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/core/selinux-access.c b/src/core/selinux-access.c
index a50dec3961..b3835d59a5 100644
--- a/src/core/selinux-access.c
+++ b/src/core/selinux-access.c
@@ -112,7 +112,7 @@ _printf_(2, 3) static int log_callback(int type, const char *fmt, ...) {
 #endif
 
         va_start(ap, fmt);
-        log_metav(LOG_USER | LOG_INFO, __FILE__, __LINE__, __FUNCTION__, fmt, ap);
+        log_metav(LOG_USER | LOG_INFO, 0, __FILE__, __LINE__, __FUNCTION__, fmt, ap);
         va_end(ap);
 
         return 0;