0005-Remove-unnecessary-global-variable-and-lock.patch

From 9651eb210234ae6fd048f74f9bc4d29989c79f2f Mon Sep 17 00:00:00 2001
From: Philippe Canal <pcanal@fnal.gov>
Date: Fri, 18 Oct 2013 04:43:11 -0500
Subject: [PATCH] Remove unnecessary global variable and lock

gUtmpContents was used only as a data passing mechanism
between related routines and its content had a short lifetime.

This avoids having to put a lock in TUnixSystem::SetDisplay
and (trivially) avoid introducing a possible dead-lock with the lock
being taken as part of 'Warning'.

Conflicts:
	core/unix/inc/TUnixSystem.h
---
 core/unix/inc/TUnixSystem.h   |    3 -
 core/unix/src/TUnixSystem.cxx |  129 +++++++++++++++++++++-------------------
 2 files changed, 68 insertions(+), 64 deletions(-)

diff --git a/core/unix/inc/TUnixSystem.h b/core/unix/inc/TUnixSystem.h
index 9e8814e..0cc6e4a 100644
--- a/core/unix/inc/TUnixSystem.h
+++ b/core/unix/inc/TUnixSystem.h
@@ -78,9 +78,6 @@ protected:
    static void         UnixDynListSymbols(const char *lib, const char *re = "");
    static void         UnixDynListLibs(const char *lib = "");
 
-   static void        *SearchUtmpEntry(int nentries, const char *tty);
-   static int          ReadUtmpFile();
-
 public:
    TUnixSystem();
    virtual ~TUnixSystem();
diff --git a/core/unix/src/TUnixSystem.cxx b/core/unix/src/TUnixSystem.cxx
index 0fc491b8..979a0df 100644
--- a/core/unix/src/TUnixSystem.cxx
+++ b/core/unix/src/TUnixSystem.cxx
@@ -304,8 +304,72 @@ enum {
 // End FPE handling includes
 
 
-static STRUCT_UTMP *gUtmpContents;
+struct TUtmpContent {
+   STRUCT_UTMP *fUtmpContents;
+   UInt_t       fEntries; // Number of entries in utmp file.
+   
+   TUtmpContent() : fUtmpContents(0) {}
+   ~TUtmpContent() { free(fUtmpContents); }
+   
+   STRUCT_UTMP *SearchUtmpEntry(const char *tty)
+   {
+      // Look for utmp entry which is connected to terminal tty.
+      
+      STRUCT_UTMP *ue = fUtmpContents;
+      
+      UInt_t n = fEntries;
+      while (n--) {
+         if (ue->ut_name[0] && !strncmp(tty, ue->ut_line, sizeof(ue->ut_line)))
+            return ue;
+         ue++;
+      }
+      return 0;
+   }
+   
+   int ReadUtmpFile()
+   {
+      // Read utmp file. Returns number of entries in utmp file.
+      
+      FILE  *utmp;
+      struct stat file_stats;
+      size_t n_read, size;
+      
+      fEntries = 0;
+      
+      R__LOCKGUARD2(gSystemMutex);
+      
+      utmp = fopen(UTMP_FILE, "r");
+      if (!utmp)
+         return 0;
+      
+      fstat(fileno(utmp), &file_stats);
+      size = file_stats.st_size;
+      if (size <= 0) {
+         fclose(utmp);
+         return 0;
+      }
+      
+      fUtmpContents = (STRUCT_UTMP *) malloc(size);
+      if (!fUtmpContents) {
+         fclose(utmp);
+         return 0;
+      }
+      
+      n_read = fread(fUtmpContents, 1, size, utmp);
+      if (!ferror(utmp)) {
+         if (fclose(utmp) != EOF && n_read == size) {
+            fEntries = size / sizeof(STRUCT_UTMP);
+            return fEntries;
+         }
+      } else
+         fclose(utmp);
+      
+      free(fUtmpContents);
+      fUtmpContents = 0;
+      return 0;
+   }
 
+};
 
 const char *kServerPath     = "/tmp";
 const char *kProtocolName   = "tcp";
@@ -618,9 +682,10 @@ void TUnixSystem::SetDisplay()
       if (tty) {
          tty += 5;               // remove "/dev/"
 
-         R__LOCKGUARD2(gSystemMutex);
+         TUtmpContent utmp;
+         utmp.ReadUtmpFile();
 
-         STRUCT_UTMP *utmp_entry = (STRUCT_UTMP *)SearchUtmpEntry(ReadUtmpFile(), tty);
+         STRUCT_UTMP *utmp_entry = utmp.SearchUtmpEntry(tty);
          if (utmp_entry) {
             if (utmp_entry->ut_host[0]) {
                if (strchr(utmp_entry->ut_host, ':')) {
@@ -649,7 +714,6 @@ void TUnixSystem::SetDisplay()
             }
 #endif
          }
-         free(gUtmpContents);
       }
    }
 }
@@ -4892,63 +4956,6 @@ void TUnixSystem::UnixDynUnload(const char *lib)
 #endif
 }
 
-//______________________________________________________________________________
-int TUnixSystem::ReadUtmpFile()
-{
-   // Read utmp file. Returns number of entries in utmp file.
-
-   FILE  *utmp;
-   struct stat file_stats;
-   size_t n_read, size;
-
-   R__LOCKGUARD2(gSystemMutex);
-
-   gUtmpContents = 0;
-
-   utmp = fopen(UTMP_FILE, "r");
-   if (!utmp)
-      return 0;
-
-   fstat(fileno(utmp), &file_stats);
-   size = file_stats.st_size;
-   if (size <= 0) {
-      fclose(utmp);
-      return 0;
-   }
-
-   gUtmpContents = (STRUCT_UTMP *) malloc(size);
-   if (!gUtmpContents) {
-      fclose(utmp);
-      return 0;
-   }
-
-   n_read = fread(gUtmpContents, 1, size, utmp);
-   if (!ferror(utmp)) {
-      if (fclose(utmp) != EOF && n_read == size)
-         return size / sizeof(STRUCT_UTMP);
-   } else
-      fclose(utmp);
-
-   free(gUtmpContents);
-   gUtmpContents = 0;
-   return 0;
-}
-
-//______________________________________________________________________________
-void *TUnixSystem::SearchUtmpEntry(int n, const char *tty)
-{
-   // Look for utmp entry which is connected to terminal tty.
-
-   STRUCT_UTMP *ue = gUtmpContents;
-
-   while (n--) {
-      if (ue->ut_name[0] && !strncmp(tty, ue->ut_line, sizeof(ue->ut_line)))
-         return ue;
-      ue++;
-   }
-   return 0;
-}
-
 //---- System, CPU and Memory info ---------------------------------------------
 
 #if defined(R__MACOSX)
-- 
1.7.4.1