posix: implement fgetc()

doc/services/portability/posix/option_groups/index.rst

@@ -222,7 +222,7 @@ POSIX_DEVICE_IO
     feof(),
     ferror(),
     fflush(),
-    fgetc(),
+    fgetc(),yes (will fail with ``ENOSYS``:ref:`†<posix_undefined_behaviour>`)
     fgets(),
     fileno(),
     fopen(),
@@ -233,8 +233,8 @@ POSIX_DEVICE_IO
     freopen(),
     fscanf(),
     fwrite(),yes
-    getc(),
-    getchar(),
+    getc(),yes (will fail with ``ENOSYS``:ref:`†<posix_undefined_behaviour>`)
+    getchar(),yes (will fail with ``ENOSYS``:ref:`†<posix_undefined_behaviour>`)
     gets(),
     open(),yes
     perror(),yes

tests/posix/headers/src/stdio_h.c

@@ -0,0 +1,19 @@
+/*
+ * Copyright (c) 2024 Dawid Osuchowski
+ *
+ * SPDX-License-Identifier: Apache-2.0
+ */
+#include "_common.h"
+#include <stdio.h>
+
+/**
+ * @brief Test existence and basic functionality of stdio.h
+ * 
+ * @see stdio.h
+*/
+ZTEST(posix_headers, test_stdio_h)
+{
+    zassert_not_null((void *)getchar, "getchar is null");
+    zassert_not_null((void *)getc, "getc is null");
+    zassert_not_null((void *)fgetc, "fgetc is null");
+}

tests/posix/stdio/CMakeLists.txt

@@ -0,0 +1,10 @@
+# SPDX-License-Identifier: Apache-2.0
+
+cmake_minimum_required(VERSION 3.20.0)
+find_package(Zephyr REQUIRED HINTS $ENV{ZEPHYR_BASE})
+project(posix_stdio)
+
+FILE(GLOB app_sources src/*.c)
+zephyr_include_directories(${ZEPHYR_BASE}/lib/posix)
+
+target_sources(app PRIVATE ${app_sources})

tests/posix/stdio/boards/qemu_riscv64.overlay

@@ -0,0 +1,25 @@
+/*
+ * Copyright (c) 2024 Dawid Osuchowski
+ *
+ * SPDX-License-Identifier: Apache-2.0
+ */
+
+/ {
+    chosen {
+        zephyr,console = &devmux0;
+        zephyr,shell_uart = &devmux0;
+    };
+
+    euart0: uart_emul0 {
+        compatible = "zephyr,uart-emul";
+        current-speed = <0>;
+        status = "okay";
+    };
+
+    devmux0: dev_mux_0 {
+        compatible = "zephyr,devmux";
+        devices = <&uart0 &euart0 &euart1>;
+        zephyr,mutable;
+        status = "okay";
+    };
+};

tests/posix/stdio/prj.conf

@@ -0,0 +1,10 @@
+CONFIG_ZTEST=y
+CONFIG_POSIX_API=y
+CONFIG_POSIX_FS=y
+CONFIG_SERIAL=y
+CONFIG_CONSOLE=y
+CONFIG_CONSOLE_SUBSYS=y
+CONFIG_DEVICE_MUTABLE=y
+CONFIG_FILE_SYSTEM=y
+CONFIG_DEVMUX=y
+CONFIG_UART_EMUL=y

tests/posix/stdio/src/stdio.c

@@ -0,0 +1,97 @@
+/*
+ * Copyright (c) 2024 Dawid Osuchowski
+ *
+ * SPDX-License-Identifier: Apache-2.0
+ */
+
+#include <zephyr/console/console.h>
+#include <zephyr/drivers/misc/devmux/devmux.h>
+#include <zephyr/drivers/serial/uart_emul.h>
+#include <zephyr/kernel.h>
+#include <zephyr/ztest.h>
+#include <stdio.h>
+#include <errno.h>
+
+#define BUF_SIZE 32
+
+/* array of const struct device* */
+#define PHANDLE_TO_DEVICE(node_id, prop, idx) DEVICE_DT_GET(DT_PHANDLE_BY_IDX(node_id, prop, idx))
+static const struct device *devs[] = {
+	DT_FOREACH_PROP_ELEM_SEP(DT_NODELABEL(devmux0), devices, PHANDLE_TO_DEVICE, (,))};
+
+/* array of names, e.g. "euart0" */
+#define PHANDLE_TO_NAME(node_id, prop, idx) DT_NODE_FULL_NAME(DT_PHANDLE_BY_IDX(node_id, prop, idx))
+static const char *const name[] = {
+	DT_FOREACH_PROP_ELEM_SEP(DT_NODELABEL(devmux0), devices, PHANDLE_TO_NAME, (,))};
+
+/* array of greetings, e.g. "Hello, euart0!" */
+#define PHANDLE_TO_TEXT(node_id, prop, idx)                                                        \
+	"Hello, " DT_NODE_FULL_NAME(DT_PHANDLE_BY_IDX(node_id, prop, idx)) "!"
+static const char *const text[] = {
+	DT_FOREACH_PROP_ELEM_SEP(DT_NODELABEL(devmux0), devices, PHANDLE_TO_TEXT, (,))};
+
+ZTEST(stdio, test_fgetc_one_char)
+{
+	size_t normal_uart = DT_PROP(DT_NODELABEL(devmux0), selected);
+	struct device *const devmux_dev = DEVICE_DT_GET(DT_NODELABEL(devmux0));
+
+	/* for each uart_emul device */
+	for (size_t i = 0, j = 0, N = ARRAY_SIZE(devs); i < 2 * N; i++, j++, j %= N) {
+		if (j == normal_uart) {
+			/* skip testing non-emul uart */
+			continue;
+		}
+
+		int ret[4];
+		char buf[BUF_SIZE] = {0};
+
+		/* read text[j] from dev[j] */
+		ret[0] = devmux_select_set(devmux_dev, j);
+		// console_getline_init();
+		ret[1] = uart_emul_put_rx_data(devs[j], (uint8_t *)"H", sizeof(uint8_t));
+		// ret[3] = uart_emul_put_rx_data(devs[j], "\n", 1);
+        ret[3] = uart_emul_flush_rx_data(devs[j]);
+        int rett = fgetc(stdin);
+		// snprintf(buf, BUF_SIZE, "%s", console_getline());
+		ret[2] = devmux_select_set(devmux_dev, normal_uart);
+
+		zassert_ok(ret[0], "Failed to select devmux %zu", j);
+		zassert_ok(ret[2], "Switching back to selection %zu failed", normal_uart);
+
+		/* verify that text[j] was written to dev[j] */
+		TC_PRINT("read '%s' from %s\n", buf, name[j]);
+        TC_PRINT("flushed %d bytes\n", ret[3]);
+        zassert_equal(rett, 'H', "Expected return value %d, got %d", 'H', rett);
+
+
+		zassert_equal(ret[1], strlen(text[j]), "Only put %zu/%zu bytes of '%s'",
+			      ret[1], strlen(text[j]), text[j]);
+		zassert_equal(0, strcmp(text[j], buf), "Strings '%s' and '%s' do not match",
+			      text[j], buf);
+	}
+}
+
+static void *setup(void)
+{
+	size_t selected = DT_PROP(DT_NODELABEL(devmux1), selected);
+	struct device *const devmux_dev = DEVICE_DT_GET(DT_NODELABEL(devmux1));
+
+	/* ensure that non-default initial selection via DT works */
+	zassert_equal(devmux_select_get(devmux_dev), selected);
+
+	return NULL;
+}
+
+static void before(void *arg)
+{
+	struct device *const devmux_dev = DEVICE_DT_GET(DT_NODELABEL(devmux0));
+
+	zassert_ok(devmux_select_set(devmux_dev, 0));
+	zassert_ok(devmux_select_get(devmux_dev));
+
+	for (size_t i = 1; i < ARRAY_SIZE(devs); ++i) {
+		uart_emul_flush_tx_data(devs[i]);
+	}
+}
+
+ZTEST_SUITE(stdio, NULL, setup, before, NULL, NULL);

tests/posix/stdio/testcase.yaml

@@ -0,0 +1,10 @@
+common:
+  tags: posix
+  platform_allow:
+    - qemu_riscv64
+  integration_platforms:
+    - qemu_riscv64
+tests:
+  portability.posix.stdio:
+    extra_configs:
+      - CONFIG_USERSPACE=y