Test more edge cases in test_unlink

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");