add lots of error checking by GThomas

29 files changed, 268 insertions, 170 deletions

diff --git a/go/directory/file_id.go b/go/directory/file_id.go
index f5f6d46d6..807a10f7a 100644
--- a/go/directory/file_id.go
+++ b/go/directory/file_id.go
@@ -1,9 +1,9 @@
 package directory
 
 import (
-	"encoding/hex"
 	"code.google.com/p/weed-fs/go/storage"
 	"code.google.com/p/weed-fs/go/util"
+	"encoding/hex"
 	"strings"
 )
 
diff --git a/go/operation/allocate_volume.go b/go/operation/allocate_volume.go
index 19166eaed..ea34901ef 100644
--- a/go/operation/allocate_volume.go
+++ b/go/operation/allocate_volume.go
@@ -1,12 +1,12 @@
 package operation
 
 import (
-	"encoding/json"
-	"errors"
-	"net/url"
 	"code.google.com/p/weed-fs/go/storage"
 	"code.google.com/p/weed-fs/go/topology"
 	"code.google.com/p/weed-fs/go/util"
+	"encoding/json"
+	"errors"
+	"net/url"
 )
 
 type AllocateVolumeResult struct {
diff --git a/go/operation/lookup_volume_id.go b/go/operation/lookup_volume_id.go
index 8512ac918..0d8f247be 100644
--- a/go/operation/lookup_volume_id.go
+++ b/go/operation/lookup_volume_id.go
@@ -1,12 +1,12 @@
 package operation
 
 import (
+	"code.google.com/p/weed-fs/go/storage"
+	"code.google.com/p/weed-fs/go/util"
 	"encoding/json"
 	"errors"
 	_ "fmt"
 	"net/url"
-	"code.google.com/p/weed-fs/go/storage"
-	"code.google.com/p/weed-fs/go/util"
 )
 
 type Location struct {
diff --git a/go/operation/upload_content.go b/go/operation/upload_content.go
index 0bdb697da..cae657b2c 100644
--- a/go/operation/upload_content.go
+++ b/go/operation/upload_content.go
@@ -21,9 +21,19 @@ func Upload(uploadUrl string, filename string, reader io.Reader) (*UploadResult,
 	body_buf := bytes.NewBufferString("")
 	body_writer := multipart.NewWriter(body_buf)
 	file_writer, err := body_writer.CreateFormFile("file", filename)
-	io.Copy(file_writer, reader)
+	if err != nil {
+		log.Println("error creating form file", err)
+		return nil, err
+	}
+	if _, err = io.Copy(file_writer, reader); err != nil {
+		log.Println("error copying data", err)
+		return nil, err
+	}
 	content_type := body_writer.FormDataContentType()
-	body_writer.Close()
+	if err = body_writer.Close(); err != nil {
+		log.Println("error closing body", err)
+		return nil, err
+	}
 	resp, err := http.Post(uploadUrl, content_type, body_buf)
 	if err != nil {
 		log.Println("failing to upload to", uploadUrl)
diff --git a/go/replication/volume_growth.go b/go/replication/volume_growth.go
index 747e07642..1f266f73f 100644
--- a/go/replication/volume_growth.go
+++ b/go/replication/volume_growth.go
@@ -1,12 +1,12 @@
 package replication
 
 import (
-	"errors"
-	"fmt"
-	"math/rand"
 	"code.google.com/p/weed-fs/go/operation"
 	"code.google.com/p/weed-fs/go/storage"
 	"code.google.com/p/weed-fs/go/topology"
+	"errors"
+	"fmt"
+	"math/rand"
 	"sync"
 )
 
diff --git a/go/replication/volume_growth_test.go b/go/replication/volume_growth_test.go
index e35dbc707..3fbeebc9e 100644
--- a/go/replication/volume_growth_test.go
+++ b/go/replication/volume_growth_test.go
@@ -1,11 +1,11 @@
 package replication
 
 import (
+	"code.google.com/p/weed-fs/go/storage"
+	"code.google.com/p/weed-fs/go/topology"
 	"encoding/json"
 	"fmt"
 	"math/rand"
-	"code.google.com/p/weed-fs/go/storage"
-	"code.google.com/p/weed-fs/go/topology"
 	"testing"
 	"time"
 )
@@ -96,7 +96,10 @@ func setup(topologyLayout string) *topology.Topology {
 				rack.LinkChildNode(server)
 				for _, v := range serverMap["volumes"].([]interface{}) {
 					m := v.(map[string]interface{})
-					vi := storage.VolumeInfo{Id: storage.VolumeId(int64(m["id"].(float64))), Size: int64(m["size"].(float64)), Version: storage.CurrentVersion}
+					vi := storage.VolumeInfo{
+						Id:      storage.VolumeId(int64(m["id"].(float64))),
+						Size:    uint64(m["size"].(float64)),
+						Version: storage.CurrentVersion}
 					server.AddOrUpdateVolume(vi)
 				}
 				server.UpAdjustMaxVolumeCountDelta(int(serverMap["limit"].(float64)))
diff --git a/go/sequence/sequence.go b/go/sequence/sequence.go
index c85289468..0237f1f80 100644
--- a/go/sequence/sequence.go
+++ b/go/sequence/sequence.go
@@ -36,10 +36,15 @@ func NewSequencer(dirname string, filename string) (m *SequencerImpl) {
 	} else {
 		decoder := gob.NewDecoder(seqFile)
 		defer seqFile.Close()
-		decoder.Decode(&m.FileIdSequence)
-		log.Println("Loading file id sequence", m.FileIdSequence, "=>", m.FileIdSequence+FileIdSaveInterval)
+		if se = decoder.Decode(&m.FileIdSequence); se != nil {
+			log.Printf("error decoding FileIdSequence: %s", se)
+			m.FileIdSequence = FileIdSaveInterval
+			log.Println("Setting file id sequence", m.FileIdSequence)
+		} else {
+			log.Println("Loading file id sequence", m.FileIdSequence, "=>", m.FileIdSequence+FileIdSaveInterval)
+			m.FileIdSequence += FileIdSaveInterval
+		}
 		//in case the server stops between intervals
-		m.FileIdSequence += FileIdSaveInterval
 	}
 	return
 }
@@ -67,5 +72,7 @@ func (m *SequencerImpl) saveSequence() {
 	}
 	defer seqFile.Close()
 	encoder := gob.NewEncoder(seqFile)
-	encoder.Encode(m.FileIdSequence)
+	if e = encoder.Encode(m.FileIdSequence); e != nil {
+		log.Fatalf("Sequence File Save [ERROR] %s\n", e)
+	}
 }
diff --git a/go/storage/compact_map_perf_test.go b/go/storage/compact_map_perf_test.go
index cfc53ef65..b885ebd93 100644
--- a/go/storage/compact_map_perf_test.go
+++ b/go/storage/compact_map_perf_test.go
@@ -1,9 +1,9 @@
 package storage
 
 import (
+	"code.google.com/p/weed-fs/go/util"
 	"log"
 	"os"
-	"code.google.com/p/weed-fs/go/util"
 	"testing"
 )
 
diff --git a/go/storage/compress.go b/go/storage/compress.go
index 256789c9c..e8816422b 100644
--- a/go/storage/compress.go
+++ b/go/storage/compress.go
@@ -10,7 +10,7 @@ import (
 
 /*
 * Default more not to gzip since gzip can be done on client side.
-*/
+ */
 func IsGzippable(ext, mtype string) bool {
 	if strings.HasPrefix(mtype, "text/") {
 		return true
diff --git a/go/storage/needle_map.go b/go/storage/needle_map.go
index 4465fab22..b2e232009 100644
--- a/go/storage/needle_map.go
+++ b/go/storage/needle_map.go
@@ -94,14 +94,17 @@ func (nm *NeedleMap) Delete(key uint64) error {
 	util.Uint32toBytes(nm.bytes[8:12], 0)
 	util.Uint32toBytes(nm.bytes[12:16], 0)
 	if _, err = nm.indexFile.Write(nm.bytes); err != nil {
-		nm.indexFile.Truncate(offset)
-		return fmt.Errorf("error writing to indexfile %s: %s", nm.indexFile, err)
+		plus := ""
+		if e := nm.indexFile.Truncate(offset); e != nil {
+			plus = "\ncouldn't truncate index file: " + e.Error()
+		}
+		return fmt.Errorf("error writing to indexfile %s: %s%s", nm.indexFile, err, plus)
 	}
 	nm.deletionCounter++
 	return nil
 }
 func (nm *NeedleMap) Close() {
-	nm.indexFile.Close()
+	_ = nm.indexFile.Close()
 }
 func (nm *NeedleMap) ContentSize() uint64 {
 	return nm.fileByteCounter
diff --git a/go/storage/needle_read_write.go b/go/storage/needle_read_write.go
index 881db50a6..c5f27ea21 100644
--- a/go/storage/needle_read_write.go
+++ b/go/storage/needle_read_write.go
@@ -1,11 +1,11 @@
 package storage
 
 import (
+	"code.google.com/p/weed-fs/go/util"
 	"errors"
 	"fmt"
 	"io"
 	"os"
-	"code.google.com/p/weed-fs/go/util"
 )
 
 const (
diff --git a/go/storage/store.go b/go/storage/store.go
index 857a62506..142ee84e2 100644
--- a/go/storage/store.go
+++ b/go/storage/store.go
@@ -1,12 +1,12 @@
 package storage
 
 import (
+	"code.google.com/p/weed-fs/go/util"
 	"encoding/json"
 	"errors"
 	"io/ioutil"
 	"log"
 	"net/url"
-	"code.google.com/p/weed-fs/go/util"
 	"strconv"
 	"strings"
 )
@@ -175,7 +175,9 @@ func (s *Store) Write(i VolumeId, n *Needle) (size uint32, err error) {
 		size, err = v.write(n)
 		if err != nil && s.volumeSizeLimit < v.ContentSize()+uint64(size) && s.volumeSizeLimit >= v.ContentSize() {
 			log.Println("volume", i, "size is", v.ContentSize(), "close to", s.volumeSizeLimit)
-			s.Join()
+			if err = s.Join(); err != nil {
+				log.Printf("error with Join: %s", err)
+			}
 		}
 		return
 	}
diff --git a/go/storage/volume.go b/go/storage/volume.go
index aeb1126d7..b9c7484d7 100644
--- a/go/storage/volume.go
+++ b/go/storage/volume.go
@@ -86,7 +86,7 @@ func (v *Volume) Close() {
 	v.accessLock.Lock()
 	defer v.accessLock.Unlock()
 	v.nm.Close()
-	v.dataFile.Close()
+	_ = v.dataFile.Close()
 }
 func (v *Volume) maybeWriteSuperBlock() error {
 	stat, e := v.dataFile.Stat()
@@ -101,7 +101,9 @@ func (v *Volume) maybeWriteSuperBlock() error {
 	return e
 }
 func (v *Volume) readSuperBlock() (err error) {
-	v.dataFile.Seek(0, 0)
+	if _, err = v.dataFile.Seek(0, 0); err != nil {
+		return fmt.Errorf("cannot seek to the beginning of %s: %s", v.dataFile, err)
+	}
 	header := make([]byte, SuperBlockSize)
 	if _, e := v.dataFile.Read(header); e != nil {
 		return fmt.Errorf("cannot read superblock: %s", e)
@@ -128,7 +130,9 @@ func (v *Volume) write(n *Needle) (size uint32, err error) {
 		return
 	}
 	if size, err = n.Append(v.dataFile, v.Version()); err != nil {
-		v.dataFile.Truncate(offset)
+		if e := v.dataFile.Truncate(offset); e != nil {
+			err = fmt.Errorf("%s\ncannot truncate %s: %s", err, v.dataFile, e)
+		}
 		return
 	}
 	nv, ok := v.nm.Get(n.Id)
@@ -143,9 +147,14 @@ func (v *Volume) delete(n *Needle) (uint32, error) {
 	nv, ok := v.nm.Get(n.Id)
 	//fmt.Println("key", n.Id, "volume offset", nv.Offset, "data_size", n.Size, "cached size", nv.Size)
 	if ok {
-		v.nm.Delete(n.Id)
-		v.dataFile.Seek(int64(nv.Offset*NeedlePaddingSize), 0)
-		_, err := n.Append(v.dataFile, v.Version())
+		var err error
+		if err = v.nm.Delete(n.Id); err != nil {
+			return nv.Size, err
+		}
+		if _, err = v.dataFile.Seek(int64(nv.Offset*NeedlePaddingSize), 0); err != nil {
+			return nv.Size, err
+		}
+		_, err = n.Append(v.dataFile, v.Version())
 		return nv.Size, err
 	}
 	return 0, nil
@@ -156,7 +165,9 @@ func (v *Volume) read(n *Needle) (int, error) {
 	defer v.accessLock.Unlock()
 	nv, ok := v.nm.Get(n.Id)
 	if ok && nv.Offset > 0 {
-		v.dataFile.Seek(int64(nv.Offset)*NeedlePaddingSize, 0)
+		if _, err := v.dataFile.Seek(int64(nv.Offset)*NeedlePaddingSize, 0); err != nil {
+			return -1, err
+		}
 		return n.Read(v.dataFile, nv.Size, v.Version())
 	}
 	return -1, errors.New("Not Found")
@@ -176,7 +187,7 @@ func (v *Volume) compact() error {
 func (v *Volume) commitCompact() error {
 	v.accessLock.Lock()
 	defer v.accessLock.Unlock()
-	v.dataFile.Close()
+	_ = v.dataFile.Close()
 	var e error
 	if e = os.Rename(path.Join(v.dir, v.Id.String()+".cpd"), path.Join(v.dir, v.Id.String()+".dat")); e != nil {
 		return e
diff --git a/go/topology/data_node.go b/go/topology/data_node.go
index ba37f0d5f..ea4ea5d39 100644
--- a/go/topology/data_node.go
+++ b/go/topology/data_node.go
@@ -1,8 +1,8 @@
 package topology
 
 import (
-	_ "fmt"
 	"code.google.com/p/weed-fs/go/storage"
+	_ "fmt"
 	"strconv"
 )
 
diff --git a/go/topology/node.go b/go/topology/node.go
index 90826dfae..786f76702 100644
--- a/go/topology/node.go
+++ b/go/topology/node.go
@@ -1,8 +1,8 @@
 package topology
 
 import (
-	"fmt"
 	"code.google.com/p/weed-fs/go/storage"
+	"fmt"
 )
 
 type NodeId string
diff --git a/go/topology/node_list.go b/go/topology/node_list.go
index 293f534ea..db7723714 100644
--- a/go/topology/node_list.go
+++ b/go/topology/node_list.go
@@ -1,9 +1,9 @@
 package topology
 
 import (
+	"code.google.com/p/weed-fs/go/storage"
 	"fmt"
 	"math/rand"
-	"code.google.com/p/weed-fs/go/storage"
 )
 
 type NodeList struct {
diff --git a/go/topology/node_list_test.go b/go/topology/node_list_test.go
index 4cd2ebaa1..c6e530724 100644
--- a/go/topology/node_list_test.go
+++ b/go/topology/node_list_test.go
@@ -7,7 +7,11 @@ import (
 )
 
 func TestXYZ(t *testing.T) {
-	topo := NewTopology("topo", "/etc/weed.conf", "/tmp", "test", 234, 5)
+	topo, err := NewTopology("topo", "/etc/weed.conf", "/tmp", "test", 234, 5)
+	if err != nil {
+		t.Error("cannot create new topology:", err)
+		t.FailNow()
+	}
 	for i := 0; i < 5; i++ {
 		dc := NewDataCenter("dc" + strconv.Itoa(i))
 		dc.activeVolumeCount = i
@@ -16,22 +20,22 @@ func TestXYZ(t *testing.T) {
 	}
 	nl := NewNodeList(topo.Children(), nil)
 
-	picked, ret := nl.RandomlyPickN(1)
+	picked, ret := nl.RandomlyPickN(1, 0)
 	if !ret || len(picked) != 1 {
 		t.Error("need to randomly pick 1 node")
 	}
 
-	picked, ret = nl.RandomlyPickN(4)
+	picked, ret = nl.RandomlyPickN(4, 0)
 	if !ret || len(picked) != 4 {
 		t.Error("need to randomly pick 4 nodes")
 	}
 
-	picked, ret = nl.RandomlyPickN(5)
+	picked, ret = nl.RandomlyPickN(5, 0)
 	if !ret || len(picked) != 5 {
 		t.Error("need to randomly pick 5 nodes")
 	}
 
-	picked, ret = nl.RandomlyPickN(6)
+	picked, ret = nl.RandomlyPickN(6, 0)
 	if ret || len(picked) != 0 {
 		t.Error("can not randomly pick 6 nodes:", ret, picked)
 	}
diff --git a/go/topology/topo_test.go b/go/topology/topo_test.go
index f8af79b21..99e570821 100644
--- a/go/topology/topo_test.go
+++ b/go/topology/topo_test.go
@@ -1,72 +1,72 @@
 package topology
 
 import (
+	"code.google.com/p/weed-fs/go/storage"
 	"encoding/json"
 	"fmt"
 	"math/rand"
-	"code.google.com/p/weed-fs/go/storage"
 	"testing"
 	"time"
 )
 
 var topologyLayout = `
 {
-  "dc1":{
-    "rack1":{
-      "server1":{
-        "volumes":[
-          {"id":1, "size":12312},
-          {"id":2, "size":12312},
-          {"id":3, "size":12312}
-        ],
-        "limit":3
-      },
-      "server2":{
-        "volumes":[
-          {"id":4, "size":12312},
-          {"id":5, "size":12312},
-          {"id":6, "size":12312}
-        ],
-        "limit":10
-      }
-    },
-    "rack2":{
-      "server1":{
-        "volumes":[
-          {"id":4, "size":12312},
-          {"id":5, "size":12312},
-          {"id":6, "size":12312}
-        ],
-        "limit":4
-      },
-      "server2":{
-        "volumes":[],
-        "limit":4
-      },
-      "server3":{
-        "volumes":[
-          {"id":2, "size":12312},
-          {"id":3, "size":12312},
-          {"id":4, "size":12312}
-        ],
-        "limit":2
-      }
-    }
-  },
-  "dc2":{
-  },
-  "dc3":{
-    "rack2":{
-      "server1":{
-        "volumes":[
-          {"id":1, "size":12312},
-          {"id":3, "size":12312},
-          {"id":5, "size":12312}
-        ],
-        "limit":4
-      }
-    }
-  }
+	"dc1":{
+		"rack1":{
+			"server1":{
+				"volumes":[
+					{"id":1, "size":12312},
+					{"id":2, "size":12312},
+					{"id":3, "size":12312}
+				],
+				"limit":3
+			},
+			"server2":{
+				"volumes":[
+					{"id":4, "size":12312},
+					{"id":5, "size":12312},
+					{"id":6, "size":12312}
+				],
+				"limit":10
+			}
+		},
+		"rack2":{
+			"server1":{
+				"volumes":[
+					{"id":4, "size":12312},
+					{"id":5, "size":12312},
+					{"id":6, "size":12312}
+				],
+				"limit":4
+			},
+			"server2":{
+				"volumes":[],
+				"limit":4
+			},
+			"server3":{
+				"volumes":[
+					{"id":2, "size":12312},
+					{"id":3, "size":12312},
+					{"id":4, "size":12312}
+				],
+				"limit":2
+			}
+		}
+	},
+	"dc2":{
+	},
+	"dc3":{
+		"rack2":{
+			"server1":{
+				"volumes":[
+					{"id":1, "size":12312},
+					{"id":3, "size":12312},
+					{"id":5, "size":12312}
+				],
+				"limit":4
+			}
+		}
+	}
 }
 `
 
@@ -78,7 +78,10 @@ func setup(topologyLayout string) *Topology {
 	}
 
 	//need to connect all nodes first before server adding volumes
-	topo := NewTopology("mynetwork", "/etc/weed.conf", "/tmp", "test", 234, 5)
+	topo, err := NewTopology("mynetwork", "/etc/weed.conf", "/tmp", "test", 234, 5)
+	if err != nil {
+		fmt.Println("error:", err)
+	}
 	mTopology := data.(map[string]interface{})
 	for dcKey, dcValue := range mTopology {
 		dc := NewDataCenter(dcKey)
@@ -94,7 +97,10 @@ func setup(topologyLayout string) *Topology {
 				rack.LinkChildNode(server)
 				for _, v := range serverMap["volumes"].([]interface{}) {
 					m := v.(map[string]interface{})
-					vi := storage.VolumeInfo{Id: storage.VolumeId(int64(m["id"].(float64))), Size: int64(m["size"].(float64)), Version: storage.CurrentVersion}
+					vi := storage.VolumeInfo{
+						Id:      storage.VolumeId(int64(m["id"].(float64))),
+						Size:    uint64(m["size"].(float64)),
+						Version: storage.CurrentVersion}
 					server.AddOrUpdateVolume(vi)
 				}
 				server.UpAdjustMaxVolumeCountDelta(int(serverMap["limit"].(float64)))
diff --git a/go/topology/topology.go b/go/topology/topology.go
index 70a1ad268..74dc1cd09 100644
--- a/go/topology/topology.go
+++ b/go/topology/topology.go
@@ -1,12 +1,12 @@
 package topology
 
 import (
-	"errors"
-	"io/ioutil"
-	"math/rand"
 	"code.google.com/p/weed-fs/go/directory"
 	"code.google.com/p/weed-fs/go/sequence"
 	"code.google.com/p/weed-fs/go/storage"
+	"errors"
+	"io/ioutil"
+	"math/rand"
 )
 
 type Topology struct {
@@ -28,7 +28,7 @@ type Topology struct {
 	configuration *Configuration
 }
 
-func NewTopology(id string, confFile string, dirname string, sequenceFilename string, volumeSizeLimit uint64, pulse int) *Topology {
+func NewTopology(id string, confFile string, dirname string, sequenceFilename string, volumeSizeLimit uint64, pulse int) (*Topology, error) {
 	t := &Topology{}
 	t.id = NodeId(id)
 	t.nodeType = "Topology"
@@ -44,9 +44,9 @@ func NewTopology(id string, confFile string, dirname string, sequenceFilename st
 	t.chanRecoveredDataNodes = make(chan *DataNode)
 	t.chanFullVolumes = make(chan storage.VolumeInfo)
 
-	t.loadConfiguration(confFile)
+	err := t.loadConfiguration(confFile)
 
-	return t
+	return t, err
 }
 
 func (t *Topology) loadConfiguration(configurationFile string) error {
diff --git a/go/topology/topology_compact.go b/go/topology/topology_compact.go
index 9c9abde4f..7215edc4e 100644
--- a/go/topology/topology_compact.go
+++ b/go/topology/topology_compact.go
@@ -1,12 +1,12 @@
 package topology
 
 import (
+	"code.google.com/p/weed-fs/go/storage"
+	"code.google.com/p/weed-fs/go/util"
 	"encoding/json"
 	"errors"
 	"fmt"
 	"net/url"
-	"code.google.com/p/weed-fs/go/storage"
-	"code.google.com/p/weed-fs/go/util"
 	"time"
 )
 
diff --git a/go/topology/topology_event_handling.go b/go/topology/topology_event_handling.go
index 9093bf884..fd2fe3bef 100644
--- a/go/topology/topology_event_handling.go
+++ b/go/topology/topology_event_handling.go
@@ -1,9 +1,9 @@
 package topology
 
 import (
+	"code.google.com/p/weed-fs/go/storage"
 	"fmt"
 	"math/rand"
-	"code.google.com/p/weed-fs/go/storage"
 	"time"
 )
 
diff --git a/go/topology/volume_layout.go b/go/topology/volume_layout.go
index b6e6e8bfe..f5c2e2360 100644
--- a/go/topology/volume_layout.go
+++ b/go/topology/volume_layout.go
@@ -1,10 +1,10 @@
 package topology
 
 import (
+	"code.google.com/p/weed-fs/go/storage"
 	"errors"
 	"fmt"
 	"math/rand"
-	"code.google.com/p/weed-fs/go/storage"
 )
 
 type VolumeLayout struct {
diff --git a/go/weed/export.go b/go/weed/export.go
index 6b391024a..9e65a4de3 100644
--- a/go/weed/export.go
+++ b/go/weed/export.go
@@ -3,12 +3,12 @@ package main
 import (
 	"archive/tar"
 	"bytes"
+	"code.google.com/p/weed-fs/go/directory"
+	"code.google.com/p/weed-fs/go/storage"
 	"fmt"
 	"log"
 	"os"
 	"path"
-	"code.google.com/p/weed-fs/go/directory"
-	"code.google.com/p/weed-fs/go/storage"
 	"strconv"
 	"strings"
 	"text/template"
diff --git a/go/weed/fix.go b/go/weed/fix.go
index 249007252..597bc0ef9 100644
--- a/go/weed/fix.go
+++ b/go/weed/fix.go
@@ -1,10 +1,10 @@
 package main
 
 import (
+	"code.google.com/p/weed-fs/go/storage"
 	"log"
 	"os"
 	"path"
-	"code.google.com/p/weed-fs/go/storage"
 	"strconv"
 )
 
@@ -52,7 +52,7 @@ func runFix(cmd *Command, args []string) bool {
 			debug("saved", count, "with error", pe)
 		} else {
 			debug("skipping deleted file ...")
-			nm.Delete(n.Id)
+			return nm.Delete(n.Id)
 		}
 		return nil
 	})
diff --git a/go/weed/master.go b/go/weed/master.go
index 3d8757c16..f6cc88df0 100644
--- a/go/weed/master.go
+++ b/go/weed/master.go
@@ -1,13 +1,13 @@
 package main
 
 import (
+	"code.google.com/p/weed-fs/go/replication"
+	"code.google.com/p/weed-fs/go/storage"
+	"code.google.com/p/weed-fs/go/topology"
 	"encoding/json"
 	"errors"
 	"log"
 	"net/http"
-	"code.google.com/p/weed-fs/go/replication"
-	"code.google.com/p/weed-fs/go/storage"
-	"code.google.com/p/weed-fs/go/topology"
 	"runtime"
 	"strconv"
 	"strings"
@@ -57,14 +57,14 @@ func dirLookupHandler(w http.ResponseWriter, r *http.Request) {
 			for _, dn := range machines {
 				ret = append(ret, map[string]string{"url": dn.Url(), "publicUrl": dn.PublicUrl})
 			}
-			writeJson(w, r, map[string]interface{}{"locations": ret})
+			writeJsonQuiet(w, r, map[string]interface{}{"locations": ret})
 		} else {
 			w.WriteHeader(http.StatusNotFound)
-			writeJson(w, r, map[string]string{"error": "volume id " + volumeId.String() + " not found. "})
+			writeJsonQuiet(w, r, map[string]string{"error": "volume id " + volumeId.String() + " not found. "})
 		}
 	} else {
 		w.WriteHeader(http.StatusNotAcceptable)
-		writeJson(w, r, map[string]string{"error": "unknown volumeId format " + vid})
+		writeJsonQuiet(w, r, map[string]string{"error": "unknown volumeId format " + vid})
 	}
 }
 
@@ -80,24 +80,27 @@ func dirAssignHandler(w http.ResponseWriter, r *http.Request) {
 	rt, err := storage.NewReplicationTypeFromString(repType)
 	if err != nil {
 		w.WriteHeader(http.StatusNotAcceptable)
-		writeJson(w, r, map[string]string{"error": err.Error()})
+		writeJsonQuiet(w, r, map[string]string{"error": err.Error()})
 		return
 	}
 	if topo.GetVolumeLayout(rt).GetActiveVolumeCount() <= 0 {
 		if topo.FreeSpace() <= 0 {
 			w.WriteHeader(http.StatusNotFound)
-			writeJson(w, r, map[string]string{"error": "No free volumes left!"})
+			writeJsonQuiet(w, r, map[string]string{"error": "No free volumes left!"})
 			return
 		} else {
-			vg.GrowByType(rt, topo)
+			if _, err = vg.GrowByType(rt, topo); err != nil {
+				writeJsonQuiet(w, r, map[string]string{"error": "Cannot grow volume group! " + err.Error()})
+				return
+			}
 		}
 	}
 	fid, count, dn, err := topo.PickForWrite(rt, c)
 	if err == nil {
-		writeJson(w, r, map[string]interface{}{"fid": fid, "url": dn.Url(), "publicUrl": dn.PublicUrl, "count": count})
+		writeJsonQuiet(w, r, map[string]interface{}{"fid": fid, "url": dn.Url(), "publicUrl": dn.PublicUrl, "count": count})
 	} else {
 		w.WriteHeader(http.StatusNotAcceptable)
-		writeJson(w, r, map[string]string{"error": err.Error()})
+		writeJsonQuiet(w, r, map[string]string{"error": err.Error()})
 	}
 }
 
@@ -112,19 +115,22 @@ func dirJoinHandler(w http.ResponseWriter, r *http.Request) {
 	s := r.RemoteAddr[0:strings.Index(r.RemoteAddr, ":")+1] + r.FormValue("port")
 	publicUrl := r.FormValue("publicUrl")
 	volumes := new([]storage.VolumeInfo)
-	json.Unmarshal([]byte(r.FormValue("volumes")), volumes)
+	if err := json.Unmarshal([]byte(r.FormValue("volumes")), volumes); err != nil {
+		writeJsonQuiet(w, r, map[string]string{"error": "Cannot unmarshal \"volumes\": " + err.Error()})
+		return
+	}
 	debug(s, "volumes", r.FormValue("volumes"))
 	topo.RegisterVolumes(init, *volumes, ip, port, publicUrl, maxVolumeCount)
 	m := make(map[string]interface{})
 	m["VolumeSizeLimit"] = uint64(*volumeSizeLimitMB) * 1024 * 1024
-	writeJson(w, r, m)
+	writeJsonQuiet(w, r, m)
 }
 
 func dirStatusHandler(w http.ResponseWriter, r *http.Request) {
 	m := make(map[string]interface{})
 	m["Version"] = VERSION
 	m["Topology"] = topo.ToMap()
-	writeJson(w, r, m)
+	writeJsonQuiet(w, r, m)
 }
 
 func volumeVacuumHandler(w http.ResponseWriter, r *http.Request) {
@@ -153,10 +159,10 @@ func volumeGrowHandler(w http.ResponseWriter, r *http.Request) {
 	}
 	if err != nil {
 		w.WriteHeader(http.StatusNotAcceptable)
-		writeJson(w, r, map[string]string{"error": "parameter replication " + err.Error()})
+		writeJsonQuiet(w, r, map[string]string{"error": "parameter replication " + err.Error()})
 	} else {
 		w.WriteHeader(http.StatusNotAcceptable)
-		writeJson(w, r, map[string]interface{}{"count": count})
+		writeJsonQuiet(w, r, map[string]interface{}{"count": count})
 	}
 }
 
@@ -164,7 +170,7 @@ func volumeStatusHandler(w http.ResponseWriter, r *http.Request) {
 	m := make(map[string]interface{})
 	m["Version"] = VERSION
 	m["Volumes"] = topo.ToVolumeMap()
-	writeJson(w, r, m)
+	writeJsonQuiet(w, r, m)
 }
 
 func redirectHandler(w http.ResponseWriter, r *http.Request) {
@@ -179,7 +185,7 @@ func redirectHandler(w http.ResponseWriter, r *http.Request) {
 		http.Redirect(w, r, "http://"+machines[0].PublicUrl+r.URL.Path, http.StatusMovedPermanently)
 	} else {
 		w.WriteHeader(http.StatusNotFound)
-		writeJson(w, r, map[string]string{"error": "volume id " + volumeId.String() + " not found. "})
+		writeJsonQuiet(w, r, map[string]string{"error": "volume id " + volumeId.String() + " not found. "})
 	}
 }
 
@@ -188,7 +194,11 @@ func runMaster(cmd *Command, args []string) bool {
 		*mMaxCpu = runtime.NumCPU()
 	}
 	runtime.GOMAXPROCS(*mMaxCpu)
-	topo = topology.NewTopology("topo", *confFile, *metaFolder, "weed", uint64(*volumeSizeLimitMB)*1024*1024, *mpulse)
+	var e error
+	if topo, e = topology.NewTopology("topo", *confFile, *metaFolder, "weed",
+		uint64(*volumeSizeLimitMB)*1024*1024, *mpulse); e != nil {
+		log.Fatalf("cannot create topology:%s", e)
+	}
 	vg = replication.NewDefaultVolumeGrowth()
 	log.Println("Volume Size Limit is", *volumeSizeLimitMB, "MB")
 	http.HandleFunc("/dir/assign", dirAssignHandler)
@@ -209,9 +219,9 @@ func runMaster(cmd *Command, args []string) bool {
 		Handler:     http.DefaultServeMux,
 		ReadTimeout: time.Duration(*mReadTimeout) * time.Second,
 	}
-	e := srv.ListenAndServe()
+	e = srv.ListenAndServe()
 	if e != nil {
-		log.Fatalf("Fail to start:%s", e.Error())
+		log.Fatalf("Fail to start:%s", e)
 	}
 	return true
 }
diff --git a/go/weed/shell.go b/go/weed/shell.go
index daf0b7e1f..4287f2148 100644
--- a/go/weed/shell.go
+++ b/go/weed/shell.go
@@ -3,6 +3,7 @@ package main
 import (
 	"bufio"
 	"fmt"
+	"log"
 	"os"
 )
 
@@ -25,8 +26,13 @@ func runShell(command *Command, args []string) bool {
 	o := bufio.NewWriter(os.Stdout)
 	e := bufio.NewWriter(os.Stderr)
 	prompt := func() {
-		o.WriteString("> ")
-		o.Flush()
+		var err error
+		if _, err = o.WriteString("> "); err != nil {
+			log.Printf("error writing to stdout: %s", err)
+		}
+		if err = o.Flush(); err != nil {
+			log.Printf("error flushing stdout: %s", err)
+		}
 	}
 	readLine := func() string {
 		ret, err := r.ReadString('\n')
@@ -38,7 +44,9 @@ func runShell(command *Command, args []string) bool {
 	}
 	execCmd := func(cmd string) int {
 		if cmd != "" {
-			o.WriteString(cmd)
+			if _, err := o.WriteString(cmd); err != nil {
+				log.Printf("error writing to stdout: %s", err)
+			}
 		}
 		return 0
 	}
diff --git a/go/weed/upload.go b/go/weed/upload.go
index 92478b7b6..a47551ddf 100644
--- a/go/weed/upload.go
+++ b/go/weed/upload.go
@@ -1,14 +1,14 @@
 package main
 
 import (
+	"code.google.com/p/weed-fs/go/operation"
+	"code.google.com/p/weed-fs/go/util"
 	"encoding/json"
 	"errors"
 	"fmt"
 	"net/url"
 	"os"
 	"path"
-	"code.google.com/p/weed-fs/go/operation"
-	"code.google.com/p/weed-fs/go/util"
 	"strconv"
 )
 
diff --git a/go/weed/volume.go b/go/weed/volume.go
index edf2ad821..fd2298541 100644
--- a/go/weed/volume.go
+++ b/go/weed/volume.go
@@ -2,13 +2,13 @@ package main
 
 import (
 	"bytes"
+	"code.google.com/p/weed-fs/go/operation"
+	"code.google.com/p/weed-fs/go/storage"
 	"log"
 	"math/rand"
 	"mime"
 	"net/http"
 	"os"
-	"code.google.com/p/weed-fs/go/operation"
-	"code.google.com/p/weed-fs/go/storage"
 	"runtime"
 	"strconv"
 	"strings"
@@ -48,41 +48,41 @@ func statusHandler(w http.ResponseWriter, r *http.Request) {
 	m := make(map[string]interface{})
 	m["Version"] = VERSION
 	m["Volumes"] = store.Status()
-	writeJson(w, r, m)
+	writeJsonQuiet(w, r, m)
 }
 func assignVolumeHandler(w http.ResponseWriter, r *http.Request) {
 	err := store.AddVolume(r.FormValue("volume"), r.FormValue("replicationType"))
 	if err == nil {
-		writeJson(w, r, map[string]string{"error": ""})
+		writeJsonQuiet(w, r, map[string]string{"error": ""})
 	} else {
-		writeJson(w, r, map[string]string{"error": err.Error()})
+		writeJsonQuiet(w, r, map[string]string{"error": err.Error()})
 	}
 	debug("assign volume =", r.FormValue("volume"), ", replicationType =", r.FormValue("replicationType"), ", error =", err)
 }
 func vacuumVolumeCheckHandler(w http.ResponseWriter, r *http.Request) {
 	err, ret := store.CheckCompactVolume(r.FormValue("volume"), r.FormValue("garbageThreshold"))
 	if err == nil {
-		writeJson(w, r, map[string]interface{}{"error": "", "result": ret})
+		writeJsonQuiet(w, r, map[string]interface{}{"error": "", "result": ret})
 	} else {
-		writeJson(w, r, map[string]interface{}{"error": err.Error(), "result": false})
+		writeJsonQuiet(w, r, map[string]interface{}{"error": err.Error(), "result": false})
 	}
 	debug("checked compacting volume =", r.FormValue("volume"), "garbageThreshold =", r.FormValue("garbageThreshold"), "vacuum =", ret)
 }
 func vacuumVolumeCompactHandler(w http.ResponseWriter, r *http.Request) {
 	err := store.CompactVolume(r.FormValue("volume"))
 	if err == nil {
-		writeJson(w, r, map[string]string{"error": ""})
+		writeJsonQuiet(w, r, map[string]string{"error": ""})
 	} else {
-		writeJson(w, r, map[string]string{"error": err.Error()})
+		writeJsonQuiet(w, r, map[string]string{"error": err.Error()})
 	}
 	debug("compacted volume =", r.FormValue("volume"), ", error =", err)
 }
 func vacuumVolumeCommitHandler(w http.ResponseWriter, r *http.Request) {
 	err := store.CommitCompactVolume(r.FormValue("volume"))
 	if err == nil {
-		writeJson(w, r, map[string]interface{}{"error": ""})
+		writeJsonQuiet(w, r, map[string]interface{}{"error": ""})
 	} else {
-		writeJson(w, r, map[string]string{"error": err.Error()})
+		writeJsonQuiet(w, r, map[string]string{"error": err.Error()})
 	}
 	debug("commit compact volume =", r.FormValue("volume"), ", error =", err)
 }
@@ -163,18 +163,29 @@ func GetHandler(w http.ResponseWriter, r *http.Request) {
 		}
 	}
 	w.Header().Set("Content-Length", strconv.Itoa(len(n.Data)))
-	w.Write(n.Data)
+	if _, e = w.Write(n.Data); e != nil {
+		debug("response write error:", e)
+	}
 }
 func PostHandler(w http.ResponseWriter, r *http.Request) {
-	r.ParseForm()
+	if e := r.ParseForm(); e != nil {
+		debug("form parse error:", e)
+		writeJsonQuiet(w, r, e)
+		return
+	}
 	vid, _, _ := parseURLPath(r.URL.Path)
 	volumeId, e := storage.NewVolumeId(vid)
 	if e != nil {
-		writeJson(w, r, e)
+		debug("NewVolumeId error:", e)
+		writeJsonQuiet(w, r, e)
+		return
+	}
+	if e != nil {
+		writeJsonQuiet(w, r, e)
 	} else {
 		needle, filename, ne := storage.NewNeedle(r)
 		if ne != nil {
-			writeJson(w, r, ne)
+			writeJsonQuiet(w, r, ne)
 		} else {
 			ret, err := store.Write(volumeId, needle)
 			errorStatus := ""
@@ -204,15 +215,19 @@ func PostHandler(w http.ResponseWriter, r *http.Request) {
 			if errorStatus == "" {
 				w.WriteHeader(http.StatusCreated)
 			} else {
-				store.Delete(volumeId, needle)
-				distributedOperation(volumeId, func(location operation.Location) bool {
-					return nil == operation.Delete("http://"+location.Url+r.URL.Path+"?type=standard")
-				})
+				if _, e = store.Delete(volumeId, needle); e != nil {
+					errorStatus += "\nCannot delete " + strconv.FormatUint(needle.Id, 10) + " from " +
+						strconv.FormatUint(uint64(volumeId), 10) + ": " + e.Error()
+				} else {
+					distributedOperation(volumeId, func(location operation.Location) bool {
+						return nil == operation.Delete("http://"+location.Url+r.URL.Path+"?type=standard")
+					})
+				}
 				w.WriteHeader(http.StatusInternalServerError)
 				m["error"] = errorStatus
 			}
 			m["size"] = ret
-			writeJson(w, r, m)
+			writeJsonQuiet(w, r, m)
 		}
 	}
 }
@@ -230,7 +245,7 @@ func DeleteHandler(w http.ResponseWriter, r *http.Request) {
 	if ok != nil {
 		m := make(map[string]uint32)
 		m["size"] = 0
-		writeJson(w, r, m)
+		writeJsonQuiet(w, r, m)
 		return
 	}
 
@@ -268,7 +283,7 @@ func DeleteHandler(w http.ResponseWriter, r *http.Request) {
 
 	m := make(map[string]uint32)
 	m["size"] = uint32(count)
-	writeJson(w, r, m)
+	writeJsonQuiet(w, r, m)
 }
 
 func parseURLPath(path string) (vid, fid, ext string) {
diff --git a/go/weed/weed.go b/go/weed/weed.go
index c03cb68ac..e97c8b550 100644
--- a/go/weed/weed.go
+++ b/go/weed/weed.go
@@ -5,6 +5,7 @@ import (
 	"flag"
 	"fmt"
 	"io"
+	"log"
 	"math/rand"
 	"net/http"
 	"os"
@@ -173,22 +174,40 @@ func exitIfErrors() {
 		exit()
 	}
 }
-func writeJson(w http.ResponseWriter, r *http.Request, obj interface{}) {
+
+func writeJson(w http.ResponseWriter, r *http.Request, obj interface{}) (err error) {
 	w.Header().Set("Content-Type", "application/javascript")
 	var bytes []byte
 	if r.FormValue("pretty") != "" {
-		bytes, _ = json.MarshalIndent(obj, "", "  ")
+		bytes, err = json.MarshalIndent(obj, "", "  ")
 	} else {
-		bytes, _ = json.Marshal(obj)
+		bytes, err = json.Marshal(obj)
+	}
+	if err != nil {
+		return
 	}
 	callback := r.FormValue("callback")
 	if callback == "" {
-		w.Write(bytes)
+		_, err = w.Write(bytes)
 	} else {
-		w.Write([]uint8(callback))
-		w.Write([]uint8("("))
+		if _, err = w.Write([]uint8(callback)); err != nil {
+			return
+		}
+		if _, err = w.Write([]uint8("(")); err != nil {
+			return
+		}
 		fmt.Fprint(w, string(bytes))
-		w.Write([]uint8(")"))
+		if _, err = w.Write([]uint8(")")); err != nil {
+			return
+		}
+	}
+	return
+}
+
+// wrapper for writeJson - just logs errors
+func writeJsonQuiet(w http.ResponseWriter, r *http.Request, obj interface{}) {
+	if err := writeJson(w, r, obj); err != nil {
+		log.Printf("error writing JSON %s: %s", obj, err)
 	}
 }