test: every last byte, CR runs and broken matches through the upload

Three more bench scenarios around the closing boundary. Every value
of the last image byte, uploaded whole and split right after the
payload, must end the part. A run of CR before the boundary of even
length passed before the fix and an odd one did not, so both are
checked. An image made of CR only, longer than a flash page, and one
made of repeated "\r\n-" exercise the broken matches back to back:
each one appends to the page buffer without a byte written, and the
page flush after both paths has to keep up.

test/test_httpd_tx.c

@@ -1147,6 +1147,52 @@ static void scenario_upload_cr_before_boundary(void)
 	      "upload: the CR and the bytes before it reach the flash unchanged");
 }
 
+static int upload_whole_and_split(uint8_t *body, uint16_t body_len)
+{
+	return upload_in_two(body, body_len, body_len) && !memcmp(flash_written, body, UPLOAD_LEN)
+		&& upload_in_two(body, body_len, UPLOAD_LEN) && !memcmp(flash_written, body, UPLOAD_LEN);
+}
+
+static void scenario_upload_last_byte(void)
+{
+	uint8_t body[UPLOAD_LEN + sizeof(UPLOAD_TRAILER)];
+	uint16_t body_len = UPLOAD_LEN + sizeof(UPLOAD_TRAILER) - 1;
+	int bad = -1;
+
+	for (uint16_t i = 0; i < UPLOAD_LEN; i++)
+		body[i] = pattern(i);
+	memcpy(body + UPLOAD_LEN, UPLOAD_TRAILER, sizeof(UPLOAD_TRAILER) - 1);
+	for (int last = 0; last < 256 && bad < 0; last++) {
+		body[UPLOAD_LEN - 1] = last;
+		if (!upload_whole_and_split(body, body_len))
+			bad = last;
+	}
+	if (bad >= 0)
+		printf("      last byte 0x%02x loses the closing boundary\n", bad);
+	CHECK(bad < 0, "upload: the part ends after the payload whatever its last byte");
+
+	body[UPLOAD_LEN - 1] = '\r';
+	body[UPLOAD_LEN - 2] = '\r';
+	CHECK(upload_whole_and_split(body, body_len), "upload: an even run of CR before the boundary");
+	body[UPLOAD_LEN - 3] = '\r';
+	CHECK(upload_whole_and_split(body, body_len), "upload: an odd run of CR before the boundary");
+}
+
+static void scenario_upload_broken_matches(void)
+{
+	uint8_t body[UPLOAD_LEN + sizeof(UPLOAD_TRAILER)];
+	uint16_t body_len = UPLOAD_LEN + sizeof(UPLOAD_TRAILER) - 1;
+
+	memcpy(body + UPLOAD_LEN, UPLOAD_TRAILER, sizeof(UPLOAD_TRAILER) - 1);
+	memset(body, '\r', UPLOAD_LEN);
+	CHECK(upload_whole_and_split(body, body_len),
+	      "upload: a run of CR longer than a flash page is staged intact");
+	for (uint16_t i = 0; i < UPLOAD_LEN; i++)
+		body[i] = "\r\n-"[i % 3];
+	CHECK(upload_whole_and_split(body, body_len),
+	      "upload: repeated partial delimiters are staged as payload");
+}
+
 int main(int argc, char **argv)
 {
 	if (argc > 1 && !strcmp(argv[1], "-v"))
@@ -1179,6 +1225,8 @@ int main(int argc, char **argv)
 	scenario_upload("MacBinary, split part terminator", "Content-Type: application/macbinary\r\n", 1);
 	scenario_upload("no part Content-Type", "", 0);
 	scenario_upload_cr_before_boundary();
+	scenario_upload_last_byte();
+	scenario_upload_broken_matches();
 
 	printf("\n%s (%d failure%s)\n",
 	       failures ? "BENCH: FAILURES" : "BENCH: ALL PASS",