From 7ca2f5840583f35b550f5d07ffa9971f5a4bffb9 Mon Sep 17 00:00:00 2001
From: Thomas Lively <tlively@google.com>
Date: Fri, 25 Feb 2022 16:50:00 -0800
Subject: [PATCH] Test more edge cases in test_unlink

Test that open files can still be read or written after they are unlinked and
that open directories can still be read after they are unlinked but that they
cannot gain new children.

Somewhat surprisingly, the old filesystem implementation passes this test with
no modifications. WasmFS cannot run it because it does not have an
implementation of `unlinkat`, and even if it did, it still would not pass.
---
 tests/other/test_unlink.cpp | 42 ++++++++++++++++++++++++++++++++-----
 1 file changed, 37 insertions(+), 5 deletions(-)

diff --git a/tests/other/test_unlink.cpp b/tests/other/test_unlink.cpp
index d0e40f18411db..f03ec270e2276 100644
--- a/tests/other/test_unlink.cpp
+++ b/tests/other/test_unlink.cpp
@@ -3,8 +3,11 @@
 // University of Illinois/NCSA Open Source License.  Both these licenses can be
 // found in the LICENSE file.
 
+#include <dirent.h>
+#include <errno.h>
 #include <fcntl.h>
 #include <stdio.h>
+#include <string.h>
 #include <sys/stat.h>
 #include <unistd.h>
 
@@ -13,13 +16,10 @@ int main() {
   const char *dirname = "test";
 
   // Create a file
-  FILE *f = fopen(filename, "wb");
+  FILE* f = fopen(filename, "w+");
   if (f == NULL) {
     return 1;
   }
-  if (fclose(f)) {
-    return 1;
-  }
   // Check it exists
   if (access(filename, F_OK) != 0) {
     return 1;
@@ -32,9 +32,30 @@ int main() {
   if (access(filename, F_OK) != -1) {
     return 1;
   }
+  // Check that we can still write to it
+  if (fwrite("hello", 1, 5, f) != 5) {
+    return 1;
+  }
+  // And seek in it.
+  if (fseek(f, 0, SEEK_SET) != 0) {
+    return 1;
+  }
+  // And read from it.
+  char buf[6] = {0};
+  if (fread(buf, 1, 5, f) != 5 || strcmp("hello", buf) != 0) {
+    return 1;
+  }
+  if (fclose(f)) {
+    return 1;
+  }
 
   // Create a directory
-  if (mkdir(dirname, 0700)) {
+  if (mkdir(dirname, 0700) != 0) {
+    return 1;
+  }
+  // Open the directory
+  DIR* d = opendir(dirname);
+  if (d == NULL) {
     return 1;
   }
   // Delete the directory
@@ -45,6 +66,17 @@ int main() {
   if (access(dirname, F_OK) != -1) {
     return 1;
   }
+  // Check that we can still read the directory, but that it is empty.
+  errno = 0;
+  if (readdir(d) != NULL || errno != 0) {
+    return 1;
+  }
+  // Check that we *cannot* create a child
+  if (openat(dirfd(d), filename, O_CREAT | O_WRONLY, S_IRWXU) != -1) {
+    return 1;
+  }
+
+  closedir(d);
 
   printf("ok\n");