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[RFC] mingw port: Allow use of cvs GDB on Windows 95
- From: "Compte ICS" <pierre dot muller at ics-cnrs dot unistra dot fr>
- To: <gdb-patches at sourceware dot org>
- Date: Fri, 4 Feb 2011 14:06:37 +0100
- Subject: [RFC] mingw port: Allow use of cvs GDB on Windows 95
I wanted to test current GDB on windows 95
systems, but CancelIo function is not present in Windows 95
kernel32 DLL which leads to a failure at startup of GDB.
According to
http://www.codeguru.com/forum/showthread.php?t=80410
CancelIo calls can be emulated on windows 95.
My patch simply installs a substitute that
calls CloseHandle instead.
I don't really care for remote serial connections
on windows 95 machines, but the currently
compiled GDB cannot be loaded on a windows 95 machine
because CancelIo is assumed to be present.
I tried to check the existing code
to see if I should reopen the handle, but to me it
rather seems that a call to CloseHandle is missing
for the normal case... Indeed, CancelIo
is called from ser_windows_close, and it seems
that the handle cannot be used anymore.
Does anyone use this serial connection?
Is this handle still valid afterwards? Or should it be
close inside ser_windows_close in all cases?
In any case, the code should function unchanged for all
systems that have CancelIo, and allows
to use GDB on windows 95 again (even if I am not sure
that serial communication will work...).
Comments welcome,
Pierre Muller
2011-02-04 Pierre Muller <muller@ics.u-strasbg.fr>
* src/gdb/ser-mingw.c (CancelIo): New macro for dynamically loaded
DLL entry.
(win95_cancelio): New function.
(_initialize_ser_windows): Use LoadLirary/GetProcAddress
to check for existence of CancelIo function in kernel32
and substitute with win95_cancelio if not found.
Index: src/gdb/ser-mingw.c
===================================================================
RCS file: /cvs/src/src/gdb/ser-mingw.c,v
retrieving revision 1.26
diff -u -p -r1.26 ser-mingw.c
--- src/gdb/ser-mingw.c 11 Jan 2011 21:53:23 -0000 1.26
+++ src/gdb/ser-mingw.c 3 Feb 2011 10:28:53 -0000
@@ -45,6 +45,21 @@ struct ser_windows_state
HANDLE except_event;
};
+/* CancelIo is not available for Windows 95 OS,
+ so we need to use LoadLibrary/GetProcAddress to avoid
+ a startup failure. */
+#define CancelIo dyn_CancelIo
+
+static BOOL WINAPI (*CancelIo) (HANDLE);
+
+/* Create a subtitute function for Windows 95, that
+ simply closes the handle. */
+static BOOL WINAPI
+win95_cancelio (HANDLE h)
+{
+ return CloseHandle (h);
+}
+
/* Open up a real live device for serial I/O. */
static int
@@ -1208,8 +1223,21 @@ _initialize_ser_windows (void)
WSADATA wsa_data;
struct serial_ops *ops;
- /* First register the serial port driver. */
+ HMODULE hm = NULL;
+
+ /* First find out if kernel32 exports CancelIo function.
+ If it doesn't use win95_cancelio substitute. */
+ hm = LoadLibrary ("kernel32.dll");
+ if (hm)
+ {
+ CancelIo = (void *) GetProcAddress (hm, "CancelIo");
+ FreeLibrary (hm);
+ }
+
+ if (!CancelIo)
+ CancelIo = (void *) win95_cancelio;
+ /* Now register the serial port driver. */
ops = XMALLOC (struct serial_ops);
memset (ops, 0, sizeof (struct serial_ops));
ops->name = "hardwire";