1 package ExtUtils::Liblist;
7 require ExtUtils::Liblist::Kid;
8 @ISA = qw(ExtUtils::Liblist::Kid File::Spec);
10 # Backwards compatibility with old interface.
12 goto &ExtUtils::Liblist::Kid::ext;
19 my @out = grep /$rex/, readdir DIR;
28 ExtUtils::Liblist - determine libraries to use and how to use them
32 require ExtUtils::Liblist;
34 $MM->ext($potential_libs, $verbose, $need_names);
36 # Usually you can get away with:
37 ExtUtils::Liblist->ext($potential_libs, $verbose, $need_names)
41 This utility takes a list of libraries in the form C<-llib1 -llib2
42 -llib3> and returns lines suitable for inclusion in an extension
43 Makefile. Extra library paths may be included with the form
44 C<-L/another/path> this will affect the searches for all subsequent
47 It returns an array of four or five scalar values: EXTRALIBS,
48 BSLOADLIBS, LDLOADLIBS, LD_RUN_PATH, and, optionally, a reference to
49 the array of the filenames of actual libraries. Some of these don't
50 mean anything unless on Unix. See the details about those platform
51 specifics below. The list of the filenames is returned only if
52 $need_names argument is true.
54 Dependent libraries can be linked in one of three ways:
58 =item * For static extensions
60 by the ld command when the perl binary is linked with the extension
61 library. See EXTRALIBS below.
63 =item * For dynamic extensions at build/link time
65 by the ld command when the shared object is built/linked. See
68 =item * For dynamic extensions at load time
70 by the DynaLoader when the shared object is loaded. See BSLOADLIBS
77 List of libraries that need to be linked with when linking a perl
78 binary which includes this extension. Only those libraries that
79 actually exist are included. These are written to a file and used
82 =head2 LDLOADLIBS and LD_RUN_PATH
84 List of those libraries which can or must be linked into the shared
85 library when created using ld. These may be static or dynamic
86 libraries. LD_RUN_PATH is a colon separated list of the directories
87 in LDLOADLIBS. It is passed as an environment variable to the process
88 that links the shared library.
92 List of those libraries that are needed but can be linked in
93 dynamically at run time on this platform. SunOS/Solaris does not need
94 this because ld records the information (from LDLOADLIBS) into the
95 object file. This list is used to create a .bs (bootstrap) file.
99 This module deals with a lot of system dependencies and has quite a
100 few architecture specific C<if>s in the code.
102 =head2 VMS implementation
104 The version of ext() which is executed under VMS differs from the
105 Unix-OS/2 version in several respects:
111 Input library and path specifications are accepted with or without the
112 C<-l> and C<-L> prefixes used by Unix linkers. If neither prefix is
113 present, a token is considered a directory to search if it is in fact
114 a directory, and a library to search for otherwise. Authors who wish
115 their extensions to be portable to Unix or OS/2 should use the Unix
116 prefixes, since the Unix-OS/2 version of ext() requires them.
120 Wherever possible, shareable images are preferred to object libraries,
121 and object libraries to plain object files. In accordance with VMS
122 naming conventions, ext() looks for files named I<lib>shr and I<lib>rtl;
123 it also looks for I<lib>lib and libI<lib> to accommodate Unix conventions
124 used in some ported software.
128 For each library that is found, an appropriate directive for a linker options
129 file is generated. The return values are space-separated strings of
130 these directives, rather than elements used on the linker command line.
134 LDLOADLIBS contains both the libraries found based on C<$potential_libs> and
135 the CRTLs, if any, specified in Config.pm. EXTRALIBS contains just those
136 libraries found based on C<$potential_libs>. BSLOADLIBS and LD_RUN_PATH
141 In addition, an attempt is made to recognize several common Unix library
142 names, and filter them out or convert them to their VMS equivalents, as
145 In general, the VMS version of ext() should properly handle input from
146 extensions originally designed for a Unix or VMS environment. If you
147 encounter problems, or discover cases where the search could be improved,
150 =head2 Win32 implementation
152 The version of ext() which is executed under Win32 differs from the
153 Unix-OS/2 version in several respects:
159 If C<$potential_libs> is empty, the return value will be empty.
160 Otherwise, the libraries specified by C<$Config{perllibs}> (see Config.pm)
161 will be appended to the list of C<$potential_libs>. The libraries
162 will be searched for in the directories specified in C<$potential_libs>,
163 C<$Config{libpth}>, and in C<$Config{installarchlib}/CORE>.
164 For each library that is found, a space-separated list of fully qualified
165 library pathnames is generated.
169 Input library and path specifications are accepted with or without the
170 C<-l> and C<-L> prefixes used by Unix linkers.
172 An entry of the form C<-La:\foo> specifies the C<a:\foo> directory to look
173 for the libraries that follow.
175 An entry of the form C<-lfoo> specifies the library C<foo>, which may be
176 spelled differently depending on what kind of compiler you are using. If
177 you are using GCC, it gets translated to C<libfoo.a>, but for other win32
178 compilers, it becomes C<foo.lib>. If no files are found by those translated
179 names, one more attempt is made to find them using either C<foo.a> or
180 C<libfoo.lib>, depending on whether GCC or some other win32 compiler is
181 being used, respectively.
183 If neither the C<-L> or C<-l> prefix is present in an entry, the entry is
184 considered a directory to search if it is in fact a directory, and a
185 library to search for otherwise. The C<$Config{lib_ext}> suffix will
186 be appended to any entries that are not directories and don't already have
189 Note that the C<-L> and C<-l> prefixes are B<not required>, but authors
190 who wish their extensions to be portable to Unix or OS/2 should use the
191 prefixes, since the Unix-OS/2 version of ext() requires them.
195 Entries cannot be plain object files, as many Win32 compilers will
196 not handle object files in the place of libraries.
200 Entries in C<$potential_libs> beginning with a colon and followed by
201 alphanumeric characters are treated as flags. Unknown flags will be ignored.
203 An entry that matches C</:nodefault/i> disables the appending of default
204 libraries found in C<$Config{perllibs}> (this should be only needed very rarely).
206 An entry that matches C</:nosearch/i> disables all searching for
207 the libraries specified after it. Translation of C<-Lfoo> and
208 C<-lfoo> still happens as appropriate (depending on compiler being used,
209 as reflected by C<$Config{cc}>), but the entries are not verified to be
210 valid files or directories.
212 An entry that matches C</:search/i> reenables searching for
213 the libraries specified after it. You can put it at the end to
214 enable searching for default libraries specified by C<$Config{perllibs}>.
218 The libraries specified may be a mixture of static libraries and
219 import libraries (to link with DLLs). Since both kinds are used
220 pretty transparently on the Win32 platform, we do not attempt to
221 distinguish between them.
225 LDLOADLIBS and EXTRALIBS are always identical under Win32, and BSLOADLIBS
226 and LD_RUN_PATH are always empty (this may change in future).
230 You must make sure that any paths and path components are properly
231 surrounded with double-quotes if they contain spaces. For example,
232 C<$potential_libs> could be (literally):
234 "-Lc:\Program Files\vc\lib" msvcrt.lib "la test\foo bar.lib"
236 Note how the first and last entries are protected by quotes in order
237 to protect the spaces.
241 Since this module is most often used only indirectly from extension
242 C<Makefile.PL> files, here is an example C<Makefile.PL> entry to add
243 a library to the build process for an extension:
247 When using GCC, that entry specifies that MakeMaker should first look
248 for C<libgl.a> (followed by C<gl.a>) in all the locations specified by
251 When using a compiler other than GCC, the above entry will search for
252 C<gl.lib> (followed by C<libgl.lib>).
254 If the library happens to be in a location not in C<$Config{libpth}>,
257 LIBS => ['-Lc:\gllibs -lgl']
259 Here is a less often used example:
261 LIBS => ['-lgl', ':nosearch -Ld:\mesalibs -lmesa -luser32']
263 This specifies a search for library C<gl> as before. If that search
264 fails to find the library, it looks at the next item in the list. The
265 C<:nosearch> flag will prevent searching for the libraries that follow,
266 so it simply returns the value as C<-Ld:\mesalibs -lmesa -luser32>,
267 since GCC can use that value as is with its linker.
269 When using the Visual C compiler, the second item is returned as
270 C<-libpath:d:\mesalibs mesa.lib user32.lib>.
272 When using the Borland compiler, the second item is returned as
273 C<-Ld:\mesalibs mesa.lib user32.lib>, and MakeMaker takes care of
274 moving the C<-Ld:\mesalibs> to the correct place in the linker
282 L<ExtUtils::MakeMaker>