log: add syslog support

Add support to log using standard syslog, add related option in dhtnode. dhtnode will use syslog by default when starting in daemon mode and no logfile is defined.
savoirfairelinux · May 30, 2017 · 39a254c · 39a254c
1 parent 3aa720f
commit 39a254c
Show file tree

Hide file tree

Showing 4 changed files with 48 additions and 6 deletions.
diff --git a/include/opendht/log.h b/include/opendht/log.h
@@ -22,8 +22,6 @@
 #include "dhtrunner.h"
 
 #include <iostream>
-#include <fstream>
-#include <chrono>
 
 namespace dht {
 namespace log {
@@ -73,5 +71,8 @@ enableFileLogging(dht::DhtRunner &dht, const std::string &path);
 OPENDHT_PUBLIC void
 disableLogging(dht::DhtRunner &dht);
 
+OPENDHT_PUBLIC void
+enableSyslog(dht::DhtRunner &dht, const char* name);
+
 } /* log */
 } /* dht  */
diff --git a/src/log.cpp b/src/log.cpp
@@ -19,6 +19,13 @@
 
 #include "log.h"
 
+#ifndef _WIN32
+#include <syslog.h>
+#endif
+
+#include <fstream>
+#include <chrono>
+
 namespace dht {
 namespace log {
 
@@ -37,9 +44,9 @@ printLog(std::ostream& s, char const *m, va_list args) {
     using namespace std::chrono;
     using log_precision = microseconds;
     constexpr auto den = log_precision::period::den;
-    auto micro = duration_cast<log_precision>(steady_clock::now().time_since_epoch()).count();
-    s << "[" << std::setfill('0') << std::setw(6) << micro / den << "."
-      << std::setfill('0') << std::setw(6) << micro % den << "]" << " ";
+    auto num = duration_cast<log_precision>(steady_clock::now().time_since_epoch()).count();
+    s << "[" << std::setfill('0') << std::setw(6) << num / den << "."
+             << std::setfill('0') << std::setw(6) << num % den << "]" << " ";
 
     // write log
     s.write(buffer.data(), std::min((size_t) ret, buffer.size()));
@@ -77,6 +84,32 @@ enableFileLogging(dht::DhtRunner &dht, const std::string &path) {
     );
 }
 
+OPENDHT_PUBLIC void
+enableSyslog(dht::DhtRunner &dht, const char* name) {
+#ifndef _WIN32
+    struct Syslog {
+        Syslog(const char* n) {
+            openlog(n, LOG_NDELAY, LOG_USER);
+        }
+        ~Syslog() {
+            closelog();
+        }
+    };
+    // syslog is global. Existing instance must be reused.
+    static std::weak_ptr<Syslog> opened_logfile;
+    auto logfile = opened_logfile.lock();
+    if (not logfile) {
+        logfile = std::make_shared<Syslog>(name);
+        opened_logfile = logfile;
+    }
+    dht.setLoggers(
+        [logfile](char const *m, va_list args) { vsyslog(LOG_ERR, m, args); },
+        [logfile](char const *m, va_list args) { vsyslog(LOG_WARNING, m, args); },
+        [logfile](char const *m, va_list args) { vsyslog(LOG_INFO, m, args); }
+    );
+#endif
+}
+
 void
 disableLogging(dht::DhtRunner &dht) {
     dht.setLoggers(dht::NOLOG, dht::NOLOG, dht::NOLOG);

diff --git a/tools/dhtnode.cpp b/tools/dhtnode.cpp
@@ -370,7 +370,9 @@ main(int argc, char **argv)
         dht->run(params.port, crt, true, params.network);
 
         if (params.log) {
-            if (not params.logfile.empty())
+            if (params.syslog or (params.daemonize and params.logfile.empty()))
+                log::enableSyslog(*dht, "dhtnode");
+            else if (not params.logfile.empty())
                 log::enableFileLogging(*dht, params.logfile);
             else
                 log::enableLogging(*dht);

diff --git a/tools/tools_common.h b/tools/tools_common.h
@@ -111,6 +111,7 @@ struct dht_params {
     bool help {false}; // print help and exit
     bool log {false};
     std::string logfile {};
+    bool syslog {false};
     in_port_t port {0};
     dht::NetId network {0};
     bool generate_identity {false};
@@ -127,6 +128,7 @@ static const constexpr struct option long_options[] = {
    {"verbose",    no_argument      , nullptr, 'v'},
    {"daemonize",  no_argument      , nullptr, 'd'},
    {"logfile",    required_argument, nullptr, 'l'},
+   {"syslog",     no_argument      , nullptr, 'L'},
    {nullptr,      0                , nullptr,  0}
 };
 
@@ -161,6 +163,10 @@ parseArgs(int argc, char **argv) {
         case 'l':
             params.logfile = optarg;
             break;
+        case 'L':
+            params.log = true;
+            params.syslog = true;
+            break;
         case 'v':
             params.log = true;
             break;