From: Masatake YAMATO <yamato@redhat.com>
Date: Fri, 7 Mar 2025 21:42:18 +0000 (+0900)
Subject: lsns: make "-Q NETNSID ..." work even if NETNSID column is not enabled
X-Git-Url: http://git.ipfire.org/?a=commitdiff_plain;h=e04238952520d485d69a0ad4d30bb7ab9a6fd075;p=thirdparty%2Futil-linux.git

lsns: make "-Q NETNSID ..." work even if NETNSID column is not enabled

With the original code, lsns didn't collect values for NETNSID
unless NETNSID column was enabled. As a result, a filter expression
referencing NETNSID value didn't work expectedly.

  # ip netns add X
  # ip netns set X 99999
  # lsns-original -Q 'NETNSID == "99999"
(PRINT NOTHING)
  # lsns-original -Q 'NETNSID == "99999" -o NETNSID
  NETNSID
    99999

With this change, lsns collects values for NETNSID if the
filter expression given to -Q option refers to NETNSID.

  # lsns-new -Q 'NETNSID == "99999"
            NS TYPE NPROCS PID USER COMMAND
    4026535564 net       0     root

Signed-off-by: Masatake YAMATO <yamato@redhat.com>
---

diff --git a/sys-utils/lsns.c b/sys-utils/lsns.c
index 1cf9640b3..a97e7ef3c 100644
--- a/sys-utils/lsns.c
+++ b/sys-utils/lsns.c
@@ -278,6 +278,26 @@ static int column_name_to_id(const char *name, size_t namesz)
 	return -1;
 }
 
+static int is_column_in_filter(int id, struct libscols_filter *filter)
+{
+	int r = 0;
+	const char *name = NULL;
+	struct libscols_iter *itr = scols_new_iter(SCOLS_ITER_FORWARD);
+
+	if (!itr)
+		err(EXIT_FAILURE, _("failed to allocate iterator"));
+
+	while (scols_filter_next_holder(filter, itr, &name, 0) == 0) {
+		if (strcmp(infos[id].name, name) == 0) {
+			r = 1;
+			break;
+		}
+	}
+
+	scols_free_iter(itr);
+	return r;
+}
+
 static int has_column(int id)
 {
 	size_t i;
@@ -1791,7 +1811,8 @@ int main(int argc, char *argv[])
 		err(EXIT_FAILURE, _("failed to allocate UID cache"));
 
 #ifdef HAVE_LINUX_NET_NAMESPACE_H
-	if (has_column(COL_NETNSID))
+	if (has_column(COL_NETNSID)
+	    || (ls.filter && is_column_in_filter(COL_NETNSID, ls.filter)))
 		netlink_fd = socket(AF_NETLINK, SOCK_RAW, NETLINK_ROUTE);
 #endif
 	ls.tab = mnt_new_table_from_file(_PATH_PROC_MOUNTINFO);