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

[Jesse Taube]

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)
+
+#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