upload-pack: optionally allow fetching reachable sha1
With uploadpack.allowReachableSHA1InWant configuration option set on the server side, "git fetch" can make a request with a "want" line that names an object that has not been advertised (likely to have been obtained out of band or from a submodule pointer). Only objects reachable from the branch tips, i.e. the union of advertised branches and branches hidden by transfer.hideRefs, will be processed. Note that there is an associated cost of having to walk back the history to check the reachability. This feature can be used when obtaining the content of a certain commit, for which the sha1 is known, without the need of cloning the whole repository, especially if a shallow fetch is used. Useful cases are e.g. repositories containing large files in the history, fetching only the needed data for a submodule checkout, when sharing a sha1 without telling which exact branch it belongs to and in Gerrit, if you think in terms of commits instead of change numbers. (The Gerrit case has already been solved through allowTipSHA1InWant as every Gerrit change has a ref.) Signed-off-by: Fredrik Medley <fredrik.medley@gmail.com> Signed-off-by: Junio C Hamano <gitster@pobox.com>
Fredrik Medley committed
May 21, 2015 at 22:23 UTC
68ee628932c2196742b77d2961c5e16360734a62
6 files changed
+97
-6
Documentation/config.txt
+6
@@ -2538,6 +2538,12 @@ uploadpack.allowTipSHA1InWant::
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of a hidden ref (by default, such a request is rejected).
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see also `uploadpack.hideRefs`.
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+uploadpack.allowReachableSHA1InWant::
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+ Allow `upload-pack` to accept a fetch request that asks for an
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+ object that is reachable from any ref tip. However, note that
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+ calculating object reachability is computationally expensive.
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+ Defaults to `false`.
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+
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uploadpack.keepAlive::
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When `upload-pack` has started `pack-objects`, there may be a
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quiet period while `pack-objects` prepares the pack. Normally
Documentation/technical/http-protocol.txt
+2
-1
@@ -319,7 +319,8 @@ Servers SHOULD support all capabilities defined here.
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Clients MUST send at least one "want" command in the request body.
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Clients MUST NOT reference an id in a "want" command which did not
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appear in the response obtained through ref discovery unless the
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-server advertises capability `allow-tip-sha1-in-want`.
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+server advertises capability `allow-tip-sha1-in-want` or
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+`allow-reachable-sha1-in-want`.
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compute_request = want_list
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have_list
Documentation/technical/protocol-capabilities.txt
+7
@@ -260,6 +260,13 @@ If the upload-pack server advertises this capability, fetch-pack may
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send "want" lines with SHA-1s that exist at the server but are not
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advertised by upload-pack.
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+allow-reachable-sha1-in-want
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+----------------------------
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+
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+If the upload-pack server advertises this capability, fetch-pack may
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+send "want" lines with SHA-1s that exist at the server but are not
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+advertised by upload-pack.
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+
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push-cert=<nonce>
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-----------------
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fetch-pack.c
+9
-1
@@ -46,6 +46,8 @@ static struct prio_queue rev_list = { compare_commits_by_commit_date };
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static int non_common_revs, multi_ack, use_sideband;
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/* Allow specifying sha1 if it is a ref tip. */
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#define ALLOW_TIP_SHA1 01
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+/* Allow request of a sha1 if it is reachable from a ref (possibly hidden ref). */
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+#define ALLOW_REACHABLE_SHA1 02
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static unsigned int allow_unadvertised_object_request;
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static void rev_list_push(struct commit *commit, int mark)
@@ -545,7 +547,8 @@ static void filter_refs(struct fetch_pack_args *args,
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}
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/* Append unmatched requests to the list */
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- if ((allow_unadvertised_object_request & ALLOW_TIP_SHA1)) {
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+ if ((allow_unadvertised_object_request &
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+ (ALLOW_TIP_SHA1 | ALLOW_REACHABLE_SHA1))) {
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for (i = 0; i < nr_sought; i++) {
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unsigned char sha1[20];
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@@ -826,6 +829,11 @@ static struct ref *do_fetch_pack(struct fetch_pack_args *args,
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fprintf(stderr, "Server supports allow-tip-sha1-in-want\n");
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allow_unadvertised_object_request |= ALLOW_TIP_SHA1;
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}
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+ if (server_supports("allow-reachable-sha1-in-want")) {
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+ if (args->verbose)
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+ fprintf(stderr, "Server supports allow-reachable-sha1-in-want\n");
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+ allow_unadvertised_object_request |= ALLOW_REACHABLE_SHA1;
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+ }
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if (!server_supports("thin-pack"))
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args->use_thin_pack = 0;
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if (!server_supports("no-progress"))
t/t5516-fetch-push.sh
+55
@@ -1120,6 +1120,61 @@ test_expect_success 'fetch exact SHA1' '
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)
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'
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+for configallowtipsha1inwant in true false
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+do
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+ test_expect_success "shallow fetch reachable SHA1 (but not a ref), allowtipsha1inwant=$configallowtipsha1inwant" '
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+ mk_empty testrepo &&
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+ (
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+ cd testrepo &&
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+ git config uploadpack.allowtipsha1inwant $configallowtipsha1inwant &&
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+ git commit --allow-empty -m foo &&
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+ git commit --allow-empty -m bar
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+ ) &&
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+ SHA1=$(git --git-dir=testrepo/.git rev-parse HEAD^) &&
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+ mk_empty shallow &&
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+ (
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+ cd shallow &&
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+ test_must_fail git fetch --depth=1 ../testrepo/.git $SHA1 &&
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+ git --git-dir=../testrepo/.git config uploadpack.allowreachablesha1inwant true &&
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+ git fetch --depth=1 ../testrepo/.git $SHA1 &&
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+ git cat-file commit $SHA1
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+ )
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+ '
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+
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+ test_expect_success "deny fetch unreachable SHA1, allowtipsha1inwant=$configallowtipsha1inwant" '
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+ mk_empty testrepo &&
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+ (
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+ cd testrepo &&
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+ git config uploadpack.allowtipsha1inwant $configallowtipsha1inwant &&
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+ git commit --allow-empty -m foo &&
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+ git commit --allow-empty -m bar &&
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+ git commit --allow-empty -m xyz
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+ ) &&
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+ SHA1_1=$(git --git-dir=testrepo/.git rev-parse HEAD^^) &&
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+ SHA1_2=$(git --git-dir=testrepo/.git rev-parse HEAD^) &&
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+ SHA1_3=$(git --git-dir=testrepo/.git rev-parse HEAD) &&
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+ (
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+ cd testrepo &&
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+ git reset --hard $SHA1_2 &&
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+ git cat-file commit $SHA1_1 &&
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+ git cat-file commit $SHA1_3
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+ ) &&
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+ mk_empty shallow &&
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+ (
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+ cd shallow &&
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+ test_must_fail git fetch ../testrepo/.git $SHA1_3 &&
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+ test_must_fail git fetch ../testrepo/.git $SHA1_1 &&
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+ git --git-dir=../testrepo/.git config uploadpack.allowreachablesha1inwant true &&
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+ git fetch ../testrepo/.git $SHA1_1 &&
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+ git cat-file commit $SHA1_1 &&
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+ test_must_fail git cat-file commit $SHA1_2 &&
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+ git fetch ../testrepo/.git $SHA1_2 &&
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+ git cat-file commit $SHA1_2 &&
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+ test_must_fail git fetch ../testrepo/.git $SHA1_3
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+ )
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+ '
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+done
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+
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test_expect_success 'fetch follows tags by default' '
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mk_test testrepo heads/master &&
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rm -fr src dst &&
upload-pack.c
+18
-4
@@ -37,6 +37,8 @@ static int use_thin_pack, use_ofs_delta, use_include_tag;
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static int no_progress, daemon_mode;
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/* Allow specifying sha1 if it is a ref tip. */
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#define ALLOW_TIP_SHA1 01
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+/* Allow request of a sha1 if it is reachable from a ref (possibly hidden ref). */
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+#define ALLOW_REACHABLE_SHA1 02
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static unsigned int allow_unadvertised_object_request;
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static int shallow_nr;
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static struct object_array have_obj;
@@ -444,7 +446,8 @@ static int get_common_commits(void)
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static int is_our_ref(struct object *o)
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{
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- int allow_hidden_ref = (allow_unadvertised_object_request & ALLOW_TIP_SHA1);
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+ int allow_hidden_ref = (allow_unadvertised_object_request &
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+ (ALLOW_TIP_SHA1 | ALLOW_REACHABLE_SHA1));
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return o->flags & ((allow_hidden_ref ? HIDDEN_REF : 0) | OUR_REF);
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}
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@@ -458,8 +461,12 @@ static void check_non_tip(void)
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char namebuf[42]; /* ^ + SHA-1 + LF */
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int i;
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- /* In the normal in-process case non-tip request can never happen */
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- if (!stateless_rpc)
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+ /*
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+ * In the normal in-process case without
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+ * uploadpack.allowReachableSHA1InWant,
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+ * non-tip requests can never happen.
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+ */
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+ if (!stateless_rpc && !(allow_unadvertised_object_request & ALLOW_REACHABLE_SHA1))
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goto error;
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cmd.argv = argv;
@@ -726,11 +733,13 @@ static int send_ref(const char *refname, const unsigned char *sha1, int flag, vo
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struct strbuf symref_info = STRBUF_INIT;
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format_symref_info(&symref_info, cb_data);
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- packet_write(1, "%s %s%c%s%s%s%s agent=%s\n",
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+ packet_write(1, "%s %s%c%s%s%s%s%s agent=%s\n",
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sha1_to_hex(sha1), refname_nons,
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0, capabilities,
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(allow_unadvertised_object_request & ALLOW_TIP_SHA1) ?
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" allow-tip-sha1-in-want" : "",
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+ (allow_unadvertised_object_request & ALLOW_REACHABLE_SHA1) ?
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+ " allow-reachable-sha1-in-want" : "",
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stateless_rpc ? " no-done" : "",
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symref_info.buf,
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git_user_agent_sanitized());
@@ -795,6 +804,11 @@ static int upload_pack_config(const char *var, const char *value, void *unused)
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allow_unadvertised_object_request |= ALLOW_TIP_SHA1;
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else
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allow_unadvertised_object_request &= ~ALLOW_TIP_SHA1;
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+ } else if (!strcmp("uploadpack.allowreachablesha1inwant", var)) {
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+ if (git_config_bool(var, value))
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+ allow_unadvertised_object_request |= ALLOW_REACHABLE_SHA1;
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+ else
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+ allow_unadvertised_object_request &= ~ALLOW_REACHABLE_SHA1;
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} else if (!strcmp("uploadpack.keepalive", var)) {
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keepalive = git_config_int(var, value);
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if (!keepalive)