Resolves zbackup#76

Now it was possible to specify path to tmp directory using TMPDIR
environment variable, i.e.:
cat /111 | TMPDIR=/tmp/ zbackup backup -O paths.respect_tmp <..>

config.cc

@@ -133,6 +133,15 @@ void Config::prefillKeywords()
       "Not default, you should specify it explicitly."
     },
 
+    {
+      "paths.respect_tmp",
+      Config::oRuntime_pathsRespectTmp,
+      Config::Runtime,
+      "ZBackup will use TMPDIR environment variable\n"
+      "for temporary files if set.\n"
+      "Not default, you should specify it explicitly."
+    },
+
     { "", Config::oBadOption, Config::None }
   };
 
@@ -475,6 +484,15 @@ bool Config::parseOrValidate( const string & option, const OptionType type,
       /* NOTREACHED */
       break;
 
+    case oRuntime_pathsRespectTmp:
+      runtime.pathsRespectTmp = true;
+
+      dPrintf( "runtime[pathsRespectTmp] = true\n" );
+
+      return true;
+      /* NOTREACHED */
+      break;
+
     case oBadOption:
     default:
       return false;

config.hh

@@ -30,12 +30,14 @@ public:
     size_t cacheSize;
     bitset< BackupExchanger::Flags > exchange;
     bool gcRepack;
+    bool pathsRespectTmp;
 
     // Default runtime config
     RuntimeConfig():
       threads( getNumberOfCpus() ),
       cacheSize( 40 * 1024 * 1024 ), // 40 MB
-      gcRepack ( false )
+      gcRepack ( false ),
+      pathsRespectTmp( false )
     {
     }
   };
@@ -61,6 +63,7 @@ public:
     oRuntime_cacheSize,
     oRuntime_exchange,
     oRuntime_gcRepack,
+    oRuntime_pathsRespectTmp,
 
     oDeprecated, oUnsupported
   } OpCodes;

zbackup_base.cc

@@ -29,8 +29,19 @@ Paths::Paths( string const & storageDir ): storageDir( storageDir )
 {
 }
 
+Paths::Paths( string const & storageDir, Config const & config ):
+  storageDir( storageDir ), config( config )
+{
+}
+
 string Paths::getTmpPath()
 {
+  if ( config.runtime.pathsRespectTmp )
+  {
+    char * tmpdir;
+    if ( ( ( tmpdir = getenv( "TMPDIR" ) ) != NULL && *tmpdir != '\0' ) )
+      return string( tmpdir );
+  }
   return string( Dir::addPath( storageDir, "tmp" ) );
 }
 
@@ -75,7 +86,7 @@ ZBackupBase::ZBackupBase( string const & storageDir, string const & password ):
 
 ZBackupBase::ZBackupBase( string const & storageDir, string const & password,
                           Config & configIn ):
-  Paths( storageDir ), storageInfo( loadStorageInfo() ),
+  Paths( storageDir, configIn ), storageInfo( loadStorageInfo() ),
   encryptionkey( password, storageInfo.has_encryption_key() ?
                    &storageInfo.encryption_key() : 0 ),
   extendedStorageInfo( loadExtendedStorageInfo( encryptionkey ) ),
@@ -105,7 +116,7 @@ ZBackupBase::ZBackupBase( string const & storageDir, string const & password,
 
 ZBackupBase::ZBackupBase( string const & storageDir, string const & password,
                           Config & configIn, bool prohibitChunkIndexLoading ):
-  Paths( storageDir ), storageInfo( loadStorageInfo() ),
+  Paths( storageDir, configIn ), storageInfo( loadStorageInfo() ),
   encryptionkey( password, storageInfo.has_encryption_key() ?
                    &storageInfo.encryption_key() : 0 ),
   extendedStorageInfo( loadExtendedStorageInfo( encryptionkey ) ),

zbackup_base.hh

@@ -13,9 +13,11 @@
 
 struct Paths
 {
+  Config config;
   std::string storageDir;
 
   Paths( std::string const & storageDir );
+  Paths( std::string const & storageDir, Config const & );
 
   std::string getTmpPath();
   std::string getRestorePath();