From: Christian Brauner <christian.brauner@ubuntu.com>
Date: Fri, 30 Jul 2021 07:15:14 +0000 (+0200)
Subject: mount_utils: add mount_fd()
X-Git-Tag: lxc-5.0.0~127^2~7
X-Git-Url: http://git.ipfire.org/cgi-bin/gitweb.cgi?a=commitdiff_plain;h=b370ffcf7e66344d543c84847f91151860626f51;p=thirdparty%2Flxc.git

mount_utils: add mount_fd()

Signed-off-by: Christian Brauner <christian.brauner@ubuntu.com>
---

diff --git a/src/lxc/mount_utils.c b/src/lxc/mount_utils.c
index 1cf71dadd..77498bbf3 100644
--- a/src/lxc/mount_utils.c
+++ b/src/lxc/mount_utils.c
@@ -635,3 +635,37 @@ int mount_beneath_fd(int fd, const char *source, const char *target,
 	TRACE("Mounted \"%s\" to \"%s\"", source, buf_target);
 	return 0;
 }
+
+int mount_fd(int fd_source, int fd_target, const char *fs_name,
+	     unsigned int flags, const void *data)
+{
+	int ret;
+	char buf_source[LXC_PROC_PID_FD_LEN], buf_target[LXC_PROC_PID_FD_LEN];
+	char *source = buf_source, *target = buf_target;
+
+	if (fd_source < 0) {
+		source = NULL;
+	} else {
+		ret = strnprintf(buf_source, sizeof(buf_source),
+				 "/proc/self/fd/%d", fd_source);
+		if (ret < 0)
+			return ret;
+	}
+
+	if (fd_target < 0) {
+		target = NULL;
+	} else {
+		ret = strnprintf(buf_target, sizeof(buf_target),
+				 "/proc/self/fd/%d", fd_target);
+		if (ret < 0)
+			return ret;
+	}
+
+	ret = mount(source, target, "none", MS_BIND, 0);
+	if (ret < 0)
+		return syserror("Failed to mount \"%s\" to \"%s\"",
+				maybe_empty(source), maybe_empty(target));
+
+	TRACE("Mounted \"%s\" to \"%s\"", maybe_empty(source), maybe_empty(target));
+	return 0;
+}
diff --git a/src/lxc/mount_utils.h b/src/lxc/mount_utils.h
index 17ff4698f..4caf34b2f 100644
--- a/src/lxc/mount_utils.h
+++ b/src/lxc/mount_utils.h
@@ -224,5 +224,7 @@ __hidden extern bool can_use_bind_mounts(void);
 __hidden extern int mount_beneath_fd(int fd, const char *source,
 				     const char *target, const char *fs_name,
 				     unsigned int flags, const void *data);
+__hidden extern int mount_fd(int fd_source, int fd_target, const char *fs_name,
+			     unsigned int flags, const void *data);
 
 #endif /* __LXC_MOUNT_UTILS_H */