From: Jonathan Rajotte <jonathan.rajotte-julien@efficios.com>
Date: Wed, 19 Jun 2019 17:28:14 +0000 (-0400)
Subject: Fix: Unmap before truncating
X-Git-Url: http://git.efficios.com/?p=babeltrace.git;a=commitdiff_plain;h=a086573a88d37419d09d13e88be197d9467750b5

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 b28845cf..9152198f 100644
--- 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) {