sd-bus: add new API call sd_bus_error_move()

This new call move an sd_bus_error into another one.

man/rules/meson.build

@@ -180,6 +180,7 @@ manpages = [
    'sd_bus_error_get_errno',
    'sd_bus_error_has_name',
    'sd_bus_error_is_set',
+   'sd_bus_error_move',
    'sd_bus_error_set',
    'sd_bus_error_set_const',
    'sd_bus_error_set_errno',

man/sd_bus_error.xml

@@ -31,6 +31,7 @@
     <refname>sd_bus_error_set_errnofv</refname>
     <refname>sd_bus_error_get_errno</refname>
     <refname>sd_bus_error_copy</refname>
+    <refname>sd_bus_error_move</refname>
     <refname>sd_bus_error_is_set</refname>
     <refname>sd_bus_error_has_name</refname>
 
@@ -114,6 +115,12 @@
         <paramdef>const sd_bus_error *<parameter>e</parameter></paramdef>
       </funcprototype>
 
+      <funcprototype>
+        <funcdef>int <function>sd_bus_error_move</function></funcdef>
+        <paramdef>sd_bus_error *<parameter>dst</parameter></paramdef>
+        <paramdef>sd_bus_error *<parameter>e</parameter></paramdef>
+      </funcprototype>
+
       <funcprototype>
         <funcdef>int <function>sd_bus_error_is_set</function></funcdef>
         <paramdef>const sd_bus_error *<parameter>e</parameter></paramdef>
@@ -245,6 +252,14 @@
     Otherwise, they will be copied. Returns a converted
     <varname>errno</varname>-like, negative error code.</para>
 
+    <para><function>sd_bus_error_move()</function> is similar to <function>sd_bus_error_copy()</function>, but will
+    move any error information from <parameter>e</parameter> into <parameter>dst</parameter>, resetting the
+    former. This function cannot fail, as no new memory is allocated. Note that if <parameter>e</parameter> is not set
+    (or <constant>NULL</constant>) <parameter>dst</parameter> is initializated to
+    <constant>SD_BUS_ERROR_NULL</constant>. Moreover, if <parameter>dst</parameter> is <constant>NULL</constant> no
+    operation is executed on it and and resources held by <parameter>e</parameter> are freed and reset. Returns a
+    converted <varname>errno</varname>-like, negative error code.</para>
+
     <para><function>sd_bus_error_is_set()</function> will return a
     non-zero value if <parameter>e</parameter> is
     non-<constant>NULL</constant> and an error has been set,
@@ -287,9 +302,8 @@
     <constant>NULL</constant>, and a positive errno value mapped from
     <parameter>e-&gt;name</parameter> otherwise.</para>
 
-    <para><function>sd_bus_error_copy()</function> returns 0 or a
-    positive integer on success, and a negative error value converted
-    from the error name otherwise.</para>
+    <para><function>sd_bus_error_copy()</function> and <function>sd_bus_error_move()</function> return 0 or a positive
+    integer on success, and a negative error value converted from the error name otherwise.</para>
 
     <para><function>sd_bus_error_is_set()</function> returns a
     non-zero value when <parameter>e</parameter> and the

src/libsystemd/libsystemd.sym

@@ -577,6 +577,8 @@ global:
         sd_bus_set_method_call_timeout;
         sd_bus_get_method_call_timeout;
 
+        sd_bus_error_move;
+
         sd_device_ref;
         sd_device_unref;
 

src/libsystemd/sd-bus/bus-error.c

@@ -308,6 +308,28 @@ finish:
         return -bus_error_name_to_errno(e->name);
 }
 
+_public_ int sd_bus_error_move(sd_bus_error *dest, sd_bus_error *e) {
+        int r;
+
+        if (!sd_bus_error_is_set(e)) {
+
+                if (dest)
+                        *dest = SD_BUS_ERROR_NULL;
+
+                return 0;
+        }
+
+        r = -bus_error_name_to_errno(e->name);
+
+        if (dest) {
+                *dest = *e;
+                *e = SD_BUS_ERROR_NULL;
+        } else
+                sd_bus_error_free(e);
+
+        return r;
+}
+
 _public_ int sd_bus_error_set_const(sd_bus_error *e, const char *name, const char *message) {
         if (!name)
                 return 0;

src/systemd/sd-bus.h

@@ -422,6 +422,7 @@ int sd_bus_error_set_errnof(sd_bus_error *e, int error, const char *format, ...)
 int sd_bus_error_set_errnofv(sd_bus_error *e, int error, const char *format, va_list ap) _sd_printf_(3,0);
 int sd_bus_error_get_errno(const sd_bus_error *e);
 int sd_bus_error_copy(sd_bus_error *dest, const sd_bus_error *e);
+int sd_bus_error_move(sd_bus_error *dest, sd_bus_error *e);
 int sd_bus_error_is_set(const sd_bus_error *e);
 int sd_bus_error_has_name(const sd_bus_error *e, const char *name);