is considered a directory to search if it is in fact
116 a directory, and a library to search for otherwise. Authors who wish
117 their extensions to be portable to Unix or OS/2 should use the Unix
118 prefixes, since the Unix-OS/2 version of ext() requires them.
122 Wherever possible, shareable images are preferred to object libraries,
123 and object libraries to plain object files. In accordance with VMS
124 naming conventions, ext() looks for files named I<lib>shr and I<lib>rtl;
125 it also looks for I<lib>lib and libI<lib> to accommodate Unix conventions
126 used in some ported software.
130 For each library that is found, an appropriate directive for a linker options
131 file is generated. The return values are space-separated strings of
132 these directives, rather than elements used on the linker command line.
136 LDLOADLIBS contains both the libraries found based on C<$potential_libs> and
137 the CRTLs, if any, specified in Config.pm. EXTRALIBS contains just those
138 libraries found based on C<$potential_libs>. BSLOADLIBS and LD_RUN_PATH
143 In addition, an attempt is made to recognize several common Unix library
144 names, and filter them out or convert them to their VMS equivalents, as
147 In general, the VMS version of ext() should properly handle input from
148 extensions originally designed for a Unix or VMS environment. If you
149 encounter problems, or discover cases where the search could be improved,
152 =head2 Win32 implementation
154 The version of ext() which is executed under Win32 differs from the
155 Unix-OS/2 version in several respects:
161 If C<$potential_libs> is empty, the return value will be empty.
162 Otherwise, the libraries specified by C<$Config{perllibs}> (see Config.pm)
163 will be appended to the list of C<$potential_libs>. The libraries
164 will be searched for in the directories specified in C<$potential_libs>,
165 C<$Config{libpth}>, and in C<$Config{installarchlib}/CORE>.
166 For each library that is found, a space-separated list of fully qualified
167 library pathnames is generated.
171 Input library and path specifications are accepted with or without the
172 C<-l> and C<-L> prefixes used by Unix linkers.
174 An entry of the form C<-La:\foo> specifies the C<a:\foo> directory to look
175 for the libraries that follow.
177 An entry of the form C<-lfoo> specifies the library C<foo>, which may be
178 spelled differently depending on what kind of compiler you are using. If
179 you are using GCC, it gets translated to C<libfoo.a>, but for other win32
180 compilers, it becomes C<foo.lib>. If no files are found by those translated
181 names, one more attempt is made to find them using either C<foo.a> or
182 C<libfoo.lib>, depending on whether GCC or some other win32 compiler is
183 being used, respectively.
185 If neither the C<-L> or C<-l> prefix is present in an entry, the entry is
186 considered a directory to search if it is in fact a directory, and a
187 library to search for otherwise. The C<$Config{lib_ext}> suffix will
188 be appended to any entries that are not directories and don't already have
191 Note that the C<-L> and C<-l> prefixes are B<not required>, but authors
192 who wish their extensions to be portable to Unix or OS/2 should use the
193 prefixes, since the Unix-OS/2 version of ext() requires them.
197 Entries cannot be plain object files, as many Win32 compilers will
198 not handle object files in the place of libraries.
202 Entries in C<$potential_libs> beginning with a colon and followed by
203 alphanumeric characters are treated as flags. Unknown flags will be ignored.
205 An entry that matches C</:nodefault/i> disables the appending of default
206 libraries found in C<$Config{perllibs}> (this should be only needed very rarely).
208 An entry that matches C</:nosearch/i> disables all searching for
209 the libraries specified after it. Translation of C<-Lfoo> and
210 C<-lfoo> still happens as appropriate (depending on compiler being used,
211 as reflected by C<$Config{cc}>), but the entries are not verified to be
212 valid files or directories.
214 An entry that matches C</:search/i> reenables searching for
215 the libraries specified after it. You can put it at the end to
216 enable searching for default libraries specified by C<$Config{perllibs}>.
220 The libraries specified may be a mixture of static libraries and
221 import libraries (to link with DLLs). Since both kinds are used
222 pretty transparently on the Win32 platform, we do not attempt to
223 distinguish between them.
227 LDLOADLIBS and EXTRALIBS are always identical under Win32, and BSLOADLIBS
228 and LD_RUN_PATH are always empty (this may change in future).
232 You must make sure that any paths and path components are properly
233 surrounded with double-quotes if they contain spaces. For example,
234 C<$potential_libs> could be (literally):
236 "-Lc:\Program Files\vc\lib" msvcrt.lib "la test\foo bar.lib"
238 Note how the first and last entries are protected by quotes in order
239 to protect the spaces.
243 Since this module is most often used only indirectly from extension
244 C<Makefile.PL> files, here is an example C<Makefile.PL> entry to add
245 a library to the build process for an extension:
249 When using GCC, that entry specifies that MakeMaker should first look
250 for C<libgl.a> (followed by C<gl.a>) in all the locations specified by
253 When using a compiler other than GCC, the above entry will search for
254 C<gl.lib> (followed by C<libgl.lib>).
256 If the library happens to be in a location not in C<$Config{libpth}>,
259 LIBS => ['-Lc:\gllibs -lgl']
261 Here is a less often used example:
263 LIBS => ['-lgl', ':nosearch -Ld:\mesalibs -lmesa -luser32']
265 This specifies a search for library C<gl> as before. If that search
266 fails to find the library, it looks at the next item in the list. The
267 C<:nosearch> flag will prevent searching for the libraries that follow,
268 so it simply returns the value as C<-Ld:\mesalibs -lmesa -luser32>,
269 since GCC can use that value as is with its linker.
271 When using the Visual C compiler, the second item is returned as
272 C<-libpath:d:\mesalibs mesa.lib user32.lib>.
274 When using the Borland compiler, the second item is returned as
275 C<-Ld:\mesalibs mesa.lib user32.lib>, and MakeMaker takes care of
276 moving the C<-Ld:\mesalibs> to the correct place in the linker
284 L<ExtUtils::MakeMaker>