Add make_system_error

config.cpp

@@ -6,7 +6,6 @@
 #include <sys/stat.h>
 #include <string>
 #include <memory>
-#include <system_error>
 
 #include "log.h"
 #include "misc.h"
@@ -17,15 +16,14 @@ static FILE* fopen_or_raise(const char* path, const char* mode, bool ignore_enoe
     if (file || (ignore_enoent && errno == ENOENT)) {
         return file;
     }
-    throw std::system_error(errno, std::generic_category(), std::string("fopen(") + quote(path) + ')');
+    throw make_system_error(std::string("fopen(") + quote(path) + ')');
 }
 
 static void fclose_and_log(FILE* file) {
     if (!fclose(file)) {
         return;
     }
-    std::system_error e = std::system_error(errno, std::generic_category(), "fclose()");
-    log(std::string("Failed to close a file: ") + e.what());
+    log(std::string("Failed to close a file: ") + make_system_error("fclose()").what());
 }
 
 static bool write(const std::string& ptr, FILE* file) {
@@ -109,7 +107,7 @@ void create_config_folders_if_necessary() {
         if (errno == EEXIST) {
             continue;
         }
-        throw std::system_error(errno, std::generic_category(), std::string("mkdir(") + quote(path) + ')');
+        throw make_system_error(std::string("mkdir(") + quote(path) + ')');
     }
 }
 
@@ -148,7 +146,7 @@ static inline Config load_config(FILE* file) {
             if (errsv == ENOMEM) {
                 throw std::bad_alloc();
             } else if (errsv != 0) {
-                throw std::system_error(errsv, std::generic_category(), "getline()");
+                throw make_system_error(errsv, "getline()");
             } else {
                 break;
             }
@@ -223,6 +221,5 @@ void write_config(const Config& config) {
     if (!rename(tmp_config_file_path.c_str(), config_file_path.c_str())) {
         return;
     }
-    throw std::system_error(errno, std::generic_category(),
-        std::string("rename(") + quote(tmp_config_file_path) + ", " + quote(config_file_path) + ')');
+    throw make_system_error(std::string("rename(") + quote(tmp_config_file_path) + ", " + quote(config_file_path) + ')');
 }

log.cpp

@@ -2,7 +2,6 @@
 #include <string>
 #include <vector>
 #include <exception>
-#include <system_error>
 
 #include "log.h"
 

misc.cpp

@@ -1,5 +1,6 @@
 #include <iomanip>
 #include <sstream>
+#include <system_error>
 
 #include "misc.h"
 
@@ -8,3 +9,19 @@ std::string quote(const std::string& str) {
     ss << std::quoted(str);
     return ss.str();
 }
+
+std::system_error make_system_error(int err, const char* what) {
+    return std::system_error(err, std::generic_category(), what);
+}
+
+std::system_error make_system_error(int err, std::string what) {
+    return std::system_error(err, std::generic_category(), std::move(what));
+}
+
+std::system_error make_system_error(const char* what) {
+    return make_system_error(errno, what);
+}
+
+std::system_error make_system_error(std::string what) {
+    return make_system_error(errno, std::move(what));
+}

misc.h

@@ -1,5 +1,10 @@
 #pragma once
 
 #include <string>
+#include <system_error>
 
 std::string quote(const std::string& str);
+std::system_error make_system_error(int err, const char* what);
+std::system_error make_system_error(int err, std::string what);
+std::system_error make_system_error(const char* what);
+std::system_error make_system_error(std::string what);