Am 17.08.2013 14:40, schrieb Steffen Prohaska:
Previously, filtering more than 2GB through an external filter (see
test) failed on Mac OS X 10.8.4 (12E55) with:
error: read from external filter cat failed
error: cannot feed the input to external filter cat
error: cat died of signal 13
error: external filter cat failed 141
error: external filter cat failed
The reason is that read() immediately returns with EINVAL if len >= 2GB.
I haven't found any information under which specific conditions this
occurs. My suspicion is that it happens when reading from a pipe, while
reading from a standard file should always be fine. I haven't tested
any other version of Mac OS X, though I'd expect that other versions are
affected as well.
The problem is fixed by always reading less than 2GB in xread().
xread() doesn't guarantee to read all the requested data at once, and
callers are expected to gracefully handle partial reads. Slicing large
reads into 2GB pieces should not hurt practical performance.
Signed-off-by: Steffen Prohaska <proha...@zib.de>
---
t/t0021-conversion.sh | 9 +++++++++
wrapper.c | 8 ++++++++
2 files changed, 17 insertions(+)
diff --git a/t/t0021-conversion.sh b/t/t0021-conversion.sh
index e50f0f7..aec1253 100755
--- a/t/t0021-conversion.sh
+++ b/t/t0021-conversion.sh
@@ -190,4 +190,13 @@ test_expect_success 'required filter clean failure' '
test_must_fail git add test.fc
'
+test_expect_success 'filter large file' '
+ git config filter.largefile.smudge cat &&
+ git config filter.largefile.clean cat &&
+ dd if=/dev/zero of=2GB count=2097152 bs=1024 &&
We don't have /dev/zero on Windows. Even if we get a file slightly over
2GB, we can't handle it on Windows, and other 32bit architectures will
very likely also be handicapped.
Finally, this test (if it remains in some form) should probably be
protected by EXPENSIVE.
+ echo "/2GB filter=largefile" >.gitattributes &&
Drop the slash, please; it may confuse our bash on Windows (it doesn't
currently because echo is a builtin, but better safe than sorry).
+ git add 2GB 2>err &&
+ ! grep -q "error" err
Executive summary: drop everything starting at "2>err".
Long story: Can it happen that (1) git add succeeds, but still produces
something on stderr, and (2) we do not care what this something is as long
as it does not contain "error"? I don't think this combination of
conditions makes sense; it's sufficient to check that git add does not fail.
BTW, if you add
... &&
rm -f 2GB &&
git checkout -- 2GB
you would also test the smudge filter code path with a huge file, no?
BTW2, to create a file with slightly over 2GB, you can use
for i in $(test_seq 0 128); do printf "%16777216d" 1; done >2GB
+'
+
test_done
diff --git a/wrapper.c b/wrapper.c
index 6a015de..2a2f496 100644
--- a/wrapper.c
+++ b/wrapper.c
@@ -139,6 +139,14 @@ ssize_t xread(int fd, void *buf, size_t len)
{
ssize_t nr;
while (1) {
+#ifdef __APPLE__
+ const size_t twoGB = (1l << 31);
+ /* len >= 2GB immediately fails on Mac OS X with EINVAL when
+ * reading from pipe. */
+ if (len >= twoGB) {
+ len = twoGB - 1;
+ }
+#endif
nr = read(fd, buf, len);
if ((nr < 0) && (errno == EAGAIN || errno == EINTR))
continue;
-- Hannes
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