[DTrace-devel] [PATCH] options, test: correct bufsize calculations and tests

[Kris Van Hees]

Reported-by: Eugene Loh <eugene.loh at oracle.com>
Signed-off-by: Kris Van Hees <kris.van.hees at oracle.com>
---
 libdtrace/dt_work.c                 |  9 +++------
 test/unittest/options/tst.b.d       | 19 ++++++++++---------
 test/unittest/options/tst.bufsize.d | 19 ++++++++++---------
 3 files changed, 23 insertions(+), 24 deletions(-)

diff --git a/libdtrace/dt_work.c b/libdtrace/dt_work.c
index c98bbfb9..11335345 100644
--- a/libdtrace/dt_work.c
+++ b/libdtrace/dt_work.c
@@ -268,15 +268,12 @@ dtrace_go(dtrace_hdl_t *dtp, uint_t cflags)
 		return dt_set_errno(dtp, errno);
 
 	/*
-	 * We need enough space for the pref_event_header, a 32-bit size, a
-	 * 4-byte gap, and the largest trace data record we may be writing to
-	 * the buffer.  In other words, the buffer needs to be large enough to
-	 * hold at least one perf-encapsulated trace data record.
+	 * The buffer needs to be large enough to hold at least one
+	 * perf-encapsulated trace data record.
 	 */
 	dtrace_getopt(dtp, "bufsize", &size);
 	if (size == 0 ||
-	    size < sizeof(struct perf_event_header) + sizeof(uint32_t) +
-		   dtp->dt_maxreclen)
+	    size < sizeof(struct perf_event_header) + dtp->dt_maxreclen)
 		return dt_set_errno(dtp, EDT_BUFTOOSMALL);
 	if (dt_pebs_init(dtp, size) == -1)
 		return dt_set_errno(dtp, EDT_NOMEM);
diff --git a/test/unittest/options/tst.b.d b/test/unittest/options/tst.b.d
index 57fa030d..af7d090a 100644
--- a/test/unittest/options/tst.b.d
+++ b/test/unittest/options/tst.b.d
@@ -1,6 +1,6 @@
 /*
  * Oracle Linux DTrace.
- * Copyright (c) 2022, Oracle and/or its affiliates. All rights reserved.
+ * Copyright (c) 2022, 2024, Oracle and/or its affiliates. All rights reserved.
  * Licensed under the Universal Permissive License v 1.0 as shown at
  * http://oss.oracle.com/licenses/upl.
  */
@@ -12,16 +12,17 @@
  */
 
 /*
- * We use a buffer size of 60 because that should be the exact size necessary
- * to hold the trace records generated in this script:
- *	- perf_event_header (40 bytes)
+ * We use a buffer size that is just large enough to store the data recorded by
+ * this script:
+ *	- perf_event_header (8 bytes)
  *	- size (4 bytes)
- *	- gap (4 bytes)
- *	- EPID (4 bytes)
- *	- tag (4 bytes)
- *	- exit value (4 bytes)
+ *	- specid (4 bytes)
+ *	- PRID (4 bytes)
+ *	- STID (4 bytes)
+ *	- arg1 through arg5 (5 x 8 bytes)
+ * So, 64 bytes.
  */
-/* @@runtest-opts: -b60 */
+/* @@runtest-opts: -b64 */
 
 BEGIN
 {
diff --git a/test/unittest/options/tst.bufsize.d b/test/unittest/options/tst.bufsize.d
index 96b0f1b8..7884c0bc 100644
--- a/test/unittest/options/tst.bufsize.d
+++ b/test/unittest/options/tst.bufsize.d
@@ -1,6 +1,6 @@
 /*
  * Oracle Linux DTrace.
- * Copyright (c) 2022, Oracle and/or its affiliates. All rights reserved.
+ * Copyright (c) 2022, 2024, Oracle and/or its affiliates. All rights reserved.
  * Licensed under the Universal Permissive License v 1.0 as shown at
  * http://oss.oracle.com/licenses/upl.
  */
@@ -12,16 +12,17 @@
  */
 
 /*
- * We use a buffer size of 60 because that should be the exact size necessary
- * to hold the trace records generated in this script:
- *	- perf_event_header (40 bytes)
+ * We use a buffer size that is just large enough to store the data recorded by
+ * this script:
+ *	- perf_event_header (8 bytes)
  *	- size (4 bytes)
- *	- gap (4 bytes)
- *	- EPID (4 bytes)
- *	- tag (4 bytes)
- *	- exit value (4 bytes)
+ *	- specid (4 bytes)
+ *	- PRID (4 bytes)
+ *	- STID (4 bytes)
+ *	- arg1 through arg5 (5 x 8 bytes)
+ * So, 64 bytes.
  */
-/* @@runtest-opts: -xbufsize=60 */
+/* @@runtest-opts: -xbufsize=64 */
 
 BEGIN
 {
-- 
2.45.2