reuse some FS errors in places where overhead is high and stack importance is low

2 files changed, 7 insertions, 1 deletions

diff --git a/src/library_fs.js b/src/library_fs.js
index bd1522a8..90f5d3b0 100644
--- a/src/library_fs.js
+++ b/src/library_fs.js
@@ -28,6 +28,7 @@ mergeInto(LibraryManager.library, {
     ignorePermissions: true,
     
     ErrnoError: null, // set during init
+    genericErrors: {},
 
     handleFSError: function(e) {
       if (!(e instanceof FS.ErrnoError)) throw e + ' : ' + stackTrace();
@@ -1079,6 +1080,11 @@ mergeInto(LibraryManager.library, {
       };
       FS.ErrnoError.prototype = new Error();
       FS.ErrnoError.prototype.constructor = FS.ErrnoError;
+      // Some errors may happen quite a bit, to avoid overhead we reuse them (and suffer a lack of stack info)
+      [ERRNO_CODES.ENOENT].forEach(function(code) {
+        FS.genericErrors[code] = new FS.ErrnoError(code);
+        FS.genericErrors[code].stack = '<generic error, no stack>';
+      });
     },
     staticInit: function() {
       FS.ensureErrnoError();
diff --git a/src/library_memfs.js b/src/library_memfs.js
index 94fd767e..51a8da16 100644
--- a/src/library_memfs.js
+++ b/src/library_memfs.js
@@ -117,7 +117,7 @@ mergeInto(LibraryManager.library, {
         }
       },
       lookup: function(parent, name) {
-        throw new FS.ErrnoError(ERRNO_CODES.ENOENT);
+        throw FS.genericErrors[ERRNO_CODES.ENOENT];
       },
       mknod: function(parent, name, mode, dev) {
         return MEMFS.createNode(parent, name, mode, dev);