Wireshark · Ethereal-dev: [Ethereal-dev] Rewrite of acinclude.m4 library check autoconf macros

["Olivier Biot" <ethereal@xxxxxxxxxx>]

Hi list,

Below you'll find a first attempt at rewriting an autoconf macro in
top level acinclude.m4 file for testing the PCRE library. The new
approach is that we don't automatically add every library to the
CFLAGS/CPPFLAGS/LDFLAGS and LIBS as the PCRE library may not be
relevant for all targets. Instead all Makefile.am files will use
@PCRE_CFLAGS@, @PCRE_CPPFLAGS@, @PCRE_LDFLAGS@ and @PCRE_LIBS@ for
those targets requiring libpcre.

If this approach is OK, then I'd like to implement it for all relevant
macros in acinclude.m4.

Fire your comments!

Regards,

Olivier

#
# AC_ETHEREAL_LIBPCRE_CHECK
#
# Test the presence and usability of the PCRE library.
# The code in configure.in ensures $want_pcre is either "yes", "no"
# or "ifpresent".
#
AC_DEFUN(AC_ETHEREAL_LIBPCRE_CHECK,
[
  if test "x$pcre_dir" != "x"
  then
    #
    # The user specified a directory in which libpcre resides,
    # so add the "include" subdirectory of that directory to
    # the include file search path and the "lib" subdirectory
    # of that directory to the library search path.
    #
    # XXX - if there's also a libpcre in a directory that's
    # already in CFLAGS, CPPFLAGS, or LDFLAGS, this won't
    # make us find the version in the specified directory,
    # as the compiler and/or linker will search that other
    # directory before it searches the specified directory.
    #
    PCRE_CFLAGS=" -I$pcre_dir/include"
    PCRE_CPPFLAGS=" -I$pcre_dir/include"
    PCRE_LDFLAGS=" -L$pcre_dir/lib"
    PCRE_LIBS="$PCRE_LDFLAGS -lpcre"
  else
    #
    # The user did not specify a directory in which libpcre resides.
    # Assume it is installed in the default location.
    #
    PCRE_CFLAGS=
    PCRE_CPPFLAGS=
    PCRE_LDFLAGS=
    PCRE_LIBS=" -lpcre"
  fi
  save_CFLAGS="$CFLAGS"
  CFLAGS="$CFLAGS$PCRE_CFLAGS"
  save_CPPFLAGS="$CPPFLAGS"
  CPPFLAGS="$CPPFLAGS$PCRE_CPPFLAGS"
  save_LDFLAGS="$LDFLAGS"
  LDFLAGS="$LDFLAGS$PCRE_LDFLAGS"
  save_LIBS="$LIBS"
  LIBS="$LIBS$PCRE_LIBS"

  #
  # Make sure we have "pcre.h".  If we don't, it means we probably
  # don't have libpcre, so don't use it.
  #
  AC_CHECK_HEADER(pcre.h,,
    [
      #
      # Unable to find the pcre.h header.
      #
      if test "x$pcre_dir" != "x"
      then
 #
 # The user used "--with-pcre=DIR" to specify a directory
 # containing libpcre, but we didn't find the header file
 # there; that either means they didn't specify the
 # right directory or are confused about whether libpcre
 # is, in fact, installed.  Report the error and give up.
 #
 AC_MSG_WARN([dnl
*** Header file pcre.h not found in directory $pcre_dir
*** specified in --with-pcre=DIR.
*** Either libpcre is not installed, or the specified directory is
incorrect.
*** Support for libpcre will be disabled.])
      else
 #
 # The user did not specify a directory containing libpcre.
 # We did not find libpcre in the default location.
 #
 if test "x$want_pcre" = "xyes"
 then
   #
   # The user tried to force us to use the library, but we couldn't
   # find the header file; warn user that libpcre won't be used.
   #
   AC_MSG_WARN([dnl
*** Header file pcre.h not found.
*** Either libpcre is not installed, or you must specify its location
*** with the --with-pcre=DIR option.
*** Support for libpcre will be disabled.])
 fi
 #
 # The case where $want_pcre equals "ifpresent" would be the "else"
 # clause, in which nothing will happen (silently ignore the absence
 # of libpcre).
 #
      fi
      want_pcre=no
    ])

  if test "x$want_pcre" != "xno"
  then
    #
    # Well, we at least have the pcre header file.
    #
    # We're only using standard functions from libpcre,
    # so we don't need to perform extra checks.
    #
    AC_CHECK_LIB(pcre, pcre_compile,
      [
 AC_DEFINE(HAVE_LIBPCRE, 1, [Define to use libpcre library])
      ],[
 if test "x$want_pcre" = "xyes"
 then
   AC_MSG_WARN([dnl
*** Unable to find pcre_compile() in libpcre, or unable to link a test
program
*** with libpcre. Maybe the library is too old or not correctly
installed.
*** Support for libpcre will be disabled.])
   want_pcre=no
 fi
      ])
  fi

  #
  # Restore the versions of CFLAGS, CPPFLAGS, LDFLAGS and LIBS
  # Use PCRE_XXX in the Makefile.am files for targets requiring
libpcre.
  #
  CFLAGS="$save_CFLAGS"
  CPPFLAGS="$save_CPPFLAGS"
  LDFLAGS="$save_LDFLAGS"
  LIBS="$save_LIBS"

  if test "x$want_pcre" = "xno"
  then
    #
    # We didn't find a working libpcre installation.
    #
    PCRE_CFLAGS=
    PCRE_CPPFLAGS=
    PCRE_LDFLAGS=
    PCRE_LIBS=
  fi

  AC_SUBST(PCRE_CFLAGS)
  AC_SUBST(PCRE_CPPFLAGS)
  AC_SUBST(PCRE_LDFLAGS)
  AC_SUBST(PCRE_LIBS)
])