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Re: [Qemu-devel] [PATCH v2 5/6] pc-bios/s390-ccw: Clean up harmless misu


From: Christian Borntraeger
Subject: Re: [Qemu-devel] [PATCH v2 5/6] pc-bios/s390-ccw: Clean up harmless misuse of isdigit()
Date: Tue, 14 May 2019 20:04:36 +0200
User-agent: Mozilla/5.0 (X11; Linux x86_64; rv:60.0) Gecko/20100101 Thunderbird/60.6.1


On 14.05.19 20:03, Markus Armbruster wrote:
> atoui() and get_index() pass char values to isdigit().  With a
> standard isdigit(), we'd get undefined behavior when the value is
> negative.  Can't happen as char is unsigned on s390x.  Even if it
> could, we're actually using isdigit() from pc-bios/s390-ccw/libc.h
> here, which works fine for negative values.  Clean up anyway, just
> to avoid setting a bad example.
> 
> Cc: Christian Borntraeger <address@hidden>
Acked-by: Christian Borntraeger <address@hidden>

> Cc: Thomas Huth <address@hidden>
> Cc: Cornelia Huck <address@hidden>
> Cc: address@hidden
> Signed-off-by: Markus Armbruster <address@hidden>
> ---
>  pc-bios/s390-ccw/libc.c | 2 +-
>  pc-bios/s390-ccw/menu.c | 2 +-
>  2 files changed, 2 insertions(+), 2 deletions(-)
> 
> diff --git a/pc-bios/s390-ccw/libc.c b/pc-bios/s390-ccw/libc.c
> index a786566c4c..3187923950 100644
> --- a/pc-bios/s390-ccw/libc.c
> +++ b/pc-bios/s390-ccw/libc.c
> @@ -38,7 +38,7 @@ uint64_t atoui(const char *str)
>      }
>  
>      while (*str) {
> -        if (!isdigit(*str)) {
> +        if (!isdigit(*(unsigned char *)str)) {
>              break;
>          }
>          val = val * 10 + *str - '0';
> diff --git a/pc-bios/s390-ccw/menu.c b/pc-bios/s390-ccw/menu.c
> index 82a4ae6315..ce3815b201 100644
> --- a/pc-bios/s390-ccw/menu.c
> +++ b/pc-bios/s390-ccw/menu.c
> @@ -134,7 +134,7 @@ static int get_index(void)
>  
>      /* Check for erroneous input */
>      for (i = 0; i < len; i++) {
> -        if (!isdigit(buf[i])) {
> +        if (!isdigit((unsigned char)buf[i])) {
>              return -1;
>          }
>      }
> 




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