Allow to avoid NUL-byte management for stringinfos and use in format.c.

In a lot of the places having appendBinaryStringInfo() maintain a
trailing NUL byte wasn't actually meaningful, e.g. when appending an
integer which can contain 0 in one of its bytes.

Removing this yields some small speedup, but more importantly will be
more consistent when providing faster variants of pq_sendint etc.

Author: Andres Freund
Discussion: https://postgr.es/m/20170914063418.sckdzgjfrsbekae4@alap3.anarazel.de

1 files changed, 20 insertions, 1 deletions

diff --git a/src/backend/lib/stringinfo.c b/src/backend/lib/stringinfo.c
index fd155671443..cb2026c3b20 100644
--- a/src/backend/lib/stringinfo.c
+++ b/src/backend/lib/stringinfo.c
@@ -202,7 +202,7 @@ appendStringInfoSpaces(StringInfo str, int count)
  * appendBinaryStringInfo
  *
  * Append arbitrary binary data to a StringInfo, allocating more space
- * if necessary.
+ * if necessary. Ensures that a trailing null byte is present.
  */
 void
 appendBinaryStringInfo(StringInfo str, const char *data, int datalen)
@@ -225,6 +225,25 @@ appendBinaryStringInfo(StringInfo str, const char *data, int datalen)
 }
 
 /*
+ * appendBinaryStringInfoNT
+ *
+ * Append arbitrary binary data to a StringInfo, allocating more space
+ * if necessary. Does not ensure a trailing null-byte exists.
+ */
+void
+appendBinaryStringInfoNT(StringInfo str, const char *data, int datalen)
+{
+	Assert(str != NULL);
+
+	/* Make more room if needed */
+	enlargeStringInfo(str, datalen);
+
+	/* OK, append the data */
+	memcpy(str->data + str->len, data, datalen);
+	str->len += datalen;
+}
+
+/*
  * enlargeStringInfo
  *
  * Make sure there is enough space for 'needed' more bytes