From 5cbc0ad3c7043ea120bb5e9d116a927d3d7567a7 Mon Sep 17 00:00:00 2001
From: Jan Steemann <jan@arangodb.com>
Date: Wed, 27 Jun 2012 11:38:43 +0200
Subject: [PATCH] added some error messages when using --pid-file

---
 lib/Basics/FileUtils.cpp | 11 +++++++++++
 lib/Basics/FileUtils.h   |  8 ++++++++
 lib/Rest/AnyServer.cpp   |  7 +++++--
 3 files changed, 24 insertions(+), 2 deletions(-)

diff --git a/lib/Basics/FileUtils.cpp b/lib/Basics/FileUtils.cpp
index 93d59bf857..c5116a7618 100644
--- a/lib/Basics/FileUtils.cpp
+++ b/lib/Basics/FileUtils.cpp
@@ -357,6 +357,17 @@ namespace triagens {
 
         return res == 0;
       }
+      
+      
+      off_t size (string const& path) {
+        struct stat stbuf;
+        int res = stat(path.c_str(), &stbuf);
+        if (res != 0) {
+          return 0;
+        }
+
+        return stbuf.st_size;
+      }
 
 
 
diff --git a/lib/Basics/FileUtils.h b/lib/Basics/FileUtils.h
index 7fec55ed97..7ebc5fb990 100644
--- a/lib/Basics/FileUtils.h
+++ b/lib/Basics/FileUtils.h
@@ -130,6 +130,14 @@ namespace triagens {
 
       bool exists (string const& path);
 
+////////////////////////////////////////////////////////////////////////////////
+/// @brief returns the size of a file. will return 0 for non-existing files
+///
+/// the caller should check first if the file exists via the exists() method
+////////////////////////////////////////////////////////////////////////////////
+
+      off_t size (string const& path);
+
 ////////////////////////////////////////////////////////////////////////////////
 /// @brief strip extension
 ////////////////////////////////////////////////////////////////////////////////
diff --git a/lib/Rest/AnyServer.cpp b/lib/Rest/AnyServer.cpp
index 7d920d823c..c8eea29870 100644
--- a/lib/Rest/AnyServer.cpp
+++ b/lib/Rest/AnyServer.cpp
@@ -68,7 +68,7 @@ static void CheckPidFile (string const& pidFile) {
       TRI_FlushLogging();
       exit(EXIT_FAILURE);
     }
-    else if (FileUtils::exists(pidFile)) {
+    else if (FileUtils::exists(pidFile) && FileUtils::size(pidFile) > 0) {
       LOGGER_INFO << "pid-file '" << pidFile << "' already exists, verifying pid";
 
       ifstream f(pidFile.c_str());
@@ -137,7 +137,7 @@ static void WritePidFile (string const& pidFile, int pid) {
   ofstream out(pidFile.c_str(), ios::trunc);
 
   if (! out) {
-    cerr << "cannot write pid\n";
+    cerr << "cannot write pid-file \"" << pidFile << "\"\n";
     exit(EXIT_FAILURE);
   }
 
@@ -159,6 +159,9 @@ static int forkProcess (string const& pidFile, string const& workingDirectory, s
     exit(EXIT_FAILURE);
   }
 
+  // Upon successful completion, fork() shall return 0 to the child process and 
+  // shall return the process ID of the child process to the parent process.
+
   // if we got a good PID, then we can exit the parent process
   if (pid > 0) {
     LOGGER_DEBUG << "started child process with pid " << pid;