env: allow to copy value from default environment into a buffer

env_get_default suffers from a particular issue int that it can only
return a value truncated to gd->env_buf (32) characters. This may be
enough for most variables but it isn't for others, so let's allow users
to provide a preallocated buffer to copy the value into instead,
allowing for more control, though it'll still be truncated if the value
size is bigger than the preallocated buffer.

Cc: Quentin Schulz <foss+uboot@0leil.net>
Reviewed-by: Tom Rini <trini@konsulko.com>
Reviewed-by: Kever Yang <kever.yang@rock-chips.com>
Signed-off-by: Quentin Schulz <quentin.schulz@theobroma-systems.com>

1 files changed, 10 insertions, 0 deletions

diff --git a/include/env.h b/include/env.h
index 9778e3e..d2a5954 100644
--- a/include/env.h
+++ b/include/env.h
@@ -356,6 +356,16 @@ int env_import_redund(const char *buf1, int buf1_read_fail,
  */
 char *env_get_default(const char *name);
 
+/**
+ * env_get_default_into() - Look up a variable from the default environment and
+ * copy its value in buf.
+ *
+ * @name: Variable to look up
+ * Return: actual length of the variable value excluding the terminating
+ *	NULL-byte, or -1 if the variable is not found
+ */
+int env_get_default_into(const char *name, char *buf, unsigned int len);
+
 /* [re]set to the default environment */
 void env_set_default(const char *s, int flags);