[PATCH v6 09/11] libio: Convert __vdprintf_internal to buffers

[Adhemerval Zanella Netto]

On 16/12/22 17:15, Florian Weimer via Libc-alpha wrote:
> The internal buffer size is set to 2048 bytes.  This is less than
> the original BUFSIZ value used by buffered_vfprintf before
> the conversion, but it hopefully covers all cases where write
> boundaries matter.

LGTM, thanks.

Reviewed-by: Adhemerval Zanella  <adhemerval.zanella@linaro.org>

> ---
>  include/printf_buffer.h            |  9 ++++
>  libio/iovdprintf.c                 | 67 +++++++++++++++++-------------
>  stdio-common/printf_buffer_flush.c |  4 ++
>  3 files changed, 52 insertions(+), 28 deletions(-)
> 
> diff --git a/include/printf_buffer.h b/include/printf_buffer.h
> index c8e22e1e90..e2ca2d72d5 100644
> --- a/include/printf_buffer.h
> +++ b/include/printf_buffer.h
> @@ -50,6 +50,7 @@ enum __printf_buffer_mode
>      __printf_buffer_mode_sprintf_chk,
>      __printf_buffer_mode_to_file,
>      __printf_buffer_mode_asprintf,
> +    __printf_buffer_mode_dprintf,
>      __printf_buffer_mode_strfmon,
>      __printf_buffer_mode_fp,         /* For __printf_fp_l_buffer.  */
>      __printf_buffer_mode_fp_to_wide, /* For __wprintf_fp_l_buffer.  */
> @@ -308,6 +309,9 @@ void __printf_buffer_flush_to_file (struct __printf_buffer_to_file *)
>  struct __printf_buffer_asprintf;
>  void __printf_buffer_flush_asprintf (struct __printf_buffer_asprintf *)
>    attribute_hidden;
> +struct __printf_buffer_dprintf;
> +void __printf_buffer_flush_dprintf (struct __printf_buffer_dprintf *)
> +  attribute_hidden;
>  struct __printf_buffer_fp;
>  void __printf_buffer_flush_fp (struct __printf_buffer_fp *)
>    attribute_hidden;
> @@ -341,4 +345,9 @@ void __wprintf_buffer_flush_to_file (struct __wprintf_buffer_to_file *)
>     (final, correctly sized) heap allocation.  */
>  #define PRINTF_BUFFER_SIZE_ASPRINTF 200
>  
> +/* This should cover most of the packet-oriented file descriptors,
> +   where boundaries between writes could be visible to readers.  But
> +   it is still small enough not to cause too many stack overflow issues.  */
> +#define PRINTF_BUFFER_SIZE_DPRINTF 2048
> +
>  #endif /* PRINTF_BUFFER_H */
> diff --git a/libio/iovdprintf.c b/libio/iovdprintf.c
> index 1e483868c9..455582e0f3 100644
> --- a/libio/iovdprintf.c
> +++ b/libio/iovdprintf.c
> @@ -24,41 +24,52 @@
>     This exception applies to code released by its copyright holders
>     in files containing the exception.  */
>  
> -#include <libioP.h>
> +#include <array_length.h>
> +#include <math_ldbl_opt.h>
> +#include <printf.h>
>  #include <stdio_ext.h>
> +#include <unistd.h>
> +#include <printf_buffer.h>
>  
> -int
> -__vdprintf_internal (int d, const char *format, va_list arg,
> -		     unsigned int mode_flags)
> +struct __printf_buffer_dprintf
>  {
> -  struct _IO_FILE_plus tmpfil;
> -  struct _IO_wide_data wd;
> -  int done;
> +  struct __printf_buffer base;
> +  int fd;
> +
> +  char buf[PRINTF_BUFFER_SIZE_DPRINTF];
> +};
>  
> -#ifdef _IO_MTSAFE_IO
> -  tmpfil.file._lock = NULL;
> -#endif
> -  _IO_no_init (&tmpfil.file, _IO_USER_LOCK, 0, &wd, &_IO_wfile_jumps);
> -  _IO_JUMPS (&tmpfil) = &_IO_file_jumps;
> -  _IO_new_file_init_internal (&tmpfil);
> -  if (_IO_file_attach (&tmpfil.file, d) == NULL)
> +void
> +__printf_buffer_flush_dprintf (struct __printf_buffer_dprintf *buf)
> +{
> +  char *p = buf->buf;
> +  char *end = buf->base.write_ptr;
> +  while (p < end)
>      {
> -      _IO_un_link (&tmpfil);
> -      return EOF;
> +      ssize_t ret = TEMP_FAILURE_RETRY (write (buf->fd, p, end - p));
> +      if (ret < 0)
> +	{
> +	  __printf_buffer_mark_failed (&buf->base);
> +	  return;
> +	}
> +      p += ret;
>      }
> -  tmpfil.file._flags |= _IO_DELETE_DONT_CLOSE;
> -
> -  _IO_mask_flags (&tmpfil.file, _IO_NO_READS,
> -		  _IO_NO_READS+_IO_NO_WRITES+_IO_IS_APPENDING);
> -
> -  done = __vfprintf_internal (&tmpfil.file, format, arg, mode_flags);
> -
> -  if (done != EOF && _IO_do_flush (&tmpfil.file) == EOF)
> -    done = EOF;
> -
> -  _IO_FINISH (&tmpfil.file);
> +  buf->base.write_ptr = buf->buf;
> +}
>  
> -  return done;
> +int
> +__vdprintf_internal (int d, const char *format, va_list arg,
> +		     unsigned int mode_flags)
> +{
> +  struct __printf_buffer_dprintf buf;
> +  __printf_buffer_init (&buf.base, buf.buf, array_length (buf.buf),
> +			__printf_buffer_mode_dprintf);
> +  buf.fd = d;
> +  __printf_buffer (&buf.base, format, arg, mode_flags);
> +  if (__printf_buffer_has_failed (&buf.base))
> +    return -1;
> +  __printf_buffer_flush_dprintf (&buf);
> +  return __printf_buffer_done (&buf.base);
>  }
>  
>  int
> diff --git a/stdio-common/printf_buffer_flush.c b/stdio-common/printf_buffer_flush.c
> index 14fe1b2df4..922340cc54 100644
> --- a/stdio-common/printf_buffer_flush.c
> +++ b/stdio-common/printf_buffer_flush.c
> @@ -28,6 +28,7 @@
>  # pragma weak __printf_buffer_flush_snprintf
>  # pragma weak __printf_buffer_flush_to_file
>  # pragma weak __printf_buffer_flush_asprintf
> +# pragma weak __printf_buffer_flush_dprintf
>  # pragma weak __printf_buffer_flush_fp
>  # pragma weak __printf_buffer_flush_fp_to_wide
>  # pragma weak __printf_buffer_flush_fphex_to_wide
> @@ -53,6 +54,9 @@ __printf_buffer_do_flush (struct __printf_buffer *buf)
>      case __printf_buffer_mode_asprintf:
>        __printf_buffer_flush_asprintf ((struct __printf_buffer_asprintf *) buf);
>        return;
> +    case __printf_buffer_mode_dprintf:
> +      __printf_buffer_flush_dprintf ((struct __printf_buffer_dprintf *) buf);
> +      return;
>      case __printf_buffer_mode_strfmon:
>        __set_errno (E2BIG);
>        __printf_buffer_mark_failed (buf);