Bug 139: portability fixes and documentation.

Document the dynamic lookup module capability in spec.xfpt.
Include a ChangeLog item.

Avoid the GNU-specific "export" make(1) directive.
Build the lookups Makefile using the existing framework.
Build with BSD Make once more.

The src/lookups/Makefile that is used at build time now has the dynamic
content come from scripts/lookups-Makefile.

Add CFLAGS_DYNAMIC support, which can be set in Local/Makefile.
Provide defaults for Linux & FreeBSD.

Ensure that build fails early if a dynamic module is requested but
CFLAGS_DYNAMIC is not defined.

2 files changed, 45 insertions, 0 deletions

diff --git a/doc/doc-docbook/spec.xfpt b/doc/doc-docbook/spec.xfpt
index 66dfab7cd..15b3a2b89 100644
--- a/doc/doc-docbook/spec.xfpt
+++ b/doc/doc-docbook/spec.xfpt
@@ -1946,6 +1946,36 @@ support has not been tested for some time.
 
 
 
+.section "Dynamically loaded lookup module support" "SECTdynamicmodules"
+.cindex "lookup modules"
+.cindex "dynamic modules"
+.cindex ".so building"
+On some platforms, Exim supports not compiling all lookup types directly into
+the main binary, instead putting some into external modules which can be loaded
+on demand.
+This permits packagers to build Exim with support for lookups with extensive
+library dependencies without requiring all users to install all of those
+dependencies.
+Most, but not all, lookup types can be built this way.
+
+Set &`LOOKUP_MODULE_DIR`& to the directory into which the modules will be
+installed; Exim will only load modules from that directory, as a security
+measure.  You will need to set &`CFLAGS_DYNAMIC`& if not already defined
+for your OS; see &_OS/Makefile-Linux_& for an example.
+Some other requirements for adjusting &`EXTRALIBS`& may also be necessary,
+see &_src/EDITME_& for details.
+
+Then, for each module to be loaded dynamically, define the relevant
+&`LOOKUP_`&<&'lookup_type'&> flags to have the value "2" instead of "yes".
+For example, this will build in lsearch but load sqlite and mysql support
+on demand:
+.code
+LOOKUP_LSEARCH=yes
+LOOKUP_SQLITE=2
+LOOKUP_MYSQL=2
+.endd
+
+
 .section "The building process" "SECID29"
 .cindex "build directory"
 Once &_Local/Makefile_& (and &_Local/eximon.conf_&, if required) have been
@@ -34208,6 +34238,13 @@ arbitrary program's being run as exim, not as root.
 
 
 
+.section "Dynamic module directory" "SECTdynmoddir"
+Any dynamically loadable modules must be installed into the directory
+defined in &`LOOKUP_MODULE_DIR`& in &_Local/Makefile_& for Exim to permit
+loading it.
+
+
+
 .section "Use of sprintf()" "SECID279"
 .cindex "&[sprintf()]&"
 A large number of occurrences of &"sprintf"& in the code are actually calls to
diff --git a/doc/doc-txt/ChangeLog b/doc/doc-txt/ChangeLog
index ef82a0cc9..e27496b75 100644
--- a/doc/doc-txt/ChangeLog
+++ b/doc/doc-txt/ChangeLog
@@ -14,6 +14,14 @@ TF/02 Log LMTP confirmation messages in the same way as SMTP,
 
 TF/03 Include the error message when we fail to unlink a spool file.
 
+DW/01 Bugzilla 139: Support dynamically loaded lookups as modules.
+      With thanks to Steve Haslam, Johannes Berg & Serge Demonchaux
+      for maintaining out-of-tree patches for some time.
+
+PP/01 Bugzilla 139: Documentation and portability issues.
+      Avoid GNU Makefile-isms, let Exim continue to build on BSD.
+      Handle per-OS dynamic-module compilation flags.
+
 
 Exim version 4.73
 -----------------