From: Masatake YAMATO <yamato@redhat.com>
Date: Sat, 29 Nov 2025 19:53:24 +0000 (+0900)
Subject: lsfd: (refactor) make call_with_foreign_fd reusable
X-Git-Tag: v2.43-devel~95^2~4
X-Git-Url: http://git.ipfire.org/gitweb.cgi?a=commitdiff_plain;h=9d76cfb729bfe7995f7626f150f9e727636a4bd2;p=thirdparty%2Futil-linux.git

lsfd: (refactor) make call_with_foreign_fd reusable

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

diff --git a/lsfd-cmd/Makemodule.am b/lsfd-cmd/Makemodule.am
index 0f96ce147..4674cff9c 100644
--- a/lsfd-cmd/Makemodule.am
+++ b/lsfd-cmd/Makemodule.am
@@ -20,7 +20,8 @@ lsfd_SOURCES = \
 	lsfd-cmd/unkn.c \
 	lsfd-cmd/fifo.c \
 	lsfd-cmd/pidfd.h \
-	lsfd-cmd/pidfd.c
+	lsfd-cmd/pidfd.c \
+	lsfd-cmd/util.c
 lsfd_LDADD = $(LDADD) $(MQ_LIBS) libsmartcols.la libcommon.la
 lsfd_CFLAGS = $(AM_CFLAGS) -I$(ul_libsmartcols_incdir)
 endif
diff --git a/lsfd-cmd/cdev.c b/lsfd-cmd/cdev.c
index 322e38b4a..989ffa481 100644
--- a/lsfd-cmd/cdev.c
+++ b/lsfd-cmd/cdev.c
@@ -466,28 +466,6 @@ static int cdev_tun_handle_fdinfo(struct cdev *cdev, const char *key, const char
 }
 
 #ifdef TUNGETDEVNETNS
-static int call_with_foreign_fd(pid_t target_pid, int target_fd,
-				int (*fn)(int, void*), void *data)
-{
-	int pidfd, tfd, r;
-
-	pidfd = pidfd_open(target_pid, 0);
-	if (pidfd < 0)
-		return pidfd;
-
-	tfd = pidfd_getfd(pidfd, target_fd, 0);
-	if (tfd < 0) {
-		close(pidfd);
-		return tfd;
-	}
-
-	r = fn(tfd, data);
-
-	close(tfd);
-	close(pidfd);
-	return r;
-}
-
 static int cdev_tun_get_devnetns(int tfd, void *data)
 {
 	struct tundata *tundata = data;
diff --git a/lsfd-cmd/lsfd.h b/lsfd-cmd/lsfd.h
index 626027a4a..553546d8b 100644
--- a/lsfd-cmd/lsfd.h
+++ b/lsfd-cmd/lsfd.h
@@ -338,4 +338,10 @@ bool is_multiplexed_by_eventpoll(int fd, struct list_head *eventpolls);
  */
 bool is_pidfs_dev(dev_t dev);
 
+/*
+ * Utility
+ */
+int call_with_foreign_fd(pid_t target_pid, int target_fd,
+			 int (*fn)(int, void*), void *data);
+
 #endif /* UTIL_LINUX_LSFD_H */
diff --git a/lsfd-cmd/meson.build b/lsfd-cmd/meson.build
index 856d5cdd0..f10ca1a41 100644
--- a/lsfd-cmd/meson.build
+++ b/lsfd-cmd/meson.build
@@ -12,6 +12,7 @@ lsfd_sources = files (
   'unkn.c',
   'fifo.c',
   'pidfd.c',
+  'util.c',
 )
 
 lsfd_manadocs = files('lsfd.1.adoc')
diff --git a/lsfd-cmd/sock-xinfo.c b/lsfd-cmd/sock-xinfo.c
index 7e6ca0cf8..d31067009 100644
--- a/lsfd-cmd/sock-xinfo.c
+++ b/lsfd-cmd/sock-xinfo.c
@@ -231,24 +231,16 @@ void load_sock_xinfo(struct path_cxt *pc, const char *name, ino_t netns)
 	}
 }
 
-void load_fdsk_xinfo(struct proc *proc, int fd)
+static int load_fdsk_xinfo_cb(int sk, void *data __attribute__((__unused__)))
 {
-	int pidfd, sk, nsfd;
+	int nsfd;
 	struct netns *nsobj;
 	struct stat sb;
-
-	/* This is additional/extra information, ignoring failures. */
-	pidfd = pidfd_open(proc->pid, 0);
-	if (pidfd < 0)
-		return;
-
-	sk = pidfd_getfd(pidfd, fd, 0);
-	if (sk < 0)
-		goto out_pidfd;
+	int r = -1;
 
 	nsfd = ioctl(sk, SIOCGSKNS);
 	if (nsfd < 0)
-		goto out_sk;
+		return nsfd;
 
 	if (fstat(nsfd, &sb) < 0)
 		goto out_nsfd;
@@ -256,15 +248,20 @@ void load_fdsk_xinfo(struct proc *proc, int fd)
 	if (is_sock_xinfo_loaded(sb.st_ino))
 		goto out_nsfd;
 
+	r = 0;
 	nsobj = mark_sock_xinfo_loaded(sb.st_ino);
 	load_sock_xinfo_with_fd(nsfd, nsobj);
 
 out_nsfd:
 	close(nsfd);
-out_sk:
-	close(sk);
-out_pidfd:
-	close(pidfd);
+	return r;
+}
+
+void load_fdsk_xinfo(struct proc *proc, int fd)
+{
+	call_with_foreign_fd(proc->pid, fd,
+			     load_fdsk_xinfo_cb, NULL);
+
 }
 
 void initialize_sock_xinfos(void)
diff --git a/lsfd-cmd/util.c b/lsfd-cmd/util.c
new file mode 100644
index 000000000..f3e3a727c
--- /dev/null
+++ b/lsfd-cmd/util.c
@@ -0,0 +1,52 @@
+/*
+ * util.c - utilities used in lsfd
+ *
+ * Copyright (C) 2021-2026 Red Hat, Inc. All rights reserved.
+ * Written by Masatake YAMATO <yamato@redhat.com>
+ *
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation; either version 2 of the License, or
+ * (at your option) any later version.
+ *
+ * This program is distributed in the hope that it would be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program; if not, write to the Free Software Foundation,
+ * Inc., 59 Temple Place, Suite 330, Boston, MA  02111-1307  USA
+ */
+#include "lsfd.h"		/* prototype decl for call_with_foreign_fd */
+#include "pidfd-utils.h"
+
+static int call_with_foreign_fd_via_pidfd(int pidfd, int target_fd,
+					  int (*fn)(int, void*), void *data)
+{
+	int tfd, r;
+
+	tfd = pidfd_getfd(pidfd, target_fd, 0);
+	if (tfd < 0)
+		return tfd;
+
+	r = fn(tfd, data);
+
+	close(tfd);
+	return r;
+}
+
+int call_with_foreign_fd(pid_t target_pid, int target_fd,
+			 int (*fn)(int, void*), void *data)
+{
+	int pidfd, r;
+
+	pidfd = pidfd_open(target_pid, 0);
+	if (pidfd < 0)
+		return pidfd;
+
+	r = call_with_foreign_fd_via_pidfd(pidfd, target_fd, fn, data);
+
+	close(pidfd);
+	return r;
+}