[PATCH v4] sha1_file: pass empty buffer to index empty file
- From
Jim Hill <gjthill@gmail.com>
- Date
- May 18, 2015, 00:41 UTC
- Message-ID
- <1431909705-29090-1-git-send-email-gjthill@gmail.com>
- In-Reply-To
- <xmqqvbfrc952.fsf@gitster.dls.corp.google.com>
`git add` of an empty file with a filter pops complaints from `copy_fd` about a bad file descriptor.
This traces back to these lines in sha1_file.c:index_core:
if (!size) {
ret = index_mem(sha1, NULL, size, type, path, flags);The problem here is that content to be added to the index can be supplied from an fd, or from a memory buffer, or from a pathname. This call is supplying a NULL buffer pointer and a zero size.
Downstream logic takes the complete absence of a buffer to mean the data is to be found elsewhere -- for instance, these, from convert.c:
if (params->src) {
write_err = (write_in_full(child_process.in, params->src, params->size) < 0);
} else {
write_err = copy_fd(params->fd, child_process.in);
}~If there's a buffer, write from that, otherwise the data must be coming from an open fd.~
Perfectly reasonable logic in a routine that's going to write from either a buffer or an fd.
So change `index_core` to supply an empty buffer when indexing an empty file.
There's a patch out there that instead changes the logic quoted above to take a `-1` fd to mean "use the buffer", but it seems to me that the distinction between a missing buffer and an empty one carries intrinsic semantics, where the logic change is adapting the code to handle incorrect arguments.
Signed-off-by: Jim Hill <gjthill@gmail.com> --- Okay, that's it: I'm officially laughably rusty, 'cause I'm laughing. This applies your fix, _thank you_ for the caution. I get it: `true` can have already exited by the time the write hits.
sha1_file.c | 2 +- t/t0021-conversion.sh | 26 ++++++++++++++++++++++++++ 2 files changed, 27 insertions(+), 1 deletion(-)
diff --git a/sha1_file.c b/sha1_file.c index f860d67..61e2735 100644 --- a/sha1_file.c +++ b/sha1_file.c @@ -3186,7 +3186,7 @@ static int index_core(unsigned char *sha1, int fd, size_t size, int ret; if (!size) { - ret = index_mem(sha1, NULL, size, type, path, flags); + ret = index_mem(sha1, "", size, type, path, flags); } else if (size <= SMALL_FILE_SIZE) { char *buf = xmalloc(size); if (size == read_in_full(fd, buf, size)) diff --git a/t/t0021-conversion.sh b/t/t0021-conversion.sh index ca7d2a6..eee4761 100755 --- a/t/t0021-conversion.sh +++ b/t/t0021-conversion.sh @@ -216,4 +216,30 @@ test_expect_success EXPENSIVE 'filter large file' ' ! test -s err ' +test_expect_success "filter: clean empty file" ' + git config filter.in-repo-header.clean "echo cleaned && cat" && + git config filter.in-repo-header.smudge "sed 1d" && + + echo "empty-in-worktree filter=in-repo-header" >>.gitattributes && + >empty-in-worktree && + + echo cleaned >expected && + git add empty-in-worktree && + git show :empty-in-worktree >actual && + test_cmp expected actual +' + +test_expect_success "filter: smudge empty file" ' + git config filter.empty-in-repo.clean "cat >/dev/null" && + git config filter.empty-in-repo.smudge "echo smudged && cat" && + + echo "empty-in-repo filter=empty-in-repo" >>.gitattributes && + echo dead data walking >empty-in-repo && + git add empty-in-repo && + + echo smudged >expected && + git checkout-index --prefix=filtered- empty-in-repo && + test_cmp expected filtered-empty-in-repo +' + test_done
-- 2.4.1.4.g08cda19