[kvm-unit-tests PATCH v3 1/2] lib: Add STR_IS_Y and STR_IS_N for checking env vars

[Andrew Jones]

On Wed, Jul 09, 2025 at 06:47:06AM -0700, Jesse Taube wrote:
> the line:
> (s && (*s == '1' || *s == 'y' || *s == 'Y'))
> is used in a few places add a macro for it and its 'n' counterpart.
> 
> Add a copy of Linux's IS_ENABLED macro to be used in GET_ENV_OR_CONFIG.
> Add GET_ENV_OR_CONFIG for CONFIG values which can be overridden by
> the environment.
> 
> Signed-off-by: Jesse Taube <jesse at rivosinc.com>
> ---
> V1 -> V2:
>  - New commit
> V2 -> V3:
>  - Add IS_ENABLED so CONFIG_##name can be undefined
>  - Change GET_ENV_OR_CONFIG to GET_CONFIG_OR_ENV
>  - Fix it's to its
> ---
>  lib/argv.h        | 38 ++++++++++++++++++++++++++++++++++++++
>  lib/errata.h      |  7 ++++---
>  riscv/sbi-tests.h |  3 ++-
>  3 files changed, 44 insertions(+), 4 deletions(-)
> 
> diff --git a/lib/argv.h b/lib/argv.h
> index 0fa77725..111af078 100644
> --- a/lib/argv.h
> +++ b/lib/argv.h
> @@ -14,4 +14,42 @@ extern void setup_args_progname(const char *args);
>  extern void setup_env(char *env, int size);
>  extern void add_setup_arg(const char *arg);
>  
> +/*
> + * Helper macros to use CONFIG_ options in C/CPP expressions. Note that
> + * these only work with boolean and tristate options.
> + */
> +
> +/*
> + * Getting something that works in C and CPP for an arg that may or may
> + * not be defined is tricky.  Here, if we have "#define CONFIG_BOOGER 1"
> + * we match on the placeholder define, insert the "0," for arg1 and generate
> + * the triplet (0, 1, 0).  Then the last step cherry picks the 2nd arg (a one).
> + * When CONFIG_BOOGER is not defined, we generate a (... 1, 0) pair, and when
> + * the last step cherry picks the 2nd arg, we get a zero.
> + */
> +#define __ARG_PLACEHOLDER_1 0,
> +#define __take_second_arg(__ignored, val, ...) val
> +#define __is_defined(x)			___is_defined(x)
> +#define ___is_defined(val)		____is_defined(__ARG_PLACEHOLDER_##val)
> +#define ____is_defined(arg1_or_junk)	__take_second_arg(arg1_or_junk 1, 0)
> +
> +/*
> + * IS_ENABLED(CONFIG_FOO) evaluates to 1 if CONFIG_FOO is set to '1', 0
> + * otherwise.
> + */
> +#define IS_ENABLED(option) __is_defined(option)

I'm tempted to say this belongs in lib/linux/kconfig.h, but since we don't
have any other kconfig stuff, then I guess argv.h is fine.

> +
> +#define STR_IS_Y(s) (s && (*s == '1' || *s == 'y' || *s == 'Y'))
> +#define STR_IS_N(s) (s && (*s == '0' || *s == 'n' || *s == 'N'))
> +
> +/*
> + * Get the boolean value of CONFIG_{name}
> + * which can be overridden by the {name}
> + * variable in the environment if present.
> + */
> +#define GET_ENV_OR_CONFIG(name) ({				\
> +	const char *genv_s = getenv(#name);			\
> +	genv_s ? STR_IS_Y(genv_s) : IS_ENABLED(CONFIG_##name);	\
> +})
> +
>  #endif
> diff --git a/lib/errata.h b/lib/errata.h
> index de8205d8..78007243 100644
> --- a/lib/errata.h
> +++ b/lib/errata.h
> @@ -7,6 +7,7 @@
>  #ifndef _ERRATA_H_
>  #define _ERRATA_H_
>  #include <libcflat.h>
> +#include <argv.h>
>  
>  #include "config.h"
>  
> @@ -28,7 +29,7 @@ static inline bool errata_force(void)
>  		return true;
>  
>  	s = getenv("ERRATA_FORCE");
> -	return s && (*s == '1' || *s == 'y' || *s == 'Y');
> +	return STR_IS_Y(s);
>  }
>  
>  static inline bool errata(const char *erratum)
> @@ -40,7 +41,7 @@ static inline bool errata(const char *erratum)
>  
>  	s = getenv(erratum);
>  
> -	return s && (*s == '1' || *s == 'y' || *s == 'Y');
> +	return STR_IS_Y(s);
>  }
>  
>  static inline bool errata_relaxed(const char *erratum)
> @@ -52,7 +53,7 @@ static inline bool errata_relaxed(const char *erratum)
>  
>  	s = getenv(erratum);
>  
> -	return !(s && (*s == '0' || *s == 'n' || *s == 'N'));
> +	return !STR_IS_N(s);
>  }
>  
>  #endif
> diff --git a/riscv/sbi-tests.h b/riscv/sbi-tests.h
> index c1ebf016..4e051dca 100644
> --- a/riscv/sbi-tests.h
> +++ b/riscv/sbi-tests.h
> @@ -37,6 +37,7 @@
>  
>  #ifndef __ASSEMBLER__
>  #include <libcflat.h>
> +#include <argv.h>
>  #include <asm/sbi.h>
>  
>  #define __sbiret_report(kfail, ret, expected_error, expected_value,						\
> @@ -94,7 +95,7 @@ static inline bool env_enabled(const char *env)
>  {
>  	char *s = getenv(env);
>  
> -	return s && (*s == '1' || *s == 'y' || *s == 'Y');
> +	return STR_IS_Y(s);
>  }
>  
>  void split_phys_addr(phys_addr_t paddr, unsigned long *hi, unsigned long *lo);
> -- 
> 2.43.0

Reviewed-by: Andrew Jones <andrew.jones at linux.dev>