incomplete work: big call lib refactor
This commit is contained in:
Aidan
parent
e57a97c601
commit
08bb7073cd
6 changed files with 163 additions and 57 deletions
428
stdlib/shell.go
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428
stdlib/shell.go
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/* SHS: Syntactically Homogeneous Shell
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* Copyright (C) 2019 Aidan Hahn
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*
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* This program is free software: you can redistribute it and/or modify
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* it under the terms of the GNU General Public License as published by
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* the Free Software Foundation, either version 3 of the License, or
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* (at your option) any later version.
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*
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* This program is distributed in the hope that it will be useful,
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* but WITHOUT ANY WARRANTY; without even the implied warranty of
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* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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* GNU General Public License for more details.
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*
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* You should have received a copy of the GNU General Public License
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* along with this program. If not, see <https://www.gnu.org/licenses/>.
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*/
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package stdlib
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import (
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"os"
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"errors"
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"os/exec"
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"context"
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"syscall"
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"golang.org/x/sys/unix"
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"gitlab.com/whom/shs/log"
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)
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func tcsetpgrp(fd int, pgrp int) error {
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return unix.IoctlSetPointerInt(fd, unix.TIOCSPGRP, pgrp)
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}
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var sigChan chan os.Signal
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var waitChan chan error
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/* mapping of pid to Proc
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*/
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var JobMap = map[int]Proc{}
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/* id of shell process group
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*/
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var pgid int
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/* Holds an os/exec Cmd object and its context cancel function
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*/
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type Proc struct {
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Ctl *exec.Cmd
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Cancel context.CancelFunc
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}
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var catchMe = []os.Signal{
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syscall.SIGINT,
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}
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/* Exit code of last run process
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*/
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var LastExitCode int
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// Job control handlers
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func signalHandler() {
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for {
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sig := <- sigChan
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switch sig {
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case syscall.SIGINT:
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log.Log(log.DEBUG,
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"caught SIGINT!",
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"jobctl")
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}
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}
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}
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func waitHandler() {
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for {
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w := <- waitChan
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exit := 0
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if w != nil {
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log.Log(log.ERR,
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"Child returned error: " + w.Error(),
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"jobctl")
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// something outrageous
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exit = -1024
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var e *exec.ExitError
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if errors.As(w, &e) {
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exit = e.Pid()
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}
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LastExitCode = exit
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}
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}
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}
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/* Sets pgid
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* Installs a sigchld handler
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* returns true if success, false on error
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*/
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func InitShellFeatures() bool {
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// TODO: adjust, make configurable, i dunno
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sigChan = make(chan os.Signal, 5)
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waitChan = make(chan error, 5)
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go signalHandler()
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go waitHandler()
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pid := os.Getpid()
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pgid = syscall.Getpgrp()
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if pid != pgid {
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syscall.Setpgid(0, 0)
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}
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tcsetpgrp(0, pid)
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return true
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}
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/* Tears down session
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*/
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func TeardownShell() {
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close(sigChan)
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close(waitChan)
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// TODO: Exit all processes in the JobMap
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}
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/* Makes and stores a new process in the job control
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* uses os/exec Cmd object. sets SysProcAttr.Foreground
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* calls Cmd.Start()
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*/
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func LaunchProcess(path string, args []string, background bool) {
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c, cancel := context.WithCancel(context.Background())
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cmd := exec.CommandContext(c, path, args...)
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cmd.SysProcAttr = &syscall.SysProcAttr{Foreground: !background, Pgid: pgid}
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cmd.Stdin = os.Stdin
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cmd.Stdout = os.Stdout
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cmd.Stderr = os.Stderr
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cmd.Start()
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pid := cmd.Process.Pid
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// TODO: check for clobber?
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JobMap[pid] = Proc{ Ctl: cmd, Cancel: cancel }
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go func(){
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waitChan <- cmd.Wait()
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}()
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if background {
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cmd.Process.Signal(syscall.SIGTSTP)
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}
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}
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/* Takes n arguments (list of tokens generated by lexing a shell command)
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* Evaluates arguments, but does not err on undefined symbols (note the last arg to Eval(...))
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* Executes shell command and returns nil
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*
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* Example (l vim file.txt)
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*/
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func Call(in *ast.Token, vt ast.VarTable, ft ast.FuncTable) *ast.Token {
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in = in.Eval(ft, vt, true)
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if in == nil {
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return nil
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}
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if in.Tag == ast.LIST {
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log.Log(log.ERR, "couldnt exec, target bin is a list", "call")
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return nil
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}
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path, err := exec.LookPath(in.Value())
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if err != nil {
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log.Log(log.ERR, "Couldnt exec " + in.Value() + ", file not found", "call")
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return nil
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}
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args := []string{}
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for i := in.Next; i != nil; i = i.Next {
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if i.Tag == ast.LIST {
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log.Log(log.ERR, "Couldnt exec " + path + ", element in arguments is a list", "call")
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return nil
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}
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args = append(args, i.Value())
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}
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LaunchProcess(path, args, false)
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return nil
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}
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/* Starts a call in the background
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* Takes n args (a shell command not delimited by string delimiters)
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*
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* Example: (bg vim file.txt)
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*/
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func Bgcall(in *ast.Token, vt ast.VarTable, ft ast.FuncTable) *ast.Token {
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if in == nil {
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return nil
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}
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if in.Tag == ast.LIST {
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log.Log(log.ERR, "couldnt exec, target bin is a list", "call")
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return nil
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}
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path, err := exec.LookPath(in.Value())
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if err != nil {
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log.Log(log.ERR, "Couldnt exec " + in.Value() + ", file not found", "call")
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return nil
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}
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args := []string{}
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for i := in.Next; i != nil; i = i.Next {
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if i.Tag == ast.LIST {
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log.Log(log.ERR, "Couldnt exec " + path + ", element in arguments is a list", "call")
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return nil
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}
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args = append(args, i.Value())
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}
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LaunchProcess(path, args, true)
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return nil
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}
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/* brings last BG'ed process into the foreground
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* returns nil
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*
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* Example:
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* (bg vim file.txt)
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* (fg)
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*/
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func Fg(in *ast.Token, vt ast.VarTable, ft ast.FuncTable) *ast.Token {
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if len(bgProcs) < 1 {
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return nil
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}
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cmd := bgProcs[0]
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bgProcs = bgProcs[1:]
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signalChan := make(chan os.Signal, 2)
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signal.Notify(signalChan, sigs...)
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go func() {
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sig := <-signalChan
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cmd.Process.Signal(sig)
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}()
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cmd.Process.Signal(syscall.SIGCONT)
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err := cmd.Wait()
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close(signalChan)
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signal.Reset(sigs...)
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if err != nil {
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if exitError, ok := err.(*exec.ExitError); ok {
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LastExitCode = exitError.ExitCode()
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} else {
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log.Log(log.ERR, "Execution step returned error: " + err.Error(), "call")
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}
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}
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return nil
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}
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/* Takes 0 args
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* returns a string containing info about current jobs
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* returns total jobs as well as their PIDs and place in the bg queue
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*
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* Example:
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* (bg ping google.com)
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* (bg .........)
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* (jobs)
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*/
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func Jobs(in *ast.Token, vt ast.VarTable, fg ast.FuncTable) *ast.Token {
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ret := &ast.Token{
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Tag: ast.LIST,
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}
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_inner := &ast.Token{
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Tag: ast.STRING,
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}
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ret.Direct(_inner)
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_inner.Set(fmt.Sprintf("Total: %d", len(bgProcs)))
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iter := &_inner
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for i := 0; i < len(bgProcs); i += 1 {
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(*iter).Next = &ast.Token{
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Tag: ast.STRING,
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}
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(*iter).Next.Set(fmt.Sprintf("[%d]: %d", i, bgProcs[i].Process.Pid))
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iter = &(*iter).Next
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}
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return ret
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}
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/* calls a command (blocks until completion)
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* captures stdout and returns it as a string
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*
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* Example: ($ echo hello world)
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*/
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func ReadCmd(in *ast.Token, vt ast.VarTable, ft ast.FuncTable) *ast.Token {
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in = in.Eval(ft, vt, true)
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if in == nil {
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return nil
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}
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if in.Tag == ast.LIST {
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log.Log(log.ERR, "couldnt exec, target bin is a list", "call")
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return nil
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}
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var out bytes.Buffer
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path, err := exec.LookPath(in.Value())
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if err != nil {
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log.Log(log.ERR, "Couldnt exec " + in.Value() + ", file not found", "call")
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return nil
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}
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args := []string{}
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for i := in.Next; i != nil; i = i.Next {
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if i.Tag == ast.LIST {
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log.Log(log.ERR, "Couldnt exec " + path + ", element in arguments is a list", "call")
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return nil
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}
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args = append(args, i.Value())
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}
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var cmd *exec.Cmd
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if len(args) > 0 {
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cmd = exec.Command(path, args...)
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} else {
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cmd = exec.Command(path)
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}
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cmd.Stdout = &out
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cmd.Stderr = os.Stderr
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cmd.Stdin = os.Stdin
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signalChan := make(chan os.Signal, 2)
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signal.Notify(signalChan, sigs...)
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go func() {
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sig := <-signalChan
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cmd.Process.Signal(sig)
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}()
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err = cmd.Run()
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close(signalChan)
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signal.Reset(sigs...)
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if err != nil {
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if exitError, ok := err.(*exec.ExitError); ok {
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LastExitCode = exitError.ExitCode()
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} else {
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log.Log(log.ERR, "Execution step returned error: " + err.Error(), "$")
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}
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}
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output := out.String()
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olen := len(output)
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if olen > 0 && output[olen - 1] == '\n' {
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output = output[:olen - 1]
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}
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ret := &ast.Token{Tag: ast.STRING}
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ret.Set(output)
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return ret
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}
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/* Takes 0 arguments
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* returns the exit code of the last executed program
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*
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* Example:
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* (sudo apt update)
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* (?) <- gets exit code
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*/
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func GetExit(in *ast.Token, vt ast.VarTable, ft ast.FuncTable) *ast.Token {
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ret := &ast.Token{Tag: ast.NUMBER}
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ret.Set(fmt.Sprintf("%d", LastExitCode))
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return ret
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}
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/* takes an argument (pid of process to be killed)
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* calls Process.Kill() on it
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* do not use this if you already have a native implementation
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* (this function not added to functable in stdlib.go)
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*/
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func Kill(in *ast.Token, vt ast.VarTable, ft ast.FuncTable) *ast.Token {
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in = in.Eval(ft, vt, true)
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if in.Tag == ast.LIST {
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log.Log(log.ERR, "non-number argument to kill function", "kill")
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return nil
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}
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pid, err := strconv.ParseInt(in.Value(), 10, 64)
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if err != nil {
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log.Log(log.ERR, "error parsing arg to kill: " + err.Error(), "kill")
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return nil
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}
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found := false
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newBgProcs := []*exec.Cmd{}
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for _, i := range bgProcs {
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if i.Process.Pid != int(pid) {
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newBgProcs = append(newBgProcs, i)
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} else {
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found = true
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err = i.Process.Kill()
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if err != nil {
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log.Log(log.ERR, fmt.Sprintf("error killing process %d: %s",
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int(pid), err.Error()), "kill")
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newBgProcs = append(newBgProcs, i)
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}
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}
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}
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bgProcs = newBgProcs
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if !found {
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// docs say no error on unix systems
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proc, _ := os.FindProcess(int(pid))
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err = proc.Kill()
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if err != nil {
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log.Log(log.ERR, fmt.Sprintf("error killing process %d: %s",
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int(pid), err.Error()), "kill")
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}
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}
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return nil
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}
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