[lxc-devel] [lxc/master] log: handle strerror_r() versions

[brauner on Github]

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From 218932e90954c6dfdd604a745383353ee9bfc55f Mon Sep 17 00:00:00 2001
From: Christian Brauner <christian.brauner at ubuntu.com>
Date: Wed, 22 Aug 2018 12:25:16 +0200
Subject: [PATCH] log: handle strerror_r() versions

Closes #2563.

Signed-off-by: Christian Brauner <christian.brauner at ubuntu.com>
---
 configure.ac  |  6 ++++++
 src/lxc/log.h | 42 +++++++++++++++++++++++++++---------------
 2 files changed, 33 insertions(+), 15 deletions(-)

diff --git a/configure.ac b/configure.ac
index 19d9ea220..ed8bbc82f 100644
--- a/configure.ac
+++ b/configure.ac
@@ -619,6 +619,12 @@ AC_HEADER_MAJOR
 # Check for some syscalls functions
 AC_CHECK_FUNCS([setns pivot_root sethostname unshare rand_r confstr faccessat gettid memfd_create])
 
+# Check for strerror_r() support. Defines:
+# - HAVE_STRERROR_R if available
+# - HAVE_DECL_STRERROR_R if defined
+# - STRERROR_R_CHAR_P if it returns char *
+AC_FUNC_STRERROR_R
+
 # Check for some functions
 AC_CHECK_LIB(pthread, main)
 AC_CHECK_FUNCS(statvfs)
diff --git a/src/lxc/log.h b/src/lxc/log.h
index 4654fd918..2c3240b21 100644
--- a/src/lxc/log.h
+++ b/src/lxc/log.h
@@ -327,22 +327,34 @@ ATTR_UNUSED static inline void LXC_##LEVEL(struct lxc_log_locinfo* locinfo,	\
 /*
  * Helper macro to define errno string.
  */
-#if (_POSIX_C_SOURCE >= 200112L || _XOPEN_SOURCE >= 600) && !defined(_GNU_SOURCE) || IS_BIONIC
-#define lxc_log_strerror_r                                               \
-	char errno_buf[MAXPATHLEN / 2] = {"Failed to get errno string"}; \
-	char *ptr = errno_buf;                                           \
-	{                                                                \
-		(void)strerror_r(errno, errno_buf, sizeof(errno_buf));   \
-	}
+#if HAVE_STRERROR_R
+	#ifndef HAVE_DECL_STRERROR_R
+		#ifdef STRERROR_R_CHAR_P
+			char *strerror_r(int errnum, char *buf, size_t buflen)
+		#else
+			int strerror_r(int errnum, char *buf, size_t buflen)
+		#endif
+	#endif
+
+	#ifdef STRERROR_R_CHAR_P
+		#define lxc_log_strerror_r                                               \
+			char errno_buf[MAXPATHLEN / 2] = {"Failed to get errno string"}; \
+			char *ptr = errno_buf;                                           \
+			{                                                                \
+				ptr = strerror_r(errno, errno_buf, sizeof(errno_buf));   \
+				if (!ptr)                                                \
+					ptr = errno_buf;                                 \
+			}
+	#else
+		#define lxc_log_strerror_r                                               \
+			char errno_buf[MAXPATHLEN / 2] = {"Failed to get errno string"}; \
+			char *ptr = errno_buf;                                           \
+			{                                                                \
+				(void)strerror_r(errno, errno_buf, sizeof(errno_buf));   \
+			}
+	#endif
 #else
-#define lxc_log_strerror_r                                               \
-	char errno_buf[MAXPATHLEN / 2] = {"Failed to get errno string"}; \
-	char *ptr;                                                       \
-	{                                                                \
-		ptr = strerror_r(errno, errno_buf, sizeof(errno_buf));   \
-		if (!ptr)                                                \
-			ptr = errno_buf;                                 \
-	}
+#define lxc_log_strerror_r char *ptr = strerror(errno)
 #endif
 
 /*