[PATCH 2/2] ntdll: Do a device check before returning a default serial port name.

[Alex Henrie]

Fixes https://bugs.winehq.org/show_bug.cgi?id=39793

Signed-off-by: Alex Henrie <alexhenrie24 at gmail.com>
---
 dlls/ntdll/directory.c | 18 ++++++++++++++++++
 1 file changed, 18 insertions(+)

diff --git a/dlls/ntdll/directory.c b/dlls/ntdll/directory.c
index f3c6aa2..05cc2a0 100644
--- a/dlls/ntdll/directory.c
+++ b/dlls/ntdll/directory.c
@@ -83,6 +83,9 @@
 #ifdef HAVE_SYS_STATFS_H
 #include <sys/statfs.h>
 #endif
+#ifdef HAVE_TERMIOS_H
+# include <termios.h>
+#endif
 #include <time.h>
 #ifdef HAVE_UNISTD_H
 # include <unistd.h>
@@ -336,6 +339,21 @@ static char *get_default_com_device( int num )
     ret = RtlAllocateHeap( GetProcessHeap(), 0, sizeof("/dev/ttyS256") );
     if (!ret) return NULL;
     sprintf( ret, "/dev/ttyS%d", num - 1 );
+
+    /* ttyS0 through ttyS3 always exist on Linux even if they don't work */
+    /* do a basic functionality check like NTDETECT does before advertising a serial port */
+    {
+        int fd;
+        struct termios attrs;
+
+        fd = open( ret, O_RDONLY );
+        if ( tcgetattr( fd, &attrs ) < 0 )
+        {
+            RtlFreeHeap( GetProcessHeap(), 0, ret );
+            ret = NULL;
+        }
+        close( fd );
+    }
 #elif defined(__FreeBSD__) || defined(__FreeBSD_kernel__)
     ret = RtlAllocateHeap( GetProcessHeap(), 0, sizeof("/dev/cuau256") );
     if (!ret) return NULL;
-- 
2.6.4