sd-bus: always fill in sd_bus_error paramters, on error

Whenever one of our calls is invoked with a non-NULL, writable
sd_bus_error parameter, let's fill in some valid error on failure. We
previously only filled in remote errors, but never local errors, which is
hard to handle by users. Hence, let's clean this up to always fill in
the error.

This introduces a new bus_assert_return() macro that works like
assert_return() but optionally also initializes a bus_error struct.

Fixes #224.

Based on a patch by Umut Tezduyar.

1 files changed, 40 insertions, 27 deletions

diff --git a/src/libsystemd/sd-bus/sd-bus.c b/src/libsystemd/sd-bus/sd-bus.c
index 763f830e2d..b9e2782564 100644
--- a/src/libsystemd/sd-bus/sd-bus.c
+++ b/src/libsystemd/sd-bus/sd-bus.c
@@ -1951,37 +1951,39 @@ _public_ int sd_bus_call(
         unsigned i;
         int r;
 
-        assert_return(m, -EINVAL);
-        assert_return(m->header->type == SD_BUS_MESSAGE_METHOD_CALL, -EINVAL);
-        assert_return(!(m->header->flags & BUS_MESSAGE_NO_REPLY_EXPECTED), -EINVAL);
-        assert_return(!bus_error_is_dirty(error), -EINVAL);
+        bus_assert_return(m, -EINVAL, error);
+        bus_assert_return(m->header->type == SD_BUS_MESSAGE_METHOD_CALL, -EINVAL, error);
+        bus_assert_return(!(m->header->flags & BUS_MESSAGE_NO_REPLY_EXPECTED), -EINVAL, error);
+        bus_assert_return(!bus_error_is_dirty(error), -EINVAL, error);
 
         if (!bus)
                 bus = m->bus;
 
-        assert_return(!bus_pid_changed(bus), -ECHILD);
-        assert_return(!bus->is_kernel || !(bus->hello_flags & KDBUS_HELLO_MONITOR), -EROFS);
+        bus_assert_return(!bus_pid_changed(bus), -ECHILD, error);
+        bus_assert_return(!bus->is_kernel || !(bus->hello_flags & KDBUS_HELLO_MONITOR), -EROFS, error);
 
-        if (!BUS_IS_OPEN(bus->state))
-                return -ENOTCONN;
+        if (!BUS_IS_OPEN(bus->state)) {
+                r = -ENOTCONN;
+                goto fail;
+        }
 
         r = bus_ensure_running(bus);
         if (r < 0)
-                return r;
+                goto fail;
 
         i = bus->rqueue_size;
 
         r = bus_seal_message(bus, m, usec);
         if (r < 0)
-                return r;
+                goto fail;
 
         r = bus_remarshal_message(bus, &m);
         if (r < 0)
-                return r;
+                goto fail;
 
         r = bus_send_internal(bus, m, &cookie, true);
         if (r < 0)
-                return r;
+                goto fail;
 
         timeout = calc_elapse(m->timeout);
 
@@ -2012,14 +2014,17 @@ _public_ int sd_bus_call(
                                         }
 
                                         r = sd_bus_error_setf(error, SD_BUS_ERROR_INCONSISTENT_MESSAGE, "Reply message contained file descriptors which I couldn't accept. Sorry.");
+                                        sd_bus_message_unref(incoming);
+                                        return r;
 
-                                } else if (incoming->header->type == SD_BUS_MESSAGE_METHOD_ERROR)
+                                } else if (incoming->header->type == SD_BUS_MESSAGE_METHOD_ERROR) {
                                         r = sd_bus_error_copy(error, &incoming->error);
-                                else
+                                        sd_bus_message_unref(incoming);
+                                        return r;
+                                } else {
                                         r = -EIO;
-
-                                sd_bus_message_unref(incoming);
-                                return r;
+                                        goto fail;
+                                }
 
                         } else if (BUS_MESSAGE_COOKIE(incoming) == cookie &&
                                    bus->unique_name &&
@@ -2035,7 +2040,8 @@ _public_ int sd_bus_call(
                                  * immediately. */
 
                                 sd_bus_message_unref(incoming);
-                                return -ELOOP;
+                                r = -ELOOP;
+                                goto fail;
                         }
 
                         /* Try to read more, right-away */
@@ -2046,10 +2052,10 @@ _public_ int sd_bus_call(
                 if (r < 0) {
                         if (r == -ENOTCONN || r == -ECONNRESET || r == -EPIPE || r == -ESHUTDOWN) {
                                 bus_enter_closing(bus);
-                                return -ECONNRESET;
+                                r = -ECONNRESET;
                         }
 
-                        return r;
+                        goto fail;
                 }
                 if (r > 0)
                         continue;
@@ -2058,8 +2064,10 @@ _public_ int sd_bus_call(
                         usec_t n;
 
                         n = now(CLOCK_MONOTONIC);
-                        if (n >= timeout)
-                                return -ETIMEDOUT;
+                        if (n >= timeout) {
+                                r = -ETIMEDOUT;
+                                goto fail;
+                        }
 
                         left = timeout - n;
                 } else
@@ -2067,20 +2075,25 @@ _public_ int sd_bus_call(
 
                 r = bus_poll(bus, true, left);
                 if (r < 0)
-                        return r;
-                if (r == 0)
-                        return -ETIMEDOUT;
+                        goto fail;
+                if (r == 0) {
+                        r = -ETIMEDOUT;
+                        goto fail;
+                }
 
                 r = dispatch_wqueue(bus);
                 if (r < 0) {
                         if (r == -ENOTCONN || r == -ECONNRESET || r == -EPIPE || r == -ESHUTDOWN) {
                                 bus_enter_closing(bus);
-                                return -ECONNRESET;
+                                r = -ECONNRESET;
                         }
 
-                        return r;
+                        goto fail;
                 }
         }
+
+fail:
+        return sd_bus_error_set_errno(error, r);
 }
 
 _public_ int sd_bus_get_fd(sd_bus *bus) {