Improve discovery of coroutine shim

The fiber-shim script couldn't find coroutine.so on npm installations
with unexcepted configurations. This makes the script use
require.resolve() internally which should improve compatibility.

Closes gh-9

bin/node-fibers

@@ -1,2 +1,33 @@
 #!/bin/bash
-`dirname "$0"`/fiber-shim node "$@"
+
+NODE=`which node`
+if [[ -z "$NODE" ]]; then
+	echo "Could not find node in PATH!" 1>&2
+	exit 1
+fi
+
+if [[ -e `dirname "$0"`/../src/fibers.node ]]; then
+	# running straight from dist
+	FIBERS_ROOT=`dirname "$0"`/../src
+else
+	# in npm
+	FIBERS_PATH=`echo 'require.resolve("fibers")' | $NODE | head -n1 | egrep -o '/[^'\'']+'`
+	FIBERS_ROOT=`dirname "$FIBERS_PATH"`/src
+	if [[ ! -e "$FIBERS_ROOT/fibers.node" ]]; then
+		echo "Could not find the coroutine shim!" 1>&2
+		exit 1
+	fi
+fi
+
+UNAME=`uname`
+if [[ "$UNAME" == "Linux" ]]; then
+	FIBER_SHIM=1 \
+	LD_PRELOAD="$FIBERS_ROOT/coroutine.so" \
+	$NODE "$@"
+elif [[ "$UNAME" == "Darwin" ]]; then
+	FIBER_SHIM=1 \
+	DYLD_INSERT_LIBRARIES="$FIBERS_ROOT/coroutine.dylib" \
+	DYLD_FORCE_FLAT_NAMESPACE=1 \
+	DYLD_LIBRARY_PATH="$FIBERS_ROOT" \
+	$NODE "$@"
+fi

fibers.js

@@ -1,7 +1,7 @@
 var fs = require('fs');
 
 if (fs.statSync(process.execPath).mtime >
-		fs.statSync(__dirname + '/src/fibers.node').mtime) {
+		fs.statSync(require.resolve('./src/fibers')).mtime) {
 	throw new Error(
 		'`node` has a newer mtime than `fiber`; it is possible your build is out of date. This ' +
 		'could happen if you upgrade node. Try `npm rebuild fibers` to rebuild. If that doesn\'t ' +

package.json

@@ -1,6 +1,6 @@
 {
 	"name": "fibers",
-	"version": "0.2.1",
+	"version": "0.2.2",
 	"description": "Cooperative multi-tasking for Javascript; or, the closest thing to a thread you'll see in node",
 	"keywords": ["fiber", "fibers", "coroutine", "thread", "async", "parallel", "worker"],
 	"homepage": "https://github.com/laverdet/node-fibers",
@@ -10,8 +10,7 @@
 		"install": "make clean all"
 	},
 	"bin": {
-		"node-fibers": "./bin/node-fibers",
-		"fiber-shim": "./bin/fiber-shim"
+		"node-fibers": "./bin/node-fibers"
 	},
 	"man": "./man/fibers.1",
 	"repository": {
@@ -20,6 +19,6 @@
 	},
 	"os": ["macos", "linux"],
 	"engines": {
-		"node": ">=0.2.0"
+		"node": ">=0.3.0"
 	}
 }