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   1  package ExtUtils::Liblist;
   2  
   3  use strict;
   4  
   5  use vars qw($VERSION @ISA);
   6  $VERSION = '6.42';
   7  
   8  use File::Spec;
   9  require ExtUtils::Liblist::Kid;
  10  @ISA = qw(ExtUtils::Liblist::Kid File::Spec);
  11  
  12  # Backwards compatibility with old interface.
  13  sub ext {
  14      goto &ExtUtils::Liblist::Kid::ext;
  15  }
  16  
  17  sub lsdir {
  18    shift;
  19    my $rex = qr/$_[1]/;
  20    opendir DIR, $_[0];
  21    my @out = grep /$rex/, readdir DIR;
  22    closedir DIR;
  23    return @out;
  24  }
  25  
  26  __END__
  27  
  28  =head1 NAME
  29  
  30  ExtUtils::Liblist - determine libraries to use and how to use them
  31  
  32  =head1 SYNOPSIS
  33  
  34    require ExtUtils::Liblist;
  35  
  36    $MM->ext($potential_libs, $verbose, $need_names);
  37  
  38    # Usually you can get away with:
  39    ExtUtils::Liblist->ext($potential_libs, $verbose, $need_names)
  40  
  41  =head1 DESCRIPTION
  42  
  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
  47  libraries.
  48  
  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.
  55  
  56  Dependent libraries can be linked in one of three ways:
  57  
  58  =over 2
  59  
  60  =item * For static extensions
  61  
  62  by the ld command when the perl binary is linked with the extension
  63  library. See EXTRALIBS below.
  64  
  65  =item * For dynamic extensions at build/link time
  66  
  67  by the ld command when the shared object is built/linked. See
  68  LDLOADLIBS below.
  69  
  70  =item * For dynamic extensions at load time
  71  
  72  by the DynaLoader when the shared object is loaded. See BSLOADLIBS
  73  below.
  74  
  75  =back
  76  
  77  =head2 EXTRALIBS
  78  
  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
  82  when linking perl.
  83  
  84  =head2 LDLOADLIBS and LD_RUN_PATH
  85  
  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.
  91  
  92  =head2 BSLOADLIBS
  93  
  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.
  98  
  99  =head1 PORTABILITY
 100  
 101  This module deals with a lot of system dependencies and has quite a
 102  few architecture specific C<if>s in the code.
 103  
 104  =head2 VMS implementation
 105  
 106  The version of ext() which is executed under VMS differs from the
 107  Unix-OS/2 version in several respects:
 108  
 109  =over 2
 110  
 111  =item *
 112  
 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.
 119  
 120  =item *
 121  
 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.
 127  
 128  =item *
 129  
 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.
 133  
 134  =item *
 135  
 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<$potential_libs>.  BSLOADLIBS and LD_RUN_PATH
 139  are always empty.
 140  
 141  =back
 142  
 143  In addition, an attempt is made to recognize several common Unix library
 144  names, and filter them out or convert them to their VMS equivalents, as
 145  appropriate.
 146  
 147  In general, the VMS version of ext() should properly handle input from
 148  extensions originally designed for a Unix or VMS environment.  If you
 149  encounter problems, or discover cases where the search could be improved,
 150  please let us know.
 151  
 152  =head2 Win32 implementation
 153  
 154  The version of ext() which is executed under Win32 differs from the
 155  Unix-OS/2 version in several respects:
 156  
 157  =over 2
 158  
 159  =item *
 160  
 161  If C<$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<$Config{installarchlib}/CORE>.
 166  For each library that is found,  a space-separated list of fully qualified
 167  library pathnames is generated.
 168  
 169  =item *
 170  
 171  Input library and path specifications are accepted with or without the
 172  C<-l> and C<-L> prefixes used by Unix linkers.
 173  
 174  An entry of the form C<-La:\foo> specifies the C<a:\foo> directory to look
 175  for the libraries that follow.
 176  
 177  An entry of the form C<-lfoo> specifies the library C<foo>, which may be
 178  spelled differently depending on what kind of compiler you are using.  If
 179  you are using GCC, it gets translated to C<libfoo.a>, but for other win32
 180  compilers, it becomes C<foo.lib>.  If no files are found by those translated
 181  names, one more attempt is made to find them using either C<foo.a> or
 182  C<libfoo.lib>, depending on whether GCC or some other win32 compiler is
 183  being used, respectively.
 184  
 185  If neither the C<-L> or C<-l> prefix is present in an entry, the entry is
 186  considered a directory to search if it is in fact a directory, and a
 187  library to search for otherwise.  The C<$Config{lib_ext}> suffix will
 188  be appended to any entries that are not directories and don't already have
 189  the suffix.
 190  
 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.
 194  
 195  =item *
 196  
 197  Entries cannot be plain object files, as many Win32 compilers will
 198  not handle object files in the place of libraries.
 199  
 200  =item *
 201  
 202  Entries in C<$potential_libs> beginning with a colon and followed by
 203  alphanumeric characters are treated as flags.  Unknown flags will be ignored.
 204  
 205  An entry that matches C</:nodefault/i> disables the appending of default
 206  libraries found in C<$Config{perllibs}> (this should be only needed very rarely).
 207  
 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<$Config{cc}>), but the entries are not verified to be
 212  valid files or directories.
 213  
 214  An entry that matches C</:search/i> reenables searching for
 215  the libraries specified after it.  You can put it at the end to
 216  enable searching for default libraries specified by C<$Config{perllibs}>.
 217  
 218  =item *
 219  
 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.
 224  
 225  =item *
 226  
 227  LDLOADLIBS and EXTRALIBS are always identical under Win32, and BSLOADLIBS
 228  and LD_RUN_PATH are always empty (this may change in future).
 229  
 230  =item *
 231  
 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<$potential_libs> could be (literally):
 235  
 236      "-Lc:\Program Files\vc\lib" msvcrt.lib "la test\foo bar.lib"
 237  
 238  Note how the first and last entries are protected by quotes in order
 239  to protect the spaces.
 240  
 241  =item *
 242  
 243  Since this module is most often used only indirectly from extension
 244  C<Makefile.PL> files, here is an example C<Makefile.PL> entry to add
 245  a library to the build process for an extension:
 246  
 247          LIBS => ['-lgl']
 248  
 249  When using GCC, that entry specifies that MakeMaker should first look
 250  for C<libgl.a> (followed by C<gl.a>) in all the locations specified by
 251  C<$Config{libpth}>.
 252  
 253  When using a compiler other than GCC, the above entry will search for
 254  C<gl.lib> (followed by C<libgl.lib>).
 255  
 256  If the library happens to be in a location not in C<$Config{libpth}>,
 257  you need:
 258  
 259          LIBS => ['-Lc:\gllibs -lgl']
 260  
 261  Here is a less often used example:
 262  
 263          LIBS => ['-lgl', ':nosearch -Ld:\mesalibs -lmesa -luser32']
 264  
 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.
 270  
 271  When using the Visual C compiler, the second item is returned as
 272  C<-libpath:d:\mesalibs mesa.lib user32.lib>.
 273  
 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
 277  command line.
 278  
 279  =back
 280  
 281  
 282  =head1 SEE ALSO
 283  
 284  L<ExtUtils::MakeMaker>
 285  
 286  =cut
 287