user: implement mlibc as the libc, finally.

It's finally done..

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

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

@@ -0,0 +1,35 @@
+#include <sys/shm.h>
+#include <assert.h>
+#include <stddef.h>
+#include <stdlib.h>
+#include <errno.h>
+#include <unistd.h>
+#include <time.h>
+
+int main(void) {
+    size_t page_size = getpagesize();
+
+    srand(time(NULL));
+
+    int shmid = -1;
+    for (int i = 0; i < 10; i++) {
+        shmid = shmget((key_t)rand(), page_size, 0644 | IPC_CREAT | IPC_EXCL);
+        if (shmid != -1) {
+            break;
+        }
+    }
+    assert(shmid != -1);
+
+    struct shmid_ds buf;
+    assert(shmctl(shmid, IPC_STAT, &buf) >= 0);
+    assert((size_t)buf.shm_segsz == page_size);
+    assert(buf.shm_cpid == getpid());
+
+    void *attach_addr = shmat(shmid, NULL, SHM_RDONLY);
+    assert(attach_addr != NULL);
+
+    assert(shmctl(shmid, IPC_RMID, &buf) >= 0);
+    assert(shmdt(attach_addr) == 0);
+
+    return 0;
+}