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@xxxxxxxx>
---
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