tools/nolibc: add uio.h with readv and writev

This is generally useful and struct iovec is also needed for other
purposes such as ptrace.

Signed-off-by: Benjamin Berg <[e-mail]>
Signed-off-by: Thomas Weißschuh <[e-mail]>

tools/include/nolibc/Makefile

···
 		sys/time.h \
 		sys/timerfd.h \
 		sys/types.h \
+		sys/uio.h \
 		sys/utsname.h \
 		sys/wait.h \
 		time.h \

tools/include/nolibc/nolibc.h

···
 #include "sys/sysmacros.h"
 #include "sys/time.h"
 #include "sys/timerfd.h"
+#include "sys/uio.h"
 #include "sys/utsname.h"
 #include "sys/wait.h"
 #include "ctype.h"

tools/include/nolibc/sys/uio.h

···
+/* SPDX-License-Identifier: LGPL-2.1 OR MIT */
+/*
+ * uio for NOLIBC
+ * Copyright (C) 2017-2021 Willy Tarreau <[e-mail]>
+ * Copyright (C) 2025 Intel Corporation
+ */
+
+/* make sure to include all global symbols */
+#include "../nolibc.h"
+
+#ifndef _NOLIBC_SYS_UIO_H
+#define _NOLIBC_SYS_UIO_H
+
+#include "../sys.h"
+#include <linux/uio.h>
+
+
+/*
+ * ssize_t readv(int fd, const struct iovec *iovec, int count);
+ */
+static __attribute__((unused))
+ssize_t sys_readv(int fd, const struct iovec *iovec, int count)
+{
+	return my_syscall3(__NR_readv, fd, iovec, count);
+}
+
+static __attribute__((unused))
+ssize_t readv(int fd, const struct iovec *iovec, int count)
+{
+	return __sysret(sys_readv(fd, iovec, count));
+}
+
+/*
+ * ssize_t writev(int fd, const struct iovec *iovec, int count);
+ */
+static __attribute__((unused))
+ssize_t sys_writev(int fd, const struct iovec *iovec, int count)
+{
+	return my_syscall3(__NR_writev, fd, iovec, count);
+}
+
+static __attribute__((unused))
+ssize_t writev(int fd, const struct iovec *iovec, int count)
+{
+	return __sysret(sys_writev(fd, iovec, count));
+}
+
+
+#endif /* _NOLIBC_SYS_UIO_H */

tools/testing/selftests/nolibc/nolibc-test.c

···
 #include <sys/sysmacros.h>
 #include <sys/time.h>
 #include <sys/timerfd.h>
+#include <sys/uio.h>
 #include <sys/utsname.h>
 #include <sys/wait.h>
 #include <dirent.h>
···
 	int proc;
 	int test;
 	int tmp;
+	struct iovec iov_one = {
+		.iov_base = &tmp,
+		.iov_len = 1,
+	};
 	int ret = 0;
 	void *p1, *p2;
 	int has_gettid = 1;
···
 		CASE_TEST(waitpid_child);     EXPECT_SYSER(1, waitpid(getpid(), &tmp, WNOHANG), -1, ECHILD); break;
 		CASE_TEST(write_badf);        EXPECT_SYSER(1, write(-1, &tmp, 1), -1, EBADF); break;
 		CASE_TEST(write_zero);        EXPECT_SYSZR(1, write(1, &tmp, 0)); break;
+		CASE_TEST(readv_badf);        EXPECT_SYSER(1, readv(-1, &iov_one, 1), -1, EBADF); break;
+		CASE_TEST(readv_zero);        EXPECT_SYSZR(1, readv(1, NULL, 0)); break;
+		CASE_TEST(writev_badf);       EXPECT_SYSER(1, writev(-1, &iov_one, 1), -1, EBADF); break;
+		CASE_TEST(writev_zero);       EXPECT_SYSZR(1, writev(1, NULL, 0)); break;
 		CASE_TEST(syscall_noargs);    EXPECT_SYSEQ(1, syscall(__NR_getpid), getpid()); break;
 		CASE_TEST(syscall_args);      EXPECT_SYSER(1, syscall(__NR_statx, 0, NULL, 0, 0, NULL), -1, EFAULT); break;
 		CASE_TEST(namespace);         EXPECT_SYSZR(euid0 && proc, test_namespace()); break;