Avoid memory growth in format_tree.

2 files changed, 15 insertions, 5 deletions

diff --git a/ChangeLog b/ChangeLog
index eced4196..603e9528 100644
--- a/ChangeLog
+++ b/ChangeLog
@@ -1,3 +1,16 @@
+2019-08-15         Arnold D. Robbins     <arnold@skeeve.com>
+
+	Revert a6df7afc605079df7d85318846a522ef64aaa44d, change of
+	2016-05-03, which used realloc to shrink the buffer, in an
+	attempt to save memory.  In actuality, it could cause increased
+	memory usage, even though there was no memory leak. See
+	https://lists.gnu.org/archive/html/bug-gawk/2019-08/msg00003.html
+	and the rest of thread for more detail.
+
+	* builtin.c (format_tree): Don't use realloc, just call
+	make_str_node with the original buffer. Remove `olen_final'
+	variable and its use.
+
 2019-08-15         Andrew J. Schorr      <aschorr@telemetry-investments.com>
 
 	Reduce memory usage by only compiling the IGNORECASE version of
diff --git a/builtin.c b/builtin.c
index 1c205aa4..503a386c 100644
--- a/builtin.c
+++ b/builtin.c
@@ -685,7 +685,7 @@ format_tree(
 	int i, nc;
 	bool toofew = false;
 	char *obuf, *obufout;
-	size_t osiz, ofre, olen_final;
+	size_t osiz, ofre;
 	const char *chbuf;
 	const char *s0, *s1;
 	int cs1;
@@ -1646,10 +1646,7 @@ mpf1:
 			_("too many arguments supplied for format string"));
 	}
 	bchunk(s0, s1 - s0);
-	olen_final = obufout - obuf;
-	if (ofre > 0)
-		erealloc(obuf, char *, olen_final + 1, "format_tree");
-	r = make_str_node(obuf, olen_final, ALREADY_MALLOCED);
+	r = make_str_node(obuf, obufout - obuf, ALREADY_MALLOCED);
 	obuf = NULL;
 out:
 	{