fixed background process execution

stdlib/shell.go

@@ -22,7 +22,6 @@ import (
     "io"
     "fmt"
     "bytes"
-    "errors"
     "os/exec"
     "context"
     "syscall"
@@ -68,7 +67,7 @@ var LastExitCode int
 func signalHandler() {
     for {
         <- sigChan
-        log.Log(log.INFO,
+        log.Log(log.DEBUG,
             "caught SIGINT",
             "jobctl")
 
@@ -78,27 +77,6 @@ func signalHandler() {
     }
 }
 
-func waitHandler() {
-    for {
-        w := <- waitChan
-        exit := 0
-        if w != nil {
-            log.Log(log.ERR,
-                "Child returned: " + w.Error(),
-                "jobctl")
-
-            // something outrageous
-            exit = -1024
-            var e *exec.ExitError
-            if errors.As(w, &e) {
-                exit = e.ExitCode()
-            }
-
-            LastExitCode = exit
-        }
-    }
-}
-
 // for some reason not implemented in stdlib
 func tcsetpgrp(fd int, pgrp int) error {
     return unix.IoctlSetPointerInt(fd, unix.TIOCSPGRP, pgrp)
@@ -120,7 +98,6 @@ func InitShellFeatures() bool {
     waitChan = make(chan error, 5)
 
     go signalHandler()
-    go waitHandler()
 
     setSigState()
     pid = os.Getpid()
@@ -161,6 +138,35 @@ func TeardownShell() {
     }
 }
 
+/* Check background processes states
+ * If any have finished, reap them
+ */
+func CheckBGProcs() {
+    for key, proc := range JobMap {
+        maybeFilePath := fmt.Sprintf("/proc/%d", key)
+        _, err := os.Stat(maybeFilePath)
+
+        if os.IsNotExist(err) {
+            if err := proc.Ctl.Process.Release(); err != nil {
+                log.Log(log.ERR,
+                    fmt.Sprintf("Failed to release exited process %d: %s",
+                        key, err.Error()),
+                    "jobctl")
+            } else {
+                // not actually an error, just abusing default visibility
+                log.Log(log.ERR,
+                    fmt.Sprintf("Child [%d] exited", key),
+                    "jobctl")
+                delete(JobMap, key)
+            }
+        } else if err != nil {
+            log.Log(log.DEBUG,
+                "Error checking if process exists in proc: " + err.Error(),
+                "jobctl")
+        }
+    }
+}
+
 /* Makes and stores a new process in the job control
  * uses os/exec Cmd object. sets SysProcAttr.Foreground
  * calls Cmd.Start()
@@ -204,14 +210,7 @@ func LaunchProcess(
     JobMap[cpid] = Proc{ Ctl: cmd, Cancel: cancel }
     CurCancel = &cancel
 
-    if background {
-        cmd.Process.Signal(syscall.SIGTSTP)
-        go func(){
-            waitChan <- cmd.Wait()
-            delete(JobMap, cpid)
-            CurCancel = nil
-        }()
-    } else {
+    if !background {
         cmd.Wait()
         tcsetpgrp(0, pgid)
         delete(JobMap, cpid)
@@ -322,7 +321,7 @@ func Fg(in *ast.Token, vt ast.VarTable, ft ast.FuncTable) *ast.Token {
     }
 
     ipid := int(pid)
-    _, ok := JobMap[ipid]
+    proc, ok := JobMap[ipid]
     if !ok {
         log.Log(log.ERR,
             "Process not found, was it started by this shell?",
@@ -330,7 +329,14 @@ func Fg(in *ast.Token, vt ast.VarTable, ft ast.FuncTable) *ast.Token {
         return nil
     }
 
-    tcsetpgrp(0, ipid)
+    if err := tcsetpgrp(0, ipid); err != nil {
+        log.Log(log.ERR,
+            "Error foregrounding process: " + err.Error(),
+            "fg")
+        return nil
+    }
+
+    proc.Ctl.Wait()
     return nil
 }