helper: Add new bytesToString function and tests

Signed-off-by: David O'Rourke <david.orourke@gmail.com>

2 files changed, 77 insertions, 0 deletions

diff --git a/collector/helper.go b/collector/helper.go
index 2bf461e..df5cd26 100644
--- a/collector/helper.go
+++ b/collector/helper.go
@@ -14,6 +14,7 @@
 package collector
 
 import (
+        "bytes"
         "io/ioutil"
         "strconv"
         "strings"
@@ -30,3 +31,16 @@ func readUintFromFile(path string) (uint64, error) {
         }
         return value, nil
 }
+
+// Take a []byte{} and return a string based on null termination.
+// This is useful for situations where the OS has returned a null terminated
+// string to use.
+// If this function happens to receive a byteArray that contains no nulls, we
+// simply convert the array to a string with no bounding.
+func bytesToString(byteArray []byte) string {
+        n := bytes.IndexByte(byteArray, 0)
+        if n < 0 {
+                return string(byteArray)
+        }
+        return string(byteArray[:n])
+}
diff --git a/collector/helper_test.go b/collector/helper_test.go
new file mode 100644
index 0000000..48a4f7c
--- /dev/null
+++ b/collector/helper_test.go
@@ -0,0 +1,63 @@
+// Copyright 2015 The Prometheus Authors
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+// http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+
+package collector
+
+import (
+        "testing"
+)
+
+func TestBytesToString(t *testing.T) {
+        tests := []struct {
+                name     string
+                b        []byte
+                expected string
+        }{
+                {
+                        "Single null byte",
+                        []byte{0},
+                        "",
+                },
+                {
+                        "Empty byte array",
+                        []byte{},
+                        "",
+                },
+                {
+                        "Not null terminated",
+                        []byte{65, 66, 67},
+                        "ABC",
+                },
+                {
+                        "Null randomly in array",
+                        []byte{65, 66, 67, 0, 65, 0, 65},
+                        "ABC",
+                },
+                {
+                        "Array starts with null and contains other valid bytes",
+                        []byte{0, 65, 66, 67, 0},
+                        "",
+                },
+        }
+
+        for _, tt := range tests {
+                name := tt.name
+                b := tt.b
+                result := bytesToString(b)
+                expected := tt.expected
+
+                if result != expected {
+                        t.Errorf("bytesToString(%#v): Name: %s, expected %#v, got %#v)", b, name, expected, result)
+                }
+        }
+}