Added errno description to sdlog exception strings

include/spdlog/common.h

@@ -100,10 +100,17 @@ enum class async_overflow_policy
 //
 // Log exception
 //
+namespace details { namespace os {
+	std::string errno_str(int err_num);	
+}}
 class spdlog_ex : public std::exception
 {
 public:
     spdlog_ex(const std::string& msg) :_msg(msg) {}
+	spdlog_ex(const std::string& msg, int last_errno)
+	{
+		_msg = msg + ": " + details::os::errno_str(last_errno);
+	}
     const char* what() const SPDLOG_NOEXCEPT override
     {
         return _msg.c_str();

include/spdlog/details/file_helper.h

@@ -17,6 +17,7 @@
 #include <cstdio>
 #include <string>
 #include <thread>
+#include <cerrno>
 
 namespace spdlog
 {
@@ -58,7 +59,7 @@ public:
             std::this_thread::sleep_for(std::chrono::milliseconds(open_interval));
         }
 
-        throw spdlog_ex("Failed opening file " + os::filename_to_str(_filename) + " for writing");
+        throw spdlog_ex("Failed opening file " + os::filename_to_str(_filename) + " for writing", errno);
     }
 
     void reopen(bool truncate)
@@ -89,7 +90,7 @@ public:
         size_t msg_size = msg.formatted.size();
         auto data = msg.formatted.data();
         if (std::fwrite(data, 1, msg_size, _fd) != msg_size)
-            throw spdlog_ex("Failed writing to file " + os::filename_to_str(_filename));
+            throw spdlog_ex("Failed writing to file " + os::filename_to_str(_filename), errno);
 
         if (_force_flush)
             std::fflush(_fd);
@@ -102,15 +103,15 @@ public:
 
         auto pos = ftell(_fd);
         if (fseek(_fd, 0, SEEK_END) != 0)
-            throw spdlog_ex("fseek failed on file " + os::filename_to_str(_filename));
+            throw spdlog_ex("fseek failed on file " + os::filename_to_str(_filename), errno);
 
         auto file_size = ftell(_fd);
 
         if(fseek(_fd, pos, SEEK_SET) !=0)
-            throw spdlog_ex("fseek failed on file " + os::filename_to_str(_filename));
+            throw spdlog_ex("fseek failed on file " + os::filename_to_str(_filename), errno);
 
         if (file_size == -1)
-            throw spdlog_ex("ftell failed on file " + os::filename_to_str(_filename));
+            throw spdlog_ex("ftell failed on file " + os::filename_to_str(_filename), errno);
 
         return file_size;
     }

include/spdlog/details/os.h

@@ -10,6 +10,7 @@
 #include <ctime>
 #include <functional>
 #include <string>
+#include <string.h>
 
 #ifdef _WIN32
 
@@ -27,12 +28,16 @@
 #endif
 
 #elif __linux__
+
 #include <sys/syscall.h> //Use gettid() syscall under linux to get thread id
 #include <sys/stat.h>
 #include <unistd.h>
 #include <chrono>
+
 #else
+
 #include <thread>
+
 #endif
 
 namespace spdlog
@@ -246,6 +251,30 @@ inline std::string filename_to_str(const filename_t& filename)
 }
 #endif
 
+
+// Return errno string (thread safe)
+inline std::string errno_str(int err_num)
+{	
+	char buf[256];	
+	constexpr auto buf_size = sizeof(buf);
+			
+#ifdef _WIN32		
+	if(strerror_s(buf, buf_size, err_num) == 0)
+		return std::string(buf);
+	else
+		return "Unkown error";
+
+#elif (_POSIX_C_SOURCE >= 200112L) && ! _GNU_SOURCE // posix version		
+	if (strerror_r(err_num, buf, buf_size) == 0)
+		return std::string(buf);
+	else
+		return "Unkown error";
+
+#else  // gnu version (might not use the given buf, so its retval pointer must be used)
+	return std::string(strerror_r(err_num, buf, buf_size));
+#endif		
+}
+
 } //os
 } //details
 } //spdlog

include/spdlog/sinks/file_sinks.h

@@ -16,6 +16,7 @@
 #include <ctime>
 #include <mutex>
 #include <string>
+#include <cerrno>
 
 namespace spdlog
 {
@@ -119,12 +120,12 @@ private:
             {
                 if (details::os::remove(target) != 0)
                 {
-                    throw spdlog_ex("rotating_file_sink: failed removing " + filename_to_str(target));
+                    throw spdlog_ex("rotating_file_sink: failed removing " + filename_to_str(target), errno);
                 }
             }
             if (details::file_helper::file_exists(src) && details::os::rename(src, target))
             {
-                throw spdlog_ex("rotating_file_sink: failed renaming " + filename_to_str(src) + " to " + filename_to_str(target));
+                throw spdlog_ex("rotating_file_sink: failed renaming " + filename_to_str(src) + " to " + filename_to_str(target), errno);
             }
         }
         _file_helper.reopen(true);