nwfilter: use virFindFileInPath for needed CLI tools

I am getting rid of determining the path to necessary CLI tools at
compile time. Instead, now the firewall driver has an initialization
function that uses virFindFileInPath() to determine the path to
necessary CLI tools and a shutdown function to free allocated memory.
The rest of the patch mostly deals with availability of the CLI tools
and to not call certain code blocks if a tool is not available and that
strings now have to be built slightly differently.

configure.ac

@@ -295,24 +295,12 @@ if test x"$with_rhel5_api" = x"yes"; then
    AC_DEFINE([WITH_RHEL5_API], [1], [whether building for the RHEL-5 API])
 fi
 
-AC_PATH_PROG([BASH_PATH], [bash], /bin/bash, [/bin:$PATH])
-AC_DEFINE_UNQUOTED([BASH_PATH], "$BASH_PATH", [path to bash binary])
-
 AC_PATH_PROG([IPTABLES_PATH], [iptables], /sbin/iptables, [/usr/sbin:$PATH])
 AC_DEFINE_UNQUOTED([IPTABLES_PATH], "$IPTABLES_PATH", [path to iptables binary])
 
-AC_PATH_PROG([IP6TABLES_PATH], [ip6tables], /sbin/ip6tables, [/usr/sbin:$PATH])
-AC_DEFINE_UNQUOTED([IP6TABLES_PATH], "$IP6TABLES_PATH", [path to ip6tables binary])
-
 AC_PATH_PROG([EBTABLES_PATH], [ebtables], /sbin/ebtables, [/usr/sbin:$PATH])
 AC_DEFINE_UNQUOTED([EBTABLES_PATH], "$EBTABLES_PATH", [path to ebtables binary])
 
-AC_PATH_PROG([GREP_PATH], [grep], /bin/grep, [/bin:$PATH])
-AC_DEFINE_UNQUOTED([GREP_PATH], "$GREP_PATH", [path to grep binary])
-
-AC_PATH_PROG([GAWK_PATH], [gawk], /bin/gawk, [/bin:$PATH])
-AC_DEFINE_UNQUOTED([GAWK_PATH], "$GAWK_PATH", [path to gawk binary])
-
 
 if test "$with_openvz" = "yes"; then
     AC_DEFINE_UNQUOTED([WITH_OPENVZ], 1, [whether OpenVZ driver is enabled])

src/conf/nwfilter_conf.h

@@ -451,6 +451,9 @@ struct domUpdateCBStruct {
 };
 
 
+typedef int (*virNWFilterTechDrvInit)(void);
+typedef void (*virNWFilterTechDrvShutdown)(void);
+
 enum virDomainNetType;
 
 typedef int (*virNWFilterRuleCreateInstance)(virConnectPtr conn,
@@ -484,9 +487,16 @@ typedef int (*virNWFilterRuleFreeInstanceData)(void * _inst);
 typedef int (*virNWFilterRuleDisplayInstanceData)(virConnectPtr conn,
                                                   void *_inst);
 
+enum techDrvFlags {
+    TECHDRV_FLAG_INITIALIZED = (1 << 0),
+};
 
 struct _virNWFilterTechDriver {
     const char *name;
+    enum techDrvFlags flags;
+
+    virNWFilterTechDrvInit init;
+    virNWFilterTechDrvShutdown shutdown;
 
     virNWFilterRuleCreateInstance createRuleInstance;
     virNWFilterRuleApplyNewRules applyNewRules;

src/nwfilter/nwfilter_driver.c

@@ -70,6 +70,8 @@ nwfilterDriverStartup(int privileged) {
     if (virNWFilterLearnInit() < 0)
         return -1;
 
+    virNWFilterTechDriversInit();
+
     if (virNWFilterConfLayerInit(virNWFilterDomainFWUpdateCB) < 0)
         goto conf_init_err;
 
@@ -126,6 +128,7 @@ alloc_err_exit:
     virNWFilterConfLayerShutdown();
 
 conf_init_err:
+    virNWFilterTechDriversShutdown();
     virNWFilterLearnShutdown();
 
     return -1;

src/nwfilter/nwfilter_gentech_driver.c

@@ -50,12 +50,35 @@ static virNWFilterTechDriverPtr filter_tech_drivers[] = {
 };
 
 
+void virNWFilterTechDriversInit() {
+    int i = 0;
+    while (filter_tech_drivers[i]) {
+        if (!(filter_tech_drivers[i]->flags & TECHDRV_FLAG_INITIALIZED))
+            filter_tech_drivers[i]->init();
+        i++;
+    }
+}
+
+
+void virNWFilterTechDriversShutdown() {
+    int i = 0;
+    while (filter_tech_drivers[i]) {
+        if ((filter_tech_drivers[i]->flags & TECHDRV_FLAG_INITIALIZED))
+            filter_tech_drivers[i]->shutdown();
+        i++;
+    }
+}
+
+
 virNWFilterTechDriverPtr
 virNWFilterTechDriverForName(const char *name) {
     int i = 0;
     while (filter_tech_drivers[i]) {
-       if (STREQ(filter_tech_drivers[i]->name, name))
+       if (STREQ(filter_tech_drivers[i]->name, name)) {
+           if ((filter_tech_drivers[i]->flags & TECHDRV_FLAG_INITIALIZED) == 0)
+               break;
            return filter_tech_drivers[i];
+       }
        i++;
     }
     return NULL;

src/nwfilter/nwfilter_gentech_driver.h

@@ -28,6 +28,8 @@ virNWFilterTechDriverPtr virNWFilterTechDriverForName(const char *name);
 int virNWFilterRuleInstAddData(virNWFilterRuleInstPtr res,
                                void *data);
 
+void virNWFilterTechDriversInit(void);
+void virNWFilterTechDriversShutdown(void);
 
 enum instCase {
     INSTANTIATE_ALWAYS,