shared code (new strerror stuff)

src/utils/log.h

@@ -1,4 +1,4 @@
-/* Copyright (C) 2014 J.F.Dockes
+/* Copyright (C) 2014-2019 J.F.Dockes
  *  This program is free software; you can redistribute it and/or modify
  *  it under the terms of the GNU Lesser General Public License as published by
  *  the Free Software Foundation; either version 2.1 of the License, or
@@ -14,23 +14,6 @@
  *  Free Software Foundation, Inc.,
  *  51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA.
  */
-/* Copyright (C) 2006-2016 J.F.Dockes
- *
- * This library is free software; you can redistribute it and/or
- * modify it under the terms of the GNU Lesser General Public
- * License as published by the Free Software Foundation; either
- * version 2.1 of the License, or (at your option) any later version.
- *
- * This library is distributed in the hope that it will be useful,
- * but WITHOUT ANY WARRANTY; without even the implied warranty of
- * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
- * Lesser General Public License for more details.
- *
- * You should have received a copy of the GNU Lesser General Public
- * License along with this library; if not, write to the Free Software
- * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA
- *   02110-1301 USA
- */
 #ifndef _LOG_H_X_INCLUDED_
 #define _LOG_H_X_INCLUDED_
 
@@ -198,20 +181,18 @@ private:
         LOGERR(who << ": " << what << "("  << arg << "): errno " << errno << \
                ": " << strerror(errno) << std::endl);                   \
     }
-#else // !WINDOWS->
+#else // not WINDOWS or sun
-#if (_POSIX_C_SOURCE >= 200112L) && !  _GNU_SOURCE
+
-#define LOGSYSERR(who, what, arg) {                                     \
+inline char *_log_check_strerror_r(int, char *errbuf) {return errbuf;}
-        char buf[200]; buf[0] = 0; strerror_r(errno, buf, 200);         \
+inline char *_log_check_strerror_r(char *cp, char *){return cp;}
-        LOGERR(who << ": " << what << "("  << arg << "): errno " << errno << \
+
-               ": " << buf << std::endl);                               \
-    }
-#else
 #define LOGSYSERR(who, what, arg) {                                     \
         char buf[200]; buf[0] = 0;                                      \
         LOGERR(who << ": " << what << "("  << arg << "): errno " << errno << \
-               ": " << strerror_r(errno, buf, 200) << std::endl);       \
+               ": " << _log_check_strerror_r(                           \
+                   strerror_r(errno, buf, 200), buf) << std::endl);     \
     }
-#endif
+
 #endif // not windows
 
 #endif /* _LOG_H_X_INCLUDED_ */

src/utils/smallut.cpp

@@ -1164,6 +1164,16 @@ secondelt:
     return true;
 }
 
+// We'd like these static, but then, as only one is used, this
+// triggers a 'defined but not used' warning.
+char *_check_strerror_r(int, char *errbuf)
+{
+    return errbuf;
+}
+char *_check_strerror_r(char *cp, char *)
+{
+    return cp;
+}
 
 void catstrerror(string *reason, const char *what, int _errno)
 {
@@ -1186,8 +1196,6 @@ void catstrerror(string *reason, const char *what, int _errno)
     // Note: sun strerror is noted mt-safe ??
     reason->append(strerror(_errno));
 #else
-#define ERRBUFSZ 200
-    char errbuf[ERRBUFSZ];
     // There are 2 versions of strerror_r.
     // - The GNU one returns a pointer to the message (maybe
     //   static storage or supplied buffer).
@@ -1198,13 +1206,15 @@ void catstrerror(string *reason, const char *what, int _errno)
     //   were returned a pointer...
     // Also couldn't find an easy way to disable the gnu version without
     // changing the cxxflags globally, so forget it. Recent gnu lib versions
-    // normally default to the posix version.
+    // normally default to the posix version. (not !)
-    // At worse we get no message at all here.
+    // The feature defines tests are too complicated and seem unreliable.
+    // In short it's a mess, but thanks to c++ function overloading and smart 
+    // people, we have a solution:
+    // https://www.zverovich.net/2015/03/13/reliable-detection-of-strerror-variants.html
+    char errbuf[200];
     errbuf[0] = 0;
-    // We don't use ret, it's there to silence a cc warning
+    reason->append(_check_strerror_r(
-    auto ret = strerror_r(_errno, errbuf, ERRBUFSZ);
+                       strerror_r(_errno, errbuf, sizeof(errbuf)), errbuf));
-    (void)ret;
-    reason->append(errbuf);
 #endif
 }
 
@@ -1232,7 +1242,7 @@ static std::unordered_map<string, string> lang_to_code {
     {"th", "iso-8859-11"},
     {"tr", "iso-8859-9"},
     {"uk", "koi8-u"},
-};
+        };
 static const string cstr_cp1252("CP1252");
 
 string langtocode(const string& lang)