linux/termios: factor out the kernel interface from termios_internal.h

Factor out the internal kernel interface from termios_internal.h, so
that it can be used in test code without causing breakage due to glibc
internals used in headers.

[ v3: fix Alpha build breakage ]

Signed-off-by: H. Peter Anvin (Intel) <hpa@zytor.com>
Reviewed-by: Adhemerval Zanella  <adhemerval.zanella@linaro.org>

3 files changed, 73 insertions, 46 deletions

diff --git a/sysdeps/unix/sysv/linux/alpha/termios_arch.h b/sysdeps/unix/sysv/linux/alpha/termios_arch.h
index 20025f2549..e671accac6 100644
--- a/sysdeps/unix/sysv/linux/alpha/termios_arch.h
+++ b/sysdeps/unix/sysv/linux/alpha/termios_arch.h
@@ -17,8 +17,8 @@
    License along with the GNU C Library; if not, see
    <https://www.gnu.org/licenses/>.  */
 
-#ifndef TERMIOS_INTERNALS_H
-# error "<termios_arch.h> should only be included from <termios_internals.h>"
+#ifndef K_TERMIOS_H
+# error "<termios_arch.h> should only be included from <k_termios.h>"
 #endif
 
 #define _TERMIOS2_NCCS 19
diff --git a/sysdeps/unix/sysv/linux/k_termios.h b/sysdeps/unix/sysv/linux/k_termios.h
new file mode 100644
index 0000000000..99abe7669b
--- /dev/null
+++ b/sysdeps/unix/sysv/linux/k_termios.h
@@ -0,0 +1,70 @@
+/* termios kernel interface for Linux
+
+   Copyright (C) 1991-2025 Free Software Foundation, Inc.
+   This file is part of the GNU C Library.
+
+   The GNU C Library is free software; you can redistribute it and/or
+   modify it under the terms of the GNU Lesser General Public
+   License as published by the Free Software Foundation; either
+   version 2.1 of the License, or (at your option) any later version.
+
+   The GNU C Library 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
+   Lesser General Public License for more details.
+
+   You should have received a copy of the GNU Lesser General Public
+   License along with the GNU C Library; if not, see
+   <https://www.gnu.org/licenses/>.  */
+
+#ifndef K_TERMIOS_H
+#define K_TERMIOS_H
+
+#include <stddef.h>
+#include <unistd.h>
+#include <termios.h>
+#include <kernel-features.h>
+#include <termios_arch.h>
+
+/* The the termios2 structure used in the kernel interfaces is not the
+   same as the termios structure we use in the libc.  Therefore we
+   must translate it here.  */
+
+struct termios2
+{
+  tcflag_t c_iflag;		/* input mode flags */
+  tcflag_t c_oflag;		/* output mode flags */
+  tcflag_t c_cflag;		/* control mode flags */
+  tcflag_t c_lflag;		/* local mode flags */
+#if _HAVE_TERMIOS2_C_CC_BEFORE_C_LINE
+  cc_t c_cc[_TERMIOS2_NCCS];	/* control characters */
+  cc_t c_line;			/* line discipline */
+#else
+  cc_t c_line;			/* line discipline */
+  cc_t c_cc[_TERMIOS2_NCCS];	/* control characters */
+#endif
+  speed_t c_ispeed;		/* input speed */
+  speed_t c_ospeed;		/* output speed */
+};
+
+/* Alpha got termios2 late, but TCGETS has exactly the same structure
+   format and function as TCGETS2. On all other platforms, the termios2
+   interface exists as far back as this version of glibc supports.
+
+   For TCSETS* it is more complicated; this is handled in tcsetattr.c.
+
+   Some other architectures only have the equivalent of the termios2
+   interface, in which case the old ioctl names are the only ones
+   presented, but are equivalent to the new ones. */
+#ifndef TCGETS2
+# define TCGETS2  TCGETS
+# define TCSETS2  TCSETS
+# define TCSETSW2 TCSETSW
+# define TCSETSF2 TCSETSF
+#elif !__ASSUME_TERMIOS2
+/* Hack for Alpha */
+# undef  TCGETS2
+# define TCGETS2 TCGETS
+#endif
+
+#endif /* KTERMIOS_H */
diff --git a/sysdeps/unix/sysv/linux/termios_internals.h b/sysdeps/unix/sysv/linux/termios_internals.h
index e8dbfe74de..db12802a35 100644
--- a/sysdeps/unix/sysv/linux/termios_internals.h
+++ b/sysdeps/unix/sysv/linux/termios_internals.h
@@ -30,50 +30,7 @@
 #include <sysdep.h>
 #include <shlib-compat.h>
 
-#include <termios_arch.h>
-
-/* ---- Kernel interface definitions ---- */
-
-/* The the termios2 structure used in the kernel interfaces is not the
-   same as the termios structure we use in the libc.  Therefore we
-   must translate it here.  */
-
-struct termios2
-{
-  tcflag_t c_iflag;		/* input mode flags */
-  tcflag_t c_oflag;		/* output mode flags */
-  tcflag_t c_cflag;		/* control mode flags */
-  tcflag_t c_lflag;		/* local mode flags */
-#if _HAVE_TERMIOS2_C_CC_BEFORE_C_LINE
-  cc_t c_cc[_TERMIOS2_NCCS];	/* control characters */
-  cc_t c_line;			/* line discipline */
-#else
-  cc_t c_line;			/* line discipline */
-  cc_t c_cc[_TERMIOS2_NCCS];	/* control characters */
-#endif
-  speed_t c_ispeed;		/* input speed */
-  speed_t c_ospeed;		/* output speed */
-};
-
-/* Alpha got termios2 late, but TCGETS has exactly the same structure
-   format and function as TCGETS2. On all other platforms, the termios2
-   interface exists as far back as this version of glibc supports.
-
-   For TCSETS* it is more complicated; this is handled in tcsetattr.c.
-
-   Some other architectures only have the equivalent of the termios2
-   interface, in which case the old ioctl names are the only ones
-   presented, but are equivalent to the new ones. */
-#ifndef TCGETS2
-# define TCGETS2  TCGETS
-# define TCSETS2  TCSETS
-# define TCSETSW2 TCSETSW
-# define TCSETSF2 TCSETSF
-#elif !__ASSUME_TERMIOS2
-/* Hack for Alpha */
-# undef  TCGETS2
-# define TCGETS2 TCGETS
-#endif
+#include <k_termios.h>
 
 /* ---- Application interface definitions ---- */