logd: Don't embed a flexible array member within another struct
C (but not C++) has a concept of a flexible array member, which
is documented at https://gcc.gnu.org/onlinedocs/gcc/Zero-Length.html .
Using a flexible array member indicates that the structure is
really a header for a variable length object.
In logd's case, the variable length structure android_event_string_t
was embedded within another structure called
android_log_event_string_t. This makes gcc's __builtin_object_size()
function really confused. When compiling with C++,
__builtin_object_size(android_log_event_string_t.payload.data, 1)
would return 0, whereas if you compiled the code with C, the same
call would (properly) return -1.
Code which does automatic bounds checking, such as the proposed
patch at https://android-review.googlesource.com/145411 , will
cause problems for logd if this syntax is used.
Don't try to embed a variable length structure within another
structure. This doesn't appear to be valid C nor C++, and
while it's worked, it seems problematic.
Instead, inline the structure so it's one big happy structure.
Change-Id: I8ac02b7142a4f6560f5f80df2effcf720f9896fc
diff --git a/logd/LogAudit.cpp b/logd/LogAudit.cpp
index 6b3e637..bdb2915 100644
--- a/logd/LogAudit.cpp
+++ b/logd/LogAudit.cpp
@@ -150,9 +150,9 @@
rc = -ENOMEM;
} else {
event->header.tag = htole32(AUDITD_LOG_TAG);
- event->payload.type = EVENT_TYPE_STRING;
- event->payload.length = htole32(l);
- memcpy(event->payload.data, str, l);
+ event->type = EVENT_TYPE_STRING;
+ event->length = htole32(l);
+ memcpy(event->data, str, l);
logbuf->log(LOG_ID_EVENTS, now, uid, pid, tid,
reinterpret_cast<char *>(event),