incomplete work: big call lib refactor

stdlib/shell.go

@@ -19,30 +19,135 @@ package stdlib
 
 import (
     "os"
-    "fmt"
-    "bytes"
-    "strconv"
+    "errors"
     "os/exec"
+    "context"
     "syscall"
-    "os/signal"
-    "gitlab.com/whom/shs/ast"
+    "golang.org/x/sys/unix"
     "gitlab.com/whom/shs/log"
 )
 
-var bgProcs = make([]*exec.Cmd, 0)
-var sigs = []os.Signal{
-    os.Interrupt,
-    syscall.SIGTERM,
-    syscall.SIGTSTP,
-    syscall.SIGTTIN,
-    syscall.SIGTTOU,
-    syscall.SIGCONT,
+func tcsetpgrp(fd int, pgrp int) error {
+    return unix.IoctlSetPointerInt(fd, unix.TIOCSPGRP, pgrp)
+}
+
+var sigChan chan os.Signal
+var waitChan chan error
+
+/* mapping of pid to Proc
+ */
+var JobMap = map[int]Proc{}
+
+/* id of shell process group
+ */
+var pgid int
+
+/* Holds an os/exec Cmd object and its context cancel function
+ */
+type Proc struct {
+    Ctl     *exec.Cmd
+    Cancel  context.CancelFunc
+}
+
+var catchMe = []os.Signal{
+    syscall.SIGINT,
 }
 
 /* Exit code of last run process
  */
 var LastExitCode int
 
+// Job control handlers
+func signalHandler() {
+    for {
+        sig := <- sigChan
+        switch sig {
+            case syscall.SIGINT:
+                log.Log(log.DEBUG,
+                    "caught SIGINT!",
+                    "jobctl")
+        }
+    }
+}
+
+func waitHandler() {
+    for {
+        w := <- waitChan
+        exit := 0
+        if w != nil {
+            log.Log(log.ERR,
+                "Child returned error: " + w.Error(),
+                "jobctl")
+
+            // something outrageous
+            exit = -1024
+            var e *exec.ExitError
+            if errors.As(w, &e) {
+                exit = e.Pid()
+            }
+
+            LastExitCode = exit
+        }
+    }
+}
+
+/* Sets pgid
+ * Installs a sigchld handler
+ * returns true if success, false on error
+ */
+func InitShellFeatures() bool {
+    // TODO: adjust, make configurable, i dunno
+    sigChan = make(chan os.Signal, 5)
+    waitChan = make(chan error, 5)
+
+    go signalHandler()
+    go waitHandler()
+
+    pid := os.Getpid()
+    pgid = syscall.Getpgrp()
+    if pid != pgid {
+        syscall.Setpgid(0, 0)
+    }
+    tcsetpgrp(0, pid)
+
+    return true
+}
+
+/* Tears down session
+ */
+func TeardownShell() {
+    close(sigChan)
+    close(waitChan)
+    // TODO: Exit all processes in the JobMap
+}
+
+/* Makes and stores a new process in the job control
+ * uses os/exec Cmd object. sets SysProcAttr.Foreground
+ * calls Cmd.Start()
+ */
+func LaunchProcess(path string, args []string, background bool) {
+    c, cancel := context.WithCancel(context.Background())
+    cmd := exec.CommandContext(c, path, args...)
+    cmd.SysProcAttr = &syscall.SysProcAttr{Foreground: !background, Pgid: pgid}
+
+    cmd.Stdin = os.Stdin
+    cmd.Stdout = os.Stdout
+    cmd.Stderr = os.Stderr
+
+    cmd.Start()
+    pid := cmd.Process.Pid
+
+    // TODO: check for clobber?
+    JobMap[pid] = Proc{ Ctl: cmd, Cancel: cancel }
+    go func(){
+        waitChan <- cmd.Wait()
+    }()
+
+    if background {
+        cmd.Process.Signal(syscall.SIGTSTP)
+    }
+}
+
 /* Takes n arguments (list of tokens generated by lexing a shell command)
  * Evaluates arguments, but does not err on undefined symbols (note the last arg to Eval(...))
  * Executes shell command and returns nil
@@ -76,35 +181,7 @@ func Call(in *ast.Token, vt ast.VarTable, ft ast.FuncTable) *ast.Token {
         args = append(args, i.Value())
     }
 
-    var cmd *exec.Cmd
-    if len(args) > 0 {
-        cmd = exec.Command(path, args...)
-    } else {
-        cmd = exec.Command(path)
-    }
-    cmd.Env = os.Environ()
-    cmd.Stdin  = os.Stdin
-    cmd.Stdout = os.Stdout
-    cmd.Stderr = os.Stderr
-
-    signalChan := make(chan os.Signal, 2)
-    signal.Notify(signalChan, sigs...)
-    go func() {
-        sig := <-signalChan
-        cmd.Process.Signal(sig)
-    }()
-
-    err = cmd.Run()
-    close(signalChan)
-    signal.Reset(sigs...)
-    if err != nil {
-        if exitError, ok := err.(*exec.ExitError); ok {
-            LastExitCode = exitError.ExitCode()
-        } else {
-            log.Log(log.ERR, "Execution step returned unparsable error: " + err.Error(), "call")
-        }
-    }
-
+    LaunchProcess(path, args, false)
     return nil
 }
 
@@ -139,21 +216,7 @@ func Bgcall(in *ast.Token, vt ast.VarTable, ft ast.FuncTable) *ast.Token {
         args = append(args, i.Value())
     }
 
-    var cmd *exec.Cmd
-    if len(args) > 0 {
-        cmd = exec.Command(path, args...)
-    } else {
-        cmd = exec.Command(path)
-    }
-    cmd.Stderr = os.Stderr
-
-    bgProcs = append(bgProcs, cmd)
-    cmd.Stdout = os.Stdout
-    cmd.Stdin = os.Stdin
-    cmd.Stderr = os.Stderr
-
-    cmd.Start()
-    cmd.Process.Signal(syscall.SIGTSTP)
+    LaunchProcess(path, args, true)
     return nil
 }