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upload-pack: introduce fetch server command
Introduce the 'fetch' server command. Signed-off-by: Brandon Williams <bmwill@google.com> Signed-off-by: Junio C Hamano <gitster@pobox.com>
This commit is contained in:
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5b872fff18
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3145ea957d
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@ -199,3 +199,128 @@ The output of ls-refs is as follows:
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ref-attribute = (symref | peeled)
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symref = "symref-target:" symref-target
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peeled = "peeled:" obj-id
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fetch
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~~~~~~~
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`fetch` is the command used to fetch a packfile in v2. It can be looked
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at as a modified version of the v1 fetch where the ref-advertisement is
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stripped out (since the `ls-refs` command fills that role) and the
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message format is tweaked to eliminate redundancies and permit easy
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addition of future extensions.
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Additional features not supported in the base command will be advertised
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as the value of the command in the capability advertisement in the form
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of a space separated list of features: "<command>=<feature 1> <feature 2>"
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A `fetch` request can take the following arguments:
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want <oid>
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Indicates to the server an object which the client wants to
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retrieve. Wants can be anything and are not limited to
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advertised objects.
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have <oid>
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Indicates to the server an object which the client has locally.
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This allows the server to make a packfile which only contains
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the objects that the client needs. Multiple 'have' lines can be
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supplied.
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done
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Indicates to the server that negotiation should terminate (or
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not even begin if performing a clone) and that the server should
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use the information supplied in the request to construct the
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packfile.
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thin-pack
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Request that a thin pack be sent, which is a pack with deltas
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which reference base objects not contained within the pack (but
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are known to exist at the receiving end). This can reduce the
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network traffic significantly, but it requires the receiving end
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to know how to "thicken" these packs by adding the missing bases
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to the pack.
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no-progress
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Request that progress information that would normally be sent on
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side-band channel 2, during the packfile transfer, should not be
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sent. However, the side-band channel 3 is still used for error
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responses.
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include-tag
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Request that annotated tags should be sent if the objects they
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point to are being sent.
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ofs-delta
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Indicate that the client understands PACKv2 with delta referring
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to its base by position in pack rather than by an oid. That is,
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they can read OBJ_OFS_DELTA (ake type 6) in a packfile.
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The response of `fetch` is broken into a number of sections separated by
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delimiter packets (0001), with each section beginning with its section
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header.
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output = *section
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section = (acknowledgments | packfile)
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(flush-pkt | delim-pkt)
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acknowledgments = PKT-LINE("acknowledgments" LF)
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(nak | *ack)
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(ready)
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ready = PKT-LINE("ready" LF)
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nak = PKT-LINE("NAK" LF)
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ack = PKT-LINE("ACK" SP obj-id LF)
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packfile = PKT-LINE("packfile" LF)
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*PKT-LINE(%x01-03 *%x00-ff)
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acknowledgments section
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* If the client determines that it is finished with negotiations
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by sending a "done" line, the acknowledgments sections MUST be
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omitted from the server's response.
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* Always begins with the section header "acknowledgments"
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* The server will respond with "NAK" if none of the object ids sent
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as have lines were common.
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* The server will respond with "ACK obj-id" for all of the
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object ids sent as have lines which are common.
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* A response cannot have both "ACK" lines as well as a "NAK"
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line.
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* The server will respond with a "ready" line indicating that
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the server has found an acceptable common base and is ready to
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make and send a packfile (which will be found in the packfile
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section of the same response)
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* If the server has found a suitable cut point and has decided
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to send a "ready" line, then the server can decide to (as an
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optimization) omit any "ACK" lines it would have sent during
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its response. This is because the server will have already
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determined the objects it plans to send to the client and no
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further negotiation is needed.
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packfile section
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* This section is only included if the client has sent 'want'
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lines in its request and either requested that no more
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negotiation be done by sending 'done' or if the server has
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decided it has found a sufficient cut point to produce a
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packfile.
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* Always begins with the section header "packfile"
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* The transmission of the packfile begins immediately after the
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section header
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* The data transfer of the packfile is always multiplexed, using
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the same semantics of the 'side-band-64k' capability from
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protocol version 1. This means that each packet, during the
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packfile data stream, is made up of a leading 4-byte pkt-line
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length (typical of the pkt-line format), followed by a 1-byte
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stream code, followed by the actual data.
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The stream code can be one of:
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1 - pack data
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2 - progress messages
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3 - fatal error message just before stream aborts
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2
serve.c
2
serve.c
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@ -6,6 +6,7 @@
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#include "argv-array.h"
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#include "ls-refs.h"
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#include "serve.h"
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#include "upload-pack.h"
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static int always_advertise(struct repository *r,
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struct strbuf *value)
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@ -54,6 +55,7 @@ struct protocol_capability {
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static struct protocol_capability capabilities[] = {
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{ "agent", agent_advertise, NULL },
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{ "ls-refs", always_advertise, ls_refs },
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{ "fetch", always_advertise, upload_pack_v2 },
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};
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static void advertise_capabilities(void)
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@ -9,6 +9,7 @@ test_expect_success 'test capability advertisement' '
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version 2
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agent=git/$(git version | cut -d" " -f3)
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ls-refs
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fetch
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0000
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EOF
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266
upload-pack.c
266
upload-pack.c
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@ -18,6 +18,7 @@
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#include "prio-queue.h"
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#include "protocol.h"
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#include "upload-pack.h"
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#include "serve.h"
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/* Remember to update object flag allocation in object.h */
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#define THEY_HAVE (1u << 11)
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@ -1065,3 +1066,268 @@ void upload_pack(struct upload_pack_options *options)
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create_pack_file();
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}
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}
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struct upload_pack_data {
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struct object_array wants;
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struct oid_array haves;
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unsigned stateless_rpc : 1;
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unsigned use_thin_pack : 1;
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unsigned use_ofs_delta : 1;
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unsigned no_progress : 1;
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unsigned use_include_tag : 1;
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unsigned done : 1;
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};
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static void upload_pack_data_init(struct upload_pack_data *data)
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{
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struct object_array wants = OBJECT_ARRAY_INIT;
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struct oid_array haves = OID_ARRAY_INIT;
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memset(data, 0, sizeof(*data));
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data->wants = wants;
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data->haves = haves;
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}
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static void upload_pack_data_clear(struct upload_pack_data *data)
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{
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object_array_clear(&data->wants);
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oid_array_clear(&data->haves);
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}
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static int parse_want(const char *line)
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{
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const char *arg;
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if (skip_prefix(line, "want ", &arg)) {
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struct object_id oid;
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struct object *o;
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if (get_oid_hex(arg, &oid))
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die("git upload-pack: protocol error, "
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"expected to get oid, not '%s'", line);
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o = parse_object(&oid);
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if (!o) {
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packet_write_fmt(1,
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"ERR upload-pack: not our ref %s",
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oid_to_hex(&oid));
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die("git upload-pack: not our ref %s",
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oid_to_hex(&oid));
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}
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if (!(o->flags & WANTED)) {
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o->flags |= WANTED;
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add_object_array(o, NULL, &want_obj);
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}
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return 1;
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}
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return 0;
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}
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static int parse_have(const char *line, struct oid_array *haves)
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{
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const char *arg;
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if (skip_prefix(line, "have ", &arg)) {
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struct object_id oid;
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if (get_oid_hex(arg, &oid))
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die("git upload-pack: expected SHA1 object, got '%s'", arg);
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oid_array_append(haves, &oid);
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return 1;
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}
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return 0;
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}
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static void process_args(struct packet_reader *request,
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struct upload_pack_data *data)
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{
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while (packet_reader_read(request) != PACKET_READ_FLUSH) {
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const char *arg = request->line;
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/* process want */
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if (parse_want(arg))
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continue;
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/* process have line */
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if (parse_have(arg, &data->haves))
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continue;
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/* process args like thin-pack */
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if (!strcmp(arg, "thin-pack")) {
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use_thin_pack = 1;
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continue;
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}
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if (!strcmp(arg, "ofs-delta")) {
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use_ofs_delta = 1;
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continue;
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}
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if (!strcmp(arg, "no-progress")) {
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no_progress = 1;
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continue;
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}
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if (!strcmp(arg, "include-tag")) {
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use_include_tag = 1;
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continue;
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}
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if (!strcmp(arg, "done")) {
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data->done = 1;
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continue;
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}
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/* ignore unknown lines maybe? */
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die("unexpect line: '%s'", arg);
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}
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}
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static int process_haves(struct oid_array *haves, struct oid_array *common)
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{
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int i;
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/* Process haves */
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for (i = 0; i < haves->nr; i++) {
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const struct object_id *oid = &haves->oid[i];
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struct object *o;
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int we_knew_they_have = 0;
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if (!has_object_file(oid))
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continue;
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oid_array_append(common, oid);
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o = parse_object(oid);
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if (!o)
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die("oops (%s)", oid_to_hex(oid));
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if (o->type == OBJ_COMMIT) {
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struct commit_list *parents;
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struct commit *commit = (struct commit *)o;
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if (o->flags & THEY_HAVE)
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we_knew_they_have = 1;
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else
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o->flags |= THEY_HAVE;
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if (!oldest_have || (commit->date < oldest_have))
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oldest_have = commit->date;
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for (parents = commit->parents;
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parents;
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parents = parents->next)
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parents->item->object.flags |= THEY_HAVE;
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}
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if (!we_knew_they_have)
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add_object_array(o, NULL, &have_obj);
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}
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return 0;
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}
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static int send_acks(struct oid_array *acks, struct strbuf *response)
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{
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int i;
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packet_buf_write(response, "acknowledgments\n");
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/* Send Acks */
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if (!acks->nr)
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packet_buf_write(response, "NAK\n");
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for (i = 0; i < acks->nr; i++) {
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packet_buf_write(response, "ACK %s\n",
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oid_to_hex(&acks->oid[i]));
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}
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if (ok_to_give_up()) {
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/* Send Ready */
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packet_buf_write(response, "ready\n");
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return 1;
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}
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return 0;
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}
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static int process_haves_and_send_acks(struct upload_pack_data *data)
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{
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struct oid_array common = OID_ARRAY_INIT;
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struct strbuf response = STRBUF_INIT;
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int ret = 0;
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process_haves(&data->haves, &common);
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if (data->done) {
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ret = 1;
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} else if (send_acks(&common, &response)) {
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packet_buf_delim(&response);
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ret = 1;
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} else {
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/* Add Flush */
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packet_buf_flush(&response);
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ret = 0;
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}
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/* Send response */
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write_or_die(1, response.buf, response.len);
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strbuf_release(&response);
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oid_array_clear(&data->haves);
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oid_array_clear(&common);
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return ret;
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}
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enum fetch_state {
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FETCH_PROCESS_ARGS = 0,
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FETCH_SEND_ACKS,
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FETCH_SEND_PACK,
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FETCH_DONE,
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};
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int upload_pack_v2(struct repository *r, struct argv_array *keys,
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struct packet_reader *request)
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{
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enum fetch_state state = FETCH_PROCESS_ARGS;
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struct upload_pack_data data;
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upload_pack_data_init(&data);
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use_sideband = LARGE_PACKET_MAX;
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while (state != FETCH_DONE) {
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switch (state) {
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case FETCH_PROCESS_ARGS:
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process_args(request, &data);
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if (!want_obj.nr) {
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/*
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* Request didn't contain any 'want' lines,
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* guess they didn't want anything.
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*/
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state = FETCH_DONE;
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} else if (data.haves.nr) {
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/*
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* Request had 'have' lines, so lets ACK them.
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*/
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state = FETCH_SEND_ACKS;
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} else {
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/*
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* Request had 'want's but no 'have's so we can
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* immedietly go to construct and send a pack.
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*/
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state = FETCH_SEND_PACK;
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}
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break;
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case FETCH_SEND_ACKS:
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if (process_haves_and_send_acks(&data))
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state = FETCH_SEND_PACK;
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else
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state = FETCH_DONE;
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break;
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case FETCH_SEND_PACK:
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packet_write_fmt(1, "packfile\n");
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create_pack_file();
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state = FETCH_DONE;
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break;
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case FETCH_DONE:
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continue;
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}
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}
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upload_pack_data_clear(&data);
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return 0;
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}
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@ -10,4 +10,10 @@ struct upload_pack_options {
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void upload_pack(struct upload_pack_options *options);
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struct repository;
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struct argv_array;
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struct packet_reader;
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extern int upload_pack_v2(struct repository *r, struct argv_array *keys,
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struct packet_reader *request);
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#endif /* UPLOAD_PACK_H */
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