user: implement mlibc as the libc, finally.

It's finally done.. Signed-off-by: kaguya <vpshinomiya@protonmail.com>
2026-05-02 03:31:49 -04:00
parent 2fa39ad85a
commit 9a9b91c940
2387 changed files with 152741 additions and 315 deletions
@@ -0,0 +1,516 @@
+#include <math.h>
+#include <stddef.h>
+#include <stdint.h>
+#include <stdlib.h>
+#include <stdio.h>
+#include <string.h>
+#include <assert.h>
+#include <wchar.h>
+
+struct format_test_cases {
+	const char *format;
+	const char *data;
+	int expected_int;
+	enum {
+		T_INT,
+		T_UINT,
+		T_CHAR,
+		T_NONE,
+	} type;
+	int ret;
+} formats[] = {
+	{"%i", "0x420", 0x420, T_INT, 1},
+	{"%i", "0420", 0420, T_INT, 1},
+	{"%i", "420", 420, T_INT, 1},
+	{"%i", "-420", -420, T_INT, 1},
+	{"%d", "-12345", -12345, T_INT, 1},
+	{"%u", "69", 69, T_UINT, 1},
+	{"%u", "0420", 420, T_UINT, 1},
+	{"%o", "0420", 0420, T_UINT, 1},
+	{"%x", "0xCB7", 0xCB7, T_UINT, 1},
+#ifndef USE_HOST_LIBC
+	{"%b", "0b1011", 0b1011, T_UINT, 1},
+	{"%b", "0B1011", 0b1011, T_UINT, 1},
+#endif
+	{"%%", "%", 0, T_NONE, 0},
+	{"%c", "         I am not a fan of this solution.", ' ', T_CHAR, 1},
+	{" %c", "           CBT (capybara therapy)", 'C', T_CHAR, 1},
+	{"%d %d %d", "  111111 I<3Managarm 1234", 111111, T_UINT, 1},
+	{"%c %d", "C", 'C', T_CHAR, 1}
+};
+
+#pragma GCC diagnostic ignored "-Wformat-security"
+
+static void test_matrix() {
+	for(size_t i = 0; i < (sizeof(formats) / sizeof(*formats)); i++) {
+		struct format_test_cases *f = &formats[i];
+		int ret = -1;
+		int data_int;
+		unsigned int data_uint;
+		char data_char;
+
+		switch(f->type) {
+			case T_INT: {
+				ret = sscanf(f->data, f->format, &data_int);
+				assert(data_int == f->expected_int);
+				break;
+			}
+			case T_UINT: {
+				ret = sscanf(f->data, f->format, &data_uint);
+				assert(data_uint == (unsigned int) f->expected_int);
+				break;
+			}
+			case T_CHAR: {
+				ret = sscanf(f->data, f->format, &data_char);
+				assert(data_char == (unsigned char) f->expected_int);
+				break;
+			}
+			case T_NONE: {
+				ret = sscanf(f->data, f->format);
+				break;
+			}
+
+		}
+
+		assert(ret == f->ret);
+	}
+}
+
+int main() {
+	{
+		int x = 0;
+		char buf[] = "12345";
+		sscanf(buf, "%d", &x);
+		assert(x == 12345);
+	}
+
+	{
+		char c;
+		int n1;
+		int n2;
+		char buf[] = "z$ 7 5 440";;
+		int count = sscanf(buf, "%*c%c %d %*d %d", &c, &n1, &n2);
+		assert(count == 3);
+		assert(c == '$');
+		assert(n1 == 7);
+		assert(n2 == 440);
+	}
+
+	{
+		// From dsda-doom
+		char buf[] = "process_priority               0\n";
+		char def[80], strparm[128];
+		memset(def, '!', 80);
+		memset(strparm, '!', 128);
+		sscanf(buf, "%s %[^\n]\n", def, strparm);
+		assert(!strcmp(def, "process_priority"));
+		assert(!strcmp(strparm, "0"));
+	}
+
+	{
+		char buf[] = "fffff100";
+		unsigned long y = 0;
+		sscanf(buf, "%lx", &y);
+		assert(y == 0xfffff100);
+	}
+
+#if !defined(__i386__) && !defined(__m68k__)
+	{
+		char buf[] = "fffffffff100";
+		unsigned long y = 0;
+		sscanf(buf, "%lx", &y);
+		assert(y == 0xfffffffff100);
+	}
+#endif
+
+	{
+		char buf[] = "410dc000";
+		unsigned long y = 0;
+		sscanf(buf, "%lx", &y);
+		assert(y == 0x410dc000);
+	}
+
+	{
+		// From webkitgtk
+		char buf[] = "MemTotal:       16299664 kB\n";
+		char token[51] = {0};
+		size_t amount = 0;
+		int ret = sscanf(buf, "%50s%zukB", token, &amount);
+		assert(ret == 2);
+		assert(!strcmp(token, "MemTotal:"));
+		assert(amount == 16299664);
+	}
+
+	{
+		char buf[] = "SIGINT";
+		int sig;
+		int ret = sscanf(buf, "%d", &sig);
+		assert(!ret);
+	}
+
+	{
+		char buf[50];
+		int ret = sscanf("", "%s", buf);
+		assert(ret == EOF);
+	}
+
+	{
+		char *str = NULL;
+		int ret = sscanf("Managarm", "%ms", &str);
+		assert(ret == 1);
+		assert(str != NULL);
+		assert(!strcmp(str, "Managarm"));
+		free(str);
+	}
+
+	test_matrix();
+
+#pragma GCC diagnostic push
+#pragma GCC diagnostic ignored "-Wformat-zero-length"
+	assert(sscanf("", "") == 0);
+#pragma GCC diagnostic pop
+	assert(sscanf("", "a") == EOF);
+	assert(sscanf(" \t\na", " a") == 0);
+	assert(sscanf("a%", "a%%") == 0);
+	assert(sscanf("ab", "abcd") == EOF);
+	assert(sscanf("abab", "abcd") == 0);
+
+	char char_value[8];
+	wchar_t wchar_value[8];
+
+	assert(sscanf("a", "%c", char_value) == 1);
+	assert(char_value[0] == 'a');
+	assert(sscanf("a", "%lc", wchar_value) == 1);
+	assert(wchar_value[0] == L'a');
+	assert(sscanf("hello", "%s", char_value) == 1);
+	assert(strcmp(char_value, "hello") == 0);
+	assert(sscanf("", "%s", char_value) == EOF);
+	assert(sscanf(" ", "%s", char_value) == EOF);
+	assert(sscanf(" a", "%sb", char_value) == 1);
+	assert(sscanf("hello", "%ls", wchar_value) == 1);
+	assert(wcscmp(wchar_value, L"hello") == 0);
+	assert(sscanf("abcd", "%[ac]bcd", char_value) == 1);
+	assert(strcmp(char_value, "a") == 0);
+	assert(sscanf("abcd", "%l[ac]bcd", wchar_value) == 1);
+	assert(wcscmp(wchar_value, L"a") == 0);
+	assert(sscanf("aacd", "%[ac]bcd", char_value) == 1);
+	assert(strcmp(char_value, "aac") == 0);
+	assert(sscanf("aacd", "%[ac]bcd", char_value) == 1);
+	assert(strcmp(char_value, "aac") == 0);
+	assert(sscanf("]", "%[]]", char_value) == 1);
+	assert(strcmp(char_value, "]") == 0);
+	assert(sscanf("]", "%[^]]", char_value) == 0);
+	assert(sscanf("abcd", "%[^ac]bcd", char_value) == 0);
+	assert(sscanf("aacd", "%[^ac]bcd", char_value) == 0);
+	assert(sscanf("aacd", "%[^ac]bcd", char_value) == 0);
+	assert(sscanf("ddd", "%[^ac]bcd", char_value) == 1);
+	assert(strcmp(char_value, "ddd") == 0);
+	assert(sscanf("abcd", "%[0-9]", char_value) == 0);
+	assert(sscanf("2a", "%[0-9]", char_value) == 1);
+	assert(strcmp(char_value, "2") == 0);
+
+	unsigned char uchar_value;
+	signed char schar_value;
+	unsigned short ushort_value;
+	short short_value;
+	unsigned int uint_value;
+	int int_value;
+	unsigned long ulong_value;
+	long long_value;
+	unsigned long long ulonglong_value;
+	long long longlong_value;
+	uintmax_t uintmax_value;
+	intmax_t intmax_value;
+	size_t size_value;
+	ptrdiff_t ptrdiff_value;
+
+	assert(sscanf("1234abc", "%d", &int_value) == 1);
+	assert(int_value == 1234);
+	assert(sscanf("123", "%hhd", &schar_value) == 1);
+	assert(schar_value == 123);
+	assert(sscanf("1234", "%hd", &short_value) == 1);
+	assert(short_value == 1234);
+	assert(sscanf("1234", "%ld", &long_value) == 1);
+	assert(long_value == 1234);
+	assert(sscanf("1234", "%lld", &longlong_value) == 1);
+	assert(longlong_value == 1234);
+	assert(sscanf("1234", "%jd", &intmax_value) == 1);
+	assert(intmax_value == 1234);
+	assert(sscanf("1234", "%zd", &size_value) == 1);
+	assert(size_value == 1234);
+	assert(sscanf("1234", "%td", &ptrdiff_value) == 1);
+	assert(ptrdiff_value == 1234);
+	assert(sscanf("    1235abc", "%d", &int_value) == 1);
+	assert(int_value == 1235);
+	assert(sscanf("+1234abc", "%d", &int_value) == 1);
+	assert(int_value == 1234);
+	assert(sscanf("-1234abc", "%d", &int_value) == 1);
+	assert(int_value == -1234);
+	assert(sscanf("-abc", "%d", &int_value) == 0);
+	assert(sscanf("-", "%d", &int_value) == 0);
+
+	assert(sscanf("1234abc", "%i", &int_value) == 1);
+	assert(int_value == 1234);
+	assert(sscanf("123", "%hhi", &schar_value) == 1);
+	assert(schar_value == 123);
+	assert(sscanf("1234", "%hi", &short_value) == 1);
+	assert(short_value == 1234);
+	assert(sscanf("1234", "%li", &long_value) == 1);
+	assert(long_value == 1234);
+	assert(sscanf("1234", "%lli", &longlong_value) == 1);
+	assert(longlong_value == 1234);
+	assert(sscanf("1234", "%ji", &intmax_value) == 1);
+	assert(intmax_value == 1234);
+	assert(sscanf("1234", "%zi", &size_value) == 1);
+	assert(size_value == 1234);
+	assert(sscanf("1234", "%ti", &ptrdiff_value) == 1);
+	assert(ptrdiff_value == 1234);
+	assert(sscanf("    1235abc", "%i", &int_value) == 1);
+	assert(int_value == 1235);
+	assert(sscanf("+1234abc", "%i", &int_value) == 1);
+	assert(int_value == 1234);
+	assert(sscanf("-1234abc", "%i", &int_value) == 1);
+	assert(int_value == -1234);
+	assert(sscanf("-abc", "%i", &int_value) == 0);
+
+	assert(sscanf(" 0b1011", "%i", &int_value) == 1);
+	assert(int_value == 0b1011);
+	assert(sscanf(" 0B1010", "%i", &int_value) == 1);
+	assert(int_value == 0b1010);
+	assert(sscanf(" +0b1011", "%i", &int_value) == 1);
+	assert(int_value == 0b1011);
+	assert(sscanf(" -0b1111", "%i", &int_value) == 1);
+	assert(int_value == -0b1111);
+
+	assert(sscanf(" 01234", "%i", &int_value) == 1);
+	assert(int_value == 01234);
+	assert(sscanf(" +01234", "%i", &int_value) == 1);
+	assert(int_value == 01234);
+	assert(sscanf(" -01234", "%i", &int_value) == 1);
+	assert(int_value == -01234);
+
+	assert(sscanf(" 0xab12", "%i", &int_value) == 1);
+	assert(int_value == 0xAB12);
+	assert(sscanf(" 0xAB12", "%i", &int_value) == 1);
+	assert(int_value == 0xAB12);
+	assert(sscanf(" 0Xab12", "%i", &int_value) == 1);
+	assert(int_value == 0xAB12);
+	assert(sscanf(" +0xab12", "%i", &int_value) == 1);
+	assert(int_value == 0xAB12);
+	assert(sscanf(" -0xab12", "%i", &int_value) == 1);
+	assert(int_value == -0xAB12);
+
+	assert(sscanf("1234abc", "%u", &uint_value) == 1);
+	assert(uint_value == 1234);
+	assert(sscanf("123", "%hhu", &uchar_value) == 1);
+	assert(uchar_value == 123);
+	assert(sscanf("1234", "%hu", &ushort_value) == 1);
+	assert(ushort_value == 1234);
+	assert(sscanf("1234", "%lu", &ulong_value) == 1);
+	assert(ulong_value == 1234);
+	assert(sscanf("1234", "%llu", &ulonglong_value) == 1);
+	assert(ulonglong_value == 1234);
+	assert(sscanf("1234", "%ju", &uintmax_value) == 1);
+	assert(uintmax_value == 1234);
+	assert(sscanf("1234", "%zu", &size_value) == 1);
+	assert(size_value == 1234);
+	assert(sscanf("1234", "%tu", &ptrdiff_value) == 1);
+	assert(ptrdiff_value == 1234);
+	assert(sscanf("    1235abc", "%u", &int_value) == 1);
+	assert(int_value == 1235);
+	assert(sscanf("+1234abc", "%u", &int_value) == 1);
+	assert(int_value == 1234);
+	assert(sscanf("-1234abc", "%u", &int_value) == 1);
+	assert(int_value == -1234);
+	assert(sscanf("-abc", "%d", &int_value) == 0);
+
+	assert(sscanf(" 12345", "%o", &int_value) == 1);
+	assert(int_value == 012345);
+	assert(sscanf("12", "%hho", &uchar_value) == 1);
+	assert(uchar_value == 012);
+	assert(sscanf("1234", "%ho", &ushort_value) == 1);
+	assert(ushort_value == 01234);
+	assert(sscanf("1234", "%lo", &ulong_value) == 1);
+	assert(ulong_value == 01234);
+	assert(sscanf("1234", "%llo", &ulonglong_value) == 1);
+	assert(ulonglong_value == 01234);
+	assert(sscanf("1234", "%jo", &uintmax_value) == 1);
+	assert(uintmax_value == 01234);
+	assert(sscanf("1234", "%zo", &size_value) == 1);
+	assert(size_value == 01234);
+	assert(sscanf("1234", "%to", &ptrdiff_value) == 1);
+	assert(ptrdiff_value == 01234);
+	assert(sscanf(" 01234", "%o", &int_value) == 1);
+	assert(int_value == 01234);
+	assert(sscanf(" +01234", "%o", &int_value) == 1);
+	assert(int_value == 01234);
+	assert(sscanf(" -01234", "%o", &int_value) == 1);
+	assert(int_value == -01234);
+
+	assert(sscanf(" 1234ab", "%x", &int_value) == 1);
+	assert(int_value == 0x1234AB);
+	assert(sscanf("12", "%hhx", &uchar_value) == 1);
+	assert(uchar_value == 0x12);
+	assert(sscanf("1234", "%hx", &ushort_value) == 1);
+	assert(ushort_value == 0x1234);
+	assert(sscanf("1234", "%lx", &ulong_value) == 1);
+	assert(ulong_value == 0x1234);
+	assert(sscanf("1234", "%llx", &ulonglong_value) == 1);
+	assert(ulonglong_value == 0x1234);
+	assert(sscanf("1234", "%jx", &uintmax_value) == 1);
+	assert(uintmax_value == 0x1234);
+	assert(sscanf("1234", "%zx", &size_value) == 1);
+	assert(size_value == 0x1234);
+	assert(sscanf("1234", "%tx", &ptrdiff_value) == 1);
+	assert(ptrdiff_value == 0x1234);
+	assert(sscanf(" 1234ABC", "%x", &int_value) == 1);
+	assert(int_value == 0x1234ABC);
+	assert(sscanf(" 1234ab", "%X", &int_value) == 1);
+	assert(int_value == 0x1234AB);
+	assert(sscanf(" 0x1234", "%x", &int_value) == 1);
+	assert(int_value == 0x1234);
+	assert(sscanf(" 0x1234A", "%x", &int_value) == 1);
+	assert(int_value == 0x1234A);
+	assert(sscanf(" 0X1234AB", "%x", &int_value) == 1);
+	assert(int_value == 0x1234AB);
+	assert(sscanf(" +0x1234", "%x", &int_value) == 1);
+	assert(int_value == 0x1234);
+	assert(sscanf(" -0x1234", "%x", &int_value) == 1);
+	assert(int_value == -0x1234);
+
+	assert(sscanf("abc", "abc%n", &int_value) == 0);
+	assert(int_value == 3);
+	assert(sscanf("1234", "1234%hhn", &uchar_value) == 0);
+	assert(uchar_value == 4);
+	assert(sscanf("1234", "1234%hn", &ushort_value) == 0);
+	assert(ushort_value == 4);
+	assert(sscanf("1234", "1234%ln", &ulong_value) == 0);
+	assert(ulong_value == 4);
+	assert(sscanf("1234", "1234%lln", &ulonglong_value) == 0);
+	assert(ulonglong_value == 4);
+	assert(sscanf("1234", "1234%jn", &uintmax_value) == 0);
+	assert(uintmax_value == 4);
+	assert(sscanf("1234", "1234%zn", &size_value) == 0);
+	assert(size_value == 4);
+	assert(sscanf("1234", "1234%tn", &ptrdiff_value) == 0);
+	assert(ptrdiff_value == 4);
+	assert(sscanf("abcd", "ab%nc%c", &int_value, char_value) == 1);
+	assert(int_value == 2);
+	assert(char_value[0] == 'd');
+
+	float float_value;
+	double double_value;
+	long double long_double_value;
+	(void)float_value;
+	(void)double_value;
+	(void)long_double_value;
+	/*assert(sscanf("1.123", "%a", &float_value) == 1);
+	assert(float_value >= 1.123f - 0.01 && float_value <= 1.123f + 0.01);
+	assert(sscanf("1.123", "%la", &double_value) == 1);
+	assert(double_value >= 1.123 - 0.01 && double_value <= 1.123 + 0.01);
+	assert(sscanf("1.123", "%La", &long_double_value) == 1);
+	assert(long_double_value >= 1.123L - 0.01 && long_double_value <= 1.123L + 0.01);
+	assert(sscanf("1.1234", "%A", &float_value) == 1);
+	assert(float_value >= 1.1234f - 0.01 && float_value <= 1.1234f + 0.01);
+	assert(sscanf("1.123", "%e", &float_value) == 1);
+	assert(float_value >= 1.123f - 0.01 && float_value <= 1.123f + 0.01);
+	assert(sscanf("1.123", "%le", &double_value) == 1);
+	assert(double_value >= 1.123 - 0.01 && double_value <= 1.123 + 0.01);
+	assert(sscanf("1.123", "%Le", &long_double_value) == 1);
+	assert(long_double_value >= 1.123L - 0.01 && long_double_value <= 1.123L + 0.01);
+	assert(sscanf("1.1234", "%E", &float_value) == 1);
+	assert(float_value >= 1.1234f - 0.01 && float_value <= 1.1234f + 0.01);
+	assert(sscanf("1.123", "%f", &float_value) == 1);
+	assert(float_value >= 1.123f - 0.01 && float_value <= 1.123f + 0.01);
+	assert(sscanf("1.123", "%lf", &double_value) == 1);
+	assert(double_value >= 1.123 - 0.01 && double_value <= 1.123 + 0.01);
+	assert(sscanf("1.123", "%Lf", &long_double_value) == 1);
+	assert(long_double_value >= 1.123L - 0.01 && long_double_value <= 1.123L + 0.01);
+	assert(sscanf("1.1234", "%F", &float_value) == 1);
+	assert(float_value >= 1.1234f - 0.01 && float_value <= 1.1234f + 0.01);
+	assert(sscanf("1.123", "%g", &float_value) == 1);
+	assert(float_value >= 1.123f - 0.01 && float_value <= 1.123f + 0.01);
+	assert(sscanf("1.123", "%lg", &double_value) == 1);
+	assert(double_value >= 1.123 - 0.01 && double_value <= 1.123 + 0.01);
+	assert(sscanf("1.123", "%Lg", &long_double_value) == 1);
+	assert(long_double_value >= 1.123L - 0.01 && long_double_value <= 1.123L + 0.01);
+	assert(sscanf("1.1234", "%G", &float_value) == 1);
+	assert(float_value >= 1.1234f - 0.01 && float_value <= 1.1234f + 0.01);
+	assert(sscanf("+1.1234", "%f", &float_value) == 1);
+	assert(float_value >= 1.1234f - 0.01 && float_value <= 1.1234f + 0.01);
+	assert(sscanf("-1.1234", "%f", &float_value) == 1);
+	assert(float_value >= -1.1234f - 0.01 && float_value <= -1.1234f + 0.01);
+	assert(sscanf("1.1234e3", "%f", &float_value) == 1);
+	assert(float_value >= 1.1234E3f - 0.01 && float_value <= 1.1234E3f + 0.01);
+	assert(sscanf("1.1234E3", "%f", &float_value) == 1);
+	assert(float_value >= 1.1234E3f - 0.01 && float_value <= 1.1234E3f + 0.01);
+	assert(sscanf("0x1234", "%f", &float_value) == 1);
+	assert(float_value >= 0x1234P0f - 0.01 && float_value <= 0x1234P0f + 0.01);
+	assert(sscanf("0X1234", "%f", &float_value) == 1);
+	assert(float_value >= 0x1234P0f - 0.01 && float_value <= 0x1234P0f + 0.01);
+	assert(sscanf("0x1.1234", "%f", &float_value) == 1);
+	assert(float_value >= 0x1.1234P0 - 0.01 && float_value <= 0x1.1234P0 + 0.01);
+	assert(sscanf("0x1.abcdP3", "%f", &float_value) == 1);
+	assert(float_value >= 0x1.ABCDP3 - 0.01 && float_value <= 0x1.ABCDP3 + 0.01);
+	assert(sscanf("0x1.abcdP+3", "%f", &float_value) == 1);
+	assert(float_value >= 0x1.ABCDP3 - 0.01 && float_value <= 0x1.ABCDP3 + 0.01);
+	assert(sscanf("0x1.abcdP-3", "%f", &float_value) == 1);
+	assert(float_value >= 0x1.ABCDP-3 - 0.01 && float_value <= 0x1.ABCDP-3 + 0.01);
+	assert(sscanf("0x1.AbCdP-3", "%f", &float_value) == 1);
+	assert(float_value >= 0x1.ABCDP-3 - 0.01 && float_value <= 0x1.ABCDP-3 + 0.01);
+	assert(sscanf("inf", "%f", &float_value) == 1);
+	assert(isinf(float_value));
+	assert(sscanf("InF", "%f", &float_value) == 1);
+	assert(isinf(float_value));
+	assert(sscanf("+inf", "%f", &float_value) == 1);
+	assert(isinf(float_value));
+	assert(sscanf("-inf", "%f", &float_value) == 1);
+	assert(isinf(float_value));
+	assert(sscanf("INF", "%f", &float_value) == 1);
+	assert(isinf(float_value));
+	assert(sscanf("infinity", "%f", &float_value) == 1);
+	assert(isinf(float_value));
+	assert(sscanf("INFINITY", "%f", &float_value) == 1);
+	assert(isinf(float_value));
+	assert(sscanf("nan", "%f", &float_value) == 1);
+	assert(isnan(float_value));
+	assert(sscanf("NaN", "%f", &float_value) == 1);
+	assert(isnan(float_value));
+	assert(sscanf("+nan", "%f", &float_value) == 1);
+	assert(isnan(float_value));
+	assert(sscanf("-nan", "%f", &float_value) == 1);
+	assert(isnan(float_value));
+	assert(sscanf("0xhello", "%f", &float_value) == 0);
+	assert(sscanf("0x1hello", "%f", &float_value) == 1);
+	assert(float_value >= 0x1P0f - 0.01 && float_value <= 0x1P0f + 0.01);
+	assert(sscanf("ab1.1234", "%f", &float_value) == 0);
+	assert(sscanf("  1.123", "%f", &float_value) == 1);
+	assert(float_value >= 1.123f - 0.01 && float_value <= 1.123f + 0.01);*/
+
+	void* ptr;
+	assert(sscanf("hello", "%p", &ptr) == 0);
+#if UINTPTR_MAX == UINT64_MAX
+	assert(sscanf("0xabcdef12abcdef12", "%p", &ptr) == 1);
+	assert(ptr == (void*)0xabcdef12abcdef12);
+#else
+	assert(sscanf("0xabcdef12", "%p", &ptr) == 1);
+	assert(ptr == (void*)0xabcdef12);
+#endif
+
+	assert(sscanf("a", "%*c") == 0);
+	char_value[2] = 'q';
+	assert(sscanf("abcd", "%2c", char_value) == 1);
+	assert(char_value[2] == 'q');
+	char_value[2] = 0;
+	assert(strcmp(char_value, "ab") == 0);
+
+	assert(sscanf("cdef", "%2s", char_value) == 1);
+	assert(strcmp(char_value, "cd") == 0);
+	assert(sscanf("c def", "%2s", char_value) == 1);
+	assert(strcmp(char_value, "c") == 0);
+
+	assert(sscanf("aacd", "%2[ac]", char_value) == 1);
+	assert(strcmp(char_value, "aa") == 0);
+
+	return 0;
+}