[Minios-devel] [UNIKRAFT PATCH 2/5] lib/nolibc: move shared definitions to special include file

[Florian Schmidt <florian.schmidt@xxxxxxxxx>]

libc mandates a bunch of definitions that defined from several header
files. At the same time, these definitions are overlapping, but not
easily solved by including one libc header file from another. As an
example (which is fixed in this patch), including stddef.h from stdio.h
provides stdio.h with the required definitions for size_t, but stddef.h
contains more definitions that stdio.h should *not* provide. If nolibc
provides too much, code that compiles with nolibc (because it expects
these over-generous provision of definitions) will not compile with
other libc implementations any more.

We take the solution found in other libc implementations such as newlib
and musl: use __NEED_x macros and include an internal header file with
definitions that cherry-picks those that we need.

This patch does this for the first three data types. More are to follow.

Signed-off-by: Florian Schmidt <florian.schmidt@xxxxxxxxx>
---
 .../include/nolibc-internal/shareddefs.h      | 57 +++++++++++++++++++
 lib/nolibc/include/stddef.h                   |  4 +-
 lib/nolibc/include/stdio.h                    |  4 +-
 lib/nolibc/include/sys/types.h                |  7 ++-
 lib/nolibc/include/unistd.h                   |  3 +
 5 files changed, 70 insertions(+), 5 deletions(-)
 create mode 100644 lib/nolibc/include/nolibc-internal/shareddefs.h

diff --git a/lib/nolibc/include/nolibc-internal/shareddefs.h 
b/lib/nolibc/include/nolibc-internal/shareddefs.h
new file mode 100644
index 0000000..9fccc15
--- /dev/null
+++ b/lib/nolibc/include/nolibc-internal/shareddefs.h
@@ -0,0 +1,57 @@
+/* SPDX-License-Identifier: BSD-3-Clause */
+/*
+ * Authors: Florian Schmidt <florian.schmidt@xxxxxxxxx>
+ *
+ * Copyright (c) 2018, NEC Labs Europe, NEC Corporation. All rights reserved.
+ *
+ * Redistribution and use in source and binary forms, with or without
+ * modification, are permitted provided that the following conditions
+ * are met:
+ *
+ * 1. Redistributions of source code must retain the above copyright
+ *    notice, this list of conditions and the following disclaimer.
+ * 2. Redistributions in binary form must reproduce the above copyright
+ *    notice, this list of conditions and the following disclaimer in the
+ *    documentation and/or other materials provided with the distribution.
+ * 3. Neither the name of the copyright holder nor the names of its
+ *    contributors may be used to endorse or promote products derived from
+ *    this software without specific prior written permission.
+ *
+ * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS"
+ * AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
+ * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
+ * ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT HOLDER OR CONTRIBUTORS BE
+ * LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
+ * CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF
+ * SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
+ * INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN
+ * CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
+ * ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
+ * POSSIBILITY OF SUCH DAMAGE.
+ *
+ * THIS HEADER MAY NOT BE EXTRACTED OR MODIFIED IN ANY WAY.
+ */
+
+/* This header does by design not have include guards, so that it can be
+ * included from multiple files. The __NEED_x macros instead make sure that
+ * only those definitions are included that are required by that specific
+ * file, and only if they haven't been defined on a previous pass through
+ * this file.
+ */
+
+#include <uk/arch/types.h>
+
+#if (defined __NEED_size_t && !defined __DEFINED_size_t)
+typedef __sz size_t;
+#define __DEFINED_size_t
+#endif
+
+#if (defined __NEED_ssize_t && !defined __DEFINED_ssize_t)
+typedef __ssz ssize_t;
+#define __DEFINED_ssize_t
+#endif
+
+#if (defined __NEED_off_t && !defined __DEFINED_off_t)
+typedef __off off_t;
+#define __DEFINED_off_t
+#endif
diff --git a/lib/nolibc/include/stddef.h b/lib/nolibc/include/stddef.h
index 1e66615..a7c600f 100644
--- a/lib/nolibc/include/stddef.h
+++ b/lib/nolibc/include/stddef.h
@@ -36,7 +36,6 @@
 #ifndef __STDDEF_H__
 #define __STDDEF_H__
 
-#include <sys/types.h> /* size_t */
 #include <uk/arch/types.h>
 
 #ifdef __cplusplus
@@ -49,6 +48,9 @@ typedef __sptr ptrdiff_t;
 #define NULL ((void *) 0)
 #endif
 
+#define __NEED_size_t
+#include <nolibc-internal/shareddefs.h>
+
 #ifdef __cplusplus
 }
 #endif
diff --git a/lib/nolibc/include/stdio.h b/lib/nolibc/include/stdio.h
index 539aecf..0dc59aa 100644
--- a/lib/nolibc/include/stdio.h
+++ b/lib/nolibc/include/stdio.h
@@ -36,13 +36,15 @@
 #ifndef __STDIO_H__
 #define __STDIO_H__
 
-#include <stddef.h>
 #include <uk/essentials.h>
 
 #ifdef __cplusplus
 extern "C" {
 #endif
 
+#define __NEED_size_t
+#include <nolibc-internal/shareddefs.h>
+
 struct _nolibc_fd;
 typedef struct _nolibc_fd FILE;
 
diff --git a/lib/nolibc/include/sys/types.h b/lib/nolibc/include/sys/types.h
index 1d61dc6..9908855 100644
--- a/lib/nolibc/include/sys/types.h
+++ b/lib/nolibc/include/sys/types.h
@@ -43,9 +43,10 @@
 extern "C" {
 #endif
 
-typedef __sz   size_t;
-typedef __ssz  ssize_t;
-typedef __off  off_t;
+#define __NEED_size_t
+#define __NEED_ssize_t
+#define __NEED_off_t
+#include <nolibc-internal/shareddefs.h>
 
 #ifdef __cplusplus
 }
diff --git a/lib/nolibc/include/unistd.h b/lib/nolibc/include/unistd.h
index b723b6a..92d8351 100644
--- a/lib/nolibc/include/unistd.h
+++ b/lib/nolibc/include/unistd.h
@@ -41,6 +41,9 @@
 extern "C" {
 #endif
 
+#define __NEED_ssize_t
+#include <nolibc-internal/shareddefs.h>
+
 int close(int fd);
 ssize_t write(int fd, const void *buf, size_t count);
 ssize_t read(int fd, void *buf, size_t count);
-- 
2.18.0


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