Wrap readdirSync to support image without /usr/sbin (#11)

lib/detect-libc.js

@@ -28,6 +28,13 @@ function versionFromMuslLdd (out) {
   return out.split(/[\r\n]+/)[1].trim().split(/\s/)[1];
 }
 
+function safeReaddirSync (path) {
+  try {
+    return readdirSync(path);
+  } catch (e) {}
+  return [];
+}
+
 var family = '';
 var version = '';
 var method = '';
@@ -52,23 +59,23 @@ if (platform === 'linux') {
       method = 'ldd';
     } else {
       // Try filesystem (family only)
-      try {
-        var lib = readdirSync('/lib');
-        var usrSbin = readdirSync('/usr/sbin');
-        if (lib.some(contains('-linux-gnu'))) {
-          family = GLIBC;
-          method = 'filesystem';
-        } else if (lib.some(contains('libc.musl-'))) {
-          family = MUSL;
-          method = 'filesystem';
-        } else if (lib.some(contains('ld-musl-'))) {
-          family = MUSL;
-          method = 'filesystem';
-        } else if (usrSbin.some(contains('glibc'))) {
+      var lib = safeReaddirSync('/lib');
+      if (lib.some(contains('-linux-gnu'))) {
+        family = GLIBC;
+        method = 'filesystem';
+      } else if (lib.some(contains('libc.musl-'))) {
+        family = MUSL;
+        method = 'filesystem';
+      } else if (lib.some(contains('ld-musl-'))) {
+        family = MUSL;
+        method = 'filesystem';
+      } else {
+        var usrSbin = safeReaddirSync('/usr/sbin');
+        if (usrSbin.some(contains('glibc'))) {
           family = GLIBC;
           method = 'filesystem';
         }
-      } catch (e) {}
+      }
     }
   }
 }

package.json

@@ -1,6 +1,6 @@
 {
   "name": "detect-libc",
-  "version": "1.0.2",
+  "version": "1.0.3",
   "description": "Node.js module to detect the C standard library (libc) implementation family and version",
   "main": "lib/detect-libc.js",
   "bin": {

tests/integration/spec.json

@@ -133,5 +133,14 @@
       "4.x": { "$detect.method": "getconf" }
     },
     "$libc.family": "glibc"
+  },
+
+  "minimal": {
+    "dist": {
+      "rmg": { "$detect.method": "filesystem", "$libc.family": "glibc", "$libc.version": "unknown", "$dist.name": "unknown", "$node.version": "8.8.1" }
+    },
+    "node": {
+      "8.x": { }
+    }
   }
 }

tests/integration/spec/minimal/minimal-rmg-nodejs-8.x.dockerfile

@@ -0,0 +1,19 @@
+# Provided by https://github.com/rmg
+
+FROM node:8.8.1
+RUN mkdir -p /rootfs
+RUN ldd /bin/sh \
+        /usr/local/bin/node \
+        /lib/x86_64-linux-gnu/libnss_files.so.* \
+        /lib/x86_64-linux-gnu/libnss_dns.so.* \
+    | grep -o -e '\/\(usr\|lib\)[^ :]\+' \
+    | sort -u | tee /rootfs.list \
+ && echo /bin/sh >> /rootfs.list
+
+# The use of 'tar | tar' here is a quick'n'dirty replacement for rsync without
+# adding any deps: rsync --files-from=/rootfs.list -L -pog / /rootfs/
+RUN cat /rootfs.list | tar -T- -cphf- | tar -C /rootfs -xpf-
+
+# noop
+FROM scratch
+COPY --from=0 /rootfs/ /