Check that the new fields set with -u, -s, -l, -g, -f, -e, -d, and -c

differ from the old ones. If a requested new value is equal to the old
one, no changes will be performed for that field. If no fields are
changed, usermod will exist successfully with a warning. This avoids
logging changes to syslog when there are actually no changes.

ChangeLog

@@ -1,3 +1,12 @@
+2008-01-23  Nicolas François  <nicolas.francois@centraliens.net>
+
+	* NEWS, src/usermod.c: Check that the new fields set with -u, -s,
+	-l, -g, -f, -e, -d, and -c differ from the old ones. If a
+	requested new value is equal to the old one, no changes will
+	be performed for that field. If no fields are changed, usermod
+	will exist successfully with a warning. This avoids logging
+	changes to syslog when there are actually no changes.
+
 2008-01-23  Nicolas François  <nicolas.francois@centraliens.net>
 
 	* src/usermod.c: Always define user_newcomment, user_newshell,

NEWS

@@ -50,6 +50,11 @@ shadow-4.1.0 -> shadow-4.1.1						UNRELEASED
 - usermod
   * Keep the access and modification time of files when moving an user's home
     directory.
+  * Check that the new fields set with -u, -s, -l, -g, -f, -e, -d, and -c
+    differ from the old ones. If a requested new value is equal to the old
+    one, no changes will be performed for that field. If no fields are
+    changed, usermod will exist successfully with a warning. This avoids
+    logging changes to syslog when there are actually no changes.
 - vipw/vigr
   * Recommend editing the shadowed (resp. regular) file if the regular (resp.
     shadowed) file was edited.

src/usermod.c

@@ -930,15 +930,7 @@ static void process_flags (int argc, char **argv)
 						 Prog, optarg);
 					exit (E_BAD_ARG);
 				}
-
-				/*
-				 * If the name does not really change, we mustn't
-				 * set the flag as this will cause rather serious
-				 * problems later!
-				 */
-				if (strcmp (user_name, optarg))
 				lflg++;
-
 				user_newname = optarg;
 				break;
 			case 'L':
@@ -982,6 +974,38 @@ static void process_flags (int argc, char **argv)
 		fprintf (stderr, _("%s: no flags given\n"), Prog);
 		exit (E_USAGE);
 	}
+
+	if (user_newid == user_id) {
+		uflg = 0;
+	}
+	if (user_newgid == user_gid) {
+		gflg = 0;
+	}
+	if (strcmp (user_newshell, user_shell) == 0) {
+		sflg = 0;
+	}
+	if (strcmp (user_newname, user_name) == 0) {
+		lflg = 0;
+	}
+	if (user_newinactive == user_inactive) {
+		fflg = 0;
+	}
+	if (user_newexpire == user_expire) {
+		eflg = 0;
+	}
+	if (strcmp (user_newhome, user_home) == 0) {
+		dflg = 0;
+	}
+	if (strcmp (user_newcomment, user_comment) == 0) {
+		cflg = 0;
+	}
+
+	if (Uflg + uflg + sflg + pflg + oflg + mflg + Lflg + lflg + Gflg +
+	    gflg + fflg + eflg + dflg + cflg == 0) {
+		fprintf (stderr, _("%s: no changes\n"), Prog);
+		exit (E_SUCCESS);
+	}
+
 	if (!is_shadow_pwd && (eflg || fflg)) {
 		fprintf (stderr,
 			 _