Fix dup*() syscalls, close emscripten-core#4017

Author: socketpair

src/library_syscall.js

@@ -128,10 +128,12 @@ 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;
+
+      FS.streams[suggestFD] = stream;
+      return suggestFD;
     },
     doReadv: function(stream, iov, iovcnt, offset) {
       var ret = 0;
@@ -375,7 +377,7 @@ var SyscallsLibrary = {
   },
   __syscall41: function(which, varargs) { // dup
     var old = SYSCALLS.getStreamFromFD();
-    return FS.open(old.path, old.flags, 0).fd;
+    return SYSCALLS.doDup(old, FS.nextfd());
   },
   __syscall42__deps: ['$PIPEFS'],
   __syscall42: function(which, varargs) { // pipe
@@ -468,7 +470,7 @@ var SyscallsLibrary = {
   __syscall63: function(which, varargs) { // dup2
     var old = SYSCALLS.getStreamFromFD(), suggestFD = SYSCALLS.get();
     if (old.fd === suggestFD) return suggestFD;
-    return SYSCALLS.doDup(old.path, old.flags, suggestFD);
+    return SYSCALLS.doDup(old, suggestFD);
   },
   __syscall64__deps: ['$PROCINFO'],
   __syscall64: function(which, varargs) { // getppid
@@ -666,7 +668,7 @@ var SyscallsLibrary = {
         for (var i = 0; i < num; i++) {
           var iovbase = {{{ makeGetValue('iov', '(' + C_STRUCTS.iovec.__size__ + ' * i) + ' + C_STRUCTS.iovec.iov_base, 'i8*') }}};
           var iovlen = {{{ makeGetValue('iov', '(' + C_STRUCTS.iovec.__size__ + ' * i) + ' + C_STRUCTS.iovec.iov_len, 'i32') }}};
-          for (var j = 0; j < iovlen; j++) {  
+          for (var j = 0; j < iovlen; j++) {
             view[offset++] = {{{ makeGetValue('iovbase', 'j', 'i8') }}};
           }
         }
@@ -852,7 +854,7 @@ var SyscallsLibrary = {
 #endif
 
     var total = 0;
-    
+
     var srcReadLow = (readfds ? {{{ makeGetValue('readfds', 0, 'i32') }}} : 0),
         srcReadHigh = (readfds ? {{{ makeGetValue('readfds', 4, 'i32') }}} : 0);
     var srcWriteLow = (writefds ? {{{ makeGetValue('writefds', 0, 'i32') }}} : 0),
@@ -919,7 +921,7 @@ var SyscallsLibrary = {
       {{{ makeSetValue('exceptfds', '0', 'dstExceptLow', 'i32') }}};
       {{{ makeSetValue('exceptfds', '4', 'dstExceptHigh', 'i32') }}};
     }
-    
+
     return total;
   },
   __syscall144: function(which, varargs) { // msync
@@ -1184,14 +1186,14 @@ var SyscallsLibrary = {
 #else
     var stream = SYSCALLS.getStreamFromFD(), cmd = SYSCALLS.get();
     switch (cmd) {
+      // TODO: FreeBSD also defines F_DUP2FD and F_DUP2FD_CLOEXEC
+      case {{{ cDefine('F_DUPFD_CLOEXEC') }}}: // ignore O_CLOEXEC in single process environment
       case {{{ cDefine('F_DUPFD') }}}: {
         var arg = SYSCALLS.get();
         if (arg < 0) {
           return -{{{ cDefine('EINVAL') }}};
         }
-        var newStream;
-        newStream = FS.open(stream.path, stream.flags, 0, arg);
-        return newStream.fd;
+        return SYSCALLS.doDup(stream, FS.nextfd(arg));
       }
       case {{{ cDefine('F_GETFD') }}}:
       case {{{ cDefine('F_SETFD') }}}:
@@ -1400,7 +1402,7 @@ var SyscallsLibrary = {
     nanoseconds = {{{ makeGetValue('times', C_STRUCTS.timespec.tv_nsec, 'i32') }}};
     var mtime = (seconds*1000) + (nanoseconds/(1000*1000));
     FS.utime(path, atime, mtime);
-    return 0;  
+    return 0;
   },
   __syscall324: function(which, varargs) { // fallocate
     var stream = SYSCALLS.getStreamFromFD(), mode = SYSCALLS.get(), offset = SYSCALLS.get64(), len = SYSCALLS.get64();
@@ -1418,8 +1420,13 @@ var SyscallsLibrary = {
 #if ASSERTIONS
     assert(!flags);
 #endif
-    if (old.fd === suggestFD) return -{{{ cDefine('EINVAL') }}};
-    return SYSCALLS.doDup(old.path, old.flags, suggestFD);
+    if (old.fd === suggestFD) return -ERRNO_CODES.EINVAL;
+
+    // intentionally ignore flags, since O_CLOEXEC make no sense in
+    // singleprocess environment
+    if (flags & ~{{{ cDefine('O_CLOEXEC') }}}) return -ERRNO_CODES.EINVAL;
+
+    return SYSCALLS.doDup(old, suggestFD);
   },
   __syscall331: function(which, varargs) { // pipe2
     return -{{{ cDefine('ENOSYS') }}}; // unsupported feature

tests/unistd/dup.c

@@ -12,14 +12,42 @@
 
 int main() {
   int f, f2, f3;
+  off_t offset;
+
+  EM_ASM(
+    FS.mkdir('/working');
+#if NODEFS
+    FS.mount(NODEFS, { root: '.' }, '/working');
+#endif
+    FS.writeFile('/working/file', 'test');
+  );
 
   printf("DUP\n");
-  f = open("/", O_RDONLY);
-  f2 = open("/", O_RDONLY);
+  f = open("/working/file", O_RDONLY);
+  f2 = open("/working/file", O_RDONLY);
   f3 = dup(f);
   printf("errno: %d\n", errno);
   printf("f: %d\n", f != f2 && f != f3);
   printf("f2,f3: %d\n", f2 != f3);
+
+  // dup()ed file descriptors should share all flags and even seek position
+  offset = lseek(f3, 0, SEEK_CUR);
+  printf("1. f3 offset was %d.    Should be 0\n", (int)offset);
+  offset = lseek(f, 1, SEEK_SET);
+  printf("2. f  offset set to %d. Should be 1\n", (int)offset);
+  offset = lseek(f2, 2, SEEK_SET);
+  printf("3. f2 offset set to %d. Should be 2\n", (int)offset);
+  offset = lseek(f, 0, SEEK_CUR);
+  printf("4. f  offset now is %d. Should be 1\n", (int)offset);
+  offset = lseek(f2, 0, SEEK_CUR);
+  printf("5. f2 offset now is %d. Should be 2\n", (int)offset);
+  offset = lseek(f3, 0, SEEK_CUR);
+  printf("6. f3 offset now is %d. Should be 1 (and not 0)\n", (int)offset);
+  offset = lseek(f3, 3, SEEK_SET);
+  printf("7. f3 offset set to %d. Should be 3\n", (int)offset);
+  offset = lseek(f, 0, SEEK_CUR);
+  printf("8. f  offset now is %d. Should be 3 (and not 1)\n", (int)offset);
+
   printf("close(f1): %d\n", close(f));
   printf("close(f2): %d\n", close(f2));
   printf("close(f3): %d\n", close(f3));
@@ -36,7 +64,6 @@ int main() {
   printf("close(f1): %d\n", close(f));
   printf("close(f2): %d\n", close(f2));
   printf("close(f3): %d\n", close(f3));
-  printf("\n");
   errno = 0;
 
   return 0;

tests/unistd/dup.out

@@ -2,6 +2,14 @@ DUP
 errno: 0
 f: 1
 f2,f3: 1
+1. f3 offset was 0.    Should be 0
+2. f  offset set to 1. Should be 1
+3. f2 offset set to 2. Should be 2
+4. f  offset now is 1. Should be 1
+5. f2 offset now is 2. Should be 2
+6. f3 offset now is 1. Should be 1 (and not 0)
+7. f3 offset set to 3. Should be 3
+8. f  offset now is 3. Should be 3 (and not 1)
 close(f1): 0
 close(f2): 0
 close(f3): 0