From 696173c28488d13ab85464531c9c52fd12d7ae89 Mon Sep 17 00:00:00 2001
From: David Young <dyoung@hdfgroup.org>
Date: Wed, 6 May 2020 14:44:59 -0500
Subject: Add esnprintf that prints to the given buffer, observing the given
 buffer size, using vsnprintf(3), but exits with err(3)/errx(3) if the buffer
 is too small or if vsnprintf returns < 0.

---
 test/vfd_swmr_common.c | 16 ++++++++++++++++
 test/vfd_swmr_common.h |  2 ++
 2 files changed, 18 insertions(+)

diff --git a/test/vfd_swmr_common.c b/test/vfd_swmr_common.c
index 7db2bba..252d6d7 100644
--- a/test/vfd_swmr_common.c
+++ b/test/vfd_swmr_common.c
@@ -34,6 +34,22 @@ static const hid_t badhid = H5I_INVALID_HID;
 int verbosity = 2;
 
 void
+esnprintf(char *buf, size_t bufsz, const char *fmt, ...)
+{
+    int rc;
+    va_list ap;
+
+    va_start(ap, fmt);
+    rc = vsnprintf(buf, bufsz, fmt, ap);
+    va_end(ap);
+
+    if (rc < 0)
+        err(EXIT_FAILURE, "%s: vsnprintf", __func__);
+    else if (rc >= bufsz)
+        errx(EXIT_FAILURE, "%s: buffer too small", __func__);
+}
+
+void
 dbgf(int level, const char *fmt, ...)
 {
     va_list ap;
diff --git a/test/vfd_swmr_common.h b/test/vfd_swmr_common.h
index cd36cc3..c6916e6 100644
--- a/test/vfd_swmr_common.h
+++ b/test/vfd_swmr_common.h
@@ -97,6 +97,8 @@ H5TEST_DLL void await_signal(hid_t);
 H5TEST_DLL hid_t vfd_swmr_create_fapl(bool, bool, bool);
 
 H5TEST_DLL void dbgf(int, const char *, ...) H5_ATTR_FORMAT(printf, 2, 3);
+H5TEST_DLL void esnprintf(char *, size_t, const char *, ...)
+    H5_ATTR_FORMAT(printf, 3, 4);
 
 H5TEST_DLL int fetch_env_ulong(const char *, unsigned long, unsigned long *);
 
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