From 210242e5c012116aebeddae4f45c43a9c1eb3674 Mon Sep 17 00:00:00 2001
From: "Wladimir J. van der Laan" <laanwj@gmail.com>
Date: Fri, 30 Sep 2016 18:02:53 +0200
Subject: [PATCH] Merge #8813: bitcoind: Daemonize using daemon(3)

a92bf4a bitcoind: Daemonize using daemon(3) (Matthew King)
---
 configure.ac  |  3 +++
 src/dashd.cpp | 23 ++++++++---------------
 src/init.cpp  |  2 +-
 3 files changed, 12 insertions(+), 16 deletions(-)

diff --git a/configure.ac b/configure.ac
index 12bee5b187..fe2ec838b2 100644
--- a/configure.ac
+++ b/configure.ac
@@ -518,6 +518,9 @@ AC_SEARCH_LIBS([inet_pton], [nsl resolv], [AC_DEFINE(HAVE_INET_PTON, 1, [Define
 
 AC_CHECK_DECLS([strnlen])
 
+# Check for daemon(3), unrelated to --with-daemon (although used by it)
+AC_CHECK_DECLS([daemon])
+
 AC_CHECK_DECLS([le16toh, le32toh, le64toh, htole16, htole32, htole64, be16toh, be32toh, be64toh, htobe16, htobe32, htobe64],,,
 		[#if HAVE_ENDIAN_H
                  #include <endian.h>
diff --git a/src/dashd.cpp b/src/dashd.cpp
index d5ec2c98ac..cfb21cbbb8 100644
--- a/src/dashd.cpp
+++ b/src/dashd.cpp
@@ -10,6 +10,7 @@
 
 #include "chainparams.h"
 #include "clientversion.h"
+#include "compat.h"
 #include "rpc/server.h"
 #include "init.h"
 #include "noui.h"
@@ -142,29 +143,21 @@ bool AppInit(int argc, char* argv[])
             fprintf(stderr, "Error: There is no RPC client functionality in dashd anymore. Use the dash-cli utility instead.\n");
             exit(EXIT_FAILURE);
         }
-#ifndef WIN32
         if (GetBoolArg("-daemon", false))
         {
+#if HAVE_DECL_DAEMON
             fprintf(stdout, "Dash Core server starting\n");
 
             // Daemonize
-            pid_t pid = fork();
-            if (pid < 0)
-            {
-                fprintf(stderr, "Error: fork() returned %d errno %d\n", pid, errno);
+            if (daemon(1, 0)) { // don't chdir (1), do close FDs (0)
+                fprintf(stderr, "Error: daemon() failed: %s\n", strerror(errno));
                 return false;
             }
-            if (pid > 0) // Parent process, pid is child process id
-            {
-                return true;
-            }
-            // Child process falls through to rest of initialization
-
-            pid_t sid = setsid();
-            if (sid < 0)
-                fprintf(stderr, "Error: setsid() returned %d errno %d\n", sid, errno);
+#else
+            fprintf(stderr, "Error: -daemon is not supported on this operating system\n");
+            return false;
+#endif // HAVE_DECL_DAEMON
         }
-#endif
         SoftSetBoolArg("-server", true);
 
         // Set this early so that parameter interactions go to console
diff --git a/src/init.cpp b/src/init.cpp
index 917473ad4d..2926e6e009 100644
--- a/src/init.cpp
+++ b/src/init.cpp
@@ -395,7 +395,7 @@ std::string HelpMessage(HelpMessageMode mode)
     strUsage += HelpMessageOpt("-conf=<file>", strprintf(_("Specify configuration file (default: %s)"), BITCOIN_CONF_FILENAME));
     if (mode == HMM_BITCOIND)
     {
-#ifndef WIN32
+#if HAVE_DECL_DAEMON
         strUsage += HelpMessageOpt("-daemon", _("Run in the background as a daemon and accept commands"));
 #endif
     }