Commit cf3c6352 authored by Jeff King's avatar Jeff King Committed by Junio C Hamano

alternates: accept double-quoted paths

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
722ff7f8 (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: default avatarJeff King <[email protected]>
Signed-off-by: default avatarJunio C Hamano <[email protected]>
parent 9b519609
......@@ -859,6 +859,12 @@ 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
......
......@@ -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);
}
......
......@@ -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
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