From: "Derrick Stolee via GitGitGadget" <gitgitgadget@gmail.com>
To: git@vger.kernel.org
Cc: Junio C Hamano <gitster@pobox.com>,
Derrick Stolee <dstolee@microsoft.com>
Subject: [PATCH 1/1] commit-graph: writing missing parents is a BUG
Date: Wed, 19 Dec 2018 12:14:07 -0800 (PST) [thread overview]
Message-ID: <907a24d2c45acec17607971b577782798c4adcbc.1545250444.git.gitgitgadget@gmail.com> (raw)
In-Reply-To: <pull.102.git.gitgitgadget@gmail.com>
From: Derrick Stolee <dstolee@microsoft.com>
When writing a commit-graph, we write GRAPH_MISSING_PARENT if the
parent's object id does not appear in the list of commits to be
written into the commit-graph. This was done as the initial design
allowed commits to have missing parents, but the final version
requires the commit-graph to be closed under reachability. Thus,
this GRAPH_MISSING_PARENT value should never be written.
However, there are reasons why it could be written! These range
from a bug in the reachable-closure code to a memory error causing
the binary search into the list of object ids to fail. In either
case, we should fail fast and avoid writing the commit-graph file
with bad data.
Remove the GRAPH_MISSING_PARENT constant in favor of the constant
GRAPH_EDGE_LAST_MASK, which has the same value.
Signed-off-by: Derrick Stolee <dstolee@microsoft.com>
---
commit-graph.c | 17 +++++++++++------
1 file changed, 11 insertions(+), 6 deletions(-)
diff --git a/commit-graph.c b/commit-graph.c
index 40c855f185..c14ada6918 100644
--- a/commit-graph.c
+++ b/commit-graph.c
@@ -34,7 +34,6 @@
#define GRAPH_OID_LEN GRAPH_OID_LEN_SHA1
#define GRAPH_OCTOPUS_EDGES_NEEDED 0x80000000
-#define GRAPH_PARENT_MISSING 0x7fffffff
#define GRAPH_EDGE_LAST_MASK 0x7fffffff
#define GRAPH_PARENT_NONE 0x70000000
@@ -496,7 +495,9 @@ static void write_graph_chunk_data(struct hashfile *f, int hash_len,
commit_to_sha1);
if (edge_value < 0)
- edge_value = GRAPH_PARENT_MISSING;
+ BUG("missing parent %s for commit %s",
+ oid_to_hex(&parent->item->object.oid),
+ oid_to_hex(&(*list)->object.oid));
}
hashwrite_be32(f, edge_value);
@@ -514,7 +515,9 @@ static void write_graph_chunk_data(struct hashfile *f, int hash_len,
nr_commits,
commit_to_sha1);
if (edge_value < 0)
- edge_value = GRAPH_PARENT_MISSING;
+ BUG("missing parent %s for commit %s",
+ oid_to_hex(&parent->item->object.oid),
+ oid_to_hex(&(*list)->object.oid));
}
hashwrite_be32(f, edge_value);
@@ -567,7 +570,9 @@ static void write_graph_chunk_large_edges(struct hashfile *f,
commit_to_sha1);
if (edge_value < 0)
- edge_value = GRAPH_PARENT_MISSING;
+ BUG("missing parent %s for commit %s",
+ oid_to_hex(&parent->item->object.oid),
+ oid_to_hex(&(*list)->object.oid));
else if (!parent->next)
edge_value |= GRAPH_LAST_EDGE;
@@ -864,7 +869,7 @@ void write_commit_graph(const char *obj_dir,
count_distinct++;
}
- if (count_distinct >= GRAPH_PARENT_MISSING)
+ if (count_distinct >= GRAPH_EDGE_LAST_MASK)
die(_("the commit graph format cannot write %d commits"), count_distinct);
commits.nr = 0;
@@ -891,7 +896,7 @@ void write_commit_graph(const char *obj_dir,
}
num_chunks = num_extra_edges ? 4 : 3;
- if (commits.nr >= GRAPH_PARENT_MISSING)
+ if (commits.nr >= GRAPH_EDGE_LAST_MASK)
die(_("too many commits to write graph"));
compute_generation_numbers(&commits, report_progress);
--
gitgitgadget
next prev parent reply other threads:[~2018-12-19 20:14 UTC|newest]
Thread overview: 3+ messages / expand[flat|nested] mbox.gz Atom feed top
2018-12-19 20:14 [PATCH 0/1] commit-graph: writing missing parents is a BUG Derrick Stolee via GitGitGadget
2018-12-19 20:14 ` Derrick Stolee via GitGitGadget [this message]
2019-01-02 23:01 ` [PATCH 1/1] " Junio C Hamano
Reply instructions:
You may reply publicly to this message via plain-text email
using any one of the following methods:
* Save the following mbox file, import it into your mail client,
and reply-to-all from there: mbox
Avoid top-posting and favor interleaved quoting:
https://en.wikipedia.org/wiki/Posting_style#Interleaved_style
List information: http://vger.kernel.org/majordomo-info.html
* Reply using the --to, --cc, and --in-reply-to
switches of git-send-email(1):
git send-email \
--in-reply-to=907a24d2c45acec17607971b577782798c4adcbc.1545250444.git.gitgitgadget@gmail.com \
--to=gitgitgadget@gmail.com \
--cc=dstolee@microsoft.com \
--cc=git@vger.kernel.org \
--cc=gitster@pobox.com \
/path/to/YOUR_REPLY
https://kernel.org/pub/software/scm/git/docs/git-send-email.html
* If your mail client supports setting the In-Reply-To header
via mailto: links, try the mailto: link
Be sure your reply has a Subject: header at the top and a blank line
before the message body.
Code repositories for project(s) associated with this public inbox
https://80x24.org/mirrors/git.git
This is a public inbox, see mirroring instructions
for how to clone and mirror all data and code used for this inbox;
as well as URLs for read-only IMAP folder(s) and NNTP newsgroup(s).