Re: How about some AC_MSG for dlopen?

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On 2024-08-19 Daiki Ueno <[email protected]> wrote:
> Andreas Metzler <[email protected]> writes:
> > On 2024-08-17 Daiki Ueno <[email protected]> wrote:
> >> Andreas Metzler <[email protected]> writes:

> >> > ./configure is quiet about whether dlopening librariers is supported,
> >> > would it make sense to a) add messages and perhaps b) provide a switch
> >> > to force use of linking instead?
[...]
> I would prefer to have the option per library, because some of the
> libraries are less likely to be available than the others (e.g.,
> tpm2-tss vs. zlib).
[...]

Hello,

Per-library quadstate ends up being rather wordy, see attached example
for handling zlib that way. I have thought about it but cannot see a
substantial abbreviation potential ad_hoc, there are 8 cases to handle.
- Do you want me follow-up, extending this approach to brotli/zstd/tpm?

The global switch is obviously simpler.

cu Andreas

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diff --git a/configure.ac b/configure.ac
index 47a7c7601b..627990eaa4 100644
--- a/configure.ac
+++ b/configure.ac
@@ -975,10 +975,13 @@ AC_RUN_IFELSE(
   [ac_cv_dlopen_soname_works=no],
   [ac_cv_dlopen_soname_works=cross-compiling])
 
 AM_CONDITIONAL([ENABLE_DLOPEN], [test "$ac_cv_dlopen_soname_works" = yes])
 need_ltlibdl=no
+AS_IF([test "$ac_cv_dlopen_soname_works" = yes],
+      [AC_MSG_NOTICE([Can dlopen helper-libraries])],
+      [AC_MSG_NOTICE([Need to link against helper-libraries])])
 
 AC_ARG_WITH(tpm2,
 	AS_HELP_STRING([--without-tpm2],
 		[Disable TPM2 support.]),
 	[with_tpm2=$withval], [with_tpm2=auto])
@@ -1091,48 +1094,79 @@ AC_SUBST(TROUSERS_LIB)
 # For minitasn1.
 AC_CHECK_SIZEOF(unsigned long int, 4)
 AC_CHECK_SIZEOF(unsigned int, 4)
 AC_CHECK_SIZEOF(time_t, 4)
 
-AC_ARG_WITH(zlib, AS_HELP_STRING([--without-zlib],
-                                 [disable zlib compression support]),
-            ac_zlib=$withval, ac_zlib=yes)
+AC_ARG_WITH(zlib,
+   [AS_HELP_STRING([--with-zlib=yes/link/dlopen/no --without-zlib],
+                  [customize/disable zlib compression support])],
+            ac_zlib=$withval, ac_zlib=try)
 if test x$ac_zlib != xno; then
     PKG_CHECK_EXISTS(zlib, ZLIB_HAS_PKGCONFIG=y, ZLIB_HAS_PKGCONFIG=n)
     if test "$ZLIB_HAS_PKGCONFIG" = "y" ; then
         PKG_CHECK_MODULES(ZLIB, [zlib])
-	ac_zlib=yes
+	ac_zlib=found-${ac_zlib}
     else
 	AC_LIB_HAVE_LINKFLAGS(z,, [#include <zlib.h>], [compress (0, 0, 0, 0);])
 	if test x$ac_cv_libz != xyes; then
 	    AC_MSG_WARN([[
 *** 
 *** ZLIB was not found. You will not be able to use ZLIB compression.
 *** ]])
+	    ac_zlib=notfound-${ac_zlib}
+        else
+	    ac_zlib=found-${ac_zlib}
         fi
-	ac_zlib=$ac_cv_libz
 	ZLIB_LIBS=$LIBZ
 	LIBZ_PC=$LIBZ
     fi
 fi
+AS_IF([test "$ac_zlib" = "notfound-yes" || test "$ac_zlib" = "notfound-link" || test "$ac_zlib" = "notfound-dlopen"],
+      AC_MSG_ERROR([zlib requested but not available]),
+      [test "$ac_zlib" = "found-dlopen" && test "$ac_cv_dlopen_soname_works" != "yes"],
+      AC_MSG_ERROR([dlopened zlib requested but dlopening not available]))
+
+case $ac_zlib in
+    no|notfound-try)
+        ac_zlib=no
+        ;;
+    found-link)
+        ac_zlib=link
+        ;;
+    found-dlopen)
+        ac_zlib=dlopen
+        ;;
+    found-try|found-yes)
+        if test "$ac_cv_dlopen_soname_works" = yes ; then
+            ac_zlib=dlopen
+        else
+            ac_zlib=link
+        fi
+        ;;
+    *)
+        AC_MSG_ERROR([autoconf coding error, should not be reached])
+        ;;
+esac
+
 if test x$ac_zlib != xno; then
     AC_DEFINE([HAVE_LIBZ], 1, [Define if ZLIB compression is enabled.])
     need_ltlibdl=yes
 fi
-AM_CONDITIONAL(HAVE_ZLIB, test "$ac_zlib" = "yes")
+AM_CONDITIONAL(HAVE_ZLIB, test "$ac_zlib" != "no")
 AC_SUBST(LIBZ_PC)
 
-AS_IF([test "$ac_cv_dlopen_soname_works" = yes], [
+AM_CONDITIONAL([ZLIB_ENABLE_DLOPEN], [test "$ac_zlib" = dlopen])
+AS_IF([test "$ac_zlib" = dlopen], [
     save_LIBS=$LIBS
     LIBS="$LIBS $ZLIB_LIBS"
     LIBGNUTLS_CHECK_SONAME([z], [AC_LANG_PROGRAM([
                    #include <zlib.h>],[
                    compress (0, 0, 0, 0);])])
     LIBS="$save_LIBS"
     CFLAGS="$save_CFLAGS"
 ],
-      [test "$ZLIB_HAS_PKGCONFIG" = y && test "$ac_zlib" = yes], [
+      [test "$ZLIB_HAS_PKGCONFIG" = y && test "$ac_zlib" = link], [
     if test "x$GNUTLS_REQUIRES_PRIVATE" = x; then
         GNUTLS_REQUIRES_PRIVATE="Requires.private: zlib"
     else
         GNUTLS_REQUIRES_PRIVATE="$GNUTLS_REQUIRES_PRIVATE, zlib"
     fi
diff --git a/lib/Makefile.am b/lib/Makefile.am
index d932b585d4..7b7e69403c 100644
--- a/lib/Makefile.am
+++ b/lib/Makefile.am
@@ -92,11 +92,11 @@ COBJECTS = range.c record.c compress.c debug.c cipher.c gthreads.h handshake-tls
 
 if HAVE_ZLIB
 COBJECTS += dlwrap/zlib.c dlwrap/zlibfuncs.h dlwrap/zlib.h
 AM_CPPFLAGS += $(ZLIB_CFLAGS)
 
-if ENABLE_DLOPEN
+if ZLIB_ENABLE_DLOPEN
 AM_CPPFLAGS += -DGNUTLS_ZLIB_ENABLE_DLOPEN=1
 else
 thirdparty_libadd += $(ZLIB_LIBS)
 endif
 endif

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diff --git a/configure.ac b/configure.ac
index 47a7c7601b..f8f04096b1 100644
--- a/configure.ac
+++ b/configure.ac
@@ -953,33 +953,48 @@ fi
 
 AM_CONDITIONAL(P11KIT_0_23_11_API, $PKG_CONFIG --atleast-version=0.23.11 p11-kit-1)
 
 AM_CONDITIONAL(ENABLE_PKCS11, test "$with_p11_kit" != "no")
 
-save_LIBS=$LIBS
-LIBS="$LIBS -lm"
-LIBGNUTLS_CHECK_SONAME([m], [AC_LANG_PROGRAM([
-               #include <math.h>],[
-               trunc (0);])])
-LIBS="$save_LIBS"
-CFLAGS="$save_CFLAGS"
-
-AC_RUN_IFELSE(
-  [AC_LANG_PROGRAM(
-    [[#include <dlfcn.h>
-      #include <stdlib.h>
-    ]],
-    [[void *handle = dlopen("$M_LIBRARY_SONAME", RTLD_LAZY | RTLD_GLOBAL);
-      return handle != NULL ? 0 : 1;
-    ]])],
-  [ac_cv_dlopen_soname_works=yes],
-  [ac_cv_dlopen_soname_works=no],
-  [ac_cv_dlopen_soname_works=cross-compiling])
+AC_ARG_ENABLE([dlopen-libs],
+  [AS_HELP_STRING([--disable-dlopen-libs],
+    [link against instead of dlopening some helper-libraries])],
+  [ac_dlopen_libs=$enableval],
+  [ac_dlopen_libs=try])
+
+AS_IF([test "$ac_dlopen_libs" != "no"],
+  [save_LIBS=$LIBS
+  LIBS="$LIBS -lm"
+  LIBGNUTLS_CHECK_SONAME([m], [AC_LANG_PROGRAM([
+                 #include <math.h>],[
+                 trunc (0);])])
+  LIBS="$save_LIBS"
+  CFLAGS="$save_CFLAGS"
+
+  AC_RUN_IFELSE(
+    [AC_LANG_PROGRAM(
+      [[#include <dlfcn.h>
+        #include <stdlib.h>
+      ]],
+      [[void *handle = dlopen("$M_LIBRARY_SONAME", RTLD_LAZY | RTLD_GLOBAL);
+        return handle != NULL ? 0 : 1;
+      ]])],
+    [ac_cv_dlopen_soname_works=yes],
+    [ac_cv_dlopen_soname_works=no],
+    [ac_cv_dlopen_soname_works=cross-compiling])],
+  [ac_cv_dlopen_soname_works=no])
 
 AM_CONDITIONAL([ENABLE_DLOPEN], [test "$ac_cv_dlopen_soname_works" = yes])
 need_ltlibdl=no
 
+AS_IF([test "$ac_cv_dlopen_soname_works" = yes],
+      AC_MSG_RESULT([will dlopen helper-libraries]),
+      [test "$ac_dlopen_libs" = "yes"],
+      AC_MSG_ERROR([--enable-dlopen-libs requested but not available]),
+      AC_MSG_RESULT([will link against instead of dlopening helper-libraries]))
+
+
 AC_ARG_WITH(tpm2,
 	AS_HELP_STRING([--without-tpm2],
 		[Disable TPM2 support.]),
 	[with_tpm2=$withval], [with_tpm2=auto])
 AS_IF([test "$with_tpm2" != no], [

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