add logic to support the --concurrent option: use a file lock to support concurrent scripts running ebtables
diff --git a/ebtables.c b/ebtables.c
index d71a981..d5d24b0 100644
--- a/ebtables.c
+++ b/ebtables.c
@@ -26,6 +26,7 @@
#include <stdio.h>
#include <stdlib.h>
#include <inttypes.h>
+#include <signal.h>
#include "include/ebtables_u.h"
#include "include/ethernetdb.h"
@@ -91,6 +92,7 @@
{ "atomic-file" , required_argument, 0, 9 },
{ "atomic-save" , no_argument , 0, 10 },
{ "init-table" , no_argument , 0, 11 },
+ { "concurrent" , no_argument , 0, 13 },
{ 0 }
};
@@ -374,6 +376,7 @@
"--set-counters -c chain\n"
" pcnt bcnt : set the counters of the to be added rule\n"
"--modprobe -M program : try to insert modules using this program\n"
+"--concurrent : use a file lock to support concurrent scripts\n"
"--version -V : print package version\n\n"
"Environment variable:\n"
ATOMIC_ENV_VARIABLE " : if set <FILE> (see above) will equal its value"
@@ -525,6 +528,12 @@
ebt_iterate_targets(merge_target);
}
+/* signal handler, installed when the option --concurrent is specified. */
+static void sighandler(int signum)
+{
+ exit(-1);
+}
+
/* We use exec_style instead of #ifdef's because ebtables.so is a shared object. */
int do_command(int argc, char *argv[], int exec_style,
struct ebt_u_replace *replace_)
@@ -1037,6 +1046,11 @@
replace->filename = (char *)malloc(strlen(optarg) + 1);
strcpy(replace->filename, optarg);
break;
+ case 13 : /* concurrent */
+ signal(SIGINT, sighandler);
+ signal(SIGTERM, sighandler);
+ use_lockfd = 1;
+ break;
case 1 :
if (!strcmp(optarg, "!"))
ebt_check_inverse2(optarg);