From 37cffddc5d4a9fd9eb7eaff4e1c843d379ad408b Mon Sep 17 00:00:00 2001
From: Josh Haberman <jhaberman@gmail.com>
Date: Fri, 15 May 2015 09:40:06 -0700
Subject: Decoder bugfix.

Don't back up decoder after skipunknown() unless we actually
successfully consumed input data.
---
 upb/pb/decoder.c | 13 ++++++++++---
 1 file changed, 10 insertions(+), 3 deletions(-)

(limited to 'upb/pb')

diff --git a/upb/pb/decoder.c b/upb/pb/decoder.c
index a780666..c37953a 100644
--- a/upb/pb/decoder.c
+++ b/upb/pb/decoder.c
@@ -587,10 +587,17 @@ static int32_t dispatch(upb_pbdecoder *d) {
   if (ret == DECODE_ENDGROUP) {
     goto_endmsg(d);
     return DECODE_OK;
-  } else {
-    d->pc = d->last - 1;  // Rewind to CHECKDELIM.
-    return ret;
+  } else if (ret == DECODE_OK) {
+    // We just consumed some input, so we might now have consumed all the data
+    // in the delmited region.  Since every opcode that can trigger dispatch is
+    // directly preceded by OP_CHECKDELIM, rewind to it now to re-check the
+    // delimited end.
+    d->pc = d->last - 1;
+    assert(getop(*d->pc) == OP_CHECKDELIM);
+    return DECODE_OK;
   }
+
+  return ret;
 }
 
 // Callers know that the stack is more than one deep because the opcodes that
-- 
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