Assert that vasprintf() succeeds as the "returned" string is undefined
on failure.  Checking the result also eliminates the only warning with
default options in KVM selftests, i.e. is the only thing getting in the
way of compile with -Werror.

  lib/test_util.c: In function ‘strdup_printf’:
  lib/test_util.c:390:9: error: ignoring return value of ‘vasprintf’
  declared with attribute ‘warn_unused_result’ [-Werror=unused-result]
  390 |         vasprintf(&str, fmt, ap);
      |         ^~~~~~~~~~~~~~~~~~~~~~~~

Don't bother capturing the return value, allegedly vasprintf() can only
fail due to a memory allocation failure.

Fixes: dfaf20af7649 ("KVM: arm64: selftests: Replace str_with_index with strdup_printf")
Cc: Andrew Jones <ajones@ventanamicro.com>
Cc: Haibo Xu <haibo1.xu@intel.com>
Cc: Anup Patel <anup@brainfault.org>
Signed-off-by: Sean Christopherson <seanjc@google.com>
---

I haven't actually run the relevant tests, someone should probably do so on
ARM and/or RISC-V to make sure I didn't do something stupid.

 tools/testing/selftests/kvm/lib/test_util.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/tools/testing/selftests/kvm/lib/test_util.c b/tools/testing/selftests/kvm/lib/test_util.c
index 3e36019eeb4a..5d7f28b02d73 100644
--- a/tools/testing/selftests/kvm/lib/test_util.c
+++ b/tools/testing/selftests/kvm/lib/test_util.c
@@ -387,7 +387,7 @@ char *strdup_printf(const char *fmt, ...)
 	char *str;
 
 	va_start(ap, fmt);
-	vasprintf(&str, fmt, ap);
+	TEST_ASSERT(vasprintf(&str, fmt, ap) >= 0, "vasprintf() failed");
 	va_end(ap);
 
 	return str;

base-commit: 0bb80ecc33a8fb5a682236443c1e740d5c917d1d
-- 
2.42.0.283.g2d96d420d3-goog

Queued, thanks.

Paolo

On Wed, Sep 13, 2023 at 06:06:36PM -0700, Sean Christopherson wrote:
> Assert that vasprintf() succeeds as the "returned" string is undefined
> on failure.  Checking the result also eliminates the only warning with
> default options in KVM selftests, i.e. is the only thing getting in the
> way of compile with -Werror.
> 
>   lib/test_util.c: In function ‘strdup_printf’:
>   lib/test_util.c:390:9: error: ignoring return value of ‘vasprintf’
>   declared with attribute ‘warn_unused_result’ [-Werror=unused-result]
>   390 |         vasprintf(&str, fmt, ap);
>       |         ^~~~~~~~~~~~~~~~~~~~~~~~
> 

Oh, darn. My compilers didn't report that or I would have fixed it.

> Don't bother capturing the return value, allegedly vasprintf() can only
> fail due to a memory allocation failure.
> 
> Fixes: dfaf20af7649 ("KVM: arm64: selftests: Replace str_with_index with strdup_printf")
> Cc: Andrew Jones <ajones@ventanamicro.com>
> Cc: Haibo Xu <haibo1.xu@intel.com>
> Cc: Anup Patel <anup@brainfault.org>
> Signed-off-by: Sean Christopherson <seanjc@google.com>
> ---
> 
> I haven't actually run the relevant tests, someone should probably do so on
> ARM and/or RISC-V to make sure I didn't do something stupid.

Done for both.

Reviewed-by: Andrew Jones <ajones@ventanamicro.com>
Tested-by: Andrew Jones <ajones@ventanamicro.com>

Thanks,
drew

> 
>  tools/testing/selftests/kvm/lib/test_util.c | 2 +-
>  1 file changed, 1 insertion(+), 1 deletion(-)
> 
> diff --git a/tools/testing/selftests/kvm/lib/test_util.c b/tools/testing/selftests/kvm/lib/test_util.c
> index 3e36019eeb4a..5d7f28b02d73 100644
> --- a/tools/testing/selftests/kvm/lib/test_util.c
> +++ b/tools/testing/selftests/kvm/lib/test_util.c
> @@ -387,7 +387,7 @@ char *strdup_printf(const char *fmt, ...)
>  	char *str;
>  
>  	va_start(ap, fmt);
> -	vasprintf(&str, fmt, ap);
> +	TEST_ASSERT(vasprintf(&str, fmt, ap) >= 0, "vasprintf() failed");
>  	va_end(ap);
>  
>  	return str;
> 
> base-commit: 0bb80ecc33a8fb5a682236443c1e740d5c917d1d
> -- 
> 2.42.0.283.g2d96d420d3-goog
>