[WASMFS] Comprehensive dup test (emscripten-core#15550)

Relevant Issue: emscripten-core#15041

Verifies that this issue has been fixed with the dup syscall: emscripten-core#4017

Author: ethanalee

tests/test_other.py

@@ -11153,8 +11153,10 @@ def test_unistd_fstatfs(self):
 
   # WASMFS tests
 
-  @also_with_wasmfs
-  def test_unistd_dup(self):
+  # TODO: This test will only work with the new file system.
+  # Addresses this issue: https://github.com/emscripten-core/emscripten/issues/4017
+  # The new file system also correctly identifies errors that the JS file system missed.
+  def test_wasmfs_dup(self):
     self.set_setting('WASMFS')
     self.do_run_in_out_file_test('wasmfs/wasmfs_dup.c')
 

tests/wasmfs/wasmfs_dup.c

@@ -9,6 +9,7 @@
 #include <errno.h>
 #include <fcntl.h>
 #include <stdio.h>
+#include <sys/stat.h>
 #include <unistd.h>
 
 // FIXME: Merge this standalone test back into dup.c after new FS can support
@@ -56,12 +57,14 @@ int main() {
   errno = 0;
   f5 = dup2(f4, -1);
   assert(f5 == -1);
+  // This error is not reported in the JS filesystem.
   assert(errno == EBADF);
 
   // Try calling dup2 with an invalid oldfd
   errno = 0;
   int f6 = dup2(-1, f5);
   assert(f6 == -1);
+  // This error is not reported in the JS filesystem.
   assert(errno == EBADF);
 
   // Try assigning a large fd
@@ -72,8 +75,57 @@ int main() {
 
   errno = 0;
   int f9 = dup(-1);
+  // This error is not reported in the JS filesystem.
   assert(f9 == -1);
   assert(errno == EBADF);
 
+  off_t offset;
+
+  errno = 0;
+  printf("DUP\n");
+  mkdir("working", 0700);
+  f = open("working/file", O_RDWR | O_CREAT);
+  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));
+  printf("\n");
+  errno = 0;
+
+  printf("DUP2\n");
+  f = open("/", O_RDONLY);
+  f2 = open("/", O_RDONLY);
+  f3 = dup2(f, f2);
+  printf("errno: %d\n", errno);
+  printf("f: %d\n", f != f2 && f != f3);
+  printf("f2,f3: %d\n", f2 == f3);
+  printf("close(f1): %d\n", close(f));
+  printf("close(f2): %d\n", close(f2));
+  printf("close(f3): %d\n", close(f3));
+  errno = 0;
+
   return 0;
 }

tests/wasmfs/wasmfs_dup.out

@@ -1,3 +1,4 @@
+DUP
 STDOUT
 CAN PRINT TO STDOUT WITH fd = 3
 DUP2
@@ -6,3 +7,26 @@ CAN PRINT TO STDOUT WITH fd = 5
 CAN PRINT TO STDOUT WITH fd = 5
 CAN PRINT TO STDOUT WITH fd = 5
 CAN PRINT TO STDOUT WITH f8 = 4069
+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
+
+DUP2
+errno: 0
+f: 1
+f2,f3: 1
+close(f1): 0
+close(f2): 0
+close(f3): 0