core: rework serialization

Let's be more careful with what we serialize: let's ensure we never
serialize strings that are longer than LONG_LINE_MAX, so that we know we
can read them back with read_line(…, LONG_LINE_MAX, …) safely.

In order to implement this all serialization functions are move to
serialize.[ch], and internally will do line size checks. We'd rather
skip a serialization line (with a loud warning) than write an overly
long line out. Of course, this is just a second level protection, after
all the data we serialize shouldn't be this long in the first place.

While we are at it also clean up logging: while serializing make sure to
always log about errors immediately. Also, (void)ify all calls we don't
expect errors in (or catch errors as part of the general
fflush_and_check() at the end.

1 files changed, 3 insertions, 7 deletions

diff --git a/src/core/dbus.c b/src/core/dbus.c
index 3ffb53cb6e..c2f77b8eef 100644
--- a/src/core/dbus.c
+++ b/src/core/dbus.c
@@ -36,6 +36,7 @@
 #include "mkdir.h"
 #include "process-util.h"
 #include "selinux-access.h"
+#include "serialize.h"
 #include "service.h"
 #include "special.h"
 #include "string-util.h"
@@ -1204,13 +1205,8 @@ void bus_track_serialize(sd_bus_track *t, FILE *f, const char *prefix) {
                 int c, j;
 
                 c = sd_bus_track_count_name(t, n);
-
-                for (j = 0; j < c; j++) {
-                        fputs(prefix, f);
-                        fputc('=', f);
-                        fputs(n, f);
-                        fputc('\n', f);
-                }
+                for (j = 0; j < c; j++)
+                        (void) serialize_item(f, prefix, n);
         }
 }