* libtool.m4: Update AC_LIBTOOL_SYS_MAX_CMD_LEN bits from upstream.

From-SVN: r97808

ChangeLog

@@ -1,3 +1,7 @@
+2005-04-07  Mike Stump  <mrs@apple.com>
+
+	* libtool.m4: Update AC_LIBTOOL_SYS_MAX_CMD_LEN bits from upstream.
+
 2005-04-04  Thomas Koenig  <Thomas.Koenig@online.de>
 
 	* MAINTAINERS (Write After Approval): Add myself.

libtool.m4

@@ -103,6 +103,8 @@ AC_REQUIRE([AC_OBJEXT])dnl
 AC_REQUIRE([AC_EXEEXT])dnl
 dnl
 
+AC_LIBTOOL_SYS_MAX_CMD_LEN
+
 # Only perform the check for file, if the check method requires it
 case $deplibs_check_method in
 file_magic*)
@@ -279,6 +281,85 @@ ifdef([AC_PROVIDE_AC_LIBTOOL_WIN32_DLL],
 esac
 ])
 
+
+# AC_LIBTOOL_SYS_MAX_CMD_LEN
+# --------------------------
+AC_DEFUN([AC_LIBTOOL_SYS_MAX_CMD_LEN],
+[# find the maximum length of command line arguments
+AC_MSG_CHECKING([the maximum length of command line arguments])
+AC_CACHE_VAL([lt_cv_sys_max_cmd_len], [dnl
+  i=0
+  teststring="ABCD"
+
+  case $build_os in
+  msdosdjgpp*)
+    # On DJGPP, this test can blow up pretty badly due to problems in libc
+    # (any single argument exceeding 2000 bytes causes a buffer overrun
+    # during glob expansion).  Even if it were fixed, the result of this
+    # check would be larger than it should be.
+    lt_cv_sys_max_cmd_len=12288;    # 12K is about right
+    ;;
+
+  cygwin* | mingw*)
+    # On Win9x/ME, this test blows up -- it succeeds, but takes
+    # about 5 minutes as the teststring grows exponentially.
+    # Worse, since 9x/ME are not pre-emptively multitasking,
+    # you end up with a "frozen" computer, even though with patience
+    # the test eventually succeeds (with a max line length of 256k).
+    # Instead, let's just punt: use the minimum linelength reported by
+    # all of the supported platforms: 8192 (on NT/2K/XP).
+    lt_cv_sys_max_cmd_len=8192;
+    ;;
+
+  amigaos*)
+    # On AmigaOS with pdksh, this test takes hours, literally.
+    # So we just punt and use a minimum line length of 8192.
+    lt_cv_sys_max_cmd_len=8192;
+    ;;
+
+  netbsd* | freebsd* | openbsd* | darwin* | dragonfly*)
+    # This has been around since 386BSD, at least.  Likely further.
+    if test -x /sbin/sysctl; then
+      lt_cv_sys_max_cmd_len=`/sbin/sysctl -n kern.argmax`
+    elif test -x /usr/sbin/sysctl; then
+      lt_cv_sys_max_cmd_len=`/usr/sbin/sysctl -n kern.argmax`
+    else
+      lt_cv_sys_max_cmd_len=65536 # usable default for *BSD
+    fi
+    # And add a safety zone
+    lt_cv_sys_max_cmd_len=`expr $lt_cv_sys_max_cmd_len \/ 4`
+    lt_cv_sys_max_cmd_len=`expr $lt_cv_sys_max_cmd_len \* 3`
+    ;;
+  *)
+    # If test is not a shell built-in, we'll probably end up computing a
+    # maximum length that is only half of the actual maximum length, but
+    # we can't tell.
+    SHELL=${SHELL-${CONFIG_SHELL-/bin/sh}}
+    while (test "X"`$SHELL [$]0 --fallback-echo "X$teststring" 2>/dev/null` \
+	       = "XX$teststring") >/dev/null 2>&1 &&
+	    new_result=`expr "X$teststring" : ".*" 2>&1` &&
+	    lt_cv_sys_max_cmd_len=$new_result &&
+	    test $i != 17 # 1/2 MB should be enough
+    do
+      i=`expr $i + 1`
+      teststring=$teststring$teststring
+    done
+    teststring=
+    # Add a significant safety factor because C++ compilers can tack on massive
+    # amounts of additional arguments before passing them to the linker.
+    # It appears as though 1/2 is a usable value.
+    lt_cv_sys_max_cmd_len=`expr $lt_cv_sys_max_cmd_len \/ 2`
+    ;;
+  esac
+])
+if test -n $lt_cv_sys_max_cmd_len ; then
+  AC_MSG_RESULT($lt_cv_sys_max_cmd_len)
+else
+  AC_MSG_RESULT(none)
+fi
+])# AC_LIBTOOL_SYS_MAX_CMD_LEN
+
+
 # AC_LIBTOOL_DLOPEN - enable checks for dlopen support
 AC_DEFUN([AC_LIBTOOL_DLOPEN], [AC_BEFORE([$0],[AC_LIBTOOL_SETUP])])