signing requests

1 files changed, 107 insertions, 0 deletions

diff --git a/gosrc/pipes.go b/gosrc/pipes.go
new file mode 100644
index 0000000..f668821
--- /dev/null
+++ b/gosrc/pipes.go
@@ -0,0 +1,107 @@
+package main
+
+import (
+	"bytes"
+	"fmt"
+	"io"
+	"os/exec"
+	"strings"
+)
+
+// Convert a shell command with a series of pipes into
+// correspondingly piped list of *exec.Cmd
+// If an arg has spaces, this will fail
+func RunString(s string) (string, error) {
+	buf := bytes.NewBuffer([]byte{})
+	sp := strings.Split(s, "|")
+	cmds := make([]*exec.Cmd, len(sp))
+	// create the commands
+	for i, c := range sp {
+		cs := strings.Split(strings.TrimSpace(c), " ")
+		cmd := cmdFromStrings(cs)
+		cmds[i] = cmd
+	}
+
+	cmds = AssemblePipes(cmds, nil, buf)
+	if err := RunCmds(cmds); err != nil {
+		return "", err
+	}
+
+	b := buf.Bytes()
+	return string(b), nil
+}
+
+func cmdFromStrings(cs []string) *exec.Cmd {
+	if len(cs) == 1 {
+		return exec.Command(cs[0])
+	} else if len(cs) == 2 {
+		return exec.Command(cs[0], cs[1])
+	}
+	return exec.Command(cs[0], cs[1:]...)
+}
+
+// Convert sequence of tokens into commands,
+// using "|" as a delimiter
+func RunStrings(tokens ...string) (string, error) {
+	if len(tokens) == 0 {
+		return "", nil
+	}
+	buf := bytes.NewBuffer([]byte{})
+	cmds := []*exec.Cmd{}
+	args := []string{}
+	// accumulate tokens until a |
+	for _, t := range tokens {
+		if t != "|" {
+			args = append(args, t)
+		} else {
+			cmds = append(cmds, cmdFromStrings(args))
+			args = []string{}
+		}
+	}
+	cmds = append(cmds, cmdFromStrings(args))
+	cmds = AssemblePipes(cmds, nil, buf)
+	if err := RunCmds(cmds); err != nil {
+		return "", fmt.Errorf("%s; %s", err.Error(), string(buf.Bytes()))
+	}
+
+	b := buf.Bytes()
+	return string(b), nil
+}
+
+// Pipe stdout of each command into stdin of next
+func AssemblePipes(cmds []*exec.Cmd, stdin io.Reader, stdout io.Writer) []*exec.Cmd {
+	cmds[0].Stdin = stdin
+	cmds[0].Stderr = stdout
+	// assemble pipes
+	for i, c := range cmds {
+		if i < len(cmds)-1 {
+			cmds[i+1].Stdin, _ = c.StdoutPipe()
+			cmds[i+1].Stderr = stdout
+		} else {
+			c.Stdout = stdout
+			c.Stderr = stdout
+		}
+	}
+	return cmds
+}
+
+// Run series of piped commands
+func RunCmds(cmds []*exec.Cmd) error {
+	// start processes in descending order
+	for i := len(cmds) - 1; i > 0; i-- {
+		if err := cmds[i].Start(); err != nil {
+			return err
+		}
+	}
+	// run the first process
+	if err := cmds[0].Run(); err != nil {
+		return err
+	}
+	// wait on processes in ascending order
+	for i := 1; i < len(cmds); i++ {
+		if err := cmds[i].Wait(); err != nil {
+			return err
+		}
+	}
+	return nil
+}