summaryrefslogtreecommitdiff
path: root/read-cache.c
diff options
context:
space:
mode:
authorJeff King <peff@peff.net>2013-08-27 16:41:12 -0400
committerJunio C Hamano <gitster@pobox.com>2013-08-28 20:54:43 -0700
commit83bd7437ca6acbee0db431fc8ec7cf823d9459ec (patch)
tree9bfcce9d17fbc39bf05419b449e45ff9d3613b91 /read-cache.c
parenta3bc3d070cacf07dbe11b4bfec57554c8bbf1957 (diff)
downloadgit-83bd7437ca6acbee0db431fc8ec7cf823d9459ec.tar.gz
write_index: optionally allow broken null sha1sjk/write-broken-index-with-nul-sha1
Commit 4337b58 (do not write null sha1s to on-disk index, 2012-07-28) added a safety check preventing git from writing null sha1s into the index. The intent was to catch errors in other parts of the code that might let such an entry slip into the index (or worse, a tree). Some existing repositories may have invalid trees that contain null sha1s already, though. Until 4337b58, a common way to clean this up would be to use git-filter-branch's index-filter to repair such broken entries. That now fails when filter-branch tries to write out the index. Introduce a GIT_ALLOW_NULL_SHA1 environment variable to relax this check and make it easier to recover from such a history. It is tempting 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 an index-filter on a history with trees with null sha1s. That would be slightly safer, but requires some specialized knowledge from the user. So let's set the GIT_ALLOW_NULL_SHA1 variable automatically when checking out the to-be-filtered trees. Advice on using filter-branch to remove such entries already exists on places like stackoverflow, and this patch makes it Just Work again on recent versions of git. Further commands that touch the index will still notice and fail, unless they actually remove the broken entries. A filter-branch whose filters do not touch the index at all will not error out (since we complain of the null sha1 only on writing, not when making a tree out of the index), but this is acceptable, as we still print a loud warning, so the problem is unlikely to go unnoticed. Signed-off-by: Jeff King <peff@peff.net> Reviewed-by: Jonathan Nieder <jrnieder@gmail.com> Signed-off-by: Junio C Hamano <gitster@pobox.com>
Diffstat (limited to 'read-cache.c')
-rw-r--r--read-cache.c13
1 files changed, 11 insertions, 2 deletions
diff --git a/read-cache.c b/read-cache.c
index d97e3bf7cd..835070e24c 100644
--- a/read-cache.c
+++ b/read-cache.c
@@ -1800,8 +1800,17 @@ 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);
+ }
if (ce_write_entry(&c, newfd, ce, previous_name) < 0)
return -1;
}