[RFC 2/3] log: add a per line log helper

[David Marchand]

gcc builtin __builtin_strchr can be used as a static assertion to check
whether passed format strings contain a \n.
This can be useful to detect double \n in log messages.

Signed-off-by: David Marchand <david.marchand at redhat.com>
---
 lib/log/rte_log.h | 21 +++++++++++++++++++++
 1 file changed, 21 insertions(+)

diff --git a/lib/log/rte_log.h b/lib/log/rte_log.h
index f7a8405de9..d6db699a07 100644
--- a/lib/log/rte_log.h
+++ b/lib/log/rte_log.h
@@ -17,6 +17,7 @@
 extern "C" {
 #endif
 
+#include <assert.h>
 #include <stdint.h>
 #include <stdio.h>
 #include <stdarg.h>
@@ -358,6 +359,26 @@ int rte_vlog(uint32_t level, uint32_t logtype, const char *format, va_list ap)
 		 RTE_LOGTYPE_ ## t, # t ": " __VA_ARGS__) :	\
 	 0)
 
+#ifdef RTE_TOOLCHAIN_GCC
+#define RTE_LOG_CHECK_NO_NEWLINE(fmt) \
+	static_assert(!__builtin_strchr(fmt, '\n'), \
+		"This log format string contains a \\n")
+#else
+#define RTE_LOG_CHECK_NO_NEWLINE(...)
+#endif
+
+#define RTE_LOG_LINE(l, t, ...) do { \
+	RTE_LOG_CHECK_NO_NEWLINE(RTE_FMT_HEAD(__VA_ARGS__,)); \
+	RTE_LOG(l, t, RTE_FMT(RTE_FMT_HEAD(__VA_ARGS__,) "\n", \
+		RTE_FMT_TAIL(__VA_ARGS__ ,))); \
+} while (0)
+
+#define RTE_LOG_DP_LINE(l, t, ...) do { \
+	RTE_LOG_CHECK_NO_NEWLINE(RTE_FMT_HEAD(__VA_ARGS__,)); \
+	RTE_LOG_DP(l, t, RTE_FMT(RTE_FMT_HEAD(__VA_ARGS__,) "\n", \
+		RTE_FMT_TAIL(__VA_ARGS__ ,))); \
+} while (0)
+
 #define RTE_LOG_REGISTER_IMPL(type, name, level)			    \
 int type;								    \
 RTE_INIT(__##type)							    \
-- 
2.41.0