[PATCH v5 2/2] ntdll: Raise SIGQUIT instead of aborting immediately if the server pipe is broken.

[Zebediah Figura]

From: Zebediah Figura

Keil UV4 C51 starts a thread and then immediately terminates it, usually while
it's in the middle of an NtClose().

The previous commit prevents the SIGQUIT from killing the thread before it exits
the fd_cache_section mutex. However, the server will still have closed its side
of the socket, resulting in the close_handle server request receiving EPIPE from
write(), or zero from read(), at which point the client calls abort_thread()
anyway, while still holding the mutex.

Raise SIGQUIT instead, which will terminate the thread once it leaves the
uninterrupted section, after releasing any relevant mutexes.

Wine-Bug: https://bugs.winehq.org/show_bug.cgi?id=54807
---
 dlls/ntdll/unix/server.c | 37 ++++++++++++++++++++++++++++---------
 1 file changed, 28 insertions(+), 9 deletions(-)

diff --git a/dlls/ntdll/unix/server.c b/dlls/ntdll/unix/server.c
index c512c1002d5..db19455c594 100644
--- a/dlls/ntdll/unix/server.c
+++ b/dlls/ntdll/unix/server.c
@@ -206,7 +206,14 @@ static unsigned int send_request( const struct __server_request_info *req )
     }

if (ret >= 0) server_protocol_error( "partial write %d\n", ret );
-    if (errno == EPIPE) abort_thread(0);
+    if (errno == EPIPE)
+    {
+        /* SIGQUIT might be blocked. We want to terminate ourselves, but only
+         * after signals have been unblocked (and e.g. mutexes have been
+         * released). */
+        raise( SIGQUIT );
+        return STATUS_THREAD_IS_TERMINATING;
+    }
     if (errno == EFAULT) return STATUS_ACCESS_VIOLATION;
     server_protocol_perror( "write" );
 }
@@ -217,7 +224,7 @@ static unsigned int send_request( const struct __server_request_info *req )
  *
  * Read data from the reply buffer; helper for wait_reply.
  */
-static void read_reply_data( void *buffer, size_t size )
+static unsigned int read_reply_data( void *buffer, size_t size )
 {
     int ret;

@@ -225,7 +232,7 @@ static void read_reply_data( void *buffer, size_t size )
     {
         if ((ret = read( ntdll_get_thread_data()->reply_fd, buffer, size )) > 0)
         {
-            if (!(size -= ret)) return;
+            if (!(size -= ret)) return STATUS_SUCCESS;
             buffer = (char *)buffer + ret;
             continue;
         }
@@ -234,8 +241,11 @@ static void read_reply_data( void *buffer, size_t size )
         if (errno == EPIPE) break;
         server_protocol_perror("read");
     }
-    /* the server closed the connection; time to die... */
-    abort_thread(0);
+    /* SIGQUIT might be blocked. We want to terminate ourselves, but only
+     * after signals have been unblocked (and e.g. mutexes have been
+     * released). */
+    raise( SIGQUIT );
+    return STATUS_THREAD_IS_TERMINATING;
 }

@@ -246,9 +256,11 @@ static void read_reply_data( void *buffer, size_t size )
  */
 static inline unsigned int wait_reply( struct __server_request_info *req )
 {
-    read_reply_data( &req->u.reply, sizeof(req->u.reply) );
-    if (req->u.reply.reply_header.reply_size)
-        read_reply_data( req->reply_data, req->u.reply.reply_header.reply_size );
+    unsigned int ret;
+    ret = read_reply_data( &req->u.reply, sizeof(req->u.reply) );
+    if (!ret && req->u.reply.reply_header.reply_size)
+        ret = read_reply_data( req->reply_data, req->u.reply.reply_header.reply_size );
+    if (ret) return ret;
     return req->u.reply.reply_header.error;
 }

@@ -907,7 +919,14 @@ void wine_server_send_fd( int fd )
         if ((ret = sendmsg( fd_socket, &msghdr, 0 )) == sizeof(data)) return;
         if (ret >= 0) server_protocol_error( "partial write %d\n", ret );
         if (errno == EINTR) continue;
-        if (errno == EPIPE) abort_thread(0);
+        if (errno == EPIPE)
+        {
+            /* SIGQUIT might be blocked. We want to terminate ourselves, but
+             * only  after signals have been unblocked (and e.g. mutexes have
+             * been released). */
+            raise( SIGQUIT );
+            return;
+        }
         server_protocol_perror( "sendmsg" );
     }
 }