Hi,
Jeff King wrote:
> ---
> I was tempted to not involve filter-branch in this commit at all, and
> instead require the user to manually invoke
>
> GIT_ALLOW_NULL_SHA1=1 git filter-branch ...
>
> to perform such a filter. That would be slightly safer, but requires
> some specialized knowledge from the user (and advice on using
> filter-branch to remove such entries already exists on places like
> stackoverflow, and this patch makes it Just Work on recent versions of
> git).
The above few paragraphs explained the most mysterious part of the
patch to me. I think they would be fine to include in the commit
message.
[...]
> --- a/read-cache.c
> +++ b/read-cache.c
> @@ -1817,8 +1817,17 @@ int write_index(struct index_state *istate, int newfd)
> continue;
> if (!ce_uptodate(ce) && is_racy_timestamp(istate, ce))
> ce_smudge_racily_clean_entry(ce);
> - if (is_null_sha1(ce->sha1))
> - return error("cache entry has null sha1: %s", ce->name);
> + if (is_null_sha1(ce->sha1)) {
> + static const char msg[] = "cache entry has null sha1:
> %s";
> + static int allow = -1;
> +
> + if (allow < 0)
> + allow = git_env_bool("GIT_ALLOW_NULL_SHA1", 0);
> + if (allow)
> + warning(msg, ce->name);
> + else
> + return error(msg, ce->name);
> + }
Makes sense.
[...]
> --- /dev/null
> +++ b/t/t7009-filter-branch-null-sha1.sh
> @@ -0,0 +1,54 @@
> +#!/bin/sh
> +
> +test_description='filter-branch removal of trees with null sha1'
> +. ./test-lib.sh
> +
> +test_expect_success 'create base commits' '
> + test_commit one &&
> + test_commit two &&
> + test_commit three
> +'
> +
> +test_expect_success 'create a commit with a bogus null sha1 in the tree' '
> + test_tick &&
> + tree=$(
> + {
> + git ls-tree HEAD &&
> + printf "160000 commit $_z40\\tbroken"
> + } | git mktree
> + ) &&
To avoid pipes involving git commands, since they can losing the exit
status (and hence information about whether git crashed):
{
git ls-tree HEAD &&
echo "160000 commit $_z40 broken"
} >listing &&
echo "add broken entry" >msg &&
tree=$(git mktree <listing) &&
test_tick &&
commit=$(git commit-tree "$tree" -p HEAD <msg) &&
git update-ref HEAD "$commit"
The rest looks good.
Thanks,
Jonathan
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