Fix for broken strerr_r definition in alpine

src/logger.cc

@@ -80,17 +80,26 @@ std::string logger::format(const std::string& fmt, ...)
     return buf;
 }
 
+// alpine has a broken definition for strerr_r
+// see https://stackoverflow.com/questions/41953104/strerror-r-is-incorrectly-declared-on-alpine-linux
+
+std::string logger::err_str(int result, char *buff, int err)
+{
+    if (result)
+        sprintf(buff, "unknown error: %d", err);
+    return buff;
+}
+
+std::string logger::err_str(char *result, char *buff, int err)
+{
+    return result;
+}
+
+
 std::string logger::err()
 {
     char buf[2048];
-
-#if (_POSIX_C_SOURCE >= 200112L || _XOPEN_SOURCE >= 600) && ! _GNU_SOURCE
-    if (strerror_r(errno, buf, sizeof(buf))
-        return "Unknown error";
-    return buf;
-#else
-    return strerror_r(errno, buf, sizeof(buf));
-#endif
+    return logger::err_str(strerror_r(errno, buf, sizeof(buf)), buf, errno);
 }
 
 logger logger::error()

src/logger.h

@@ -74,6 +74,7 @@ public:
     static std::string err();
 
 private:
+
     int _pri;
 
     std::stringstream _ss;
@@ -91,7 +92,9 @@ private:
 
     static int _max_pri;
 
-
+    // fixes for strerr_r on alpine
+    static std::string err_str(int result, char *buff, int err);
+    static std::string err_str(char *result, char *buff, int err);
 };
 
 NDPPD_NS_END