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Unmap the microdescriptor cache before replacing it. 

This is a reprise of the fix in bdff7e3299d78; 6905c1f6 reintroduced
that bug.  Briefly: windows doesn't seem to like deleting a mapped
file.  I tried adding the PROT_SHARED_DELETE flag to the createfile
all, but that didn't actually fix this issue.  Fortunately, the unit
test I added in 4f4fc63fea should
prevent us from making this particular screw-up again.

This patch also tries to limit the crash potential of a failure to
write by a little bit, although it could do a better job of retaining
microdescriptor bodies.

Fix for bug 8822, bugfix on 0.2.4.12-alpha.
This commit is contained in:
Nick Mathewson 2013-06-12 12:04:33 -04:00
parent fff9386af8
commit f455686b77
2 changed files with 22 additions and 3 deletions
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5
changes/bug8822 Normal file
View File

@ -0,0 +1,5 @@
o Major bugfixes (windows):
- Prevent failures on Windows Vista and later when rebuilding the
microdescriptor cache. Diagnosed by Robert Ransom. Fixes bug 8822;
bugfix on 0.2.4.12-alpha.

20
src/or/microdesc.c
View File

@ -474,15 +474,29 @@ microdesc_cache_rebuild(microdesc_cache_t *cache, int force)
smartlist_add(wrote, md);
}
/* We must do this unmap _before_ we call finish_writing_to_file(), or
* windows will not actually replace the file. */
if (cache->cache_content)
tor_munmap_file(cache->cache_content);
if (finish_writing_to_file(open_file) < 0) {
log_warn(LD_DIR, "Error rebuilding microdescriptor cache: %s",
strerror(errno));
/* Okay. Let's prevent from making things worse elsewhere. */
cache->cache_content = NULL;
HT_FOREACH(mdp, microdesc_map, &cache->map) {
microdesc_t *md = *mdp;
if (md->saved_location == SAVED_IN_CACHE) {
md->off = 0;
md->saved_location = SAVED_NOWHERE;
md->body = NULL;
md->bodylen = 0;
md->no_save = 1;
}
}
return -1;
}
if (cache->cache_content)
tor_munmap_file(cache->cache_content);
cache->cache_content = tor_mmap_file(cache->cache_fname);
if (!cache->cache_content && smartlist_len(wrote)) {