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>

1 files changed, 66 insertions, 5 deletions

diff --git a/common/env.c b/common/env.c
index 33a871f7eb..748b655a6b 100644
--- a/common/env.c
+++ b/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);