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, 10 insertions, 4 deletions

diff --git a/src/shared/conf-parser.h b/src/shared/conf-parser.h
index 69d32711b7..2507a44444 100644
--- a/src/shared/conf-parser.h
+++ b/src/shared/conf-parser.h
@@ -119,10 +119,16 @@ int config_parse_mode(const char *unit, const char *filename, unsigned line, con
 int config_parse_log_facility(const char *unit, const char *filename, unsigned line, const char *section, unsigned section_line, const char *lvalue, int ltype, const char *rvalue, void *data, void *userdata);
 int config_parse_log_level(const char *unit, const char *filename, unsigned line, const char *section, unsigned section_line, const char *lvalue, int ltype, const char *rvalue, void *data, void *userdata);
 
-int log_syntax_internal(const char *unit, int level,
-                        const char *file, unsigned line, const char *func,
-                        const char *config_file, unsigned config_line,
-                        int error, const char *format, ...) _printf_(9, 10);
+int log_syntax_internal(
+                const char *unit,
+                int level,
+                const char *file,
+                int line,
+                const char *func,
+                const char *config_file,
+                unsigned config_line,
+                int error,
+                const char *format, ...) _printf_(9, 10);
 
 #define log_syntax(unit, level, config_file, config_line, error, ...)   \
         log_syntax_internal(unit, level,                                \