environment variables: introduce new helpers

This introduces some new environment variable helpers and updates
the existing ones. Newly introduced are:

getenv_bool: read a bool variable
getenv_ul: read an unsigned long variable
getenev_uint: read an unsigned int variable
getenv_nonempty: like normal getenv, but does return NULL instead of an
                 empty string

All new helpers take a pointer to the value. This value is only modified
when the variable exists. This allows the following programming scheme:

	unsigned int myvalue = sanedefault;

	getenv_uint("myvalue", &myvalue);

So without checking the return value myvalue contains the best possible
value.

getenv_ull is updated to this scheme.

Signed-off-by: Sascha Hauer <s.hauer@pengutronix.de>

arch/arm/lib/armlinux.c

@@ -42,11 +42,9 @@
 static struct tag *params;
 static void *armlinux_bootparams = NULL;
 
-#ifndef CONFIG_ENVIRONMENT_VARIABLES
 static int armlinux_architecture;
 static u32 armlinux_system_rev;
 static u64 armlinux_system_serial;
-#endif
 
 BAREBOX_MAGICVAR(armlinux_architecture, "ARM machine ID");
 BAREBOX_MAGICVAR(armlinux_system_rev, "ARM system revision");
@@ -54,56 +52,41 @@ BAREBOX_MAGICVAR(armlinux_system_serial, "ARM system serial");
 
 void armlinux_set_architecture(int architecture)
 {
-#ifdef CONFIG_ENVIRONMENT_VARIABLES
 	export_env_ull("armlinux_architecture", architecture);
-#else
 	armlinux_architecture = architecture;
-#endif
 }
 
 int armlinux_get_architecture(void)
 {
-#ifdef CONFIG_ENVIRONMENT_VARIABLES
-	return getenv_ull("armlinux_architecture");
-#else
+	getenv_uint("armlinux_architecture", &armlinux_architecture);
+
 	return armlinux_architecture;
-#endif
 }
 
 void armlinux_set_revision(unsigned int rev)
 {
-#ifdef CONFIG_ENVIRONMENT_VARIABLES
 	export_env_ull("armlinux_system_rev", rev);
-#else
 	armlinux_system_rev = rev;
-#endif
 }
 
 unsigned int armlinux_get_revision(void)
 {
-#ifdef CONFIG_ENVIRONMENT_VARIABLES
-	return getenv_ull("armlinux_system_rev");
-#else
+	getenv_uint("armlinux_system_rev", &armlinux_system_rev);
+
 	return armlinux_system_rev;
-#endif
 }
 
 void armlinux_set_serial(u64 serial)
 {
-#ifdef CONFIG_ENVIRONMENT_VARIABLES
 	export_env_ull("armlinux_system_serial", serial);
-#else
 	armlinux_system_serial = serial;
-#endif
 }
 
 u64 armlinux_get_serial(void)
 {
-#ifdef CONFIG_ENVIRONMENT_VARIABLES
-	return getenv_ull("armlinux_system_serial");
-#else
+	getenv_ull("armlinux_system_serial", &armlinux_system_serial);
+
 	return armlinux_system_serial;
-#endif
 }
 
 #ifdef CONFIG_ARM_BOARD_APPEND_ATAG

common/env.c

@@ -267,13 +267,74 @@ void export_env_ull(const char *name, unsigned long long val)
 }
 EXPORT_SYMBOL(export_env_ull);
 
-unsigned long long getenv_ull(const char *name)
+/*
+ * Like regular getenv, but never returns an empty string.
+ * If the string is empty, NULL is returned instead
+ */
+const char *getenv_nonempty(const char *var)
 {
-	const char *valstr = getenv(name);
+	const char *val = getenv(var);
 
-	if (!valstr)
-		return 0;
+	if (val && *val)
+		return val;
 
-	return simple_strtoull(valstr, NULL, 0);
+	return NULL;
+}
+EXPORT_SYMBOL(getenv_nonempty);
+
+int getenv_ull(const char *var , unsigned long long *val)
+{
+	const char *valstr = getenv(var);
+
+	if (!valstr || !*valstr)
+		return -EINVAL;
+
+	*val = simple_strtoull(valstr, NULL, 0);
+
+	return 0;
 }
 EXPORT_SYMBOL(getenv_ull);
+
+int getenv_ul(const char *var , unsigned long *val)
+{
+	const char *valstr = getenv(var);
+
+	if (!valstr || !*valstr)
+		return -EINVAL;
+
+	*val = simple_strtoul(valstr, NULL, 0);
+
+	return 0;
+}
+EXPORT_SYMBOL(getenv_ul);
+
+int getenv_uint(const char *var , unsigned int *val)
+{
+	const char *valstr = getenv(var);
+
+	if (!valstr || !*valstr)
+		return -EINVAL;
+
+	*val = simple_strtoul(valstr, NULL, 0);
+
+	return 0;
+}
+EXPORT_SYMBOL(getenv_uint);
+
+int getenv_bool(const char *var, int *val)
+{
+	const char *valstr = getenv(var);
+
+	if (!valstr || !*valstr)
+		return -EINVAL;
+
+	if (!*valstr)
+		*val = false;
+	else if (*valstr == '0')
+		*val = false;
+	else
+		*val = true;
+
+	return 0;
+}
+EXPORT_SYMBOL(getenv_bool);

include/environment.h

@@ -45,7 +45,11 @@ char *var_name(struct variable_d *);
 const char *getenv(const char *);
 int setenv(const char *, const char *);
 void export_env_ull(const char *name, unsigned long long val);
-unsigned long long getenv_ull(const char *name);
+int getenv_ull(const char *name, unsigned long long *val);
+int getenv_ul(const char *name, unsigned long *val);
+int getenv_uint(const char *name, unsigned int *val);
+int getenv_bool(const char *var, int *val);
+const char *getenv_nonempty(const char *var);
 #else
 static inline char *getenv(const char *var)
 {
@@ -56,10 +60,22 @@ static inline int setenv(const char *var, const char *val)
 {
 	return 0;
 }
+
 static inline void export_env_ull(const char *name, unsigned long long val) {}
-static inline unsigned long long getenv_ull(const char *name)
+
+static inline int getenv_ull(const char *name, unsigned long long *val)
 {
-	return 0;
+	return -EINVAL;
+}
+
+static inline int getenv_ul(const char *name, unsigned long *val)
+{
+	return -EINVAL;
+}
+
+static inline int getenv_uint(const char *name, unsigned int *val)
+{
+	return -EINVAL;
 }
 
 static inline int export(const char *var)
@@ -67,6 +83,15 @@ static inline int export(const char *var)
 	return -EINVAL;
 }
 
+static inline int getenv_bool(const char *var, int *val)
+{
+	return -EINVAL;
+}
+
+static inline const char *getenv_nonempty(const char *var)
+{
+	return NULL;
+}
 #endif
 
 int env_pop_context(void);