README update and missing dependencies.

vendor/golang.org/x/sys/unix/linux/mksysnum.go

@@ -0,0 +1,143 @@
+// Copyright 2018 The Go Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style
+// license that can be found in the LICENSE file.
+
+// +build ignore
+
+package main
+
+import (
+	"bufio"
+	"fmt"
+	"os"
+	"os/exec"
+	"regexp"
+	"strconv"
+	"strings"
+)
+
+var (
+	goos, goarch string
+)
+
+// cmdLine returns this programs's commandline arguments
+func cmdLine() string {
+	return "go run linux/mksysnum.go " + strings.Join(os.Args[1:], " ")
+}
+
+// buildTags returns build tags
+func buildTags() string {
+	return fmt.Sprintf("%s,%s", goarch, goos)
+}
+
+func format(name string, num int, offset int) string {
+	if num > 999 {
+		// ignore deprecated syscalls that are no longer implemented
+		// https://git.kernel.org/cgit/linux/kernel/git/torvalds/linux.git/tree/include/uapi/asm-generic/unistd.h?id=refs/heads/master#n716
+		return ""
+	}
+	name = strings.ToUpper(name)
+	num = num + offset
+	return fmt.Sprintf("	SYS_%s = %d;\n", name, num)
+}
+
+func checkErr(err error) {
+	if err != nil {
+		fmt.Fprintf(os.Stderr, "%v\n", err)
+		os.Exit(1)
+	}
+}
+
+// source string and substring slice for regexp
+type re struct {
+	str string   // source string
+	sub []string // matched sub-string
+}
+
+// Match performs regular expression match
+func (r *re) Match(exp string) bool {
+	r.sub = regexp.MustCompile(exp).FindStringSubmatch(r.str)
+	if r.sub != nil {
+		return true
+	}
+	return false
+}
+
+func main() {
+	// Get the OS and architecture (using GOARCH_TARGET if it exists)
+	goos = os.Getenv("GOOS")
+	goarch = os.Getenv("GOARCH_TARGET")
+	if goarch == "" {
+		goarch = os.Getenv("GOARCH")
+	}
+	// Check if GOOS and GOARCH environment variables are defined
+	if goarch == "" || goos == "" {
+		fmt.Fprintf(os.Stderr, "GOARCH or GOOS not defined in environment\n")
+		os.Exit(1)
+	}
+	// Check that we are using the new build system if we should
+	if os.Getenv("GOLANG_SYS_BUILD") != "docker" {
+		fmt.Fprintf(os.Stderr, "In the new build system, mksysnum should not be called directly.\n")
+		fmt.Fprintf(os.Stderr, "See README.md\n")
+		os.Exit(1)
+	}
+
+	cc := os.Getenv("CC")
+	if cc == "" {
+		fmt.Fprintf(os.Stderr, "CC is not defined in environment\n")
+		os.Exit(1)
+	}
+	args := os.Args[1:]
+	args = append([]string{"-E", "-dD"}, args...)
+	cmd, err := exec.Command(cc, args...).Output() // execute command and capture output
+	if err != nil {
+		fmt.Fprintf(os.Stderr, "can't run %s", cc)
+		os.Exit(1)
+	}
+	text := ""
+	s := bufio.NewScanner(strings.NewReader(string(cmd)))
+	var offset, prev int
+	for s.Scan() {
+		t := re{str: s.Text()}
+		if t.Match(`^#define __NR_Linux\s+([0-9]+)`) {
+			// mips/mips64: extract offset
+			offset, _ = strconv.Atoi(t.sub[1]) // Make offset=0 if empty or non-numeric
+		} else if t.Match(`^#define __NR(\w*)_SYSCALL_BASE\s+([0-9]+)`) {
+			// arm: extract offset
+			offset, _ = strconv.Atoi(t.sub[1]) // Make offset=0 if empty or non-numeric
+		} else if t.Match(`^#define __NR_syscalls\s+`) {
+			// ignore redefinitions of __NR_syscalls
+		} else if t.Match(`^#define __NR_(\w*)Linux_syscalls\s+`) {
+			// mips/mips64: ignore definitions about the number of syscalls
+		} else if t.Match(`^#define __NR_(\w+)\s+([0-9]+)`) {
+			prev, err = strconv.Atoi(t.sub[2])
+			checkErr(err)
+			text += format(t.sub[1], prev, offset)
+		} else if t.Match(`^#define __NR3264_(\w+)\s+([0-9]+)`) {
+			prev, err = strconv.Atoi(t.sub[2])
+			checkErr(err)
+			text += format(t.sub[1], prev, offset)
+		} else if t.Match(`^#define __NR_(\w+)\s+\(\w+\+\s*([0-9]+)\)`) {
+			r2, err := strconv.Atoi(t.sub[2])
+			checkErr(err)
+			text += format(t.sub[1], prev+r2, offset)
+		} else if t.Match(`^#define __NR_(\w+)\s+\(__NR_(?:SYSCALL_BASE|Linux) \+ ([0-9]+)`) {
+			r2, err := strconv.Atoi(t.sub[2])
+			checkErr(err)
+			text += format(t.sub[1], r2, offset)
+		}
+	}
+	err = s.Err()
+	checkErr(err)
+	fmt.Printf(template, cmdLine(), buildTags(), text)
+}
+
+const template = `// %s
+// Code generated by the command above; see README.md. DO NOT EDIT.
+
+// +build %s
+
+package unix
+
+const(
+%s)`