uart: add host-tested immutable tx frame copy

Makefile

@@ -24,6 +24,7 @@ test-host:
 			lib/host_tests/test_sam_startup_ui.c \
 			lib/host_tests/test_sam_key_label.c \
 		lib/host_tests/test_ccid_logic.c \
+		lib/host_tests/test_uart_tx_logic.c \
 		lib/host_tests/test_t1_existing.c \
 		lib/host_tests/test_t1_protocol.c \
 		lib/host_tests/test_snmp.c \
@@ -40,6 +41,7 @@ test-host:
 			board_power_lifecycle.c \
 			sam_startup_ui.c \
 			ccid_logic.c \
+			uart_tx_logic.c \
 			allocation_policy.c \
 			worker_loop_policy.c \
 		credential_sio_label.c \

lib/host_tests/test_main.c

@@ -6,6 +6,7 @@ extern MunitSuite test_board_power_lifecycle_suite;
 extern MunitSuite test_hf_read_lifecycle_suite;
 extern MunitSuite test_sam_startup_ui_suite;
 extern MunitSuite test_ccid_logic_suite;
+extern MunitSuite test_uart_tx_logic_suite;
 extern MunitSuite test_sam_key_label_suite;
 extern MunitSuite test_t1_existing_suite;
 extern MunitSuite test_t1_protocol_suite;
@@ -40,6 +41,7 @@ int main(int argc, char* argv[]) {
         {"/t1", test_t1_existing_suite.tests, NULL, 1, MUNIT_SUITE_OPTION_NONE},
         {"/t1", test_t1_protocol_suite.tests, NULL, 1, MUNIT_SUITE_OPTION_NONE},
         {"/ccid", test_ccid_logic_suite.tests, NULL, 1, MUNIT_SUITE_OPTION_NONE},
+        {"/uart-tx", test_uart_tx_logic_suite.tests, NULL, 1, MUNIT_SUITE_OPTION_NONE},
         {"/snmp", test_snmp_suite.tests, NULL, 1, MUNIT_SUITE_OPTION_NONE},
         {"/uhf-status-label", test_uhf_status_label_suite.tests, NULL, 1, MUNIT_SUITE_OPTION_NONE},
         {"/credential-sio-label", test_credential_sio_label_suite.tests, NULL, 1, MUNIT_SUITE_OPTION_NONE},

lib/host_tests/test_uart_tx_logic.c

@@ -0,0 +1,114 @@
+#include <string.h>
+
+#include "munit.h"
+#include "uart_tx_logic.h"
+
+static MunitResult test_tx_frame_copy_rejects_invalid_inputs(
+    const MunitParameter params[],
+    void* fixture) {
+    (void)params;
+    (void)fixture;
+
+    SeaderUartTxFrame frame = {0};
+    const uint8_t data[] = {0x01U};
+
+    munit_assert_false(seader_uart_tx_frame_copy(NULL, data, sizeof(data), sizeof(data)));
+    munit_assert_false(seader_uart_tx_frame_copy(&frame, NULL, sizeof(data), sizeof(data)));
+    munit_assert_false(seader_uart_tx_frame_copy(&frame, data, 0U, sizeof(data)));
+    munit_assert_false(seader_uart_tx_frame_copy(&frame, data, sizeof(data), 0U));
+    return MUNIT_OK;
+}
+
+static MunitResult test_tx_frame_copy_preserves_frame_bytes(
+    const MunitParameter params[],
+    void* fixture) {
+    (void)params;
+    (void)fixture;
+
+    SeaderUartTxFrame frame = {0};
+    const uint8_t data[] = {0x01U, 0x02U, 0x03U};
+
+    munit_assert_true(seader_uart_tx_frame_copy(&frame, data, sizeof(data), sizeof(frame.data)));
+    munit_assert_size(frame.len, ==, sizeof(data));
+    munit_assert_memory_equal(sizeof(data), frame.data, data);
+    return MUNIT_OK;
+}
+
+static MunitResult test_tx_frame_copy_is_immutable_after_source_reuse(
+    const MunitParameter params[],
+    void* fixture) {
+    (void)params;
+    (void)fixture;
+
+    SeaderUartTxFrame frame = {0};
+    uint8_t scratch[] = {0xAAU, 0xBBU, 0xCCU};
+    const uint8_t expected[] = {0xAAU, 0xBBU, 0xCCU};
+
+    munit_assert_true(
+        seader_uart_tx_frame_copy(&frame, scratch, sizeof(scratch), sizeof(frame.data)));
+    memset(scratch, 0x11, sizeof(scratch));
+
+    munit_assert_size(frame.len, ==, sizeof(expected));
+    munit_assert_memory_equal(sizeof(expected), frame.data, expected);
+    return MUNIT_OK;
+}
+
+static MunitResult test_back_to_back_copies_preserve_distinct_frames(
+    const MunitParameter params[],
+    void* fixture) {
+    (void)params;
+    (void)fixture;
+
+    SeaderUartTxFrame first = {0};
+    SeaderUartTxFrame second = {0};
+    uint8_t scratch[] = {0x10U, 0x20U};
+    const uint8_t first_expected[] = {0x10U, 0x20U};
+    const uint8_t second_expected[] = {0x30U, 0x40U};
+
+    munit_assert_true(
+        seader_uart_tx_frame_copy(&first, scratch, sizeof(scratch), sizeof(first.data)));
+    scratch[0] = 0x30U;
+    scratch[1] = 0x40U;
+    munit_assert_true(
+        seader_uart_tx_frame_copy(&second, scratch, sizeof(scratch), sizeof(second.data)));
+
+    munit_assert_memory_equal(sizeof(first_expected), first.data, first_expected);
+    munit_assert_memory_equal(sizeof(second_expected), second.data, second_expected);
+    return MUNIT_OK;
+}
+
+static MunitTest test_uart_tx_logic_cases[] = {
+    {(char*)"/copy/rejects-invalid",
+     test_tx_frame_copy_rejects_invalid_inputs,
+     NULL,
+     NULL,
+     MUNIT_TEST_OPTION_NONE,
+     NULL},
+    {(char*)"/copy/preserves-bytes",
+     test_tx_frame_copy_preserves_frame_bytes,
+     NULL,
+     NULL,
+     MUNIT_TEST_OPTION_NONE,
+     NULL},
+    {(char*)"/copy/immutable-after-source-reuse",
+     test_tx_frame_copy_is_immutable_after_source_reuse,
+     NULL,
+     NULL,
+     MUNIT_TEST_OPTION_NONE,
+     NULL},
+    {(char*)"/copy/back-to-back-distinct",
+     test_back_to_back_copies_preserve_distinct_frames,
+     NULL,
+     NULL,
+     MUNIT_TEST_OPTION_NONE,
+     NULL},
+    {NULL, NULL, NULL, NULL, 0, NULL},
+};
+
+MunitSuite test_uart_tx_logic_suite = {
+    "",
+    test_uart_tx_logic_cases,
+    NULL,
+    1,
+    MUNIT_SUITE_OPTION_NONE,
+};

uart_tx_logic.c

@@ -0,0 +1,17 @@
+#include "uart_tx_logic.h"
+
+#include <string.h>
+
+bool seader_uart_tx_frame_copy(
+    SeaderUartTxFrame* out,
+    const uint8_t* data,
+    size_t len,
+    size_t max_len) {
+    if(!out || !data || len == 0U || len > max_len || len > sizeof(out->data)) {
+        return false;
+    }
+
+    out->len = len;
+    memcpy(out->data, data, len);
+    return true;
+}

uart_tx_logic.h

@@ -0,0 +1,18 @@
+#pragma once
+
+#include <stdbool.h>
+#include <stddef.h>
+#include <stdint.h>
+
+#define SEADER_UART_TX_FRAME_MAX_SIZE (272U)
+
+typedef struct {
+    size_t len;
+    uint8_t data[SEADER_UART_TX_FRAME_MAX_SIZE];
+} SeaderUartTxFrame;
+
+bool seader_uart_tx_frame_copy(
+    SeaderUartTxFrame* out,
+    const uint8_t* data,
+    size_t len,
+    size_t max_len);