* lib/commonio.c: Avoid PATH_MAX. On glibc, we can use realpath

with a NULL argument.
	* src/useradd.c: Replace PATH_MAX by a fixed constant. The buffer
	was not meant as a storage for a path.
	* src/useradd.c, src/newusers.c, src/chpasswd.c: Better detection
	of fgets errors. Lines shall end with a \n, unless we reached the
	end of file.
	* libmisc/copydir.c: Avoid PATH_MAX. Support file paths with any
	length. Added readlink_malloc().

lib/commonio.c

@@ -83,21 +83,36 @@ static bool nscd_need_reload = false;
  */
 int lrename (const char *old, const char *new)
 {
-
-	char resolved_path[PATH_MAX];
 	int res;
+	char *r = NULL;
 
 #if defined(S_ISLNK)
+#ifndef __GLIBC__
+	char resolved_path[PATH_MAX];
+#endif				/* !__GLIBC__ */
 	struct stat sb;
 	if (lstat (new, &sb) == 0 && S_ISLNK (sb.st_mode)) {
-		if (realpath (new, resolved_path) == NULL) {
+#ifdef __GLIBC__ /* now a POSIX.1-2008 feature */
+		r = realpath (new, NULL);
+#else				/* !__GLIBC__ */
+		r = realpath (new, resolved_path);
+#endif				/* !__GLIBC__ */
+		if (NULL == r) {
 			perror ("realpath in lrename()");
 		} else {
-			new = resolved_path;
+			new = r;
 		}
 	}
-#endif
+#endif				/* S_ISLNK */
+
 	res = rename (old, new);
+
+#ifdef __GLIBC__
+	if (NULL != r) {
+		free (r);
+	}
+#endif				/* __GLIBC__ */
+
 	return res;
 }