[VOL-4291] Rw-core updates for gRPC migration
Change-Id: I8d5a554409115b29318089671ca4e1ab3fa98810
diff --git a/vendor/github.com/prometheus/procfs/internal/util/sysreadfile.go b/vendor/github.com/prometheus/procfs/internal/util/sysreadfile.go
new file mode 100644
index 0000000..c07de0b
--- /dev/null
+++ b/vendor/github.com/prometheus/procfs/internal/util/sysreadfile.go
@@ -0,0 +1,48 @@
+// Copyright 2018 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.
+
+// +build linux,!appengine
+
+package util
+
+import (
+ "bytes"
+ "os"
+ "syscall"
+)
+
+// SysReadFile is a simplified ioutil.ReadFile that invokes syscall.Read directly.
+// https://github.com/prometheus/node_exporter/pull/728/files
+//
+// Note that this function will not read files larger than 128 bytes.
+func SysReadFile(file string) (string, error) {
+ f, err := os.Open(file)
+ if err != nil {
+ return "", err
+ }
+ defer f.Close()
+
+ // On some machines, hwmon drivers are broken and return EAGAIN. This causes
+ // Go's ioutil.ReadFile implementation to poll forever.
+ //
+ // Since we either want to read data or bail immediately, do the simplest
+ // possible read using syscall directly.
+ const sysFileBufferSize = 128
+ b := make([]byte, sysFileBufferSize)
+ n, err := syscall.Read(int(f.Fd()), b)
+ if err != nil {
+ return "", err
+ }
+
+ return string(bytes.TrimSpace(b[:n])), nil
+}