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005c1a0e 1package ExtUtils::Liblist;
17f410f9 2
d0843067 3use vars qw($VERSION);
dedf98bc 4$VERSION = '1.01';
d0843067 5
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6use File::Spec;
7require ExtUtils::Liblist::Kid;
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8@ISA = qw(ExtUtils::Liblist::Kid File::Spec);
9
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10# Backwards compatibility with old interface.
11sub ext {
12 goto &ExtUtils::Liblist::Kid::ext;
13}
14
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15sub lsdir {
16 shift;
17 my $rex = qr/$_[1]/;
57b1a898 18 opendir DIR, $_[0];
479d2113 19 my @out = grep /$rex/, readdir DIR;
57b1a898 20 closedir DIR;
479d2113 21 return @out;
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22}
23
864a5fa8 24__END__
cb1a09d0 25
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26=head1 NAME
27
28ExtUtils::Liblist - determine libraries to use and how to use them
29
30=head1 SYNOPSIS
31
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32 require ExtUtils::Liblist;
33
34 $MM->ext($potential_libs, $verbose, $need_names);
864a5fa8 35
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36 # Usually you can get away with:
37 ExtUtils::Liblist->ext($potential_libs, $verbose, $need_names)
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38
39=head1 DESCRIPTION
40
41This utility takes a list of libraries in the form C<-llib1 -llib2
76c6a468 42-llib3> and returns lines suitable for inclusion in an extension
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43Makefile. Extra library paths may be included with the form
44C<-L/another/path> this will affect the searches for all subsequent
45libraries.
46
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47It returns an array of four or five scalar values: EXTRALIBS,
48BSLOADLIBS, LDLOADLIBS, LD_RUN_PATH, and, optionally, a reference to
49the array of the filenames of actual libraries. Some of these don't
50mean anything unless on Unix. See the details about those platform
51specifics below. The list of the filenames is returned only if
52$need_names argument is true.
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53
54Dependent libraries can be linked in one of three ways:
55
56=over 2
57
58=item * For static extensions
59
60by the ld command when the perl binary is linked with the extension
61library. See EXTRALIBS below.
62
f6d6199c 63=item * For dynamic extensions at build/link time
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64
65by the ld command when the shared object is built/linked. See
66LDLOADLIBS below.
67
f6d6199c 68=item * For dynamic extensions at load time
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69
70by the DynaLoader when the shared object is loaded. See BSLOADLIBS
71below.
72
73=back
74
75=head2 EXTRALIBS
76
77List of libraries that need to be linked with when linking a perl
a7665c5e 78binary which includes this extension. Only those libraries that
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79actually exist are included. These are written to a file and used
80when linking perl.
81
82=head2 LDLOADLIBS and LD_RUN_PATH
83
84List of those libraries which can or must be linked into the shared
85library when created using ld. These may be static or dynamic
86libraries. LD_RUN_PATH is a colon separated list of the directories
87in LDLOADLIBS. It is passed as an environment variable to the process
88that links the shared library.
89
90=head2 BSLOADLIBS
91
92List of those libraries that are needed but can be linked in
93dynamically at run time on this platform. SunOS/Solaris does not need
94this because ld records the information (from LDLOADLIBS) into the
95object file. This list is used to create a .bs (bootstrap) file.
96
97=head1 PORTABILITY
98
99This module deals with a lot of system dependencies and has quite a
a7665c5e 100few architecture specific C<if>s in the code.
864a5fa8 101
55497cff 102=head2 VMS implementation
103
104The version of ext() which is executed under VMS differs from the
105Unix-OS/2 version in several respects:
106
107=over 2
108
109=item *
110
111Input library and path specifications are accepted with or without the
de592821 112C<-l> and C<-L> prefixes used by Unix linkers. If neither prefix is
55497cff 113present, a token is considered a directory to search if it is in fact
114a directory, and a library to search for otherwise. Authors who wish
115their extensions to be portable to Unix or OS/2 should use the Unix
116prefixes, since the Unix-OS/2 version of ext() requires them.
117
118=item *
119
120Wherever possible, shareable images are preferred to object libraries,
121and object libraries to plain object files. In accordance with VMS
122naming conventions, ext() looks for files named I<lib>shr and I<lib>rtl;
de592821 123it also looks for I<lib>lib and libI<lib> to accommodate Unix conventions
55497cff 124used in some ported software.
125
126=item *
127
128For each library that is found, an appropriate directive for a linker options
129file is generated. The return values are space-separated strings of
130these directives, rather than elements used on the linker command line.
131
132=item *
133
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134LDLOADLIBS contains both the libraries found based on C<$potential_libs> and
135the CRTLs, if any, specified in Config.pm. EXTRALIBS contains just those
136libraries found based on C<$potential_libs>. BSLOADLIBS and LD_RUN_PATH
137are always empty.
55497cff 138
139=back
140
141In addition, an attempt is made to recognize several common Unix library
142names, and filter them out or convert them to their VMS equivalents, as
143appropriate.
144
145In general, the VMS version of ext() should properly handle input from
146extensions originally designed for a Unix or VMS environment. If you
147encounter problems, or discover cases where the search could be improved,
148please let us know.
149
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150=head2 Win32 implementation
151
152The version of ext() which is executed under Win32 differs from the
153Unix-OS/2 version in several respects:
154
155=over 2
156
157=item *
158
944acd49 159If C<$potential_libs> is empty, the return value will be empty.
9c839522 160Otherwise, the libraries specified by C<$Config{perllibs}> (see Config.pm)
944acd49 161will be appended to the list of C<$potential_libs>. The libraries
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162will be searched for in the directories specified in C<$potential_libs>,
163C<$Config{libpth}>, and in C<$Config{installarchlib}/CORE>.
164For each library that is found, a space-separated list of fully qualified
165library pathnames is generated.
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166
167=item *
168
3e3baf6d 169Input library and path specifications are accepted with or without the
de592821 170C<-l> and C<-L> prefixes used by Unix linkers.
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171
172An entry of the form C<-La:\foo> specifies the C<a:\foo> directory to look
173for the libraries that follow.
174
175An entry of the form C<-lfoo> specifies the library C<foo>, which may be
176spelled differently depending on what kind of compiler you are using. If
177you are using GCC, it gets translated to C<libfoo.a>, but for other win32
178compilers, it becomes C<foo.lib>. If no files are found by those translated
179names, one more attempt is made to find them using either C<foo.a> or
180C<libfoo.lib>, depending on whether GCC or some other win32 compiler is
181being used, respectively.
182
183If neither the C<-L> or C<-l> prefix is present in an entry, the entry is
184considered a directory to search if it is in fact a directory, and a
185library to search for otherwise. The C<$Config{lib_ext}> suffix will
186be appended to any entries that are not directories and don't already have
187the suffix.
188
de592821 189Note that the C<-L> and C<-l> prefixes are B<not required>, but authors
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190who wish their extensions to be portable to Unix or OS/2 should use the
191prefixes, since the Unix-OS/2 version of ext() requires them.
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192
193=item *
194
195Entries cannot be plain object files, as many Win32 compilers will
196not handle object files in the place of libraries.
197
198=item *
199
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200Entries in C<$potential_libs> beginning with a colon and followed by
201alphanumeric characters are treated as flags. Unknown flags will be ignored.
202
203An entry that matches C</:nodefault/i> disables the appending of default
9c839522 204libraries found in C<$Config{perllibs}> (this should be only needed very rarely).
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205
206An entry that matches C</:nosearch/i> disables all searching for
207the libraries specified after it. Translation of C<-Lfoo> and
208C<-lfoo> still happens as appropriate (depending on compiler being used,
209as reflected by C<$Config{cc}>), but the entries are not verified to be
210valid files or directories.
3e3baf6d 211
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212An entry that matches C</:search/i> reenables searching for
213the libraries specified after it. You can put it at the end to
9c839522 214enable searching for default libraries specified by C<$Config{perllibs}>.
e47a9bbc 215
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216=item *
217
218The libraries specified may be a mixture of static libraries and
219import libraries (to link with DLLs). Since both kinds are used
a7665c5e 220pretty transparently on the Win32 platform, we do not attempt to
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221distinguish between them.
222
223=item *
224
225LDLOADLIBS and EXTRALIBS are always identical under Win32, and BSLOADLIBS
226and LD_RUN_PATH are always empty (this may change in future).
227
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228=item *
229
230You must make sure that any paths and path components are properly
231surrounded with double-quotes if they contain spaces. For example,
232C<$potential_libs> could be (literally):
233
234 "-Lc:\Program Files\vc\lib" msvcrt.lib "la test\foo bar.lib"
235
236Note how the first and last entries are protected by quotes in order
237to protect the spaces.
238
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239=item *
240
241Since this module is most often used only indirectly from extension
242C<Makefile.PL> files, here is an example C<Makefile.PL> entry to add
e47a9bbc 243a library to the build process for an extension:
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244
245 LIBS => ['-lgl']
246
247When using GCC, that entry specifies that MakeMaker should first look
248for C<libgl.a> (followed by C<gl.a>) in all the locations specified by
249C<$Config{libpth}>.
250
251When using a compiler other than GCC, the above entry will search for
252C<gl.lib> (followed by C<libgl.lib>).
253
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254If the library happens to be in a location not in C<$Config{libpth}>,
255you need:
256
257 LIBS => ['-Lc:\gllibs -lgl']
258
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259Here is a less often used example:
260
261 LIBS => ['-lgl', ':nosearch -Ld:\mesalibs -lmesa -luser32']
262
263This specifies a search for library C<gl> as before. If that search
264fails to find the library, it looks at the next item in the list. The
265C<:nosearch> flag will prevent searching for the libraries that follow,
266so it simply returns the value as C<-Ld:\mesalibs -lmesa -luser32>,
267since GCC can use that value as is with its linker.
268
269When using the Visual C compiler, the second item is returned as
270C<-libpath:d:\mesalibs mesa.lib user32.lib>.
271
272When using the Borland compiler, the second item is returned as
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273C<-Ld:\mesalibs mesa.lib user32.lib>, and MakeMaker takes care of
274moving the C<-Ld:\mesalibs> to the correct place in the linker
275command line.
944acd49 276
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277=back
278
279
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280=head1 SEE ALSO
281
282L<ExtUtils::MakeMaker>
283
284=cut
285