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# Filename: package/.../ipvsadm2/ipvsadm-1.24.backwards_compat.patch
# Copyright (C) 2004 - 2006 The T2 SDE Project
#
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http://www.in-addr.de/pipermail/lvs-users/2005-January/013076.html
Horms <horms@verge.net.au>

BACKWARDS_COMPET_DEFINE= let you use ipvsadm on lx2.4 and lx2.6
NOTE: original patch exec `ipvsadm-1.21` but i choosed `ipvsadm.old`
Alejandro

diff -ruN ipvsadm-1.24/Makefile ipvsadm-1.24.backwards_compat/Makefile
--- ipvsadm-1.24/Makefile	2004-10-28 00:53:07.000000000 +0900
+++ ipvsadm-1.24.backwards_compat/Makefile	2005-01-27 13:24:45.000000000 +0900
@@ -74,10 +75,15 @@
 POPT_DEFINE = -DHAVE_POPT
 endif
 
+# If defined then if the version of ipvs in the kernel is too old
+# for ipvsadm 1.24, then instead of trying to execute ipvsadm.1.21,
+# print a warning and soldier on
+BACKWARDS_COMPET_DEFINE= -DNO_BACKWARDS_COMPAT
+
 OBJS		= ipvsadm.o config_stream.o dynamic_array.o
 LIBS		= $(POPT_LIB)
 DEFINES		= -DVERSION=\"$(VERSION)\" -DSCHEDULERS=\"$(SCHEDULERS)\" \
-		  $(POPT_DEFINE)
+		  $(POPT_DEFINE) $(BACKWARDS_COMPET_DEFINE)
 DEFINES		+= $(shell if [ ! -f ../ip_vs.h ]; then	\
 		     echo "-DHAVE_NET_IP_VS_H"; fi;)
 
diff -ruN ipvsadm-1.24/ipvsadm.c ipvsadm-1.24.backwards_compat/ipvsadm.c
--- ipvsadm-1.24/ipvsadm.c	2004-01-10 18:39:03.000000000 +0900
+++ ipvsadm-1.24.backwards_compat/ipvsadm.c	2005-01-27 13:32:46.000000000 +0900
@@ -54,6 +54,7 @@
  *                                processing options.
  *        Alexandre Cassen    :   added ipvs_syncd SyncdID support to filter
  *                                incoming sync messages.
+ *        Horms		      :   Added backwards compatibility code
  *
  *
  *      ippfvsadm - Port Fowarding & Virtual Server ADMinistration program
@@ -301,9 +302,11 @@
 static void list_daemon(void);
 
 static int modprobe_ipvs(void);
-static void check_ipvs_version(void);
+static void check_ipvs_version(char **argv);
 static int process_options(int argc, char **argv, int reading_stdin);
 
+static void exec_old(char **argv);
+
 
 int main(int argc, char **argv)
 {
@@ -319,7 +322,7 @@
 	}
 
 	/* warn the user if the IPVS version is out of date */
-	check_ipvs_version();
+	check_ipvs_version(argv);
 
 	/* list the table if there is no other arguement */
 	if (argc == 1){
@@ -1393,13 +1396,14 @@
 }
 
 
-static void check_ipvs_version(void)
+static void check_ipvs_version(char *argv[])
 {
 	/* verify the IPVS version */
 	if (ipvs_info.version <
 	    IPVS_VERSION(MINIMUM_IPVS_VERSION_MAJOR,
 			 MINIMUM_IPVS_VERSION_MINOR,
 			 MINIMUM_IPVS_VERSION_PATCH)) {
+		exec_old(argv);
 		fprintf(stderr,
 			"Warning: IPVS version missmatch: \n"
 			"  Kernel compiled with IPVS version %d.%d.%d\n"
@@ -1896,3 +1900,46 @@
 
 	return (offset<top)?0:1;
 }
+
+
+/* Simple backwards compat code to exec old version */
+/* Based on code form module-init-tools 3.1 */
+
+#ifndef NO_BACKWARDS_COMPAT
+
+static void exec_old(char **argv)
+{
+	char *sep;
+	pid_t pid;
+	char ascii_pid[32];
+	char pathname[strlen(argv[0])+1];
+	char oldname[strlen(argv[0])+strlen("ipvsadm.old")+1];
+
+	memset(pathname, 0, strlen(argv[0])+1);
+	sep = strrchr(argv[0], '/');
+	if (sep)
+		memcpy(pathname, argv[0], sep - argv[0]+1);
+	sprintf(oldname, "%sipvsadm.old", pathname);
+
+	/* Use an environment variable for recursion detection */
+	pid = getpid();
+	snprintf(ascii_pid, sizeof(ascii_pid), "%lu", (unsigned long)pid);
+	if (strcmp(getenv("IPVSADM_RECURSE") ?: "", ascii_pid) == 0) {
+		fprintf(stderr, "WARNING: %s: I am not the old version!\n",
+			oldname);
+		return;
+	}
+	setenv("IPVSADM_RECURSE", ascii_pid, 1);
+
+	execvp(oldname, argv);
+	fprintf(stderr,
+		"Kernel requires old ipvsadm, but couldn't run %s: %s\n",
+		oldname, strerror(errno));
+	exit(2);
+}
+
+#else /* NO_BACKWARDS_COMPAT */
+static void exec_old(char **argv)
+{
+}
+#endif /* !NO_BACKWARDS_COMPAT */