From: Christian Brauner <christian.brauner@ubuntu.com>
Date: Tue, 17 Aug 2021 08:38:44 +0000 (+0200)
Subject: file_utils: add same_device() helper
X-Git-Tag: lxc-5.0.0~108^2~11
X-Git-Url: http://git.ipfire.org/cgi-bin/gitweb.cgi?a=commitdiff_plain;h=d06abe2f9c47c2a355b3ea1a5194abe3fa8d7cb5;p=thirdparty%2Flxc.git

file_utils: add same_device() helper

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

diff --git a/src/lxc/file_utils.c b/src/lxc/file_utils.c
index a361d188e..eaa9a5a40 100644
--- a/src/lxc/file_utils.c
+++ b/src/lxc/file_utils.c
@@ -766,3 +766,35 @@ bool same_file_lax(int fda, int fdb)
 	return (st_fda.st_dev == st_fdb.st_dev) &&
 	       (st_fda.st_ino == st_fdb.st_ino);
 }
+
+bool same_device(int fda, const char *patha, int fdb, const char *pathb)
+{
+	int ret;
+	mode_t modea, modeb;
+	struct stat st_fda, st_fdb;
+
+        if (fda == fdb)
+                return true;
+
+	if (is_empty_string(patha))
+		ret = fstat(fda, &st_fda);
+	else
+		ret = fstatat(fda, patha, &st_fda, 0);
+	if (ret)
+		return false;
+
+	if (is_empty_string(pathb))
+		ret = fstat(fdb, &st_fdb);
+	else
+		ret = fstatat(fdb, pathb, &st_fdb, 0);
+	if (ret)
+		return false;
+
+	errno = EINVAL;
+	modea = (st_fda.st_mode & S_IFMT);
+	modeb = (st_fdb.st_mode & S_IFMT);
+	if (modea != modeb || !IN_SET(modea, S_IFCHR, S_IFBLK))
+		return false;
+
+	return (st_fda.st_rdev == st_fdb.st_rdev);
+}
diff --git a/src/lxc/file_utils.h b/src/lxc/file_utils.h
index faf7454dd..c9765da50 100644
--- a/src/lxc/file_utils.h
+++ b/src/lxc/file_utils.h
@@ -123,4 +123,7 @@ static inline int dup_cloexec(int fd)
 	return move_fd(fd_dup);
 }
 
+__hidden extern bool same_device(int fda, const char *patha, int fdb,
+				 const char *pathb);
+
 #endif /* __LXC_FILE_UTILS_H */