[PATCH v2 06/14] stdio-common: Add __printf_function_invoke

[Adhemerval Zanella]

On 23/05/2022 11:07, Florian Weimer via Libc-alpha wrote:
> And __wprintf_function_invoke.  These functions will be used to
> to call registered printf specifier callbacks on printf buffers
> after vfprintf and vfwprintf have been converted to buffers.
> ---
>  include/printf.h                       | 10 ++++++
>  stdio-common/Makefile                  |  2 ++
>  stdio-common/Xprintf_function_invoke.c | 42 ++++++++++++++++++++++++++
>  stdio-common/printf_function_invoke.c  | 22 ++++++++++++++
>  stdio-common/wprintf_function_invoke.c | 22 ++++++++++++++
>  5 files changed, 98 insertions(+)
>  create mode 100644 stdio-common/Xprintf_function_invoke.c
>  create mode 100644 stdio-common/printf_function_invoke.c
>  create mode 100644 stdio-common/wprintf_function_invoke.c
> 
> diff --git a/include/printf.h b/include/printf.h
> index 78accaab6d..8f064149d3 100644
> --- a/include/printf.h
> +++ b/include/printf.h
> @@ -41,6 +41,16 @@ union printf_arg
>      void *pa_user;
>  };
>  
> +/* Invoke a registered printf callback.  Called from vfprintf and vfwprintf.  */
> +int __printf_function_invoke (void *, printf_function callback,
> +			      union printf_arg *args_value,
> +			      size_t ndata_args,
> +			      struct printf_info *info) attribute_hidden;
> +int __wprintf_function_invoke (void *, printf_function callback,
> +			       union printf_arg *args_value,
> +			       size_t ndata_args,
> +			       struct printf_info *info) attribute_hidden;
> +
>  #include <bits/types/locale_t.h>
>  
>  /* Now define the internal interfaces.  */
> diff --git a/stdio-common/Makefile b/stdio-common/Makefile
> index 5ba381fe41..9195b209cd 100644
> --- a/stdio-common/Makefile
> +++ b/stdio-common/Makefile
> @@ -63,6 +63,7 @@ routines := \
>    printf_buffer_write \
>    printf_fp \
>    printf_fphex \
> +  printf_function_invoke \
>    printf_size \
>    psiginfo \
>    psignal \
> @@ -101,6 +102,7 @@ routines := \
>    wprintf_buffer_puts_1 \
>    wprintf_buffer_to_file \
>    wprintf_buffer_write \
> +  wprintf_function_invoke \
>    # routines
>  
>  aux := \
> diff --git a/stdio-common/Xprintf_function_invoke.c b/stdio-common/Xprintf_function_invoke.c
> new file mode 100644
> index 0000000000..f631469ba9
> --- /dev/null
> +++ b/stdio-common/Xprintf_function_invoke.c
> @@ -0,0 +1,42 @@
> +/* Invoke a printf specifier handler.  Generic version.
> +   Copyright (C) 1991-2022 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/>.  */
> +
> +int
> +Xprintf (function_invoke) (void *buf,
> +                           printf_function callback,
> +                           union printf_arg *args_value,
> +                           size_t ndata_args,
> +                           struct printf_info *info)
> +{
> +  const void *args[ndata_args];
> +  for (unsigned int i = 0; i < ndata_args; ++i)
> +    args[i] = &args_value[i];

Do we really a VLA here? My understanding is we are trying to move away to
alloca/VLA within glibc in favor to fixed size stack data structures (such
as scratch_buffer and dynarray).

> +
> +  struct Xprintf (buffer_as_file) s;
> +  Xprintf (buffer_as_file_init) (&s, buf);
> +
> +  /* Call the function.  */
> +  int done = callback (Xprintf (buffer_as_file_get) (&s), info, args);
> +
> +  if (!Xprintf (buffer_as_file_terminate) (&s))
> +    /* Low-level error.  */
> +    return -1;
> +
> +  /* Potential error from the callback function.  */
> +  return done;
> +}
> diff --git a/stdio-common/printf_function_invoke.c b/stdio-common/printf_function_invoke.c
> new file mode 100644
> index 0000000000..8919b892ca
> --- /dev/null
> +++ b/stdio-common/printf_function_invoke.c
> @@ -0,0 +1,22 @@
> +/* Invoke a printf specifier handler.  Multibyte version.
> +   Copyright (C) 2022 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/>.  */
> +
> +#include <printf.h>
> +#include <printf_buffer_as_file.h>
> +#include "printf_buffer-char.h"
> +#include "Xprintf_function_invoke.c"
> diff --git a/stdio-common/wprintf_function_invoke.c b/stdio-common/wprintf_function_invoke.c
> new file mode 100644
> index 0000000000..29a6b4e073
> --- /dev/null
> +++ b/stdio-common/wprintf_function_invoke.c
> @@ -0,0 +1,22 @@
> +/* Invoke a printf specifier handler.  Wide version.
> +   Copyright (C) 2022 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/>.  */
> +
> +#include <printf.h>
> +#include <printf_buffer_as_file.h>
> +#include "printf_buffer-wchar_t.h"
> +#include "Xprintf_function_invoke.c"