log: add an "error" parameter to all low-level logging calls and intrdouce log_error_errno() as log calls that take error numbers

This change has two benefits:

- The format string %m will now resolve to the specified error (or to
  errno if the specified error is 0. This allows getting rid of a ton of
  strerror() invocations, a function that is not thread-safe.

- The specified error can be passed to the journal in the ERRNO= field.

Now of course, we just need somebody to convert all cases of this:

        log_error("Something happened: %s", strerror(-r));

into thus:

        log_error_errno(-r, "Something happened: %m");

1 files changed, 1 insertions, 1 deletions

diff --git a/src/libsystemd-network/dhcp-internal.h b/src/libsystemd-network/dhcp-internal.h
index d358a49307..d76d0c29d0 100644
--- a/src/libsystemd-network/dhcp-internal.h
+++ b/src/libsystemd-network/dhcp-internal.h
@@ -71,4 +71,4 @@ DEFINE_TRIVIAL_CLEANUP_FUNC(sd_dhcp_client*, sd_dhcp_client_unref);
 #define DHCP_CLIENT_DONT_DESTROY(client) \
         _cleanup_dhcp_client_unref_ _unused_ sd_dhcp_client *_dont_destroy_##client = sd_dhcp_client_ref(client)
 
-#define log_dhcp_client(client, fmt, ...) log_meta(LOG_DEBUG, __FILE__, __LINE__, __func__, "DHCP CLIENT (0x%x): " fmt, client->xid, ##__VA_ARGS__)
+#define log_dhcp_client(client, fmt, ...) log_meta(LOG_DEBUG, 0, __FILE__, __LINE__, __func__, "DHCP CLIENT (0x%x): " fmt, client->xid, ##__VA_ARGS__)