From 1f9494979268b62ed4b4588fb7d9e790c0e12100 Mon Sep 17 00:00:00 2001
From: Dirk Engling <erdgeist@erdgeist.org>
Date: Mon, 26 Oct 2026 22:32:52 +0100
Subject: replace all calls to sprintf with a format helper that advances a
 cursor. Also convert the meta-formatter (i.e. results printer) to this scheme

---
 tests/t_fmt.c | 108 ++++++++++++++++++++++++++++++++++++++++++++++++++++++++++
 1 file changed, 108 insertions(+)
 create mode 100644 tests/t_fmt.c

(limited to 'tests/t_fmt.c')

diff --git a/tests/t_fmt.c b/tests/t_fmt.c
new file mode 100644
index 0000000..bc23ed5
--- /dev/null
+++ b/tests/t_fmt.c
@@ -0,0 +1,108 @@
+/* This software was written by Dirk Engling <erdgeist@erdgeist.org>
+   It is considered beerware. Prost. Skol. Cheers or whatever.
+
+   $id$ */
+
+/* System */
+#include <string.h>
+
+/* Opentracker */
+#include "ot_fmt.h"
+#include "test.h"
+
+static void case_appends_in_sequence(void) {
+  char  buffer[64];
+  char *r = buffer, *re = buffer + sizeof(buffer);
+
+  test_case("appends follow each other and advance the cursor");
+  fmt_append(&r, re, "d8:completei%zde", (size_t)7);
+  fmt_append(&r, re, "ee");
+  *r = 0;
+  CHECK_STR(buffer, "d8:completei7eee");
+  CHECK_INT(r - buffer, 16);
+}
+
+static void case_truncation_stops_at_the_end(void) {
+  char  buffer[16];
+  char *r = buffer, *re = buffer + 8; /* pretend the buffer ends early */
+
+  memset(buffer, '#', sizeof(buffer));
+  test_case("a value too long for the room left stops at the end");
+  fmt_append(&r, re, "%s", "0123456789");
+  CHECK_PTR(r, re);
+
+  test_case("and writes nothing past it");
+  CHECK_INT(buffer[8], '#');
+  CHECK_INT(buffer[15], '#');
+}
+
+static void case_a_full_buffer_takes_nothing_more(void) {
+  char  buffer[16];
+  char *r = buffer + 8, *re = buffer + 8;
+
+  memset(buffer, '#', sizeof(buffer));
+  test_case("appending to a cursor already at the end changes nothing");
+  fmt_append(&r, re, "more");
+  CHECK_PTR(r, re);
+  CHECK_INT(buffer[8], '#');
+}
+
+static void case_an_append_that_just_fits(void) {
+  char  buffer[8];
+  char *r = buffer, *re = buffer + 3;
+
+  memset(buffer, '#', sizeof(buffer));
+  test_case("three characters into three bytes of room still truncate");
+  fmt_append(&r, re, "abc");
+  CHECK_PTR(r, re);
+  CHECK_INT(buffer[0], 'a');
+  CHECK_INT(buffer[1], 'b');
+
+  test_case("because snprintf spends the last byte on its terminator");
+  CHECK_INT(buffer[2], 0);
+  CHECK_INT(buffer[3], '#');
+}
+
+static void case_bytes_are_all_or_nothing(void) {
+  char  buffer[16];
+  char *r = buffer, *re = buffer + 8;
+
+  memset(buffer, '#', sizeof(buffer));
+  test_case("a run of bytes is written when it fits");
+  fmt_bytes(&r, re, "\0\1\2\3", 4);
+  CHECK_PTR(r, buffer + 4);
+  CHECK_MEM(buffer, "\0\1\2\3", 4);
+
+  test_case("a run that would not fit is refused whole");
+  fmt_bytes(&r, re, "abcde", 5);
+  CHECK_PTR(r, re);
+  CHECK_INT(buffer[4], '#');
+
+  test_case("a run of exactly the room left is written");
+  r = buffer + 4;
+  fmt_bytes(&r, re, "wxyz", 4);
+  CHECK_PTR(r, re);
+  CHECK_MEM(buffer + 4, "wxyz", 4);
+  CHECK_INT(buffer[8], '#');
+}
+
+static void case_bytes_do_not_terminate(void) {
+  char  buffer[8];
+  char *r = buffer, *re = buffer + 4;
+
+  memset(buffer, '#', sizeof(buffer));
+  test_case("unlike an append, a run of bytes may fill the room exactly");
+  fmt_bytes(&r, re, "abcd", 4);
+  CHECK_PTR(r, re);
+  CHECK_MEM(buffer, "abcd", 4);
+  CHECK_INT(buffer[4], '#');
+}
+
+void test_fmt(void) {
+  case_appends_in_sequence();
+  case_truncation_stops_at_the_end();
+  case_a_full_buffer_takes_nothing_more();
+  case_an_append_that_just_fits();
+  case_bytes_are_all_or_nothing();
+  case_bytes_do_not_terminate();
+}
-- 
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