Avoid overflowing 32-bit systems when mmapping value log of default s…

…ize. Correct an overflow check.
oliveiradan · Aug 10, 2018 · 341a135 · 341a135
1 parent be3a85f
commit 341a135
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Showing 2 changed files with 5 additions and 2 deletions.
diff --git a/options.go b/options.go
@@ -124,7 +124,10 @@ var DefaultOptions = Options{
 	NumVersionsToKeep:       1,
 	// Nothing to read/write value log using standard File I/O
 	// MemoryMap to mmap() the value log files
-	ValueLogFileSize:   1 << 30,
+	// (2^30 - 1)*2 when mmapping < 2^31 - 1, max int32.
+	// -1 so 2*ValueLogFileSize won't overflow on 32-bit systems.
+	ValueLogFileSize: 1<<30 - 1,
+
 	ValueLogMaxEntries: 1000000,
 	ValueThreshold:     32,
 	Truncate:           false,

diff --git a/value.go b/value.go
@@ -857,7 +857,7 @@ func (vlog *valueLog) write(reqs []*request) error {
 			}
 
 			newid := atomic.AddUint32(&vlog.maxFid, 1)
-			y.AssertTruef(newid <= math.MaxUint32, "newid will overflow uint32: %v", newid)
+			y.AssertTruef(newid > 0, "newid has overflown uint32: %v", newid)
 			newlf, err := vlog.createVlogFile(newid)
 			if err != nil {
 				return err