Bug#413602: exim4: 50_localscan_dlopen.patch: Reduce dynamic symbol
table
Marc Haber
mh+debian-packages at zugschlus.de
Wed Mar 21 12:01:33 CET 2007
On Mon, Mar 19, 2007 at 06:10:33PM +0100, Magnus Holmgren wrote:
> EDITME.
>
> I.e. the patch to the patch becomes something along
This would result in the attached 50_localscan_dlopen.dpatch file,
right?
Greetings
Marc
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#! /bin/sh /usr/share/dpatch/dpatch-run
## 50_localscan_dlopen.dpatch by Marc MERLIN
##
## All lines beginning with `## DP:' are a description of the patch.
## DP: Allow to use and switch between different local_scan functions without
## DP: recompiling exim.
## DP: http://marc.merlins.org/linux/exim/files/sa-exim-current/
## DP: Original patch from David Woodhouse, modified first by Derrick 'dman'
## DP: Hudson and then by Marc MERLIN for SA-Exim and minor/major API version
## DP: tracking
@DPATCH@
diff -urNad experimental~/build-tree/src/EDITME experimental/build-tree/src/EDITME
--- experimental~/build-tree/src/EDITME 2007-01-08 15:25:36.000000000 +0100
+++ experimental/build-tree/src/EDITME 2007-03-21 11:55:52.000000000 +0100
@@ -615,6 +615,21 @@
#------------------------------------------------------------------------------
+# On systems which support dynamic loading of shared libraries, Exim can
+# load a local_scan function specified in its config file instead of having
+# to be recompiled with the desired local_scan function. For a full
+# description of the API to this function, see the Exim specification.
+
+DLOPEN_LOCAL_SCAN=yes
+
+# If you set DLOPEN_LOCAL_SCAN, then you need to include -rdynamic in the
+# linker flags. Without it, the loaded .so won't be able to access any
+# functions from exim.
+
+LDFLAGS += -rdynamic
+CFLAGS += -fvisibility=hidden
+
+#------------------------------------------------------------------------------
# The default distribution of Exim contains only the plain text form of the
# documentation. Other forms are available separately. If you want to install
# the documentation in "info" format, first fetch the Texinfo documentation
diff -urNad experimental~/build-tree/src/config.h.defaults experimental/build-tree/src/config.h.defaults
--- experimental~/build-tree/src/config.h.defaults 2007-01-08 15:25:36.000000000 +0100
+++ experimental/build-tree/src/config.h.defaults 2007-03-21 11:54:26.000000000 +0100
@@ -27,6 +27,8 @@
#define AUTH_VARS 3
+#define DLOPEN_LOCAL_SCAN
+
#define BIN_DIRECTORY
#define CONFIGURE_FILE
diff -urNad experimental~/build-tree/src/globals.c experimental/build-tree/src/globals.c
--- experimental~/build-tree/src/globals.c 2007-03-21 11:54:26.000000000 +0100
+++ experimental/build-tree/src/globals.c 2007-03-21 11:54:26.000000000 +0100
@@ -123,6 +123,9 @@
uschar *tls_verify_hosts = NULL;
#endif
+#ifdef DLOPEN_LOCAL_SCAN
+uschar *local_scan_path = NULL;
+#endif
/* Input-reading functions for messages, so we can use special ones for
incoming TCP/IP. The defaults use stdin. We never need these for any
diff -urNad experimental~/build-tree/src/globals.h experimental/build-tree/src/globals.h
--- experimental~/build-tree/src/globals.h 2007-01-08 15:25:36.000000000 +0100
+++ experimental/build-tree/src/globals.h 2007-03-21 11:54:26.000000000 +0100
@@ -85,6 +85,9 @@
extern uschar *tls_verify_hosts; /* Mandatory client verification */
#endif
+#ifdef DLOPEN_LOCAL_SCAN
+extern uschar *local_scan_path; /* Path to local_scan() library */
+#endif
/* Input-reading functions for messages, so we can use special ones for
incoming TCP/IP. */
diff -urNad experimental~/build-tree/src/local_scan.c experimental/build-tree/src/local_scan.c
--- experimental~/build-tree/src/local_scan.c 2007-01-08 15:25:36.000000000 +0100
+++ experimental/build-tree/src/local_scan.c 2007-03-21 11:54:26.000000000 +0100
@@ -7,60 +7,131 @@
/* Copyright (c) University of Cambridge 1995 - 2007 */
/* See the file NOTICE for conditions of use and distribution. */
+#include "exim.h"
-/******************************************************************************
-This file contains a template local_scan() function that just returns ACCEPT.
-If you want to implement your own version, you should copy this file to, say
-Local/local_scan.c, and edit the copy. To use your version instead of the
-default, you must set
+#ifdef DLOPEN_LOCAL_SCAN
+#include <dlfcn.h>
+static int (*local_scan_fn)(int fd, uschar **return_text) = NULL;
+static int load_local_scan_library(void);
+#endif
-LOCAL_SCAN_SOURCE=Local/local_scan.c
+int
+local_scan(int fd, uschar **return_text)
+{
+fd = fd; /* Keep picky compilers happy */
+return_text = return_text;
+#ifdef DLOPEN_LOCAL_SCAN
+/* local_scan_path is defined AND not the empty string */
+if (local_scan_path && *local_scan_path)
+ {
+ if (!local_scan_fn)
+ {
+ if (!load_local_scan_library())
+ {
+ char *base_msg , *error_msg , *final_msg ;
+ int final_length = -1 ;
-in your Local/Makefile. This makes it easy to copy your version for use with
-subsequent Exim releases.
+ base_msg=US"Local configuration error - local_scan() library failure\n";
+ error_msg = dlerror() ;
-For a full description of the API to this function, see the Exim specification.
-******************************************************************************/
+ final_length = strlen(base_msg) + strlen(error_msg) + 1 ;
+ final_msg = (char*)malloc( final_length*sizeof(char) ) ;
+ *final_msg = '\0' ;
+ strcat( final_msg , base_msg ) ;
+ strcat( final_msg , error_msg ) ;
-/* This is the only Exim header that you should include. The effect of
-including any other Exim header is not defined, and may change from release to
-release. Use only the documented interface! */
+ *return_text = final_msg ;
+ return LOCAL_SCAN_TEMPREJECT;
+ }
+ }
+ return local_scan_fn(fd, return_text);
+ }
+else
+#endif
+ return LOCAL_SCAN_ACCEPT;
+}
-#include "local_scan.h"
+#ifdef DLOPEN_LOCAL_SCAN
+static int load_local_scan_library(void)
+{
+/* No point in keeping local_scan_lib since we'll never dlclose() anyway */
+void *local_scan_lib = NULL;
+int (*local_scan_version_fn)(void);
+int vers_maj;
+int vers_min;
-/* This is a "do-nothing" version of a local_scan() function. The arguments
-are:
+local_scan_lib = dlopen(local_scan_path, RTLD_NOW);
+if (!local_scan_lib)
+ {
+ log_write(0, LOG_MAIN|LOG_REJECT, "local_scan() library open failed - "
+ "message temporarily rejected");
+ return FALSE;
+ }
- fd The file descriptor of the open -D file, which contains the
- body of the message. The file is open for reading and
- writing, but modifying it is dangerous and not recommended.
+local_scan_version_fn = dlsym(local_scan_lib, "local_scan_version_major");
+if (!local_scan_version_fn)
+ {
+ dlclose(local_scan_lib);
+ log_write(0, LOG_MAIN|LOG_REJECT, "local_scan() library doesn't contain "
+ "local_scan_version_major() function - message temporarily rejected");
+ return FALSE;
+ }
- return_text A pointer to an unsigned char* variable which you can set in
- order to return a text string. It is initialized to NULL.
+/* The major number is increased when the ABI is changed in a non
+ backward compatible way. */
+vers_maj = local_scan_version_fn();
-The return values of this function are:
+local_scan_version_fn = dlsym(local_scan_lib, "local_scan_version_minor");
+if (!local_scan_version_fn)
+ {
+ dlclose(local_scan_lib);
+ log_write(0, LOG_MAIN|LOG_REJECT, "local_scan() library doesn't contain "
+ "local_scan_version_minor() function - message temporarily rejected");
+ return FALSE;
+ }
- LOCAL_SCAN_ACCEPT
- The message is to be accepted. The return_text argument is
- saved in $local_scan_data.
+/* The minor number is increased each time a new feature is added (in a
+ way that doesn't break backward compatibility) -- Marc */
+vers_min = local_scan_version_fn();
- LOCAL_SCAN_REJECT
- The message is to be rejected. The returned text is used
- in the rejection message.
- LOCAL_SCAN_TEMPREJECT
- This specifies a temporary rejection. The returned text
- is used in the rejection message.
-*/
+if (vers_maj != LOCAL_SCAN_ABI_VERSION_MAJOR)
+ {
+ dlclose(local_scan_lib);
+ local_scan_lib = NULL;
+ log_write(0, LOG_MAIN|LOG_REJECT, "local_scan() has an incompatible major"
+ "version number, you need to recompile your module for this version"
+ "of exim (The module was compiled for version %d.%d and this exim provides"
+ "ABI version %d.%d)", vers_maj, vers_min, LOCAL_SCAN_ABI_VERSION_MAJOR,
+ LOCAL_SCAN_ABI_VERSION_MINOR);
+ return FALSE;
+ }
+else if (vers_min > LOCAL_SCAN_ABI_VERSION_MINOR)
+ {
+ dlclose(local_scan_lib);
+ local_scan_lib = NULL;
+ log_write(0, LOG_MAIN|LOG_REJECT, "local_scan() has an incompatible minor"
+ "version number, you need to recompile your module for this version"
+ "of exim (The module was compiled for version %d.%d and this exim provides"
+ "ABI version %d.%d)", vers_maj, vers_min, LOCAL_SCAN_ABI_VERSION_MAJOR,
+ LOCAL_SCAN_ABI_VERSION_MINOR);
+ return FALSE;
+ }
-int
-local_scan(int fd, uschar **return_text)
-{
-fd = fd; /* Keep picky compilers happy */
-return_text = return_text;
-return LOCAL_SCAN_ACCEPT;
+local_scan_fn = dlsym(local_scan_lib, "local_scan");
+if (!local_scan_fn)
+ {
+ dlclose(local_scan_lib);
+ log_write(0, LOG_MAIN|LOG_REJECT, "local_scan() library doesn't contain "
+ "local_scan() function - message temporarily rejected");
+ return FALSE;
+ }
+
+return TRUE;
}
+#endif /* DLOPEN_LOCAL_SCAN */
+
/* End of local_scan.c */
diff -urNad experimental~/build-tree/src/local_scan.h experimental/build-tree/src/local_scan.h
--- experimental~/build-tree/src/local_scan.h 2007-01-08 15:25:36.000000000 +0100
+++ experimental/build-tree/src/local_scan.h 2007-03-21 11:58:27.000000000 +0100
@@ -18,6 +18,7 @@
settings, and the store functions. */
#include <sys/types.h>
+#pragma GCC visibility push(default)
#include "config.h"
#include "mytypes.h"
#include "store.h"
@@ -188,4 +189,6 @@
extern uschar *string_copyn(uschar *, int);
extern uschar *string_sprintf(char *, ...);
+#pragma GCC visibility pop
+
/* End of local_scan.h */
diff -urNad experimental~/build-tree/src/readconf.c experimental/build-tree/src/readconf.c
--- experimental~/build-tree/src/readconf.c 2007-01-08 15:25:36.000000000 +0100
+++ experimental/build-tree/src/readconf.c 2007-03-21 11:54:26.000000000 +0100
@@ -247,6 +247,9 @@
{ "local_from_prefix", opt_stringptr, &local_from_prefix },
{ "local_from_suffix", opt_stringptr, &local_from_suffix },
{ "local_interfaces", opt_stringptr, &local_interfaces },
+#ifdef DLOPEN_LOCAL_SCAN
+ { "local_scan_path", opt_stringptr, &local_scan_path },
+#endif
{ "local_scan_timeout", opt_time, &local_scan_timeout },
{ "local_sender_retain", opt_bool, &local_sender_retain },
{ "localhost_number", opt_stringptr, &host_number_string },
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