[v5,08/13] string: Simplify strerror_r

Use snprintf instead of mempcpy plus itoa_word and remove unused
definitions.  There is no potential for infinite recursion because
snprintf only use strerror_r for the %m specifier.

Checked on x86-64-linux-gnu, i686-linux-gnu, powerpc64le-linux-gnu,
and s390x-linux-gnu.
---
 string/_strerror.c       | 41 ++----------------------
 sysdeps/mach/_strerror.c | 67 +++-------------------------------------
 2 files changed, 7 insertions(+), 101 deletions(-)

On 6/19/20 9:43 AM, Adhemerval Zanella wrote:
> Use snprintf instead of mempcpy plus itoa_word and remove unused
> definitions.  There is no potential for infinite recursion because
> snprintf only use strerror_r for the %m specifier.
> 
> Checked on x86-64-linux-gnu, i686-linux-gnu, powerpc64le-linux-gnu,
> and s390x-linux-gnu.

OK for master. I like the simplification and it makes sense to me.

No regressions on x86_64 and i686.

Tested-by: Carlos O'Donell <carlos@redhat.com>
Reviewed-by: Carlos O'Donell <carlos@redhat.com>

> ---
>  string/_strerror.c       | 41 ++----------------------
>  sysdeps/mach/_strerror.c | 67 +++-------------------------------------
>  2 files changed, 7 insertions(+), 101 deletions(-)
> 
> diff --git a/string/_strerror.c b/string/_strerror.c
> index 01226e3d4b..da3b22f5b1 100644
> --- a/string/_strerror.c
> +++ b/string/_strerror.c
> @@ -15,22 +15,10 @@
>     License along with the GNU C Library; if not, see
>     <https://www.gnu.org/licenses/>.  */
>  
> +#include <string.h>
>  #include <libintl.h>
> -#include <stdbool.h>
>  #include <stdio.h>
>  #include <stdlib.h>
> -#include <string.h>
> -#include <sys/param.h>
> -#include <_itoa.h>
> -
> -/* It is critical here that we always use the `dcgettext' function for
> -   the message translation.  Since <libintl.h> only defines the macro
> -   `dgettext' to use `dcgettext' for optimizing programs this is not
> -   always guaranteed.  */
> -#ifndef dgettext
> -# include <locale.h>		/* We need LC_MESSAGES.  */
> -# define dgettext(domainname, msgid) dcgettext (domainname, msgid, LC_MESSAGES)
> -#endif

OK.

>  
>  /* Return a string describing the errno code in ERRNUM.  */
>  char *
> @@ -39,32 +27,7 @@ __strerror_r (int errnum, char *buf, size_t buflen)
>    char *err = (char *) __get_errlist (errnum);
>    if (__glibc_unlikely (err == NULL))
>      {
> -      /* Buffer we use to print the number in.  For a maximum size for
> -	 `int' of 8 bytes we never need more than 20 digits.  */
> -      char numbuf[21];
> -      const char *unk = _("Unknown error ");
> -      size_t unklen = strlen (unk);
> -      char *p, *q;
> -      bool negative = errnum < 0;
> -
> -      numbuf[20] = '\0';
> -      p = _itoa_word (abs (errnum), &numbuf[20], 10, 0);
> -
> -      /* Now construct the result while taking care for the destination
> -	 buffer size.  */
> -      q = __mempcpy (buf, unk, MIN (unklen, buflen));
> -      if (negative && unklen < buflen)
> -	{
> -	  *q++ = '-';
> -	  ++unklen;
> -	}
> -      if (unklen < buflen)
> -	memcpy (q, p, MIN ((size_t) (&numbuf[21] - p), buflen - unklen));
> -
> -      /* Terminate the string in any case.  */
> -      if (buflen > 0)
> -	buf[buflen - 1] = '\0';
> -
> +      __snprintf (buf, buflen, "%s%d", _("Unknown error "), errnum);

OK. No %m specifier.

>        return buf;
>      }
>  
> diff --git a/sysdeps/mach/_strerror.c b/sysdeps/mach/_strerror.c
> index d932b1bd58..399de330d9 100644
> --- a/sysdeps/mach/_strerror.c
> +++ b/sysdeps/mach/_strerror.c
> @@ -15,22 +15,12 @@
>     License along with the GNU C Library; if not, see
>     <https://www.gnu.org/licenses/>.  */
>  
> +#include <string.h>
>  #include <libintl.h>
>  #include <stdio.h>
>  #include <string.h>
>  #include <mach/error.h>
>  #include <errorlib.h>
> -#include <sys/param.h>
> -#include <_itoa.h>
> -
> -/* It is critical here that we always use the `dcgettext' function for
> -   the message translation.  Since <libintl.h> only defines the macro
> -   `dgettext' to use `dcgettext' for optimizing programs this is not
> -   always guaranteed.  */
> -#ifndef dgettext
> -# include <locale.h>		/* We need LC_MESSAGES.  */
> -# define dgettext(domainname, msgid) dcgettext (domainname, msgid, LC_MESSAGES)
> -#endif
>  

OK.

>  /* Return a string describing the errno code in ERRNUM.  */
>  char *
> @@ -50,26 +40,8 @@ __strerror_r (int errnum, char *buf, size_t buflen)
>  
>    if (system > err_max_system || ! __mach_error_systems[system].bad_sub)
>      {
> -      /* Buffer we use to print the number in.  For a maximum size for
> -	 `int' of 8 bytes we never need more than 20 digits.  */
> -      char numbuf[21];
> -      const char *unk = _("Error in unknown error system: ");
> -      const size_t unklen = strlen (unk);
> -      char *p, *q;
> -
> -      numbuf[20] = '\0';
> -      p = _itoa_word (errnum, &numbuf[20], 16, 1);
> -
> -      /* Now construct the result while taking care for the destination
> -	 buffer size.  */
> -      q = __mempcpy (buf, unk, MIN (unklen, buflen));
> -      if (unklen < buflen)
> -	memcpy (q, p, MIN (&numbuf[21] - p, buflen - unklen));
> -
> -      /* Terminate the string in any case.  */
> -      if (buflen > 0)
> -	buf[buflen - 1] = '\0';
> -
> +      __snprintf (buf, buflen, "%s: %d", _("Error in unknown error system: "),
> +		  errnum);

OK. No %m.

>        return buf;
>      }
>  
> @@ -80,37 +52,8 @@ __strerror_r (int errnum, char *buf, size_t buflen)
>  
>    if (code >= es->subsystem[sub].max_code)
>      {
> -      /* Buffer we use to print the number in.  For a maximum size for
> -	 `int' of 8 bytes we never need more than 20 digits.  */
> -      char numbuf[21];
> -      const char *unk = _("Unknown error ");
> -      const size_t unklen = strlen (unk);
> -      char *p, *q;
> -      size_t len = strlen (es->subsystem[sub].subsys_name);
> -
> -      numbuf[20] = '\0';
> -      p = _itoa_word (errnum, &numbuf[20], 10, 0);
> -
> -      /* Now construct the result while taking care for the destination
> -	 buffer size.  */
> -      q = __mempcpy (buf, unk, MIN (unklen, buflen));
> -      if (unklen < buflen)
> -	{
> -	  q = __mempcpy (q, es->subsystem[sub].subsys_name,
> -			 MIN (len, buflen - unklen));
> -	  if (unklen + len < buflen)
> -	    {
> -	      *q++ = ' ';
> -	      if (unklen + len + 1 < buflen)
> -		memcpy (q, p,
> -			MIN (&numbuf[21] - p, buflen - unklen - len - 1));
> -	    }
> -	}
> -
> -       /* Terminate the string in any case.  */
> -      if (buflen > 0)
> -	buf[buflen - 1] = '\0';
> -
> +      __snprintf (buf, buflen, "%s%s %d", _("Unknown error "),
> +		  es->subsystem[sub].subsys_name, errnum);

OK. Perfect.

>        return buf;
>      }
>  
>