syscalls: mkdirat and gethostname + uname stubs in mlibc

kernel-src/sys/syscalls/mkdirat.c

@@ -0,0 +1,62 @@
+#include <kernel/syscalls.h>
+#include <kernel/file.h>
+#include <kernel/vfs.h>
+#include <kernel/alloc.h>
+#include <kernel/abi.h>
+#include <arch/cpu.h>
+
+syscallret_t syscall_mkdirat(context_t *, int dirfd, const char *upath, mode_t mode) {
+	syscallret_t ret = {
+		.ret = -1
+	};
+
+	char *path = alloc(strlen(upath) + 1);
+	if (path == NULL) {
+		ret.errno = ENOMEM;
+		return ret;
+	}
+
+	// TODO safe strcopy
+	strcpy(path, upath);
+
+	vnode_t *dirnode = NULL;
+	file_t *file = NULL;
+	if (*path == '/') {
+		dirnode = sched_getroot();
+	} else if (dirfd == AT_FDCWD) {
+		dirnode = sched_getcwd();
+	} else {
+		file = fd_get(dirfd);
+		if (file == NULL) {
+			ret.errno = EBADF;
+			goto cleanup;
+		}
+
+		dirnode = file->vnode;
+
+		if (dirnode->type != V_TYPE_DIR) {
+			ret.errno = ENOTDIR;
+			goto cleanup;
+		}
+	}
+
+	vattr_t attr = {
+		.mode = mode,
+		.gid = _cpu()->thread->proc->cred.gid,
+		.uid = _cpu()->thread->proc->cred.uid
+	};
+
+	ret.errno = vfs_create(dirnode, path, &attr, V_TYPE_DIR, NULL);
+	ret.ret = ret.errno ? -1 : 0;
+
+	cleanup:
+
+	if (file)
+		fd_release(file);
+	else
+		VOP_RELEASE(dirnode);
+
+	free(path);
+
+	return ret;
+}