1 package ExtUtils::Liblist;
7 require ExtUtils::Liblist::Kid;
8 @ISA = qw(ExtUtils::Liblist::Kid File::Spec);
14 grep /$rex/, readdir DIR;
22 ExtUtils::Liblist - determine libraries to use and how to use them
26 C<require ExtUtils::Liblist;>
28 C<ExtUtils::Liblist::ext($self, $potential_libs, $verbose, $need_names);>
32 This utility takes a list of libraries in the form C<-llib1 -llib2
33 -llib3> and returns lines suitable for inclusion in an extension
34 Makefile. Extra library paths may be included with the form
35 C<-L/another/path> this will affect the searches for all subsequent
38 It returns an array of four or five scalar values: EXTRALIBS,
39 BSLOADLIBS, LDLOADLIBS, LD_RUN_PATH, and, optionally, a reference to
40 the array of the filenames of actual libraries. Some of these don't
41 mean anything unless on Unix. See the details about those platform
42 specifics below. The list of the filenames is returned only if
43 $need_names argument is true.
45 Dependent libraries can be linked in one of three ways:
49 =item * For static extensions
51 by the ld command when the perl binary is linked with the extension
52 library. See EXTRALIBS below.
54 =item * For dynamic extensions at build/link time
56 by the ld command when the shared object is built/linked. See
59 =item * For dynamic extensions at load time
61 by the DynaLoader when the shared object is loaded. See BSLOADLIBS
68 List of libraries that need to be linked with when linking a perl
69 binary which includes this extension. Only those libraries that
70 actually exist are included. These are written to a file and used
73 =head2 LDLOADLIBS and LD_RUN_PATH
75 List of those libraries which can or must be linked into the shared
76 library when created using ld. These may be static or dynamic
77 libraries. LD_RUN_PATH is a colon separated list of the directories
78 in LDLOADLIBS. It is passed as an environment variable to the process
79 that links the shared library.
83 List of those libraries that are needed but can be linked in
84 dynamically at run time on this platform. SunOS/Solaris does not need
85 this because ld records the information (from LDLOADLIBS) into the
86 object file. This list is used to create a .bs (bootstrap) file.
90 This module deals with a lot of system dependencies and has quite a
91 few architecture specific C<if>s in the code.
93 =head2 VMS implementation
95 The version of ext() which is executed under VMS differs from the
96 Unix-OS/2 version in several respects:
102 Input library and path specifications are accepted with or without the
103 C<-l> and C<-L> prefixes used by Unix linkers. If neither prefix is
104 present, a token is considered a directory to search if it is in fact
105 a directory, and a library to search for otherwise. Authors who wish
106 their extensions to be portable to Unix or OS/2 should use the Unix
107 prefixes, since the Unix-OS/2 version of ext() requires them.
111 Wherever possible, shareable images are preferred to object libraries,
112 and object libraries to plain object files. In accordance with VMS
113 naming conventions, ext() looks for files named I<lib>shr and I<lib>rtl;
114 it also looks for I<lib>lib and libI<lib> to accommodate Unix conventions
115 used in some ported software.
119 For each library that is found, an appropriate directive for a linker options
120 file is generated. The return values are space-separated strings of
121 these directives, rather than elements used on the linker command line.
125 LDLOADLIBS contains both the libraries found based on C<$potential_libs> and
126 the CRTLs, if any, specified in Config.pm. EXTRALIBS contains just those
127 libraries found based on C<$potential_libs>. BSLOADLIBS and LD_RUN_PATH
132 In addition, an attempt is made to recognize several common Unix library
133 names, and filter them out or convert them to their VMS equivalents, as
136 In general, the VMS version of ext() should properly handle input from
137 extensions originally designed for a Unix or VMS environment. If you
138 encounter problems, or discover cases where the search could be improved,
141 =head2 Win32 implementation
143 The version of ext() which is executed under Win32 differs from the
144 Unix-OS/2 version in several respects:
150 If C<$potential_libs> is empty, the return value will be empty.
151 Otherwise, the libraries specified by C<$Config{perllibs}> (see Config.pm)
152 will be appended to the list of C<$potential_libs>. The libraries
153 will be searched for in the directories specified in C<$potential_libs>,
154 C<$Config{libpth}>, and in C<$Config{installarchlib}/CORE>.
155 For each library that is found, a space-separated list of fully qualified
156 library pathnames is generated.
160 Input library and path specifications are accepted with or without the
161 C<-l> and C<-L> prefixes used by Unix linkers.
163 An entry of the form C<-La:\foo> specifies the C<a:\foo> directory to look
164 for the libraries that follow.
166 An entry of the form C<-lfoo> specifies the library C<foo>, which may be
167 spelled differently depending on what kind of compiler you are using. If
168 you are using GCC, it gets translated to C<libfoo.a>, but for other win32
169 compilers, it becomes C<foo.lib>. If no files are found by those translated
170 names, one more attempt is made to find them using either C<foo.a> or
171 C<libfoo.lib>, depending on whether GCC or some other win32 compiler is
172 being used, respectively.
174 If neither the C<-L> or C<-l> prefix is present in an entry, the entry is
175 considered a directory to search if it is in fact a directory, and a
176 library to search for otherwise. The C<$Config{lib_ext}> suffix will
177 be appended to any entries that are not directories and don't already have
180 Note that the C<-L> and C<-l> prefixes are B<not required>, but authors
181 who wish their extensions to be portable to Unix or OS/2 should use the
182 prefixes, since the Unix-OS/2 version of ext() requires them.
186 Entries cannot be plain object files, as many Win32 compilers will
187 not handle object files in the place of libraries.
191 Entries in C<$potential_libs> beginning with a colon and followed by
192 alphanumeric characters are treated as flags. Unknown flags will be ignored.
194 An entry that matches C</:nodefault/i> disables the appending of default
195 libraries found in C<$Config{perllibs}> (this should be only needed very rarely).
197 An entry that matches C</:nosearch/i> disables all searching for
198 the libraries specified after it. Translation of C<-Lfoo> and
199 C<-lfoo> still happens as appropriate (depending on compiler being used,
200 as reflected by C<$Config{cc}>), but the entries are not verified to be
201 valid files or directories.
203 An entry that matches C</:search/i> reenables searching for
204 the libraries specified after it. You can put it at the end to
205 enable searching for default libraries specified by C<$Config{perllibs}>.
209 The libraries specified may be a mixture of static libraries and
210 import libraries (to link with DLLs). Since both kinds are used
211 pretty transparently on the Win32 platform, we do not attempt to
212 distinguish between them.
216 LDLOADLIBS and EXTRALIBS are always identical under Win32, and BSLOADLIBS
217 and LD_RUN_PATH are always empty (this may change in future).
221 You must make sure that any paths and path components are properly
222 surrounded with double-quotes if they contain spaces. For example,
223 C<$potential_libs> could be (literally):
225 "-Lc:\Program Files\vc\lib" msvcrt.lib "la test\foo bar.lib"
227 Note how the first and last entries are protected by quotes in order
228 to protect the spaces.
232 Since this module is most often used only indirectly from extension
233 C<Makefile.PL> files, here is an example C<Makefile.PL> entry to add
234 a library to the build process for an extension:
238 When using GCC, that entry specifies that MakeMaker should first look
239 for C<libgl.a> (followed by C<gl.a>) in all the locations specified by
242 When using a compiler other than GCC, the above entry will search for
243 C<gl.lib> (followed by C<libgl.lib>).
245 If the library happens to be in a location not in C<$Config{libpth}>,
248 LIBS => ['-Lc:\gllibs -lgl']
250 Here is a less often used example:
252 LIBS => ['-lgl', ':nosearch -Ld:\mesalibs -lmesa -luser32']
254 This specifies a search for library C<gl> as before. If that search
255 fails to find the library, it looks at the next item in the list. The
256 C<:nosearch> flag will prevent searching for the libraries that follow,
257 so it simply returns the value as C<-Ld:\mesalibs -lmesa -luser32>,
258 since GCC can use that value as is with its linker.
260 When using the Visual C compiler, the second item is returned as
261 C<-libpath:d:\mesalibs mesa.lib user32.lib>.
263 When using the Borland compiler, the second item is returned as
264 C<-Ld:\mesalibs mesa.lib user32.lib>, and MakeMaker takes care of
265 moving the C<-Ld:\mesalibs> to the correct place in the linker
273 L<ExtUtils::MakeMaker>