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Cygwin: Try to fix potential data corruption in pipe write

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* fhandler.cc (fhandler_base_overlapped::raw_write): When performing
        nonblocking I/O, copy user space data into own buffer.  Add longish
        comment to explain why.
        * fhandler.h (fhandler_base_overlapped::atomic_write_buf): New member.
        (fhandler_base_overlapped::fhandler_base_overlapped): Initialize
        atomic_write_buf.
        (fhandler_base_overlapped::fhandler_base_overlapped): New destructor,
        free'ing atomic_write_buf.
        (fhandler_base_overlapped::copyto): Set atomic_write_buf to NULL in
        copied fhandler.

Signed-off-by: Corinna Vinschen <corinna@vinschen.de>
This commit is contained in:
Corinna Vinschen
2015-08-15 12:30:09 +02:00
parent 36d500e425
commit 344860a104
4 changed files with 66 additions and 1 deletions
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9
winsup/cygwin/fhandler.h
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@@ -661,6 +661,7 @@ protected:
OVERLAPPED io_status;
OVERLAPPED *overlapped;
size_t max_atomic_write;
void *atomic_write_buf;
public:
wait_return __reg3 wait_overlapped (bool, bool, DWORD *, bool, DWORD = 0);
int __reg1 setup_overlapped ();
@@ -670,7 +671,7 @@ public:
OVERLAPPED *&get_overlapped () {return overlapped;}
OVERLAPPED *get_overlapped_buffer () {return &io_status;}
void set_overlapped (OVERLAPPED *ov) {overlapped = ov;}
fhandler_base_overlapped (): io_pending (false), overlapped (NULL), max_atomic_write (0)
fhandler_base_overlapped (): io_pending (false), overlapped (NULL), max_atomic_write (0), atomic_write_buf (NULL)
{
memset (&io_status, 0, sizeof io_status);
}
@@ -686,11 +687,17 @@ public:
static void __reg1 flush_all_async_io ();;
fhandler_base_overlapped (void *) {}
~fhandler_base_overlapped ()
{
if (atomic_write_buf)
cfree (atomic_write_buf);
}
virtual void copyto (fhandler_base *x)
{
x->pc.free_strings ();
*reinterpret_cast<fhandler_base_overlapped *> (x) = *this;
reinterpret_cast<fhandler_base_overlapped *> (x)->atomic_write_buf = NULL;
x->reset (this);
}