ipfs cat

cli/cat.go

+package main
+
+import (
+	"github.com/gonuts/flag"
+	"github.com/jbenet/commander"
+	u "github.com/jbenet/go-ipfs/util"
+	mh "github.com/jbenet/go-multihash"
+)
+
+var cmdIpfsCat = &commander.Command{
+	UsageLine: "cat",
+	Short:     "Show ipfs object data.",
+	Long: `ipfs cat <ipfs-path> - Show ipfs object data.
+
+    Retrieves the object named by <ipfs-path> and displays the Data
+    it contains.
+`,
+	Run:  catCmd,
+	Flag: *flag.NewFlagSet("ipfs-cat", flag.ExitOnError),
+}
+
+func catCmd(c *commander.Command, inp []string) error {
+	if len(inp) < 1 {
+		u.POut(c.Long)
+		return nil
+	}
+
+	// for now only hashes, no path resolution
+	h, err := mh.FromB58String(inp[0])
+	if err != nil {
+		return err
+	}
+
+	n, err := localNode()
+	if err != nil {
+		return err
+	}
+
+	nd, err := n.GetDagNode(u.Key(h))
+	if err != nil {
+		return err
+	}
+
+	u.POut("%s", nd.Data)
+	return nil
+}

cli/ipfs.go

@@ -37,6 +37,7 @@ Use "ipfs help <command>" for more information about a command.
 	Run: ipfsCmd,
 	Subcommands: []*commander.Command{
 		cmdIpfsAdd,
+		cmdIpfsCat,
 		cmdIpfsVersion,
 		cmdIpfsCommands,
 	},
@@ -52,7 +53,7 @@ func main() {
 	err := CmdIpfs.Dispatch(os.Args[1:])
 	if err != nil {
 		if len(err.Error()) > 0 {
-			fmt.Fprintf(os.Stderr, "%v\n", err)
+			fmt.Fprintf(os.Stderr, "ipfs %s: %v\n", os.Args[1], err)
 		}
 		os.Exit(1)
 	}

core/core.go

@@ -83,3 +83,12 @@ func (n *IpfsNode) AddDagNode(nd *merkledag.Node) (u.Key, error) {
 
 	return n.Blocks.AddBlock(b)
 }
+
+func (n *IpfsNode) GetDagNode(k u.Key) (*merkledag.Node, error) {
+	b, err := n.Blocks.GetBlock(k)
+	if err != nil {
+		return nil, err
+	}
+
+	return merkledag.Decoded(b.Data)
+}

merkledag/coding.go

@@ -71,3 +71,9 @@ func (n *Node) Encoded(force bool) ([]byte, error) {
 
 	return n.encoded, nil
 }
+
+func Decoded(encoded []byte) (*Node, error) {
+	n := &Node{}
+	err := n.Unmarshal(encoded)
+	return n, err
+}