1 files changed, 183 insertions, 0 deletions
diff --git a/libgo/go/exec/exec.go b/libgo/go/exec/exec.go
new file mode 100644
index 000000000..ba9bd2472
--- /dev/null
+++ b/libgo/go/exec/exec.go
@@ -0,0 +1,183 @@
+// Copyright 2009 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.
+
+// The exec package runs external commands.
+package exec
+
+import (
+	"os"
+)
+
+// Arguments to Run.
+const (
+	DevNull = iota
+	PassThrough
+	Pipe
+	MergeWithStdout
+)
+
+// A Cmd represents a running command.
+// Stdin, Stdout, and Stderr are Files representing pipes
+// connected to the running command's standard input, output, and error,
+// or else nil, depending on the arguments to Run.
+// Pid is the running command's operating system process ID.
+type Cmd struct {
+	Stdin  *os.File
+	Stdout *os.File
+	Stderr *os.File
+	Pid    int
+}
+
+// Given mode (DevNull, etc), return file for child
+// and file to record in Cmd structure.
+func modeToFiles(mode, fd int) (*os.File, *os.File, os.Error) {
+	switch mode {
+	case DevNull:
+		rw := os.O_WRONLY
+		if fd == 0 {
+			rw = os.O_RDONLY
+		}
+		f, err := os.Open(os.DevNull, rw, 0)
+		return f, nil, err
+	case PassThrough:
+		switch fd {
+		case 0:
+			return os.Stdin, nil, nil
+		case 1:
+			return os.Stdout, nil, nil
+		case 2:
+			return os.Stderr, nil, nil
+		}
+	case Pipe:
+		r, w, err := os.Pipe()
+		if err != nil {
+			return nil, nil, err
+		}
+		if fd == 0 {
+			return r, w, nil
+		}
+		return w, r, nil
+	}
+	return nil, nil, os.EINVAL
+}
+
+// Run starts the named binary running with
+// arguments argv and environment envv.
+// It returns a pointer to a new Cmd representing
+// the command or an error.
+//
+// The parameters stdin, stdout, and stderr
+// specify how to handle standard input, output, and error.
+// The choices are DevNull (connect to /dev/null),
+// PassThrough (connect to the current process's standard stream),
+// Pipe (connect to an operating system pipe), and
+// MergeWithStdout (only for standard error; use the same
+// file descriptor as was used for standard output).
+// If a parameter is Pipe, then the corresponding field (Stdin, Stdout, Stderr)
+// of the returned Cmd is the other end of the pipe.
+// Otherwise the field in Cmd is nil.
+func Run(name string, argv, envv []string, dir string, stdin, stdout, stderr int) (p *Cmd, err os.Error) {
+	p = new(Cmd)
+	var fd [3]*os.File
+
+	if fd[0], p.Stdin, err = modeToFiles(stdin, 0); err != nil {
+		goto Error
+	}
+	if fd[1], p.Stdout, err = modeToFiles(stdout, 1); err != nil {
+		goto Error
+	}
+	if stderr == MergeWithStdout {
+		fd[2] = fd[1]
+	} else if fd[2], p.Stderr, err = modeToFiles(stderr, 2); err != nil {
+		goto Error
+	}
+
+	// Run command.
+	p.Pid, err = os.ForkExec(name, argv, envv, dir, fd[0:])
+	if err != nil {
+		goto Error
+	}
+	if fd[0] != os.Stdin {
+		fd[0].Close()
+	}
+	if fd[1] != os.Stdout {
+		fd[1].Close()
+	}
+	if fd[2] != os.Stderr && fd[2] != fd[1] {
+		fd[2].Close()
+	}
+	return p, nil
+
+Error:
+	if fd[0] != os.Stdin && fd[0] != nil {
+		fd[0].Close()
+	}
+	if fd[1] != os.Stdout && fd[1] != nil {
+		fd[1].Close()
+	}
+	if fd[2] != os.Stderr && fd[2] != nil && fd[2] != fd[1] {
+		fd[2].Close()
+	}
+	if p.Stdin != nil {
+		p.Stdin.Close()
+	}
+	if p.Stdout != nil {
+		p.Stdout.Close()
+	}
+	if p.Stderr != nil {
+		p.Stderr.Close()
+	}
+	return nil, err
+}
+
+// Wait waits for the running command p,
+// returning the Waitmsg returned by os.Wait and an error.
+// The options are passed through to os.Wait.
+// Setting options to 0 waits for p to exit;
+// other options cause Wait to return for other
+// process events; see package os for details.
+func (p *Cmd) Wait(options int) (*os.Waitmsg, os.Error) {
+	if p.Pid <= 0 {
+		return nil, os.ErrorString("exec: invalid use of Cmd.Wait")
+	}
+	w, err := os.Wait(p.Pid, options)
+	if w != nil && (w.Exited() || w.Signaled()) {
+		p.Pid = -1
+	}
+	return w, err
+}
+
+// Close waits for the running command p to exit,
+// if it hasn't already, and then closes the non-nil file descriptors
+// p.Stdin, p.Stdout, and p.Stderr.
+func (p *Cmd) Close() os.Error {
+	if p.Pid > 0 {
+		// Loop on interrupt, but
+		// ignore other errors -- maybe
+		// caller has already waited for pid.
+		_, err := p.Wait(0)
+		for err == os.EINTR {
+			_, err = p.Wait(0)
+		}
+	}
+
+	// Close the FDs that are still open.
+	var err os.Error
+	if p.Stdin != nil && p.Stdin.Fd() >= 0 {
+		if err1 := p.Stdin.Close(); err1 != nil {
+			err = err1
+		}
+	}
+	if p.Stdout != nil && p.Stdout.Fd() >= 0 {
+		if err1 := p.Stdout.Close(); err1 != nil && err != nil {
+			err = err1
+		}
+	}
+	if p.Stderr != nil && p.Stderr != p.Stdout && p.Stderr.Fd() >= 0 {
+		if err1 := p.Stderr.Close(); err1 != nil && err != nil {
+			err = err1
+		}
+	}
+	return err
+}