fix(monika): _kern_close double close

Fixed a bug when `_kern_close` translates into two host `close`
syscalls when the file descriptor refers to a directory.

This bug appear harmless for single-threaded programs but affects
programs like `launch_daemon` which opens a directory on both the
launcher thread and the main worker thread. The data race of one
thread closing a fd a second time right after the other thread
opening a new fd makes those programs think that there was
actually an error with the new fd.

After this fix `launch_daemon` should reliably launch on
`hyclone_server` startup. There should be no more
"id: cannot find name for user ID 0" errors on HyClone.

haiku_loader/loader_readdir.h

@@ -9,7 +9,7 @@
 // a directory fd may cause directory entries to be left behind.
 
 void loader_opendir(int fd);
-void loader_closedir(int fd);
+bool loader_closedir(int fd);
 int loader_readdir(int fd, void* buffer, size_t bufferSize, int maxCount);
 void loader_rewinddir(int fd);
 void loader_dupdir(int oldFd, int newFd);

haiku_loader/sys/linux/loader_readdir.cpp

@@ -67,10 +67,10 @@ void loader_opendir(int fd)
     loader_opendir_unlocked(fd);
 }
 
-void loader_closedir(int fd)
+bool loader_closedir(int fd)
 {
     std::unique_lock<std::mutex> lock(sFdMapMutex);
-    sFdMap.erase(fd);
+    return sFdMap.erase(fd);
 }
 
 void loader_dupdir(int oldFd, int newFd)

monika/linux/io.cpp

@@ -548,14 +548,16 @@ int _moni_close(int fd)
         return HAIKU_POSIX_EBADF;
     }
 
-    int result = LINUX_SYSCALL1(__NR_close, fd);
-
-    if (result < 0)
+    if (!GET_HOSTCALLS()->closedir(fd))
     {
-        return LinuxToB(-result);
+        int result = LINUX_SYSCALL1(__NR_close, fd);
+
+        if (result < 0)
+        {
+            return LinuxToB(-result);
+        }
     }
 
-    GET_HOSTCALLS()->closedir(fd);
     GET_SERVERCALLS()->unregister_fd(fd);
 
     return B_OK;

shared_headers/extended_commpage.h

@@ -85,7 +85,7 @@ struct hostcalls
 
     // Readdir
     void (*opendir)(int fd);
-    void (*closedir)(int fd);
+    bool (*closedir)(int fd);
     int (*readdir)(int fd, void* buffer, size_t bufferSize, int maxCount);
     void (*rewinddir)(int fd);
     void (*dupdir)(int oldFd, int newFd);