From 40956dee436737d9dd40e0b57c6e2ebd26569920 Mon Sep 17 00:00:00 2001
From: Hood <hood@mit.edu>
Date: Wed, 8 Sep 2021 17:49:15 -0700
Subject: [PATCH 2/4] Fix dup

This fixes two problems with the `dup` system calls:
1. `dup` expects that every file descriptor has a corresponding file (so pipes and (https://github.com/emscripten-core/emscripten/issues/14640)
   files that have been unlinked (https://github.com/emscripten-core/emscripten/issues/15012) cannot be duplicated ).
2. The dup'd file descriptor does not share flags and position with the original file desciptor.

This is a simplification of an upstream pull request that would fix this problem.
https://github.com/emscripten-core/emscripten/pull/9396/files
This patch is simpler than the upstream one but leaves NODERAWFS broken.
---
 src/library_fs.js      |  7 ++++++-
 src/library_syscall.js | 12 ++++++------
 2 files changed, 12 insertions(+), 7 deletions(-)

diff --git a/src/library_fs.js b/src/library_fs.js
index 50b06c264..fc8d0193a 100644
--- a/src/library_fs.js
+++ b/src/library_fs.js
@@ -429,11 +429,16 @@ FS.staticInit();` +
           },
           isAppend: {
             get: function() { return (this.flags & {{{ cDefine('O_APPEND') }}}); }
-          }
+          },
+          get flags() { return this.shared.flags; },
+          set flags(value) { this.shared.flags = value; },
+          get position() { return this.shared.position; },
+          set position(value) { this.shared.position = value; },
         };
       }
       // clone it, so we can return an instance of FSStream
       var newStream = new FS.FSStream();
+      newStream.shared = {};
       for (var p in stream) {
         newStream[p] = stream[p];
       }
diff --git a/src/library_syscall.js b/src/library_syscall.js
index c704a0604..09721d025 100644
--- a/src/library_syscall.js
+++ b/src/library_syscall.js
@@ -137,10 +137,10 @@ var SyscallsLibrary = {
       }
       return 0;
     },
-    doDup: function(path, flags, suggestFD) {
+    doDup: function(stream, suggestFD) {
       var suggest = FS.getStream(suggestFD);
       if (suggest) FS.close(suggest);
-      return FS.open(path, flags, 0, suggestFD, suggestFD).fd;
+      return FS.createStream(stream, suggestFD, suggestFD).fd;
     },
     doReadv: function(stream, iov, iovcnt, offset) {
       var ret = 0;
@@ -374,7 +374,7 @@ var SyscallsLibrary = {
   },
   __sys_dup: function(fd) {
     var old = SYSCALLS.getStreamFromFD(fd);
-    return FS.open(old.path, old.flags, 0).fd;
+    return FS.createStream(old, 0).fd;
   },
   __sys_pipe__deps: ['$PIPEFS'],
   __sys_pipe: function(fdPtr) {
@@ -461,7 +461,7 @@ var SyscallsLibrary = {
   __sys_dup2: function(oldfd, suggestFD) {
     var old = SYSCALLS.getStreamFromFD(oldfd);
     if (old.fd === suggestFD) return suggestFD;
-    return SYSCALLS.doDup(old.path, old.flags, suggestFD);
+    return SYSCALLS.doDup(old, suggestFD);
   },
   __sys_getppid__nothrow: true,
   __sys_getppid__proxy: false,
@@ -1108,7 +1108,7 @@ var SyscallsLibrary = {
           return -{{{ cDefine('EINVAL') }}};
         }
         var newStream;
-        newStream = FS.open(stream.path, stream.flags, 0, arg);
+        newStream = FS.createStream(stream, arg);
         return newStream.fd;
       }
       case {{{ cDefine('F_GETFD') }}}:
@@ -1330,7 +1330,7 @@ var SyscallsLibrary = {
     assert(!flags);
 #endif
     if (old.fd === suggestFD) return -{{{ cDefine('EINVAL') }}};
-    return SYSCALLS.doDup(old.path, old.flags, suggestFD);
+    return SYSCALLS.doDup(old, suggestFD);
   },
 
   __sys_prlimit64: function(pid, resource, new_limit, old_limit) {
-- 
2.25.1