lib: Exec func on each netns

Added possibility to run some func on each netns.
Signed-off-by: Vadim Kochan <vadim4j@gmail.com>

include/namespace.h

@@ -44,5 +44,11 @@ static inline int setns(int fd, int nstype)
 
 extern int netns_switch(char *netns);
 extern int netns_get_fd(const char *netns);
+extern int netns_foreach(int (*func)(char *nsname, void *arg), void *arg);
+
+struct netns_func {
+	int (*func)(char *nsname, void *arg);
+	void *arg;
+};
 
 #endif /* __NAMESPACE_H__ */

include/utils.h

@@ -5,6 +5,7 @@
 #include <asm/types.h>
 #include <resolv.h>
 #include <stdlib.h>
+#include <stdbool.h>
 
 #include "libnetlink.h"
 #include "ll_map.h"
@@ -162,4 +163,7 @@ int iplink_parse(int argc, char **argv, struct iplink_req *req,
 		char **name, char **type, char **link, char **dev,
 		int *group, int *index);
 
+extern int do_each_netns(int (*func)(char *nsname, void *arg), void *arg,
+		bool show_label);
+
 #endif /* __UTILS_H__ */

lib/namespace.c

@@ -99,3 +99,25 @@ int netns_get_fd(const char *name)
 	}
 	return open(path, O_RDONLY);
 }
+
+int netns_foreach(int (*func)(char *nsname, void *arg), void *arg)
+{
+	DIR *dir;
+	struct dirent *entry;
+
+	dir = opendir(NETNS_RUN_DIR);
+	if (!dir)
+		return -1;
+
+	while ((entry = readdir(dir)) != NULL) {
+		if (strcmp(entry->d_name, ".") == 0)
+			continue;
+		if (strcmp(entry->d_name, "..") == 0)
+			continue;
+		if (func(entry->d_name, arg))
+			break;
+	}
+
+	closedir(dir);
+	return 0;
+}

lib/utils.c

@@ -31,6 +31,7 @@
 
 
 #include "utils.h"
+#include "namespace.h"
 
 int timestamp_short = 0;
 
@@ -878,3 +879,30 @@ void print_nlmsg_timestamp(FILE *fp, const struct nlmsghdr *n)
 	tstr[strlen(tstr)-1] = 0;
 	fprintf(fp, "Timestamp: %s %lu us\n", tstr, usecs);
 }
+
+static int on_netns(char *nsname, void *arg)
+{
+	struct netns_func *f = arg;
+
+	if (netns_switch(nsname))
+		return -1;
+
+	return f->func(nsname, f->arg);
+}
+
+static int on_netns_label(char *nsname, void *arg)
+{
+	printf("\nnetns: %s\n", nsname);
+	return on_netns(nsname, arg);
+}
+
+int do_each_netns(int (*func)(char *nsname, void *arg), void *arg,
+		bool show_label)
+{
+	struct netns_func nsf = { .func = func, .arg = arg };
+
+	if (show_label)
+		return netns_foreach(on_netns_label, &nsf);
+
+	return netns_foreach(on_netns, &nsf);
+}