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/dhcp6-internal.h b/src/libsystemd-network/dhcp6-internal.h
index 6cc0aa8a8d..3737d49a3a 100644
--- a/src/libsystemd-network/dhcp6-internal.h
+++ b/src/libsystemd-network/dhcp6-internal.h
@@ -56,7 +56,7 @@ struct DHCP6IA {
 
 typedef struct DHCP6IA DHCP6IA;
 
-#define log_dhcp6_client(p, fmt, ...) log_meta(LOG_DEBUG, __FILE__, __LINE__, __func__, "DHCPv6 CLIENT: " fmt, ##__VA_ARGS__)
+#define log_dhcp6_client(p, fmt, ...) log_meta(LOG_DEBUG, 0, __FILE__, __LINE__, __func__, "DHCPv6 CLIENT: " fmt, ##__VA_ARGS__)
 
 int dhcp_network_icmp6_bind_router_solicitation(int index);
 int dhcp_network_icmp6_send_router_solicitation(int s, const struct ether_addr *ether_addr);