[PATCH] is_hfs_dotgit: loosen over-eager match of \u{..47}
- From
Jeff King <peff@peff.net>
- Date
- Dec 23, 2014, 08:45 UTC
- Message-ID
- <20141223084536.GA25190@peff.net>
Our is_hfs_dotgit function relies on the hackily-implemented next_hfs_char to give us the next character that an HFS+ filename comparison would look at. It's hacky because it doesn't implement the full case-folding table of HFS+; it gives us just enough to see if the path matches ".git".
At the end of next_hfs_char, we use tolower() to convert our 32-bit code point to lowercase. Our tolower() implementation only takes an 8-bit char, though; it throws away the upper 24 bits. This means we can't have any false negatives for is_hfs_dotgit. We only care about matching 7-bit ASCII characters in ".git", and we will correctly process 'G' or 'g'.
However, we _can_ have false positives. Because we throw away the upper bits, code point \u{0147} (for example) will look like 'G' and get downcased to 'g'. It's not known whether a sequence of code points whose truncation ends up as ".git" is meaningful in any language, but it does not hurt to be more accurate here. We can just pass out the full 32-bit code point, and compare it manually to the upper and lowercase characters we care about.
Signed-off-by: Jeff King <peff@peff.net> --- I saw Linus ask about this on G+. I had done the "no false negative" analysis when writing the patch, but didn't consider the false positive.
Another way of accomplishing the same thing is for next_hfs_char to continue folding case, but _only_ do so for 8-bit code points. Like:
return (out & 0xffffff00) ? out : tolower(out);
I think the what's below is more obvious (and is actually how I originally wrote it; I switched to using tolower() during development to try to make it more readable).
t/t1450-fsck.sh | 16 ++++++++++++++++ utf8.c | 17 ++++++++++++----- 2 files changed, 28 insertions(+), 5 deletions(-)
diff --git a/t/t1450-fsck.sh b/t/t1450-fsck.sh index 1f04b8a..3f5883d 100755 --- a/t/t1450-fsck.sh +++ b/t/t1450-fsck.sh @@ -349,6 +349,22 @@ dot-backslash-case .\\\\.GIT\\\\foobar dotgit-case-backslash .git\\\\foobar EOF +test_expect_success 'fsck allows .Ňit' ' + ( + git init not-dotgit && + cd not-dotgit && + echo content >file && + git add file && + git commit -m base && + blob=$(git rev-parse :file) && + printf "100644 blob $blob\t.\\305\\207it" >tree && + tree=$(git mktree <tree) && + git fsck 2>err && + cat err && + ! test -s err + ) +' + # create a static test repo which is broken by omitting # one particular object ($1, which is looked up via rev-parse # in the new repository). diff --git a/utf8.c b/utf8.c index 9a3f4ad..34a779e 100644 --- a/utf8.c +++ b/utf8.c @@ -606,7 +606,7 @@ static ucs_char_t next_hfs_char(const char **in) * but this is enough to catch anything that will convert * to ".git" */ - return tolower(out); + return out; } } @@ -614,10 +614,17 @@ int is_hfs_dotgit(const char *path) { ucs_char_t c; - if (next_hfs_char(&path) != '.' || - next_hfs_char(&path) != 'g' || - next_hfs_char(&path) != 'i' || - next_hfs_char(&path) != 't') + c = next_hfs_char(&path); + if (c != '.') + return 0; + c = next_hfs_char(&path); + if (c != 'g' && c != 'G') + return 0; + c = next_hfs_char(&path); + if (c != 'i' && c != 'I') + return 0; + c = next_hfs_char(&path); + if (c != 't' && c != 'T') return 0; c = next_hfs_char(&path); if (c && !is_dir_sep(c))
-- 2.2.1.376.gec59d43