On Tue, Mar 28, 2017 at 11:27:19AM -0400, Jeff Hostetler wrote:
> > Hrm, there shouldn't be any dependency of the config on the index (and
> > there are a handful of options which impact the index already). Did you
> > try it and run into problems?
>
> Yeah, I tried adding a new "core.verifyindex" property and the
> corresponding global variable. But read_index() and verify_hdr()
> was being called BEFORE the config was loaded. And it wasn't clear
> how best to solve that.
>
> The issue was in "git status" where cmd_status() called
> status_init_config() which called gitmodules_config() before
> git_config(). but gitmodules_config() called read_index(),
> so my settings weren't loaded yet in verify_hdr().
Ugh, yeah, the callback-oriented interface suffers from these kind of
dependency cycles. You can fix it by doing a limited "basic config that
should always be loaded" git_config() call before anything else, and
then following up with the application-level config.
For something low-level that should _always_ be respected, even in
plumbing programs, I think we're better off lazy-loading the config
inside the function. The configset cache makes them more or less free.
I.e., something like:
diff --git a/read-cache.c b/read-cache.c
index e44775182..89bbf8d1e 100644
--- a/read-cache.c
+++ b/read-cache.c
@@ -1376,17 +1376,23 @@ static int verify_hdr(struct cache_header *hdr, unsigned long size)
git_SHA_CTX c;
unsigned char sha1[20];
int hdr_version;
+ int do_checksum = 0;
if (hdr->hdr_signature != htonl(CACHE_SIGNATURE))
return error("bad signature");
hdr_version = ntohl(hdr->hdr_version);
if (hdr_version < INDEX_FORMAT_LB || INDEX_FORMAT_UB < hdr_version)
return error("bad index version %d", hdr_version);
- git_SHA1_Init(&c);
- git_SHA1_Update(&c, hdr, size - 20);
- git_SHA1_Final(sha1, &c);
- if (hashcmp(sha1, (unsigned char *)hdr + size - 20))
- return error("bad index file sha1 signature");
+
+ git_config_get_bool("core.checksumindex", &do_checksum);
+ if (do_checksum) {
+ git_SHA1_Init(&c);
+ git_SHA1_Update(&c, hdr, size - 20);
+ git_SHA1_Final(sha1, &c);
+ if (hashcmp(sha1, (unsigned char *)hdr + size - 20))
+ return error("bad index file sha1 signature");
+ }
+
return 0;
}
-Peff