DockerCLI/vendor/github.com/Nvveen/Gotty/gotty.go

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// Copyright 2012 Neal van Veen. All rights reserved.
// Usage of this source code is governed by a BSD-style license that can be
// found in the LICENSE file.
// Gotty is a Go-package for reading and parsing the terminfo database
package gotty
// TODO add more concurrency to name lookup, look for more opportunities.
import (
"bytes"
"encoding/binary"
"errors"
"fmt"
"os"
"path"
"reflect"
"strings"
"sync"
)
// Open a terminfo file by the name given and construct a TermInfo object.
// If something went wrong reading the terminfo database file, an error is
// returned.
func OpenTermInfo(termName string) (*TermInfo, error) {
if len(termName) == 0 {
return nil, errors.New("No termname given")
}
// Find the environment variables
if termloc := os.Getenv("TERMINFO"); len(termloc) > 0 {
return readTermInfo(path.Join(termloc, string(termName[0]), termName))
} else {
// Search like ncurses
locations := []string{}
if h := os.Getenv("HOME"); len(h) > 0 {
locations = append(locations, path.Join(h, ".terminfo"))
}
locations = append(locations,
"/etc/terminfo/",
"/lib/terminfo/",
"/usr/share/terminfo/")
for _, str := range locations {
term, err := readTermInfo(path.Join(str, string(termName[0]), termName))
if err == nil {
return term, nil
}
}
return nil, errors.New("No terminfo file(-location) found")
}
}
// Open a terminfo file from the environment variable containing the current
// terminal name and construct a TermInfo object. If something went wrong
// reading the terminfo database file, an error is returned.
func OpenTermInfoEnv() (*TermInfo, error) {
termenv := os.Getenv("TERM")
return OpenTermInfo(termenv)
}
// Return an attribute by the name attr provided. If none can be found,
// an error is returned.
func (term *TermInfo) GetAttribute(attr string) (stacker, error) {
// Channel to store the main value in.
var value stacker
// Add a blocking WaitGroup
var block sync.WaitGroup
// Keep track of variable being written.
written := false
// Function to put into goroutine.
f := func(ats interface{}) {
var ok bool
var v stacker
// Switch on type of map to use and assign value to it.
switch reflect.TypeOf(ats).Elem().Kind() {
case reflect.Bool:
v, ok = ats.(map[string]bool)[attr]
case reflect.Int16:
v, ok = ats.(map[string]int16)[attr]
case reflect.String:
v, ok = ats.(map[string]string)[attr]
}
// If ok, a value is found, so we can write.
if ok {
value = v
written = true
}
// Goroutine is done
block.Done()
}
block.Add(3)
// Go for all 3 attribute lists.
go f(term.boolAttributes)
go f(term.numAttributes)
go f(term.strAttributes)
// Wait until every goroutine is done.
block.Wait()
// If a value has been written, return it.
if written {
return value, nil
}
// Otherwise, error.
return nil, fmt.Errorf("Erorr finding attribute")
}
// Return an attribute by the name attr provided. If none can be found,
// an error is returned. A name is first converted to its termcap value.
func (term *TermInfo) GetAttributeName(name string) (stacker, error) {
tc := GetTermcapName(name)
return term.GetAttribute(tc)
}
// A utility function that finds and returns the termcap equivalent of a
// variable name.
func GetTermcapName(name string) string {
// Termcap name
var tc string
// Blocking group
var wait sync.WaitGroup
// Function to put into a goroutine
f := func(attrs []string) {
// Find the string corresponding to the name
for i, s := range attrs {
if s == name {
tc = attrs[i+1]
}
}
// Goroutine is finished
wait.Done()
}
wait.Add(3)
// Go for all 3 attribute lists
go f(BoolAttr[:])
go f(NumAttr[:])
go f(StrAttr[:])
// Wait until every goroutine is done
wait.Wait()
// Return the termcap name
return tc
}
// This function takes a path to a terminfo file and reads it in binary
// form to construct the actual TermInfo file.
func readTermInfo(path string) (*TermInfo, error) {
// Open the terminfo file
file, err := os.Open(path)
defer file.Close()
if err != nil {
return nil, err
}
// magic, nameSize, boolSize, nrSNum, nrOffsetsStr, strSize
// Header is composed of the magic 0432 octal number, size of the name
// section, size of the boolean section, the amount of number values,
// the number of offsets of strings, and the size of the string section.
var header [6]int16
// Byte array is used to read in byte values
var byteArray []byte
// Short array is used to read in short values
var shArray []int16
// TermInfo object to store values
var term TermInfo
// Read in the header
err = binary.Read(file, binary.LittleEndian, &header)
if err != nil {
return nil, err
}
// If magic number isn't there or isn't correct, we have the wrong filetype
if header[0] != 0432 {
return nil, errors.New(fmt.Sprintf("Wrong filetype"))
}
// Read in the names
byteArray = make([]byte, header[1])
err = binary.Read(file, binary.LittleEndian, &byteArray)
if err != nil {
return nil, err
}
term.Names = strings.Split(string(byteArray), "|")
// Read in the booleans
byteArray = make([]byte, header[2])
err = binary.Read(file, binary.LittleEndian, &byteArray)
if err != nil {
return nil, err
}
term.boolAttributes = make(map[string]bool)
for i, b := range byteArray {
if b == 1 {
term.boolAttributes[BoolAttr[i*2+1]] = true
}
}
// If the number of bytes read is not even, a byte for alignment is added
// We know the header is an even number of bytes so only need to check the
// total of the names and booleans.
if (header[1]+header[2])%2 != 0 {
err = binary.Read(file, binary.LittleEndian, make([]byte, 1))
if err != nil {
return nil, err
}
}
// Read in shorts
shArray = make([]int16, header[3])
err = binary.Read(file, binary.LittleEndian, &shArray)
if err != nil {
return nil, err
}
term.numAttributes = make(map[string]int16)
for i, n := range shArray {
if n != 0377 && n > -1 {
term.numAttributes[NumAttr[i*2+1]] = n
}
}
// Read the offsets into the short array
shArray = make([]int16, header[4])
err = binary.Read(file, binary.LittleEndian, &shArray)
if err != nil {
return nil, err
}
// Read the actual strings in the byte array
byteArray = make([]byte, header[5])
err = binary.Read(file, binary.LittleEndian, &byteArray)
if err != nil {
return nil, err
}
term.strAttributes = make(map[string]string)
// We get an offset, and then iterate until the string is null-terminated
for i, offset := range shArray {
if offset > -1 {
if int(offset) >= len(byteArray) {
return nil, errors.New("array out of bounds reading string section")
}
r := bytes.IndexByte(byteArray[offset:], 0)
if r == -1 {
return nil, errors.New("missing nul byte reading string section")
}
r += int(offset)
term.strAttributes[StrAttr[i*2+1]] = string(byteArray[offset:r])
}
}
return &term, nil
}