Merge pull request #27701 from poettering/switch-root-same-file

switch-root: use same_files() logic when checking whether new and old root dir are actually the same

src/basic/namespace-util.c

@@ -109,7 +109,7 @@ int namespace_enter(int pidns_fd, int mntns_fd, int netns_fd, int userns_fd, int
                 /* Can't setns to your own userns, since then you could escalate from non-root to root in
                  * your own namespace, so check if namespaces are equal before attempting to enter. */
 
-                r = files_same(FORMAT_PROC_FD_PATH(userns_fd), "/proc/self/ns/user", 0);
+                r = inode_same_at(userns_fd, "", AT_FDCWD, "/proc/self/ns/user", AT_EMPTY_PATH);
                 if (r < 0)
                         return r;
                 if (r)

src/basic/path-util.c

@@ -485,8 +485,8 @@ int path_compare(const char *a, const char *b) {
         }
 }
 
-bool path_equal_or_files_same(const char *a, const char *b, int flags) {
-        return path_equal(a, b) || files_same(a, b, flags) > 0;
+bool path_equal_or_inode_same(const char *a, const char *b, int flags) {
+        return path_equal(a, b) || inode_same(a, b, flags) > 0;
 }
 
 int path_compare_filename(const char *a, const char *b) {

src/basic/path-util.h

@@ -77,7 +77,7 @@ static inline bool path_equal_filename(const char *a, const char *b) {
         return path_compare_filename(a, b) == 0;
 }
 
-bool path_equal_or_files_same(const char *a, const char *b, int flags);
+bool path_equal_or_inode_same(const char *a, const char *b, int flags);
 
 char* path_extend_internal(char **x, ...);
 #define path_extend(x, ...) path_extend_internal(x, __VA_ARGS__, POINTER_MAX)

src/basic/process-util.c

@@ -946,7 +946,7 @@ int pid_from_same_root_fs(pid_t pid) {
 
         root = procfs_file_alloca(pid, "root");
 
-        return files_same(root, "/proc/1/root", 0);
+        return inode_same(root, "/proc/1/root", 0);
 }
 
 bool is_main_thread(void) {

src/basic/socket-util.c

@@ -223,7 +223,7 @@ bool socket_address_equal(const SocketAddress *a, const SocketAddress *b) {
                         return false;
 
                 if (a->sockaddr.un.sun_path[0]) {
-                        if (!path_equal_or_files_same(a->sockaddr.un.sun_path, b->sockaddr.un.sun_path, 0))
+                        if (!path_equal_or_inode_same(a->sockaddr.un.sun_path, b->sockaddr.un.sun_path, 0))
                                 return false;
                 } else {
                         if (a->size != b->size)

src/basic/stat-util.c

@@ -183,16 +183,18 @@ int path_is_read_only_fs(const char *path) {
         return fd_is_read_only_fs(fd);
 }
 
-int files_same(const char *filea, const char *fileb, int flags) {
+int inode_same_at(int fda, const char *filea, int fdb, const char *fileb, int flags) {
         struct stat a, b;
 
+        assert(fda >= 0 || fda == AT_FDCWD);
         assert(filea);
+        assert(fdb >= 0 || fdb == AT_FDCWD);
         assert(fileb);
 
-        if (fstatat(AT_FDCWD, filea, &a, flags) < 0)
+        if (fstatat(fda, filea, &a, flags) < 0)
                 return log_debug_errno(errno, "Cannot stat %s: %m", filea);
 
-        if (fstatat(AT_FDCWD, fileb, &b, flags) < 0)
+        if (fstatat(fdb, fileb, &b, flags) < 0)
                 return log_debug_errno(errno, "Cannot stat %s: %m", fileb);
 
         return stat_inode_same(&a, &b);

src/basic/stat-util.h

@@ -37,7 +37,11 @@ static inline int null_or_empty_path(const char *fn) {
 
 int path_is_read_only_fs(const char *path);
 
-int files_same(const char *filea, const char *fileb, int flags);
+int inode_same_at(int fda, const char *filea, int fdb, const char *fileb, int flags);
+
+static inline int inode_same(const char *filea, const char *fileb, int flags) {
+        return inode_same_at(AT_FDCWD, filea, AT_FDCWD, fileb, flags);
+}
 
 /* The .f_type field of struct statfs is really weird defined on
  * different archs. Let's give its type a name. */

src/basic/virt.c

@@ -891,7 +891,7 @@ int running_in_chroot(void) {
         if (getpid_cached() == 1)
                 return false;  /* We're PID 1, we can't be in a chroot. */
 
-        r = files_same("/proc/1/root", "/", 0);
+        r = inode_same("/proc/1/root", "/", 0);
         if (r == -ENOENT) {
                 r = proc_mounted();
                 if (r == 0) {