Add a snprintf_safe() helper function

Returns true on success or false on error _or_ truncation. Since truncation is
almost always an error anyway, we might as well make this easier to check.

Signed-off-by: Peter Hutterer <peter.hutterer@who-t.net>

1 files changed, 50 insertions, 0 deletions

diff --git a/test/utils.c b/test/utils.c
new file mode 100644
index 0000000..a385a78
--- /dev/null
+++ b/test/utils.c
@@ -0,0 +1,50 @@
+/*
+ * Copyright © 2019 Red Hat, Inc.
+ *
+ * Permission is hereby granted, free of charge, to any person obtaining a
+ * copy of this software and associated documentation files (the "Software"),
+ * to deal in the Software without restriction, including without limitation
+ * the rights to use, copy, modify, merge, publish, distribute, sublicense,
+ * and/or sell copies of the Software, and to permit persons to whom the
+ * Software is furnished to do so, subject to the following conditions:
+ *
+ * The above copyright notice and this permission notice (including the next
+ * paragraph) shall be included in all copies or substantial portions of the
+ * Software.
+ *
+ * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
+ * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
+ * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT.  IN NO EVENT SHALL
+ * THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
+ * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING
+ * FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER
+ * DEALINGS IN THE SOFTWARE.
+ */
+
+#include "config.h"
+
+#include <assert.h>
+#include <stdio.h>
+#include <stdlib.h>
+#include <string.h>
+
+#include "test.h"
+#include "utils.h"
+
+int
+main(void)
+{
+    char buffer[10];
+
+    assert(!snprintf_safe(buffer, 0, "foo"));
+    assert(!snprintf_safe(buffer, 1, "foo"));
+    assert(!snprintf_safe(buffer, 3, "foo"));
+
+    assert(snprintf_safe(buffer, 10, "foo"));
+    assert(streq(buffer, "foo"));
+
+    assert(!snprintf_safe(buffer, 10, "%s", "1234567890"));
+    assert(snprintf_safe(buffer, 10, "%s", "123456789"));
+
+    return 0;
+}