WriteFile util function

R=rsc
DELTA=41  (41 added, 0 deleted, 0 changed)
OCL=31349
CL=31358

diff --git a/src/pkg/io/utils.go b/src/pkg/io/utils.go
index 96d23bcf00b624068d7a208cd9fae54bc368e889..f3331a20c5f8b8c9ae2cebc00482f75a5a3629d8 100644 (file)
--- a/src/pkg/io/utils.go
+++ b/src/pkg/io/utils.go
@@ -28,3 +28,19 @@ func ReadFile(filename string) ([]byte, os.Error) {
        defer f.Close();
        return ReadAll(f);
 }
+
+// WriteFile writes data to a file named by filename.
+// If the file does not exist, WriteFile creates it with permissions perm.
+//
+func WriteFile(filename string, data []byte, perm int) os.Error {
+       f, err := os.Open(filename, os.O_WRONLY | os.O_CREAT | os.O_TRUNC, perm);
+       if err != nil {
+               return err;
+       }
+       n, err := f.Write(data);
+       if err == nil && n < len(data) {
+               err = ErrShortWrite;
+       }
+       f.Close();
+       return err;
+}

diff --git a/src/pkg/io/utils_test.go b/src/pkg/io/utils_test.go
index f35dad60c9dd9d212b3247d65b464cc3ddf4011c..4538337436e35a767de533e041b9d9fdf13f6a38 100644 (file)
--- a/src/pkg/io/utils_test.go
+++ b/src/pkg/io/utils_test.go
@@ -7,6 +7,7 @@ package io
 import (
        "io";
        "os";
+       "strings";
        "testing";
 )
 
@@ -35,3 +36,27 @@ func TestReadFile(t *testing.T) {
 
        checkSize(t, filename, uint64(len(contents)));
 }
+
+func TestWriteFile(t *testing.T) {
+       filename := "_obj/rumpelstilzchen";
+       data :=
+               "Programming today is a race between software engineers striving to "
+               "build bigger and better idiot-proof programs, and the Universe trying "
+               "to produce bigger and better idiots. So far, the Universe is winning.";
+
+       if err := WriteFile(filename, strings.Bytes(data), 0644); err != nil {
+               t.Fatalf("WriteFile %s: %v", filename, err);
+       }
+
+       contents, err := ReadFile(filename);
+       if err != nil {
+               t.Fatalf("ReadFile %s: %v", filename, err);
+       }
+
+       if string(contents) != data {
+               t.Fatalf("contents = %q\nexpected = %q", string(contents), data);
+       }
+
+       // cleanup
+       os.Remove(filename);  // ignore error
+}