[PATCH v2 2/3] linux/termios: factor out the kernel interface from termios_internal.h

[Adhemerval Zanella Netto]

On 10/09/25 18:36, H. Peter Anvin wrote:
> 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.
> 
> Signed-off-by: H. Peter Anvin (Intel) <hpa@zytor.com>

I think it might need some work from the alpha breakage.

> ---
>  sysdeps/unix/sysv/linux/k_termios.h         | 70 +++++++++++++++++++++
>  sysdeps/unix/sysv/linux/termios_internals.h | 45 +------------
>  2 files changed, 71 insertions(+), 44 deletions(-)
>  create mode 100644 sysdeps/unix/sysv/linux/k_termios.h
> 
> diff --git a/sysdeps/unix/sysv/linux/k_termios.h b/sysdeps/unix/sysv/linux/k_termios.h
> new file mode 100644
> index 000000000000..99abe7669bd2
> --- /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 e8dbfe74ded5..db12802a35db 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 ---- */
>