Imported Upstream version 2012.03.22upstream-weekly/2012.03.22

2 files changed, 13 insertions, 3 deletions

diff --git a/src/pkg/io/io.go b/src/pkg/io/io.go
index 7074834d6..54bf159eb 100644
--- a/src/pkg/io/io.go
+++ b/src/pkg/io/io.go
@@ -173,6 +173,13 @@ type ReaderAt interface {
 // at offset off.  It returns the number of bytes written from p (0 <= n <= len(p))
 // and any error encountered that caused the write to stop early.
 // WriteAt must return a non-nil error if it returns n < len(p).
+//
+// If WriteAt is writing to a destination with a seek offset,
+// WriteAt should not affect nor be affected by the underlying
+// seek offset.
+//
+// Clients of WriteAt can execute parallel WriteAt calls on the same
+// destination if the ranges do not overlap.
 type WriterAt interface {
 	WriteAt(p []byte, off int64) (n int, err error)
 }
diff --git a/src/pkg/io/ioutil/ioutil.go b/src/pkg/io/ioutil/ioutil.go
index 180afc2c2..f072b8c75 100644
--- a/src/pkg/io/ioutil/ioutil.go
+++ b/src/pkg/io/ioutil/ioutil.go
@@ -53,10 +53,13 @@ func ReadFile(filename string) ([]byte, error) {
 	defer f.Close()
 	// It's a good but not certain bet that FileInfo will tell us exactly how much to
 	// read, so let's try it but be prepared for the answer to be wrong.
-	fi, err := f.Stat()
 	var n int64
-	if size := fi.Size(); err == nil && size < 2e9 { // Don't preallocate a huge buffer, just in case.
-		n = size
+
+	if fi, err := f.Stat(); err == nil {
+		// Don't preallocate a huge buffer, just in case.
+		if size := fi.Size(); size < 1e9 {
+			n = size
+		}
 	}
 	// As initial capacity for readAll, use n + a little extra in case Size is zero,
 	// and to avoid another allocation after Read has filled the buffer.  The readAll