[RFC] libsframe: add local sframe-swap.h header

Currently libsframe includes libctf/swap.h for byteswapping functions.
This cross-directory inclusion of a private header leads to build
conflicts during in-tree builds when both libsframe/config.h and
libctf/config.h are present, causing duplicate macro warnings (More
details at
https://inbox.sourceware.org/binutils/27dfa5e4c684cfdd773e207e8022234109eb1b91.1786465076.git.aburgess@redhat.com/T/#u).

To completely decouple libsframe from libctf, add a local header
libsframe/sframe-swap.h containing the byte-swapping utility functions,
and remove the -I/../libctf from libsframe/Makefile.am.

libsframe/
	* Makefile.am (AM_CPPFLAGS): Remove -I/../libctf.
	* Makefile.in: Regenerate.
	* sframe-swap.h: New header.
	* sframe.c: Include sframe-swap.h instead of swap.h.
---
 libsframe/Makefile.am   |  3 +-
 libsframe/Makefile.in   |  3 +-
 libsframe/sframe-swap.h | 94 +++++++++++++++++++++++++++++++++++++++++
 libsframe/sframe.c      |  2 +-
 4 files changed, 97 insertions(+), 5 deletions(-)
 create mode 100644 libsframe/sframe-swap.h
---

Notes:

This is a follow up on the existing thread proposing removal of
including config.h from libctf/swap.h (and possible short term
resolution to:).

https://inbox.sourceware.org/binutils/[email protected]/T/#t

diff --git a/libsframe/Makefile.am b/libsframe/Makefile.am
index 8f4ed7e1f8b..8f4f50ea849 100644
--- a/libsframe/Makefile.am
+++ b/libsframe/Makefile.am
@@ -26,8 +26,7 @@ DISTCLEANFILES =
 MAINTAINERCLEANFILES =
 
 INCDIR = $(srcdir)/../include
-# include libctf for swap.h
-AM_CPPFLAGS = -I$(srcdir)/../include -I$(srcdir)/../libctf
+AM_CPPFLAGS = -I$(srcdir)/../include
 AM_CFLAGS = @ac_libsframe_warn_cflags@
 libsframe_version_info = -version-info `grep -v '^\#' $(srcdir)/libtool-version`
 # libsframe does not restrict the set of exported symbols.  So, if linker does
diff --git a/libsframe/Makefile.in b/libsframe/Makefile.in
index bd61638262b..4f7e295efe6 100644
--- a/libsframe/Makefile.in
+++ b/libsframe/Makefile.in
@@ -559,8 +559,7 @@ info_TEXINFOS = $(am__append_1)
 DISTCLEANFILES = $(am__append_2)
 MAINTAINERCLEANFILES = $(am__append_3)
 INCDIR = $(srcdir)/../include
-# include libctf for swap.h
-AM_CPPFLAGS = -I$(srcdir)/../include -I$(srcdir)/../libctf
+AM_CPPFLAGS = -I$(srcdir)/../include
 AM_CFLAGS = @ac_libsframe_warn_cflags@
 libsframe_version_info = -version-info `grep -v '^\#' $(srcdir)/libtool-version`
 @HAVE_LD_VERSION_SCRIPT_TRUE@@HAVE_SOLARIS_LD_FALSE@libsframe_version_script = -Wl,--version-script=$(srcdir)/libsframe.ver
diff --git a/libsframe/sframe-swap.h b/libsframe/sframe-swap.h
new file mode 100644
index 00000000000..ebe7865f8e9
--- /dev/null
+++ b/libsframe/sframe-swap.h
@@ -0,0 +1,94 @@
+/* Interface to byteswapping functions for libsframe.
+
+   Copyright (C) 2026 Free Software Foundation, Inc.
+
+   This file is part of libsframe.
+
+   This program is free software; you can redistribute it and/or modify
+   it under the terms of the GNU General Public License as published by
+   the Free Software Foundation; either version 3 of the License, or
+   (at your option) any later version.
+
+   This program is distributed in the hope that it will be useful,
+   but WITHOUT ANY WARRANTY; without even the implied warranty of
+   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+   GNU General Public License for more details.
+
+   You should have received a copy of the GNU General Public License
+   along with this program.  If not, see <http://www.gnu.org/licenses/>.  */
+
+
+#ifndef _SFRAME_SWAP_H
+#define _SFRAME_SWAP_H
+
+#include "config.h"
+#include <stdint.h>
+#include <assert.h>
+
+#ifdef HAVE_BYTESWAP_H
+#include <byteswap.h>
+#endif /* defined(HAVE_BYTESWAP_H) */
+
+/* Provide our own versions of the byteswap functions.  */
+
+#if !HAVE_DECL_BSWAP_16
+static inline uint16_t
+bswap_16 (uint16_t v)
+{
+  return ((v >> 8) & 0xff) | ((v & 0xff) << 8);
+}
+#endif /* !HAVE_DECL_BSWAP16 */
+
+#if !HAVE_DECL_BSWAP_32
+static inline uint32_t
+bswap_32 (uint32_t v)
+{
+  return (  ((v & 0xff000000) >> 24)
+	  | ((v & 0x00ff0000) >>  8)
+	  | ((v & 0x0000ff00) <<  8)
+	  | ((v & 0x000000ff) << 24));
+}
+#endif /* !HAVE_DECL_BSWAP32 */
+
+#if !HAVE_DECL_BSWAP_64
+static inline uint64_t
+bswap_64 (uint64_t v)
+{
+  return (  ((v & 0xff00000000000000ULL) >> 56)
+	  | ((v & 0x00ff000000000000ULL) >> 40)
+	  | ((v & 0x0000ff0000000000ULL) >> 24)
+	  | ((v & 0x000000ff00000000ULL) >>  8)
+	  | ((v & 0x00000000ff000000ULL) <<  8)
+	  | ((v & 0x0000000000ff0000ULL) << 24)
+	  | ((v & 0x000000000000ff00ULL) << 40)
+	  | ((v & 0x00000000000000ffULL) << 56));
+}
+#endif /* !HAVE_DECL_BSWAP64 */
+
+/* < C11? define away static assertions.  */
+
+#if !defined (__STDC_VERSION__) || __STDC_VERSION__ < 201112L
+#ifndef _Static_assert
+#define _Static_assert(cond, err)
+#endif
+#endif
+
+/* Swap the endianness of something.  */
+
+#define swap_thing(x)							\
+  do									\
+    {									\
+      _Static_assert (sizeof (x) == 1 || (sizeof (x) % 2 == 0		\
+					  && sizeof (x) <= 8),		\
+		      "Invalid size, update endianness code");		\
+      switch (sizeof (x)) {						\
+      case 2: x = bswap_16 (x); break;					\
+      case 4: x = bswap_32 (x); break;					\
+      case 8: x = bswap_64 (x); break;					\
+      case 1: /* Nothing needs doing */					\
+	break;								\
+      }									\
+    }									\
+  while (0);
+
+#endif /* _SFRAME_SWAP_H */
diff --git a/libsframe/sframe.c b/libsframe/sframe.c
index cd6bb3022db..286b7d90e64 100644
--- a/libsframe/sframe.c
+++ b/libsframe/sframe.c
@@ -24,7 +24,7 @@
 #include <string.h>
 #include <stddef.h>
 #include "sframe-impl.h"
-#include "swap.h"
+#include "sframe-swap.h"
 
 /* Representation of SFrame FDE internal to libsframe.  */
 typedef struct sframe_func_desc_entry_int
-- 
2.43.0