printf: Convert %h to %ph

In order to make printf more standard, use %ph. Pass a pointer to
a struct describing the buffer, including its size. Add a convenience
macro so that conversion between the old style and new style is purely
mechanical. The old style of %h cannot be converted directly to %ph as-is
because the C standard doesn't allow flags, precision, or field width on
%p.

Ultimately the goal is to enable compile-time printf format checking.
This gets us one step closer to that.

BUG=chromium:984041
TEST=make -j buildall
BRANCH=None

Cq-Depend:chrome-internal:1559798,chrome-internal:1560598
Change-Id: I9c0ca124a048314c9b62d64bd55b36be55034e0e
Signed-off-by: Evan Green <evgreen@chromium.org>
Reviewed-on: https://chromium-review.googlesource.com/c/chromiumos/platform/ec/+/1730605

1 files changed, 16 insertions, 0 deletions

diff --git a/include/console.h b/include/console.h
index 73e9d9094c..dc15e5b6d3 100644
--- a/include/console.h
+++ b/include/console.h
@@ -10,6 +10,22 @@
 
 #include "common.h"
 
+/*
+ * The EC code base has been using %h to print a hex buffer. Encode the
+ * parameters to do that in a pointer to a structure that's passed as the
+ * printf argument. This is done rather than something like %.123ph because
+ * the C standard doesn't allow flags, precision, and field width on %p.
+ */
+struct hex_buffer_params {
+	const void *buffer;
+	uint16_t size;
+};
+
+#define HEX_BUF(_buffer, _size) (&(const struct hex_buffer_params){ \
+	.buffer = (_buffer), \
+	.size = (_size) \
+})
+
 #define PRINTF_TIMESTAMP_NOW NULL
 
 /* Console command; used by DECLARE_CONSOLE_COMMAND macro. */