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Re: [PATCH v1 2/2] entry.c: check if file exists after checkout

From
Junio C Hamano <gitster@pobox.com>
Date
Oct 6, 2017, 04:26 UTC
Message-ID
<xmqqlgkoyk8n.fsf@gitster.mtv.corp.google.com>
In-Reply-To
<20171005112355.lsoqxybgsovpqriy@sigill.intra.peff.net>
Jeff King <peff@peff.net> writes:
Show 20 quoted lines
>> diff --git a/entry.c b/entry.c
>> index 5dab656364..2252d96756 100644
>> --- a/entry.c
>> +++ b/entry.c
>> @@ -355,7 +355,8 @@ static int write_entry(struct cache_entry *ce,
>>  	if (state->refresh_cache) {
>>  		assert(state->istate);
>>  		if (!fstat_done)
>> -			lstat(ce->name, &st);
>> +			if (lstat(ce->name, &st) < 0)
>> +				return error("unable to get status of file %s", ce->name);
>
> We could probably be a bit more specific about the situation, since the
> user will see this message with no context. Maybe something like:
>
>   unable to stat just-written file %s
>
> or something. We should probably also use error_errno(). I'd bet if this
> ever triggers that it's likely to be ENOENT, but certainly if it _isn't_
> that would be interesting information.

ENOTDIR and to a lesser degree EACCES and ELOOP are also uninteresting, as we are talking about somebody else mucking with the filesystem.

To tie the loose end, here is what will be queued and merged to 'next' soonish.

Thanks.
-- >8 --
From: Lars Schneider <larsxschneider@gmail.com>
Date: Thu, 5 Oct 2017 12:44:07 +0200
Subject: [PATCH] entry.c: check if file exists after checkout

If we are checking out a file and somebody else racily deletes our file, then we would write garbage to the cache entry. Fix that by checking the result of the lstat() call on that file. Print an error to the user if the file does not exist.

Reported-by: Jeff King <peff@peff.net>
Signed-off-by: Lars Schneider <larsxschneider@gmail.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
---
 entry.c | 4 +++-
 1 file changed, 3 insertions(+), 1 deletion(-)
diff --git a/entry.c b/entry.c
index f879758c73..6d9de3a5aa 100644
--- a/entry.c
+++ b/entry.c
@@ -341,7 +341,9 @@ static int write_entry(struct cache_entry *ce,
 	if (state->refresh_cache) {
 		assert(state->istate);
 		if (!fstat_done)
-			lstat(ce->name, &st);
+			if (lstat(ce->name, &st) < 0)
+				return error_errno("unable stat just-written file %s",
+						   ce->name);
 		fill_stat_cache_info(ce, &st);
 		ce->ce_flags |= CE_UPDATE_IN_BASE;
 		state->istate->cache_changed |= CE_ENTRY_CHANGED;
-- 
2.15.0-rc0-155-g07e9c1a78d
Previous: Jeff KingNext: Jeff King
Message 4 of 26 in “fix temporary garbage in the cache entry”
  1. 0/2 fix temporary garbage in the cache entrylars.schneider@autodesk.com, Oct 5, 2017
  2. 2/2 entry.c: check if file exists after checkoutlars.schneider@autodesk.com, Oct 5, 2017
  3. Jeff KingOct 5, 2017
  4. Junio C HamanoOct 6, 2017
  5. Jeff KingOct 6, 2017
  6. Junio C HamanoOct 6, 2017
  7. Jeff KingOct 6, 2017
  8. Junio C HamanoOct 6, 2017
  9. Lars SchneiderOct 8, 2017
  10. 1/2 entry.c: update cache entry only for existing fileslars.schneider@autodesk.com, Oct 5, 2017
  11. Jeff KingOct 5, 2017
  12. Junio C HamanoOct 5, 2017
  13. Jeff KingOct 5, 2017
  14. Junio C HamanoOct 5, 2017
  15. Jeff KingOct 6, 2017
  16. Lars SchneiderOct 8, 2017
  17. Jeff KingOct 9, 2017
  18. 1/3 write_entry: fix leak when retrying delayed filterJeff King, Oct 9, 2017
  19. Junio C HamanoOct 10, 2017
  20. Simon RuderichOct 10, 2017
  21. Jeff KingOct 10, 2017
  22. Simon RuderichOct 10, 2017
  23. 2/3 write_entry: avoid reading blobs in CE_RETRY caseJeff King, Oct 9, 2017
  24. Junio C HamanoOct 10, 2017
  25. 3/3 write_entry: untangle symlink and regular-file casesJeff King, Oct 9, 2017
  26. Junio C HamanoOct 10, 2017

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