Add SPDX license identifiers to source files under the LGPL

[thirdparty/systemd.git] / src / basic / user-util.c

diff --git a/src/basic/user-util.c b/src/basic/user-util.c
index de6c93056eca7c140241fe834520b9621804f1dc..24686591c2365ed13737e9e7a33476ccac2949ff 100644 (file)
--- a/src/basic/user-util.c
+++ b/src/basic/user-util.c
@@ -1,3 +1,4 @@
+/* SPDX-License-Identifier: LGPL-2.1+ */
 /***
   This file is part of systemd.
 
@@ -34,7 +35,7 @@
 #include "alloc-util.h"
 #include "fd-util.h"
 #include "fileio.h"
-#include "formats-util.h"
+#include "format-util.h"
 #include "macro.h"
 #include "missing.h"
 #include "parse-util.h"
@@ -46,6 +47,8 @@
 
 bool uid_is_valid(uid_t uid) {
 
+        /* Also see POSIX IEEE Std 1003.1-2008, 2016 Edition, 3.436. */
+
         /* Some libc APIs use UID_INVALID as special placeholder */
         if (uid == (uid_t) UINT32_C(0xFFFFFFFF))
                 return false;
@@ -519,7 +522,15 @@ bool valid_user_group_name(const char *u) {
         const char *i;
         long sz;
 
-        /* Checks if the specified name is a valid user/group name. */
+        /* Checks if the specified name is a valid user/group name. Also see POSIX IEEE Std 1003.1-2008, 2016 Edition,
+         * 3.437. We are a bit stricter here however. Specifically we deviate from POSIX rules:
+         *
+         * - We don't allow any dots (this would break chown syntax which permits dots as user/group name separator)
+         * - We require that names fit into the appropriate utmp field
+         * - We don't allow empty user names
+         *
+         * Note that other systems are even more restrictive, and don't permit underscores or uppercase characters.
+         */
 
         if (isempty(u))
                 return false;
@@ -533,8 +544,7 @@ bool valid_user_group_name(const char *u) {
                 if (!(*i >= 'a' && *i <= 'z') &&
                     !(*i >= 'A' && *i <= 'Z') &&
                     !(*i >= '0' && *i <= '9') &&
-                    *i != '_' &&
-                    *i != '-')
+                    !IN_SET(*i, '_', '-'))
                         return false;
         }