Fix: Unmap before truncating

The mmap/mman compat layer for mingw uses the CreateFileMapping
and UnmapViewOfFile thus implicitly imposes an order for truncation and
ummapping [1].

For truncation calls, the underlying windows API call is SetEndOfFile.
This function requires that the file be unmapped before being called [1].

[1]
  If CreateFileMapping is called to create a file mapping object for
  hFile, UnmapViewOfFile must be called first to unmap all views and
  call CloseHandle to close the file mapping object before you can call
  SetEndOfFile.

[1] https://docs.microsoft.com/en-us/windows/desktop/api/fileapi/nf-fileapi-setendoffile#remarks

Change-Id: Id4713ca3af612baa24e1fa4a749384eab452598a
Signed-off-by: Jonathan Rajotte <jonathan.rajotte-julien@efficios.com>
Reviewed-on: https://review.lttng.org/c/babeltrace/+/1519
Reviewed-by: Philippe Proulx <eeppeliteloop@gmail.com>
Reviewed-by: Michael Jeanson <mjeanson@efficios.com>

diff --git a/src/ctfser/ctfser.c b/src/ctfser/ctfser.c
index b28845cf8f5649bad43d69f7a4d87ea98e9faf0a..9152198f661df1f8b6fa980effc4b8361fa48a43 100644 (file)
--- a/src/ctfser/ctfser.c
+++ b/src/ctfser/ctfser.c
@@ -144,6 +144,19 @@ int bt_ctfser_fini(struct bt_ctfser *ctfser)
                goto free_path;
        }
 
+       if (ctfser->base_mma) {
+               /* Unmap old base */
+               ret = munmap_align(ctfser->base_mma);
+               if (ret) {
+                       BT_LOGE_ERRNO("Failed to unmap stream file",
+                               ": ret=%d, size-bytes=%" PRIu64,
+                               ret, ctfser->stream_size_bytes);
+                       goto end;
+               }
+
+               ctfser->base_mma = NULL;
+       }
+
        /*
         * Truncate the stream file's size to the minimum required to
         * fit the last packet as we might have grown it too much during
@@ -160,18 +173,6 @@ int bt_ctfser_fini(struct bt_ctfser *ctfser)
                goto end;
        }
 
-       if (ctfser->base_mma) {
-               /* Unmap old base */
-               ret = munmap_align(ctfser->base_mma);
-               if (ret) {
-                       BT_LOGE_ERRNO("Failed to unmap stream file",
-                               ": ret=%d, size-bytes=%" PRIu64,
-                               ret, ctfser->stream_size_bytes);
-                       goto end;
-               }
-
-               ctfser->base_mma = NULL;
-       }
 
        ret = close(ctfser->fd);
        if (ret) {