Restore modified use of realloc in format_tree.

2 files changed, 16 insertions, 3 deletions

diff --git a/ChangeLog b/ChangeLog
index b608e023..edf4bf57 100644
--- a/ChangeLog
+++ b/ChangeLog
@@ -1,3 +1,12 @@
+2019-08-29         Arnold D. Robbins     <arnold@skeeve.com>
+
+	Restore a modified version of the change of
+	2016-05-03, which used realloc to shrink the buffer.
+
+	* builtin.c (format_tree): Reduce INITIAL_OUT_SIZE to 64.
+	At the end, call realloc only if there is more
+	than (2 * INITIAL_OUT_SIZE) bytes to give back.
+
 2019-08-23         Arnold D. Robbins     <arnold@skeeve.com>
 
 	* main.c (main): Fix whitespace issues.
diff --git a/builtin.c b/builtin.c
index 503a386c..1c107d3b 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;
+	size_t osiz, ofre, olen_final;
 	const char *chbuf;
 	const char *s0, *s1;
 	int cs1;
@@ -735,7 +735,7 @@ format_tree(
 	static const char lchbuf[] = "0123456789abcdef";
 	static const char Uchbuf[] = "0123456789ABCDEF";
 
-#define INITIAL_OUT_SIZE	512
+#define INITIAL_OUT_SIZE	64
 	emalloc(obuf, char *, INITIAL_OUT_SIZE, "format_tree");
 	obufout = obuf;
 	osiz = INITIAL_OUT_SIZE;
@@ -1646,7 +1646,11 @@ mpf1:
 			_("too many arguments supplied for format string"));
 	}
 	bchunk(s0, s1 - s0);
-	r = make_str_node(obuf, obufout - obuf, ALREADY_MALLOCED);
+	olen_final = obufout - obuf;
+#define GIVE_BACK_SIZE (INITIAL_OUT_SIZE * 2)
+	if (ofre > GIVE_BACK_SIZE)
+		erealloc(obuf, char *, olen_final + 1, "format_tree");
+	r = make_str_node(obuf, olen_final, ALREADY_MALLOCED);
 	obuf = NULL;
 out:
 	{