[PATCH] Add "%d" support to _dl_debug_vdprintf

[Adhemerval Zanella]

On 05/06/2020 12:03, H.J. Lu via Libc-alpha wrote:
> "%d" will be used to print out signed value.

LGTM with some smalls nits below.

> ---
>  elf/dl-misc.c | 31 +++++++++++++++++++++++++++++--
>  1 file changed, 29 insertions(+), 2 deletions(-)
> 
> diff --git a/elf/dl-misc.c b/elf/dl-misc.c
> index ab70481fda..c82c8ae6fa 100644
> --- a/elf/dl-misc.c
> +++ b/elf/dl-misc.c
> @@ -167,6 +167,7 @@ _dl_debug_vdprintf (int fd, int tag_p, const char *fmt, va_list arg)
>  	  switch (*fmt)
>  	    {
>  	      /* Integer formatting.  */
> +	    case 'd':
>  	    case 'u':
>  	    case 'x':
>  	      {

Ok.

> @@ -179,11 +180,34 @@ _dl_debug_vdprintf (int fd, int tag_p, const char *fmt, va_list arg)
>  #else
>  		unsigned long int num = va_arg (arg, unsigned int);
>  #endif
> +		bool negative = false;
> +		if (*fmt == 'd')
> +		  {
> +#if LONG_MAX != INT_MAX
> +		    if (long_mod)
> +		      {
> +			if ((long) num < 0)

Full type specify on cast.

> +			  negative = true;
> +		      }
> +		    else
> +		      {
> +			if ((int) num < 0)> +			  {
> +			    num = (unsigned int) num;
> +			    negative = true;
> +			  }
> +		      }
> +#else
> +		    if ((int) num < 0)
> +		      negative = true;
> +#endif
> +		  }
> +
>  		/* We use alloca() to allocate the buffer with the most
>  		   pessimistic guess for the size.  Using alloca() allows
>  		   having more than one integer formatting in a call.  */
> -		char *buf = (char *) alloca (3 * sizeof (unsigned long int));
> -		char *endp = &buf[3 * sizeof (unsigned long int)];
> +		char *buf = (char *) alloca (1 + 3 * sizeof (unsigned long int));
> +		char *endp = &buf[1 + 3 * sizeof (unsigned long int)];

I think we can remove alloca here and use INT_STRLEN_BOUND (since the
string is not '\0' bounded due the writev usage).  Something like:

  char buf[INT_STRLEN_BOUND (unsigned long int)];
  char *endp = &buf[INT_STRLEN_BOUND (unsigned long int)];

>  		char *cp = _itoa (num, endp, *fmt == 'x' ? 16 : 10, 0);
>  
>  		/* Pad to the width the user specified.  */
> @@ -191,6 +215,9 @@ _dl_debug_vdprintf (int fd, int tag_p, const char *fmt, va_list arg)
>  		  while (endp - cp < width)
>  		    *--cp = fill;
>  
> +		if (negative)
> +		  *--cp = '-';
> +
>  		iov[niov].iov_base = cp;
>  		iov[niov].iov_len = endp - cp;
>  		++niov;
> 

Ok.