`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@xxxxxxxxx>
---
Junio C Hamano wrote:
> Please lose that word.
Check.
> Good spotting.
Thanks :-)
> I am not enthused to see a new test script wasted just for one piece
> of test. Don't we have other
Yup. Didn't see a place I liked for it in the add and update-index
test suites, didn't think to look for a filter test suite...
Check.
> Please do not be cryptic and show a good example, e.g.
> Also lose the blank line from that test.
>~Say `>emptyfile &&`
Checkcheckcheck
> check that 'err' does not contain the copy-fd error
Implemented this out of necessity, because the add works and returns
success despite the complaints to stderr.
sha1_file.c | 2 +-
t/t0021-conversion.sh | 11 +++++++++++
2 files changed, 12 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..5986bb0 100755
--- a/t/t0021-conversion.sh
+++ b/t/t0021-conversion.sh
@@ -216,4 +216,15 @@ test_expect_success EXPENSIVE 'filter large file' '
! test -s err
'
+test_expect_success "filtering empty file should not produce complaints" '
+ echo "emptyfile filter=cat" >>.gitattributes &&
+ git config filter.cat.clean cat &&
+ git config filter.cat.smudge cat &&
+ git add . &&
+ git commit -m "cat filter for emptyfile" &&
+ > emptyfile &&
+ git add emptyfile 2>err &&
+ ! grep -Fiqs "bad file descriptor" err
+'
+
test_done
--
2.4.1.4.gd9c648d
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