~ubuntu-branches/ubuntu/saucy/golang/saucy

// Copyright 2013 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.

 

package main

 

import (

        "bytes"

        "fmt"

        "os"

        "strings"

        "unicode"

)

 

var (

        nl         = []byte("\n")

        slashSlash = []byte("//")

        plusBuild  = []byte("+build")

)

 

// checkBuildTag checks that build tags are in the correct location and well-formed.

func checkBuildTag(name string, data []byte) {

        if !vet("buildtags") {

                return

        }

        lines := bytes.SplitAfter(data, nl)

 

        // Determine cutpoint where +build comments are no longer valid.

        // They are valid in leading // comments in the file followed by

        // a blank line.

        var cutoff int

        for i, line := range lines {

                line = bytes.TrimSpace(line)

                if len(line) == 0 {

                        cutoff = i

                        continue

                }

                if bytes.HasPrefix(line, slashSlash) {

                        continue

                }

                break

        }

 

        for i, line := range lines {

                line = bytes.TrimSpace(line)

                if !bytes.HasPrefix(line, slashSlash) {

                        continue

                }

                text := bytes.TrimSpace(line[2:])

                if bytes.HasPrefix(text, plusBuild) {

                        fields := bytes.Fields(text)

                        if !bytes.Equal(fields[0], plusBuild) {

                                // Comment is something like +buildasdf not +build.

                                fmt.Fprintf(os.Stderr, "%s:%d: possible malformed +build comment\n", name, i+1)

                                continue

                        }

                        if i >= cutoff {

                                fmt.Fprintf(os.Stderr, "%s:%d: +build comment appears too late in file\n", name, i+1)

                                setExit(1)

                                continue

                        }

                        // Check arguments.

                Args:

                        for _, arg := range fields[1:] {

                                for _, elem := range strings.Split(string(arg), ",") {

                                        if strings.HasPrefix(elem, "!!") {

                                                fmt.Fprintf(os.Stderr, "%s:%d: invalid double negative in build constraint: %s\n", name, i+1, arg)

                                                setExit(1)

                                                break Args

                                        }

                                        if strings.HasPrefix(elem, "!") {

                                                elem = elem[1:]

                                        }

                                        for _, c := range elem {

                                                if !unicode.IsLetter(c) && !unicode.IsDigit(c) && c != '_' && c != '.' {

                                                        fmt.Fprintf(os.Stderr, "%s:%d: invalid non-alphanumeric build constraint: %s\n", name, i+1, arg)

                                                        setExit(1)

                                                        break Args

                                                }

                                        }

                                }

                        }

                        continue

                }

                // Comment with +build but not at beginning.

                if bytes.Contains(line, plusBuild) && i < cutoff {

                        fmt.Fprintf(os.Stderr, "%s:%d: possible malformed +build comment\n", name, i+1)

                        continue

                }

        }

}