Factor out .la validity checks

[Noah Misch]

This patch (against HEAD) factors out a common sanity check for the validity of
a .la file.  The check varied slightly throughout ltmain.m4sh, and it regularly
failed to quote the file name.  This also eliminates a sub-shell, which might
speed things up on some platforms.  Comments and test results appreciated.

2004-10-22  Noah Misch  <address@hidden>

        * config/ltmain.m4sh (func_lalib_p, func_ltwrapper_p): New
        functions that abstract .la sanity checking.
        (func_mode_execute, func_mode_install, func_mode_link,
        func_mode_uninstall): Use them.

diff -X dontdiff -uwrp lt-clean/config/ltmain.m4sh 
lt-func_lalib_p/config/ltmain.m4sh
--- lt-clean/config/ltmain.m4sh Fri Oct 22 03:05:59 2004
+++ lt-func_lalib_p/config/ltmain.m4sh  Fri Oct 22 18:26:11 2004
@@ -135,6 +135,19 @@ func_fatal_configuration ()
     func_fatal_error "Fatal configuration error."
 }
 
+# func_lalib_p file - true iff `file' is a libtool `.la' library
+# func_ltwrapper_p file - true iff `file' is a libtool wrapper script
+#
+# These functions are only basic sanity checks; they will hardly flush
+# out determined imposters.
+func_lalib_p ()
+{
+    $SED -e 4q "$1" | $GREP "^# Generated by .*$PACKAGE" >/dev/null 2>&1
+}
+func_ltwrapper_p ()
+{
+    func_lalib_p "$1"
+}
 
 # func_config
 # Display the configuration for all the tags in this script.
@@ -1430,7 +1443,7 @@ func_mode_execute ()
       case $file in
       *.la)
        # Check to see that this really is a libtool archive.
-       (${SED} -e '2q' $file | $GREP "^# Generated by .*$PACKAGE") >/dev/null 
2>&1 || \
+        func_lalib_p "$file" || \
          func_fatal_help "\`$lib' is not a valid libtool archive"
 
        # Read the libtool library.
@@ -1497,7 +1510,7 @@ func_mode_execute ()
       -*) ;;
       *)
        # Do a test to see if this is really a libtool program.
-       if (${SED} -e '4q' $file | $GREP "^# Generated by .*$PACKAGE") 
>/dev/null 2>&1; then
+       if func_lalib_p "$file"; then
          # If there is no directory component, then add one.
          case $file in
          */* | *\\*) . $file ;;
@@ -1758,7 +1771,7 @@ func_mode_install ()
 
       *.la)
        # Check to see that this really is a libtool archive.
-       (${SED} -e '2q' $file | $GREP "^# Generated by ltmain.sh ") >/dev/null 
2>&1 || \
+        func_lalib_p "$file" || \
          func_fatal_help "\`$file' is not a valid libtool archive"
 
        library_names=
@@ -1939,7 +1952,7 @@ func_mode_install ()
            wrapper=$file
            ;;
        esac
-       if (${SED} -e '4q' $wrapper | $GREP "^# Generated by 
.*$PACKAGE")>/dev/null 2>&1; then
+        if func_ltwrapper_p "$wrapper"; then
          notinst_deplibs=
          relink_command=
 
@@ -2289,7 +2302,7 @@ func_mode_link ()
              # A libtool-controlled object.
 
              # Check to see that this really is a libtool object.
-             if (${SED} -e '2q' $arg | $GREP "^# Generated by ltmain.sh ") 
>/dev/null 2>&1; then
+             if func_lalib_p "$arg"; then
                pic_object=
                non_pic_object=
 
@@ -2784,7 +2797,7 @@ func_mode_link ()
        # A libtool-controlled object.
 
        # Check to see that this really is a libtool object.
-       if (${SED} -e '2q' $arg | $GREP "^# Generated by .*$PACKAGE") 
>/dev/null 2>&1; then
+       if func_lalib_p "$arg"; then
          pic_object=
          non_pic_object=
 
@@ -3124,8 +3137,7 @@ func_mode_link ()
            if test "X$allow_libtool_libs_with_static_runtimes" = "Xyes" ; then
              case " $predeps $postdeps " in
              *" $deplib "*)
-               if (${SED} -e '2q' $lib |
-                   $GREP "^# Generated by .*$PACKAGE") >/dev/null 2>&1; then
+               if func_lalib_p "$lib"; then
                  library_names=
                  old_library=
                  case $lib in
@@ -3294,10 +3306,8 @@ func_mode_link ()
        fi
 
        # Check to see that this really is a libtool archive.
-       if (${SED} -e '2q' $lib | $GREP "^# Generated by ltmain.sh ") 
>/dev/null 2>&1; then :
-       else
+        func_lalib_p "$lib" || \
          func_fatal_error "\`$lib' is not a valid libtool archive"
-       fi
 
        ladir=`$ECHO "X$lib" | $Xsed -e 's%/[[^/]]*$%%'`
        test "X$ladir" = "X$lib" && ladir="."
@@ -6490,7 +6500,7 @@ func_mode_uninstall ()
       case $name in
       *.la)
        # Possibly a libtool archive, so verify it.
-       if (${SED} -e '2q' $file | $GREP "^# Generated by .*$PACKAGE") 
>/dev/null 2>&1; then
+       if func_lalib_p "$file"; then
          . $dir/$name
 
          # Delete the libtool libraries and symlinks.
@@ -6539,7 +6549,7 @@ func_mode_uninstall ()
 
       *.lo)
        # Possibly a libtool object, so verify it.
-       if (${SED} -e '2q' $file | $GREP "^# Generated by .*$PACKAGE") 
>/dev/null 2>&1; then
+       if func_lalib_p "$file"; then
 
          # Read the .lo file
          . $dir/$name
@@ -6571,7 +6581,7 @@ func_mode_uninstall ()
            ;;
          esac
          # Do a test to see if this is a libtool program.
-         if (${SED} -e '4q' $file | $GREP "^# Generated by .*$PACKAGE") 
>/dev/null 2>&1; then
+         if func_ltwrapper_p "$file"; then
            relink_command=
            . $dir/$noexename