[PATCH] util/cutils: Use qemu_isdigit() instead of isdigit()

[PATCH] util/cutils: Use qemu_isdigit() instead of isdigit()

[Thomas Huth]

When building QEMU for NetBSD ("make vm-build-netbsd"), the compiler
complains:

  In file included from /usr/include/ctype.h:100,
                 from ../src/include/qemu/osdep.h:123,
                 from ../src/util/cutils.c:25:
  ../src/util/cutils.c: In function 'do_strtosz':
  ../src/util/cutils.c:245:61: warning: array subscript has type 'char' [-Wchar-subscripts]
  245 |         if (retval == 0 && *endptr == '.' && !isdigit(endptr[1])) {

isdigit() should not be used with plain "char" variables since these
can be signed and isdigit() could be implemented as a macro that uses
its parameter to index into an array. Use our wrapper qemu_isdigit()
to fix this problem.

Signed-off-by: Thomas Huth <thuth@redhat.com>
---
 util/cutils.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/util/cutils.c b/util/cutils.c
index 96c80d4d429..91ddadfd15a 100644
--- a/util/cutils.c
+++ b/util/cutils.c
@@ -242,7 +242,7 @@ static int do_strtosz(const char *nptr, const char **end,
          */
         double fraction = 0.0;
 
-        if (retval == 0 && *endptr == '.' && !isdigit(endptr[1])) {
+        if (retval == 0 && *endptr == '.' && !qemu_isdigit(endptr[1])) {
             /* If we got here, we parsed at least one digit already. */
             endptr++;
         } else {
-- 
2.55.0

Re: [PATCH] util/cutils: Use qemu_isdigit() instead of isdigit()

[Daniel P. Berrangé]

On Thu, Sep 10, 2026 at 01:21:00PM +0200, Thomas Huth wrote:
> When building QEMU for NetBSD ("make vm-build-netbsd"), the compiler
> complains:
> 
>   In file included from /usr/include/ctype.h:100,
>                  from ../src/include/qemu/osdep.h:123,
>                  from ../src/util/cutils.c:25:
>   ../src/util/cutils.c: In function 'do_strtosz':
>   ../src/util/cutils.c:245:61: warning: array subscript has type 'char' [-Wchar-subscripts]
>   245 |         if (retval == 0 && *endptr == '.' && !isdigit(endptr[1])) {
> 
> isdigit() should not be used with plain "char" variables since these
> can be signed and isdigit() could be implemented as a macro that uses
> its parameter to index into an array. Use our wrapper qemu_isdigit()
> to fix this problem.
> 
> Signed-off-by: Thomas Huth <thuth@redhat.com>
> ---
>  util/cutils.c | 2 +-
>  1 file changed, 1 insertion(+), 1 deletion(-)

Reviewed-by: Daniel P. Berrangé <berrange@redhat.com>

With regards,
Daniel
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