Introduce error_string() as a portable replacement for strerror_r()

Makefile.in

@@ -29,6 +29,7 @@ SOURCE=\
 	base/base64.cc \
 	base/endian_utils.cc \
 	base/error_state.cc \
+	base/error_string.cc \
 	base/progress_monitor.cc \
 	base/xml_utils.cc \
 	block-cache/block_cache.cc \
@@ -98,6 +99,7 @@ CFLAGS+=-g -Wall -O3
 CXXFLAGS+=-g -Wall -fno-strict-aliasing
 CXXFLAGS+=@CXXOPTIMISE_FLAG@
 CXXFLAGS+=@CXXDEBUG_FLAG@
+CXXFLAGS+=@CXX_STRERROR_FLAG@
 INCLUDES+=-I$(TOP_BUILDDIR) -I$(TOP_DIR) -I$(TOP_DIR)/thin-provisioning
 LIBS:=-lstdc++ -laio -lexpat
 INSTALL:=@INSTALL@

caching/cache_check.cc

@@ -13,6 +13,7 @@
 #include <unistd.h>
 
 #include "base/error_state.h"
+#include "base/error_string.h"
 #include "base/nested_output.h"
 #include "caching/commands.h"
 #include "caching/metadata.h"
@@ -202,10 +203,7 @@ namespace {
 		int r = ::stat(path.c_str(), &info);
 		if (r) {
 			ostringstream msg;
-			char buffer[128], *ptr;
+			msg << path << ": " << error_string(errno);
-
-			ptr = ::strerror_r(errno, buffer, sizeof(buffer));
-			msg << path << ": " << ptr;
 			throw runtime_error(msg.str());
 		}
 

configure.ac

@@ -42,6 +42,13 @@ AC_PROG_MAKE_SET
 AC_PROG_MKDIR_P
 AC_PROG_INSTALL
 
+################################################################
+dnl -- Checks for functions.
+AC_FUNC_STRERROR_R
+if test x$ac_cv_func_strerror_r_char_p = xyes; then
+   CXX_STRERROR_FLAG="-DSTRERROR_R_CHAR_P"
+fi
+
 ################################################################################
 dnl -- Prefix is /usr by default, the exec_prefix default is setup later
 AC_PREFIX_DEFAULT(/usr)
@@ -136,6 +143,7 @@ VERSION_PATCHLEVEL=`echo "$VER" | $AWK -F '[[(.]]' '{print $3}'`
 ################################################################
 AC_SUBST(CXXDEBUG_FLAG)
 AC_SUBST(CXXOPTIMISE_FLAG)
+AC_SUBST(CXX_STRERROR_FLAG)
 AC_SUBST(INSTALL)
 AC_SUBST(prefix)
 AC_SUBST(RELEASE_DATE)

era/era_check.cc

@@ -13,6 +13,7 @@
 #include <unistd.h>
 
 #include "base/error_state.h"
+#include "base/error_string.h"
 #include "base/nested_output.h"
 #include "era/commands.h"
 #include "era/writeset_tree.h"
@@ -186,10 +187,7 @@ namespace {
 		int r = ::stat(path.c_str(), &info);
 		if (r) {
 			ostringstream msg;
-			char buffer[128], *ptr;
+			msg << path << ": " << error_string(errno);;
-
-			ptr = ::strerror_r(errno, buffer, sizeof(buffer));
-			msg << path << ": " << ptr;
 			throw runtime_error(msg.str());
 		}
 

persistent-data/block.tcc

@@ -18,13 +18,14 @@
 
 #include "block.h"
 
+#include "base/error_string.h"
+
 #include <errno.h>
 #include <fcntl.h>
 #include <sys/stat.h>
 #include <sys/types.h>
 #include <unistd.h>
 #include <fcntl.h>
-#include <string.h>
 
 #include <boost/bind.hpp>
 #include <stdexcept>
@@ -44,11 +45,8 @@ namespace {
 	// FIXME: introduce a new exception for this, or at least lift this
 	// to exception.h
 	void syscall_failed(char const *call) {
-		char buffer[128];
-		char *msg = strerror_r(errno, buffer, sizeof(buffer));
-
 		ostringstream out;
-		out << "syscall '" << call << "' failed: " << msg;
+		out << "syscall '" << call << "' failed: " << base::error_string(errno);;
 		throw runtime_error(out.str());
 	}