From cc65317e85af70253a5754b9c6d36d998440e59a Mon Sep 17 00:00:00 2001
From: Paul Cercueil <paul@crapouillou.net>
Date: Thu, 23 Nov 2023 12:08:47 +0100
Subject: [PATCH] CMake: Add option to specify the maximum log level

This makes sense for embedded, as compiling with a lower maximum log
level means that all strings that correspond to the higher log levels
will be automatically discarded by the compiler, resulting in a smaller
binary.

Signed-off-by: Paul Cercueil <paul@crapouillou.net>
---
 CMakeLists.txt          | 12 +++++++++++-
 iio-config.h.cmakein    |  1 +
 include/iio/iio-debug.h | 43 ++++++++++++++++++++++++++++++++---------
 3 files changed, 46 insertions(+), 10 deletions(-)

diff --git a/CMakeLists.txt b/CMakeLists.txt
index 1d6e78cb1..9f57a5fbd 100644
--- a/CMakeLists.txt
+++ b/CMakeLists.txt
@@ -170,16 +170,26 @@ option(WITH_EXAMPLES "Build examples" OFF)
 option(WITH_UTILS "Build the Libiio utility programs" ON)
 
 if (NOT LOG_LEVEL)
-	set(LOG_LEVEL Info CACHE STRING "Log level" FORCE)
+	set(LOG_LEVEL Info CACHE STRING "Default log level" FORCE)
 	set_property(CACHE LOG_LEVEL PROPERTY STRINGS NoLog Error Warning Info Debug)
 endif()
 
+if (NOT MAX_LOG_LEVEL)
+	set(MAX_LOG_LEVEL Debug CACHE STRING "Maximum log level supported" FORCE)
+	set_property(CACHE MAX_LOG_LEVEL PROPERTY STRINGS NoLog Error Warning Info Debug)
+endif()
+
 set(LEVEL_NoLog 1)
 set(LEVEL_Error 2)
 set(LEVEL_Warning 3)
 set(LEVEL_Info 4)
 set(LEVEL_Debug 5)
 set(DEFAULT_LOG_LEVEL ${LEVEL_${LOG_LEVEL}})
+set(MAX_LOG_LEVEL_VALUE ${LEVEL_${MAX_LOG_LEVEL}})
+
+if (DEFAULT_LOG_LEVEL GREATER MAX_LOG_LEVEL_VALUE)
+	message(SEND_ERROR "Default log level cannot be more than the maximum log level.")
+endif()
 
 if (MSVC)
 	target_compile_options(iio PRIVATE /Zi /W4 /wd4200 /wd4127 /wd4100)
diff --git a/iio-config.h.cmakein b/iio-config.h.cmakein
index 6f2f84d3d..9b617105b 100644
--- a/iio-config.h.cmakein
+++ b/iio-config.h.cmakein
@@ -7,6 +7,7 @@
 
 #define LOG_LEVEL @LOG_LEVEL@_L
 #define DEFAULT_LOG_LEVEL @DEFAULT_LOG_LEVEL@
+#define MAX_LOG_LEVEL @MAX_LOG_LEVEL_VALUE@
 
 #define IIO_MODULES_DIR "@IIO_MODULES_DIR@"
 #define IIO_LIBRARY_SUFFIX "@CMAKE_SHARED_LIBRARY_SUFFIX@"
diff --git a/include/iio/iio-debug.h b/include/iio/iio-debug.h
index ad6aa6639..c1218fe8d 100644
--- a/include/iio/iio-debug.h
+++ b/include/iio/iio-debug.h
@@ -21,6 +21,13 @@
 #   define __iio_printf
 #endif
 
+#ifdef LIBIIO_EXPORTS
+#include "iio-config.h"
+#define LIBIIO_MAX_LOG_LEVEL MAX_LOG_LEVEL
+#else
+#define LIBIIO_MAX_LOG_LEVEL LEVEL_DEBUG
+#endif
+
 #define __FIRST(a, ...)		a
 #define ___OTHERS(a, ...)	a, __VA_ARGS__
 #define __OTHERS(a, b, ...)	___OTHERS(a, __VA_ARGS__)
@@ -44,10 +51,26 @@ iio_prm_printf(const struct iio_context_params *params,
 #define __dev_id_or_null(dev)	((dev) ? iio_device_get_id(dev) : NULL)
 #define __chn_id_or_null(chn)	((chn) ? iio_channel_get_id(chn) : NULL)
 
-#define prm_err(prm, ...)	iio_prm_printf((prm), LEVEL_ERROR, "ERROR: " __VA_ARGS__)
-#define prm_warn(prm, ...)	iio_prm_printf((prm), LEVEL_WARNING, "WARNING: " __VA_ARGS__)
-#define prm_info(prm, ...)	iio_prm_printf((prm), LEVEL_INFO, __VA_ARGS__)
-#define prm_dbg(prm, ...)	iio_prm_printf((prm), LEVEL_DEBUG, "DEBUG: " __VA_ARGS__)
+#define prm_err(prm, ...) \
+	do { \
+		if (LIBIIO_MAX_LOG_LEVEL >= LEVEL_ERROR) \
+			iio_prm_printf((prm), LEVEL_ERROR, "ERROR: " __VA_ARGS__); \
+	} while (0)
+#define prm_warn(prm, ...) \
+	do { \
+		if (LIBIIO_MAX_LOG_LEVEL >= LEVEL_WARNING) \
+			iio_prm_printf((prm), LEVEL_WARNING, "WARNING: " __VA_ARGS__); \
+	} while (0)
+#define prm_info(prm, ...) \
+	do { \
+		if (LIBIIO_MAX_LOG_LEVEL >= LEVEL_INFO) \
+			iio_prm_printf((prm), LEVEL_INFO, __VA_ARGS__); \
+	} while (0)
+#define prm_dbg(prm, ...) \
+	do { \
+		if (LIBIIO_MAX_LOG_LEVEL >= LEVEL_DEBUG) \
+			iio_prm_printf((prm), LEVEL_DEBUG, "DEBUG: "__VA_ARGS__); \
+	} while (0)
 
 #define ctx_err(ctx, ...)	prm_err(__ctx_params_or_null(ctx), __VA_ARGS__)
 #define ctx_warn(ctx, ...)	prm_warn(__ctx_params_or_null(ctx), __VA_ARGS__)
@@ -89,11 +112,13 @@ iio_prm_printf(const struct iio_context_params *params,
 					__SKIPFIRST(__VA_ARGS__, ""))
 
 #define prm_perror(params, err, ...) do {				\
-	char _buf[1024];						\
-	int _err = -(err);						\
-	iio_strerror(_err, _buf, sizeof(_buf));				\
-	prm_err(params, __FIRST(__VA_ARGS__, 0)				\
-		__OTHERS(": %s\n",__VA_ARGS__, _buf));			\
+	if (LIBIIO_MAX_LOG_LEVEL >= LEVEL_ERROR) {			\
+		char _buf[1024];					\
+		int _err = -(err);					\
+		iio_strerror(_err, _buf, sizeof(_buf));			\
+		prm_err(params, __FIRST(__VA_ARGS__, 0)			\
+			__OTHERS(": %s\n",__VA_ARGS__, _buf));		\
+	}								\
 } while (0)
 #define ctx_perror(ctx, err, ...)	prm_perror(__ctx_params_or_null(ctx), err, __VA_ARGS__)
 #define dev_perror(dev, err, ...)	ctx_perror(__dev_ctx_or_null(dev), err, \