postgres.git / summary / log / commit / refs

commit    e7f5d8ea1c75cc341a966897760a812e437c4668
Author:   Tom Lane <tgl@sss.pgh.pa.us>
Date:     Fri Sep 23 14:09:52 2016 +0000
First released in: 10.0, 9.4.10, 9.5.5, 9.6.0

    Don't trust CreateFileMapping() to clear the error code on success.
    
    We must test GetLastError() even when CreateFileMapping() returns a
    non-null handle.  If that value were left over from some previous system
    call, we might be fooled into thinking the segment already existed.
    Experimentation on Windows 7 suggests that CreateFileMapping() clears
    the error code on success, but it is not documented to do so, so let's
    not rely on that happening in all Windows releases.
    
    Amit Kapila
    
    Discussion: <20811.1474390987@sss.pgh.pa.us>


 src/backend/storage/ipc/dsm_impl.c | 3 +++
 1 file changed, 3 insertions(+)

diff --git a/src/backend/storage/ipc/dsm_impl.c b/src/backend/storage/ipc/dsm_impl.c
index 9cc9c5d2c29..8c706aee002 100644
--- a/src/backend/storage/ipc/dsm_impl.c
+++ b/src/backend/storage/ipc/dsm_impl.c
@@ -681,6 +681,9 @@ dsm_impl_windows(dsm_op op, dsm_handle handle, Size request_size,
 #endif
 		size_low = (DWORD) request_size;
 
+		/* CreateFileMapping might not clear the error code on success */
+		SetLastError(0);
+
 		hmap = CreateFileMapping(INVALID_HANDLE_VALUE,	/* Use the pagefile */
 								 NULL,	/* Default security attrs */
 								 PAGE_READWRITE,		/* Memory is read/write */


[parent: b251379fb44b]