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, 3 insertions, 4 deletions

diff --git a/include/printf.h b/include/printf.h
index c55c8f7d2b..6e245a3f2a 100644
--- a/include/printf.h
+++ b/include/printf.h
@@ -40,10 +40,6 @@
  * Type may be:
  *   - 'c' - character
  *   - 's' - null-terminated ASCII string
- *   - 'h' - binary data, print as hex; precision is length of data in bytes.
- *           So "%.8h" prints 8 bytes of binary data
- *   - 'pP'- raw pointer. %p followed by another character represents a %p
- *           extension.
  *   - 'd' - signed integer
  *   - 'i' - signed integer if CONFIG_PRINTF_LEGACY_LI_FORMAT is set (ignore l)
  *   - 'u' - unsigned integer
@@ -52,6 +48,9 @@
  *   - 'b' - unsigned integer, print as binary
  *
  * Special format codes:
+ *   - '%ph' - binary data, print as hex; Use HEX_BUF(buffer, size) to encode
+ *             parameters.
+ *   - '%pP' - raw pointer.
  *   - "%pT" - current time in seconds - interpreted as "%.6T" for precision.
  *           Supply PRINTF_TIMESTAMP_NOW to use the current time, or supply a
  *           pointer to a 64-bit timestamp to print.