From db92d3c50c716a383ede28911de4ea089ae94290 Mon Sep 17 00:00:00 2001
From: Lennart Poettering <lennart@poettering.net>
Date: Thu, 21 Jul 2016 20:23:51 +0200
Subject: [PATCH] sd-id128: handle NULL return parameter in
 sd_id128_from_string() nicer

If the return parameter is NULL, simply validate the string, and return no
error.
---
 man/sd_id128_to_string.xml         | 12 +++++-------
 src/libelogind/sd-id128/sd-id128.c |  4 ++--
 2 files changed, 7 insertions(+), 9 deletions(-)

diff --git a/man/sd_id128_to_string.xml b/man/sd_id128_to_string.xml
index 8f3efc145..11bee6919 100644
--- a/man/sd_id128_to_string.xml
+++ b/man/sd_id128_to_string.xml
@@ -74,13 +74,11 @@
     lowercase hexadecimal digits and be terminated by a
     <constant>NUL</constant> byte.</para>
 
-    <para><function>sd_id128_from_string()</function> implements the
-    reverse operation: it takes a 33 character string with 32
-    hexadecimal digits (either lowercase or uppercase, terminated by
-    <constant>NUL</constant>) and parses them back into a 128-bit ID
-    returned in <parameter>ret</parameter>. Alternatively, this call
-    can also parse a 37-character string with a 128-bit ID formatted
-    as RFC UUID.</para>
+    <para><function>sd_id128_from_string()</function> implements the reverse operation: it takes a 33 character string
+    with 32 hexadecimal digits (either lowercase or uppercase, terminated by <constant>NUL</constant>) and parses them
+    back into a 128-bit ID returned in <parameter>ret</parameter>. Alternatively, this call can also parse a
+    37-character string with a 128-bit ID formatted as RFC UUID. If <parameter>ret</parameter> is passed as NULL the
+    function will validate the passed ID string, but not actually return it in parsed form.</para>
 
     <para>For more information about the <literal>sd_id128_t</literal>
     type see
diff --git a/src/libelogind/sd-id128/sd-id128.c b/src/libelogind/sd-id128/sd-id128.c
index 1470e4c01..9f47d04e6 100644
--- a/src/libelogind/sd-id128/sd-id128.c
+++ b/src/libelogind/sd-id128/sd-id128.c
@@ -52,7 +52,6 @@ _public_ int sd_id128_from_string(const char s[], sd_id128_t *ret) {
         bool is_guid = false;
 
         assert_return(s, -EINVAL);
-        assert_return(ret, -EINVAL);
 
         for (n = 0, i = 0; n < 16;) {
                 int a, b;
@@ -90,7 +89,8 @@ _public_ int sd_id128_from_string(const char s[], sd_id128_t *ret) {
         if (s[i] != 0)
                 return -EINVAL;
 
-        *ret = t;
+        if (ret)
+                *ret = t;
         return 0;
 }
 
-- 
2.30.2