[PATCH 1/2] alternates: accept double-quoted paths
- From
Jeff King <peff@peff.net>
- Date
- Dec 12, 2016, 19:52 UTC
- Message-ID
- <20161212195222.rxnabok6amklt2zf@sigill.intra.peff.net>
- In-Reply-To
- <20161212194929.bdcihf7orjabzb2h@sigill.intra.peff.net>
We read lists of alternates from objects/info/alternates files (delimited by newline), as well as from the GIT_ALTERNATE_OBJECT_DIRECTORIES environment variable (delimited by colon or semi-colon, depending on the platform).
There's no mechanism for quoting the delimiters, so it's impossible to specify an alternate path that contains a colon in the environment, or one that contains a newline in a file. We've lived with that restriction for ages because both alternates and filenames with colons are relatively rare, and it's only a problem when the two meet. But since 722ff7f87 (receive-pack: quarantine objects until pre-receive accepts, 2016-10-03), which builds on the alternates system, every push causes the receiver to set GIT_ALTERNATE_OBJECT_DIRECTORIES internally.
It would be convenient to have some way to quote the delimiter so that we can represent arbitrary paths.
The simplest thing would be an escape character before a quoted delimiter (e.g., "\:" as a literal colon). But that creates a backwards compatibility problem: any path which uses that escape character is now broken, and we've just shifted the problem. We could choose an unlikely escape character (e.g., something from the non-printable ASCII range), but that's awkward to use.
Instead, let's treat names as unquoted unless they begin with a double-quote, in which case they are interpreted via our usual C-stylke quoting rules. This also breaks backwards-compatibility, but in a smaller way: it only matters if your file has a double-quote as the very _first_ character in the path (whereas an escape character is a problem anywhere in the path). It's also consistent with many other parts of git, which accept either a bare pathname or a double-quoted one, and the sender can choose to quote or not as required.
Signed-off-by: Jeff King <peff@peff.net> --- This also lets you specify paths that start with "#", or ones that contain newlines in an alternates file, though I doubt anybody really cares much in practice. I didn't even bother to add them to the test suite, mostly because of the compatibility hassle (though I guess we could just mark them with !MINGW and be OK).
Documentation/git.txt | 6 ++++++ sha1_file.c | 47 ++++++++++++++++++++++++++++++++++++----------- t/t5615-alternate-env.sh | 18 ++++++++++++++++++ 3 files changed, 60 insertions(+), 11 deletions(-)
diff --git a/Documentation/git.txt b/Documentation/git.txt index af191c51b..98033302b 100644 --- a/Documentation/git.txt +++ b/Documentation/git.txt @@ -871,6 +871,12 @@ Git so take care if using a foreign front-end. specifies a ":" separated (on Windows ";" separated) list of Git object directories which can be used to search for Git objects. New objects will not be written to these directories. ++ + Entries that begin with `"` (double-quote) will be interpreted + as C-style quoted paths, removing leading and trailing + double-quotes and respecting backslash escapes. E.g., the value + `"path-with-\"-and-:-in-it":vanilla-path` has two paths: + `path-with-"-and-:-in-it` and `vanilla-path`. `GIT_DIR`:: If the `GIT_DIR` environment variable is set then it diff --git a/sha1_file.c b/sha1_file.c index 9c86d1924..117307185 100644 --- a/sha1_file.c +++ b/sha1_file.c @@ -26,6 +26,7 @@ #include "mru.h" #include "list.h" #include "mergesort.h" +#include "quote.h" #ifndef O_NOATIME #if defined(__linux__) && (defined(__i386__) || defined(__PPC__)) @@ -329,13 +330,40 @@ static int link_alt_odb_entry(const char *entry, const char *relative_base, return 0; } +static const char *parse_alt_odb_entry(const char *string, + int sep, + struct strbuf *out) +{ + const char *end; + + strbuf_reset(out); + + if (*string == '#') { + /* comment; consume up to next separator */ + end = strchrnul(string, sep); + } else if (*string == '"' && !unquote_c_style(out, string, &end)) { + /* + * quoted path; unquote_c_style has copied the + * data for us and set "end". Broken quoting (e.g., + * an entry that doesn't end with a quote) falls + * back to the unquoted case below. + */ + } else { + /* normal, unquoted path */ + end = strchrnul(string, sep); + strbuf_add(out, string, end - string); + } + + if (*end) + end++; + return end; +} + static void link_alt_odb_entries(const char *alt, int len, int sep, const char *relative_base, int depth) { - struct string_list entries = STRING_LIST_INIT_NODUP; - char *alt_copy; - int i; struct strbuf objdirbuf = STRBUF_INIT; + struct strbuf entry = STRBUF_INIT; if (depth > 5) { error("%s: ignoring alternate object stores, nesting too deep.", @@ -348,16 +376,13 @@ static void link_alt_odb_entries(const char *alt, int len, int sep, die("unable to normalize object directory: %s", objdirbuf.buf); - alt_copy = xmemdupz(alt, len); - string_list_split_in_place(&entries, alt_copy, sep, -1); - for (i = 0; i < entries.nr; i++) { - const char *entry = entries.items[i].string; - if (entry[0] == '\0' || entry[0] == '#') + while (*alt) { + alt = parse_alt_odb_entry(alt, sep, &entry); + if (!entry.len) continue; - link_alt_odb_entry(entry, relative_base, depth, objdirbuf.buf); + link_alt_odb_entry(entry.buf, relative_base, depth, objdirbuf.buf); } - string_list_clear(&entries, 0); - free(alt_copy); + strbuf_release(&entry); strbuf_release(&objdirbuf); } diff --git a/t/t5615-alternate-env.sh b/t/t5615-alternate-env.sh index eec4137ca..69fd8f891 100755 --- a/t/t5615-alternate-env.sh +++ b/t/t5615-alternate-env.sh @@ -68,4 +68,22 @@ test_expect_success 'access alternate via relative path (subdir)' ' EOF ' +# set variables outside test to avoid quote insanity; the \057 is '/', +# which doesn't need quoting, but just confirms that de-quoting +# is working. +quoted='"one.git\057objects"' +unquoted='two.git/objects' +test_expect_success 'mix of quoted and unquoted alternates' ' + check_obj "$quoted:$unquoted" <<-EOF + $one blob + $two blob +' + +test_expect_success 'broken quoting falls back to interpreting raw' ' + mv one.git \"one.git && + check_obj \"one.git/objects <<-EOF + $one blob + EOF +' + test_done
-- 2.11.0.203.g6657065