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authorNick Mathewson <nickm@torproject.org>2013-06-12 09:53:46 -0400
committerNick Mathewson <nickm@torproject.org>2013-06-12 09:53:46 -0400
commit884a0e269c382f9e927d8c8b1ef4ef9d2d48379d (patch)
treec1c30f848d4a75d64faa06f8c7c1b3ef84f6c2ab
parent4835faebf533f93eb390649dfcb5c8cc0289e3d3 (diff)
downloadtor-884a0e269c382f9e927d8c8b1ef4ef9d2d48379d.tar.gz
tor-884a0e269c382f9e927d8c8b1ef4ef9d2d48379d.zip
Use the FILE_SHARE_DELETE flag for CreateFile on a mapping
A comment by rransom on #8795 taken together with a comment by doorss recorded on #2077 suggest that *every* attempt to replace the md cache will fail on Vista/Win7 if we don't have the FILE_SHARE_DELETE flag passed to CreateFile, and if we try to replace the file ourselves before unmapping it. I'm adding the FILE_SHARE_DELETE, since that's this simplest fix. Broken indexers (the favored #2077 hypothesis) could still cause trouble here, but at least this patch should make us stop stepping on our own feet. Likely fix for #2077 and its numerous duplicates. Bugfix on 0.2.2.6-alpha, which first had a microdescriptor cache that would get replaced before remapping it.
-rw-r--r--changes/bug2077_share_delete7
-rw-r--r--src/common/compat.c2
2 files changed, 8 insertions, 1 deletions
diff --git a/changes/bug2077_share_delete b/changes/bug2077_share_delete
new file mode 100644
index 0000000000..71e9160538
--- /dev/null
+++ b/changes/bug2077_share_delete
@@ -0,0 +1,7 @@
+ o Major bugfixes (windows):
+ - Open files to be mapped with FILE_SHARE_DELETE so that we can
+ replace them before closing the mapping. This is a likely cause of
+ warnings and crashes when replacing the microdescriptor cache
+ file. Diagnosed based on comments by "doorss" and by Robert
+ Ransom. Possible fix for bug 2077; bugfix on 0.2.2.6-alpha.
+
diff --git a/src/common/compat.c b/src/common/compat.c
index 59e3898deb..7f7405f6fd 100644
--- a/src/common/compat.c
+++ b/src/common/compat.c
@@ -238,7 +238,7 @@ tor_mmap_file(const char *filename)
strlcpy(tfilename,filename,MAX_PATH);
#endif
file_handle = CreateFile(tfilename,
- GENERIC_READ, FILE_SHARE_READ,
+ GENERIC_READ, FILE_SHARE_READ|FILE_SHARE_DELETE,
NULL,
OPEN_EXISTING,
FILE_ATTRIBUTE_NORMAL,