user: implement mlibc as the libc, finally.

It's finally done..

Signed-off-by: kaguya <vpshinomiya@protonmail.com>

user/include/mlibc/tests/posix/popen.c

@@ -0,0 +1,42 @@
+#include <stdio.h>
+#include <string.h>
+#include <assert.h>
+#include <unistd.h>
+
+#ifdef USE_HOST_LIBC
+#define TEST_FILE "popen-host-libc.tmp"
+#else
+#define TEST_FILE "popen.tmp"
+#endif
+
+#define TEST_STRING1 "the quick brown fox jumps over the lazy dog"
+#define TEST_STRING1_LEN 43
+#define TEST_STRING2 "Lorem ipsum dolor sit amet, consectetur adipiscing elit"
+#define TEST_STRING2_LEN 55
+
+int main() {
+	// Test reading
+	FILE *f1 = popen("echo -n '" TEST_STRING1 "'", "r");
+	assert(f1);
+	char buf1[TEST_STRING1_LEN];
+	assert(fread(buf1, 1, TEST_STRING1_LEN, f1) == TEST_STRING1_LEN);
+	assert(memcmp(buf1, TEST_STRING1, TEST_STRING1_LEN) == 0);
+	pclose(f1);
+
+	// Test writing
+	FILE *f2 = popen("cat - > " TEST_FILE, "w");
+	assert(f2);
+	assert(fwrite(TEST_STRING2, 1, TEST_STRING2_LEN, f2) == TEST_STRING2_LEN);
+	pclose(f2);
+
+	// Read test file back
+	FILE *test_file = fopen(TEST_FILE, "r");
+	assert(test_file);
+	char buf2[TEST_STRING2_LEN];
+	assert(fread(buf2, 1, TEST_STRING2_LEN, test_file) == TEST_STRING2_LEN);
+	assert(memcmp(buf2, TEST_STRING2, TEST_STRING2_LEN) == 0);
+	fclose(test_file);
+	assert(unlink(TEST_FILE) == 0);
+
+	return 0;
+}