core: clean up some confusing regarding SI decimal and IEC binary suffixes for sizes

According to Wikipedia it is customary to specify hardware metrics and
transfer speeds to the basis 1000 (SI decimal), while software metrics
and physical volatile memory (RAM) sizes to the basis 1024 (IEC binary).
So far we specified everything in IEC, let's fix that and be more
true to what's otherwise customary. Since we don't want to parse "Mi"
instead of "M" we document each time what the context used is.

src/shared/conf-parser.c

@@ -447,8 +447,7 @@ DEFINE_PARSER(double, double, safe_atod)
 DEFINE_PARSER(nsec, nsec_t, parse_nsec)
 DEFINE_PARSER(sec, usec_t, parse_sec)
 
-
-int config_parse_bytes_size(const char* unit,
+int config_parse_iec_size(const char* unit,
                             const char *filename,
                             unsigned line,
                             const char *section,
@@ -468,10 +467,9 @@ int config_parse_bytes_size(const char* unit,
         assert(rvalue);
         assert(data);
 
-        r = parse_bytes(rvalue, &o);
+        r = parse_size(rvalue, 1024, &o);
         if (r < 0 || (off_t) (size_t) o != o) {
-                log_syntax(unit, LOG_ERR, filename, line, -r,
-                           "Failed to parse byte value, ignoring: %s", rvalue);
+                log_syntax(unit, LOG_ERR, filename, line, r < 0 ? -r : ERANGE, "Failed to parse size value, ignoring: %s", rvalue);
                 return 0;
         }
 
@@ -479,8 +477,37 @@ int config_parse_bytes_size(const char* unit,
         return 0;
 }
 
+int config_parse_si_size(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_bytes_off(const char* unit,
+        size_t *sz = data;
+        off_t o;
+        int r;
+
+        assert(filename);
+        assert(lvalue);
+        assert(rvalue);
+        assert(data);
+
+        r = parse_size(rvalue, 1000, &o);
+        if (r < 0 || (off_t) (size_t) o != o) {
+                log_syntax(unit, LOG_ERR, filename, line, r < 0 ? -r : ERANGE, "Failed to parse size value, ignoring: %s", rvalue);
+                return 0;
+        }
+
+        *sz = (size_t) o;
+        return 0;
+}
+
+int config_parse_iec_off(const char* unit,
                            const char *filename,
                            unsigned line,
                            const char *section,
@@ -501,10 +528,9 @@ int config_parse_bytes_off(const char* unit,
 
         assert_cc(sizeof(off_t) == sizeof(uint64_t));
 
-        r = parse_bytes(rvalue, bytes);
+        r = parse_size(rvalue, 1024, bytes);
         if (r < 0)
-                log_syntax(unit, LOG_ERR, filename, line, -r,
-                           "Failed to parse bytes value, ignoring: %s", rvalue);
+                log_syntax(unit, LOG_ERR, filename, line, -r, "Failed to parse size value, ignoring: %s", rvalue);
 
         return 0;
 }