Add a platform variant for installing a musl binary (#1836)

Add a platform variant for installing a musl binary

lib/extensions.js

@@ -23,6 +23,7 @@ function getHumanPlatform(platform) {
     case 'darwin': return 'OS X';
     case 'freebsd': return 'FreeBSD';
     case 'linux': return 'Linux';
+    case 'linux_musl': return 'Linux/musl';
     case 'win32': return 'Windows';
     default: return false;
   }
@@ -171,7 +172,9 @@ function getArgument(name, args) {
  */
 
 function getBinaryName() {
-  var binaryName;
+  var binaryName,
+    variant,
+    platform = process.platform;
 
   if (getArgument('--sass-binary-name')) {
     binaryName = getArgument('--sass-binary-name');
@@ -182,8 +185,13 @@ function getBinaryName() {
   } else if (pkg.nodeSassConfig && pkg.nodeSassConfig.binaryName) {
     binaryName = pkg.nodeSassConfig.binaryName;
   } else {
+    variant = getPlatformVariant();
+    if (variant) {
+      platform += '_' + variant;
+    }
+
     binaryName = [
-      process.platform, '-',
+      platform, '-',
       process.arch, '-',
       process.versions.modules
     ].join('');
@@ -256,7 +264,7 @@ function getBinaryPath() {
   } else if (pkg.nodeSassConfig && pkg.nodeSassConfig.binaryPath) {
     binaryPath = pkg.nodeSassConfig.binaryPath;
   } else {
-    binaryPath = path.join(defaultBinaryPath, getBinaryName().replace(/_/, '/'));
+    binaryPath = path.join(defaultBinaryPath, getBinaryName().replace(/_(?=binding\.node)/, '/'));
   }
 
   return binaryPath;
@@ -359,6 +367,36 @@ function getVersionInfo(binding) {
   ].join(eol);
 }
 
+/**
+ * Gets the platform variant, currently either an empty string or 'musl' for Linux/musl platforms.
+ *
+ * @api public
+ */
+
+function getPlatformVariant() {
+  var contents = '';
+
+  if (process.platform !== 'linux') {
+    return '';
+  }
+
+  try {
+    contents = fs.readFileSync(process.execPath);
+
+    // Buffer.indexOf was added in v1.5.0 so cast to string for old node
+    // Delay contents.toStrings because it's expensive
+    if (!contents.indexOf) {
+      contents = contents.toString();
+    }
+
+    if (contents.indexOf('libc.musl-x86_64.so.1') !== -1) {
+      return 'musl';
+    }
+  } catch (err) { } // eslint-disable-line no-empty
+
+  return '';
+}
+
 module.exports.hasBinary = hasBinary;
 module.exports.getBinaryUrl = getBinaryUrl;
 module.exports.getBinaryName = getBinaryName;