Handle a bunch of unchecked errors (#365)

As discovered by "gosec".

Signed-off-by: Julius Volz <julius.volz@gmail.com>

block.go

@@ -504,10 +504,13 @@ Outer:
 func (pb *Block) CleanTombstones(dest string, c Compactor) (*ulid.ULID, error) {
 	numStones := 0
 
-	pb.tombstones.Iter(func(id uint64, ivs Intervals) error {
+	if err := pb.tombstones.Iter(func(id uint64, ivs Intervals) error {
 		numStones += len(ivs)
 		return nil
-	})
+	}); err != nil {
+		// This should never happen, as the iteration function only returns nil.
+		panic(err)
+	}
 	if numStones == 0 {
 		return nil, nil
 	}

cmd/tsdb/main.go

@@ -145,7 +145,9 @@ func (b *writeBenchmark) run() {
 		if err := b.storage.Close(); err != nil {
 			exitWithError(err)
 		}
-		b.stopProfiling()
+		if err := b.stopProfiling(); err != nil {
+			exitWithError(err)
+		}
 	})
 }
 
@@ -248,7 +250,9 @@ func (b *writeBenchmark) startProfiling() {
 	if err != nil {
 		exitWithError(fmt.Errorf("bench: could not create cpu profile: %v", err))
 	}
-	pprof.StartCPUProfile(b.cpuprof)
+	if err := pprof.StartCPUProfile(b.cpuprof); err != nil {
+		exitWithError(fmt.Errorf("bench: could not start CPU profile: %v", err))
+	}
 
 	// Start memory profiling.
 	b.memprof, err = os.Create(filepath.Join(b.outPath, "mem.prof"))
@@ -271,29 +275,36 @@ func (b *writeBenchmark) startProfiling() {
 	runtime.SetMutexProfileFraction(20)
 }
 
-func (b *writeBenchmark) stopProfiling() {
+func (b *writeBenchmark) stopProfiling() error {
 	if b.cpuprof != nil {
 		pprof.StopCPUProfile()
 		b.cpuprof.Close()
 		b.cpuprof = nil
 	}
 	if b.memprof != nil {
-		pprof.Lookup("heap").WriteTo(b.memprof, 0)
+		if err := pprof.Lookup("heap").WriteTo(b.memprof, 0); err != nil {
+			return fmt.Errorf("error writing mem profile: %v", err)
+		}
 		b.memprof.Close()
 		b.memprof = nil
 	}
 	if b.blockprof != nil {
-		pprof.Lookup("block").WriteTo(b.blockprof, 0)
+		if err := pprof.Lookup("block").WriteTo(b.blockprof, 0); err != nil {
+			return fmt.Errorf("error writing block profile: %v", err)
+		}
 		b.blockprof.Close()
 		b.blockprof = nil
 		runtime.SetBlockProfileRate(0)
 	}
 	if b.mtxprof != nil {
-		pprof.Lookup("mutex").WriteTo(b.mtxprof, 0)
+		if err := pprof.Lookup("mutex").WriteTo(b.mtxprof, 0); err != nil {
+			return fmt.Errorf("error writing mutex profile: %v", err)
+		}
 		b.mtxprof.Close()
 		b.mtxprof = nil
 		runtime.SetMutexProfileFraction(0)
 	}
+	return nil
 }
 
 func measureTime(stage string, f func()) time.Duration {

compact.go

@@ -626,7 +626,9 @@ func (c *LeveledCompactor) populateBlock(blocks []BlockReader, meta *BlockMeta,
 		}
 
 		for _, chk := range chks {
-			c.chunkPool.Put(chk.Chunk)
+			if err := c.chunkPool.Put(chk.Chunk); err != nil {
+				return errors.Wrap(err, "put chunk")
+			}
 		}
 
 		for _, l := range lset {

head.go

@@ -793,7 +793,7 @@ func (h *Head) gc() {
 	symbols := make(map[string]struct{})
 	values := make(map[string]stringset, len(h.values))
 
-	h.postings.Iter(func(t labels.Label, _ index.Postings) error {
+	if err := h.postings.Iter(func(t labels.Label, _ index.Postings) error {
 		symbols[t.Name] = struct{}{}
 		symbols[t.Value] = struct{}{}
 
@@ -804,7 +804,10 @@ func (h *Head) gc() {
 		}
 		ss.set(t.Value)
 		return nil
-	})
+	}); err != nil {
+		// This should never happen, as the iteration function only returns nil.
+		panic(err)
+	}
 
 	h.symMtx.Lock()
 

index/index.go

@@ -271,7 +271,9 @@ func (w *Writer) AddSeries(ref uint64, lset labels.Labels, chunks ...chunks.Meta
 	}
 	// We add padding to 16 bytes to increase the addressable space we get through 4 byte
 	// series references.
-	w.addPadding(16)
+	if err := w.addPadding(16); err != nil {
+		return errors.Errorf("failed to write padding bytes: %v", err)
+	}
 
 	if w.pos%16 != 0 {
 		return errors.Errorf("series write not 16-byte aligned at %d", w.pos)

tombstones.go

@@ -16,12 +16,13 @@ package tsdb
 import (
 	"encoding/binary"
 	"fmt"
-	"github.com/pkg/errors"
 	"io"
 	"io/ioutil"
 	"os"
 	"path/filepath"
 	"sync"
+
+	"github.com/pkg/errors"
 )
 
 const tombstoneFilename = "tombstones"
@@ -72,7 +73,7 @@ func writeTombstoneFile(dir string, tr TombstoneReader) error {
 
 	mw := io.MultiWriter(f, hash)
 
-	tr.Iter(func(ref uint64, ivs Intervals) error {
+	if err := tr.Iter(func(ref uint64, ivs Intervals) error {
 		for _, iv := range ivs {
 			buf.reset()
 
@@ -86,7 +87,9 @@ func writeTombstoneFile(dir string, tr TombstoneReader) error {
 			}
 		}
 		return nil
-	})
+	}); err != nil {
+		return fmt.Errorf("error writing tombstones: %v", err)
+	}
 
 	_, err = f.Write(hash.Sum(nil))
 	if err != nil {