Update dependencies

vendor/github.com/digitalocean/go-smbios/smbios/stream_memory.go

@@ -0,0 +1,125 @@
+// Copyright 2017-2018 DigitalOcean.
+//
+// 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 smbios
+
+import (
+	"bytes"
+	"errors"
+	"io"
+	"io/ioutil"
+	"os"
+)
+
+const (
+	// devMem is the UNIX-like system memory device location used to
+	// find SMBIOS information.
+	devMem = "/dev/mem"
+
+	// SMBIOS specification indicates that the entry point should exist
+	// between these two memory addresses.
+	startAddr = 0x000f0000
+	endAddr   = 0x000fffff
+)
+
+// memoryStream reads the SMBIOS entry point and structure stream from
+// an io.ReadSeeker (usually system memory).
+//
+// memoryStream is an entry point for tests.
+func memoryStream(rs io.ReadSeeker, startAddr, endAddr int) (io.ReadCloser, EntryPoint, error) {
+	// Try to find the entry point.
+	addr, err := findEntryPoint(rs, startAddr, endAddr)
+	if err != nil {
+		return nil, nil, err
+	}
+
+	// Found it; seek to the location of the entry point.
+	if _, err := rs.Seek(int64(addr), io.SeekStart); err != nil {
+		return nil, nil, err
+	}
+
+	// Read the entry point and determine where the SMBIOS table is.
+	ep, err := ParseEntryPoint(rs)
+	if err != nil {
+		return nil, nil, err
+	}
+
+	// Seek to the start of the SMBIOS table.
+	tableAddr, tableSize := ep.Table()
+	if _, err := rs.Seek(int64(tableAddr), io.SeekStart); err != nil {
+		return nil, nil, err
+	}
+
+	// Make a copy of the memory so we don't return a handle to system memory
+	// to the caller.
+	out := make([]byte, tableSize)
+	if _, err := io.ReadFull(rs, out); err != nil {
+		return nil, nil, err
+	}
+
+	return ioutil.NopCloser(bytes.NewReader(out)), ep, nil
+}
+
+// findEntryPoint attempts to locate the entry point structure in the io.ReadSeeker
+// using the start and end bound as hints for its location.
+func findEntryPoint(rs io.ReadSeeker, start, end int) (int, error) {
+	// Begin searching at the start bound.
+	if _, err := rs.Seek(int64(start), io.SeekStart); err != nil {
+		return 0, err
+	}
+
+	// Iterate one "paragraph" of memory at a time until we either find the entry point
+	// or reach the end bound.
+	const paragraph = 16
+	b := make([]byte, paragraph)
+
+	var (
+		addr  int
+		found bool
+	)
+
+	for addr = start; addr < end; addr += paragraph {
+		if _, err := io.ReadFull(rs, b); err != nil {
+			return 0, err
+		}
+
+		// Both the 32-bit and 64-bit entry point have a similar prefix.
+		if bytes.HasPrefix(b, magicPrefix) {
+			found = true
+			break
+		}
+	}
+
+	if !found {
+		return 0, errors.New("no SMBIOS entry point found in memory")
+	}
+
+	// Return the exact memory location of the entry point.
+	return addr, nil
+}
+
+// devMemStream reads the SMBIOS entry point and structure stream from
+// the UNIX-like system /dev/mem device.
+//
+// This is UNIX-like system specific, but since it doesn't employ any system
+// calls or OS-dependent constants, it remains in this file for simplicity.
+func devMemStream() (io.ReadCloser, EntryPoint, error) {
+	mem, err := os.Open(devMem)
+	if err != nil {
+		return nil, nil, err
+	}
+	defer mem.Close()
+
+	return memoryStream(mem, startAddr, endAddr)
+}