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1 '\" t
2 .\" Title: gitprotocol-v2
3 .\" Author: [FIXME: author] [see http://www.docbook.org/tdg5/en/html/author]
4 .\" Generator: DocBook XSL Stylesheets vsnapshot <http://docbook.sf.net/>
5 .\" Date: 10/27/2022
6 .\" Manual: Git Manual
7 .\" Source: Git 2.38.1.220.g9388e93f00
8 .\" Language: English
9 .\"
10 .TH "GITPROTOCOL\-V2" "5" "10/27/2022" "Git 2\&.38\&.1\&.220\&.g9388e9" "Git Manual"
11 .\" -----------------------------------------------------------------
12 .\" * Define some portability stuff
13 .\" -----------------------------------------------------------------
14 .\" ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
15 .\" http://bugs.debian.org/507673
16 .\" http://lists.gnu.org/archive/html/groff/2009-02/msg00013.html
17 .\" ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
18 .ie \n(.g .ds Aq \(aq
19 .el .ds Aq '
20 .\" -----------------------------------------------------------------
21 .\" * set default formatting
22 .\" -----------------------------------------------------------------
23 .\" disable hyphenation
24 .nh
25 .\" disable justification (adjust text to left margin only)
26 .ad l
27 .\" -----------------------------------------------------------------
28 .\" * MAIN CONTENT STARTS HERE *
29 .\" -----------------------------------------------------------------
30 .SH "NAME"
31 gitprotocol-v2 \- Git Wire Protocol, Version 2
32 .SH "SYNOPSIS"
33 .sp
34 .nf
35 <over\-the\-wire\-protocol>
36 .fi
37 .sp
38 .SH "DESCRIPTION"
39 .sp
40 This document presents a specification for a version 2 of Git\(cqs wire protocol\&. Protocol v2 will improve upon v1 in the following ways:
41 .sp
42 .RS 4
43 .ie n \{\
44 \h'-04'\(bu\h'+03'\c
45 .\}
46 .el \{\
47 .sp -1
48 .IP \(bu 2.3
49 .\}
50 Instead of multiple service names, multiple commands will be supported by a single service
51 .RE
52 .sp
53 .RS 4
54 .ie n \{\
55 \h'-04'\(bu\h'+03'\c
56 .\}
57 .el \{\
58 .sp -1
59 .IP \(bu 2.3
60 .\}
61 Easily extendable as capabilities are moved into their own section of the protocol, no longer being hidden behind a NUL byte and limited by the size of a pkt\-line
62 .RE
63 .sp
64 .RS 4
65 .ie n \{\
66 \h'-04'\(bu\h'+03'\c
67 .\}
68 .el \{\
69 .sp -1
70 .IP \(bu 2.3
71 .\}
72 Separate out other information hidden behind NUL bytes (e\&.g\&. agent string as a capability and symrefs can be requested using
73 \fIls\-refs\fR)
74 .RE
75 .sp
76 .RS 4
77 .ie n \{\
78 \h'-04'\(bu\h'+03'\c
79 .\}
80 .el \{\
81 .sp -1
82 .IP \(bu 2.3
83 .\}
84 Reference advertisement will be omitted unless explicitly requested
85 .RE
86 .sp
87 .RS 4
88 .ie n \{\
89 \h'-04'\(bu\h'+03'\c
90 .\}
91 .el \{\
92 .sp -1
93 .IP \(bu 2.3
94 .\}
95 ls\-refs command to explicitly request some refs
96 .RE
97 .sp
98 .RS 4
99 .ie n \{\
100 \h'-04'\(bu\h'+03'\c
101 .\}
102 .el \{\
103 .sp -1
104 .IP \(bu 2.3
105 .\}
106 Designed with http and stateless\-rpc in mind\&. With clear flush semantics the http remote helper can simply act as a proxy
107 .RE
108 .sp
109 In protocol v2 communication is command oriented\&. When first contacting a server a list of capabilities will advertised\&. Some of these capabilities will be commands which a client can request be executed\&. Once a command has completed, a client can reuse the connection and request that other commands be executed\&.
110 .SH "PACKET\-LINE FRAMING"
111 .sp
112 All communication is done using packet\-line framing, just as in v1\&. See \fBgitprotocol-pack\fR(5) and \fBgitprotocol-common\fR(5) for more information\&.
113 .sp
114 In protocol v2 these special packets will have the following semantics:
115 .sp
116 .RS 4
117 .ie n \{\
118 \h'-04'\(bu\h'+03'\c
119 .\}
120 .el \{\
121 .sp -1
122 .IP \(bu 2.3
123 .\}
124 \fI0000\fR
125 Flush Packet (flush\-pkt) \- indicates the end of a message
126 .RE
127 .sp
128 .RS 4
129 .ie n \{\
130 \h'-04'\(bu\h'+03'\c
131 .\}
132 .el \{\
133 .sp -1
134 .IP \(bu 2.3
135 .\}
136 \fI0001\fR
137 Delimiter Packet (delim\-pkt) \- separates sections of a message
138 .RE
139 .sp
140 .RS 4
141 .ie n \{\
142 \h'-04'\(bu\h'+03'\c
143 .\}
144 .el \{\
145 .sp -1
146 .IP \(bu 2.3
147 .\}
148 \fI0002\fR
149 Response End Packet (response\-end\-pkt) \- indicates the end of a response for stateless connections
150 .RE
151 .SH "INITIAL CLIENT REQUEST"
152 .sp
153 In general a client can request to speak protocol v2 by sending \fBversion=2\fR through the respective side\-channel for the transport being used which inevitably sets \fBGIT_PROTOCOL\fR\&. More information can be found in \fBgitprotocol-pack\fR(5) and \fBgitprotocol-http\fR(5), as well as the \fBGIT_PROTOCOL\fR definition in \fBgit\&.txt\fR\&. In all cases the response from the server is the capability advertisement\&.
154 .SS "Git Transport"
155 .sp
156 When using the git:// transport, you can request to use protocol v2 by sending "version=2" as an extra parameter:
157 .sp
158 .if n \{\
159 .RS 4
160 .\}
161 .nf
162 003egit\-upload\-pack /project\&.git\e0host=myserver\&.com\e0\e0version=2\e0
163 .fi
164 .if n \{\
165 .RE
166 .\}
167 .SS "SSH and File Transport"
168 .sp
169 When using either the ssh:// or file:// transport, the GIT_PROTOCOL environment variable must be set explicitly to include "version=2"\&. The server may need to be configured to allow this environment variable to pass\&.
170 .SS "HTTP Transport"
171 .sp
172 When using the http:// or https:// transport a client makes a "smart" info/refs request as described in \fBgitprotocol-http\fR(5) and requests that v2 be used by supplying "version=2" in the \fBGit\-Protocol\fR header\&.
173 .sp
174 .if n \{\
175 .RS 4
176 .\}
177 .nf
178 C: GET $GIT_URL/info/refs?service=git\-upload\-pack HTTP/1\&.0
179 C: Git\-Protocol: version=2
180 .fi
181 .if n \{\
182 .RE
183 .\}
184 .sp
185 A v2 server would reply:
186 .sp
187 .if n \{\
188 .RS 4
189 .\}
190 .nf
191 S: 200 OK
192 S: <Some headers>
193 S: \&.\&.\&.
194 S:
195 S: 000eversion 2\en
196 S: <capability\-advertisement>
197 .fi
198 .if n \{\
199 .RE
200 .\}
201 .sp
202 Subsequent requests are then made directly to the service \fB$GIT_URL/git\-upload\-pack\fR\&. (This works the same for git\-receive\-pack)\&.
203 .sp
204 Uses the \fB\-\-http\-backend\-info\-refs\fR option to \fBgit-upload-pack\fR(1)\&.
205 .sp
206 The server may need to be configured to pass this header\(cqs contents via the \fBGIT_PROTOCOL\fR variable\&. See the discussion in \fBgit\-http\-backend\&.txt\fR\&.
207 .SH "CAPABILITY ADVERTISEMENT"
208 .sp
209 A server which decides to communicate (based on a request from a client) using protocol version 2, notifies the client by sending a version string in its initial response followed by an advertisement of its capabilities\&. Each capability is a key with an optional value\&. Clients must ignore all unknown keys\&. Semantics of unknown values are left to the definition of each key\&. Some capabilities will describe commands which can be requested to be executed by the client\&.
210 .sp
211 .if n \{\
212 .RS 4
213 .\}
214 .nf
215 capability\-advertisement = protocol\-version
216 capability\-list
217 flush\-pkt
218 .fi
219 .if n \{\
220 .RE
221 .\}
222 .sp
223 .if n \{\
224 .RS 4
225 .\}
226 .nf
227 protocol\-version = PKT\-LINE("version 2" LF)
228 capability\-list = *capability
229 capability = PKT\-LINE(key[=value] LF)
230 .fi
231 .if n \{\
232 .RE
233 .\}
234 .sp
235 .if n \{\
236 .RS 4
237 .\}
238 .nf
239 key = 1*(ALPHA | DIGIT | "\-_")
240 value = 1*(ALPHA | DIGIT | " \-_\&.,?\e/{}[]()<>!@#$%^&*+=:;")
241 .fi
242 .if n \{\
243 .RE
244 .\}
245 .SH "COMMAND REQUEST"
246 .sp
247 After receiving the capability advertisement, a client can then issue a request to select the command it wants with any particular capabilities or arguments\&. There is then an optional section where the client can provide any command specific parameters or queries\&. Only a single command can be requested at a time\&.
248 .sp
249 .if n \{\
250 .RS 4
251 .\}
252 .nf
253 request = empty\-request | command\-request
254 empty\-request = flush\-pkt
255 command\-request = command
256 capability\-list
257 delim\-pkt
258 command\-args
259 flush\-pkt
260 command = PKT\-LINE("command=" key LF)
261 command\-args = *command\-specific\-arg
262 .fi
263 .if n \{\
264 .RE
265 .\}
266 .sp
267 .if n \{\
268 .RS 4
269 .\}
270 .nf
271 command\-specific\-args are packet line framed arguments defined by
272 each individual command\&.
273 .fi
274 .if n \{\
275 .RE
276 .\}
277 .sp
278 The server will then check to ensure that the client\(cqs request is comprised of a valid command as well as valid capabilities which were advertised\&. If the request is valid the server will then execute the command\&. A server MUST wait till it has received the client\(cqs entire request before issuing a response\&. The format of the response is determined by the command being executed, but in all cases a flush\-pkt indicates the end of the response\&.
279 .sp
280 When a command has finished, and the client has received the entire response from the server, a client can either request that another command be executed or can terminate the connection\&. A client may optionally send an empty request consisting of just a flush\-pkt to indicate that no more requests will be made\&.
281 .SH "CAPABILITIES"
282 .sp
283 There are two different types of capabilities: normal capabilities, which can be used to convey information or alter the behavior of a request, and commands, which are the core actions that a client wants to perform (fetch, push, etc)\&.
284 .sp
285 Protocol version 2 is stateless by default\&. This means that all commands must only last a single round and be stateless from the perspective of the server side, unless the client has requested a capability indicating that state should be maintained by the server\&. Clients MUST NOT require state management on the server side in order to function correctly\&. This permits simple round\-robin load\-balancing on the server side, without needing to worry about state management\&.
286 .SS "agent"
287 .sp
288 The server can advertise the \fBagent\fR capability with a value \fBX\fR (in the form \fBagent=X\fR) to notify the client that the server is running version \fBX\fR\&. The client may optionally send its own agent string by including the \fBagent\fR capability with a value \fBY\fR (in the form \fBagent=Y\fR) in its request to the server (but it MUST NOT do so if the server did not advertise the agent capability)\&. The \fBX\fR and \fBY\fR strings may contain any printable ASCII characters except space (i\&.e\&., the byte range 32 < x < 127), and are typically of the form "package/version" (e\&.g\&., "git/1\&.8\&.3\&.1")\&. The agent strings are purely informative for statistics and debugging purposes, and MUST NOT be used to programmatically assume the presence or absence of particular features\&.
289 .SS "ls\-refs"
290 .sp
291 \fBls\-refs\fR is the command used to request a reference advertisement in v2\&. Unlike the current reference advertisement, ls\-refs takes in arguments which can be used to limit the refs sent from the server\&.
292 .sp
293 Additional features not supported in the base command will be advertised as the value of the command in the capability advertisement in the form of a space separated list of features: "<command>=<feature 1> <feature 2>"
294 .sp
295 ls\-refs takes in the following arguments:
296 .sp
297 .if n \{\
298 .RS 4
299 .\}
300 .nf
301 symrefs
302 In addition to the object pointed by it, show the underlying ref
303 pointed by it when showing a symbolic ref\&.
304 peel
305 Show peeled tags\&.
306 ref\-prefix <prefix>
307 When specified, only references having a prefix matching one of
308 the provided prefixes are displayed\&. Multiple instances may be
309 given, in which case references matching any prefix will be
310 shown\&. Note that this is purely for optimization; a server MAY
311 show refs not matching the prefix if it chooses, and clients
312 should filter the result themselves\&.
313 .fi
314 .if n \{\
315 .RE
316 .\}
317 .sp
318 If the \fIunborn\fR feature is advertised the following argument can be included in the client\(cqs request\&.
319 .sp
320 .if n \{\
321 .RS 4
322 .\}
323 .nf
324 unborn
325 The server will send information about HEAD even if it is a symref
326 pointing to an unborn branch in the form "unborn HEAD
327 symref\-target:<target>"\&.
328 .fi
329 .if n \{\
330 .RE
331 .\}
332 .sp
333 The output of ls\-refs is as follows:
334 .sp
335 .if n \{\
336 .RS 4
337 .\}
338 .nf
339 output = *ref
340 flush\-pkt
341 obj\-id\-or\-unborn = (obj\-id | "unborn")
342 ref = PKT\-LINE(obj\-id\-or\-unborn SP refname *(SP ref\-attribute) LF)
343 ref\-attribute = (symref | peeled)
344 symref = "symref\-target:" symref\-target
345 peeled = "peeled:" obj\-id
346 .fi
347 .if n \{\
348 .RE
349 .\}
350 .SS "fetch"
351 .sp
352 \fBfetch\fR is the command used to fetch a packfile in v2\&. It can be looked at as a modified version of the v1 fetch where the ref\-advertisement is stripped out (since the \fBls\-refs\fR command fills that role) and the message format is tweaked to eliminate redundancies and permit easy addition of future extensions\&.
353 .sp
354 Additional features not supported in the base command will be advertised as the value of the command in the capability advertisement in the form of a space separated list of features: "<command>=<feature 1> <feature 2>"
355 .sp
356 A \fBfetch\fR request can take the following arguments:
357 .sp
358 .if n \{\
359 .RS 4
360 .\}
361 .nf
362 want <oid>
363 Indicates to the server an object which the client wants to
364 retrieve\&. Wants can be anything and are not limited to
365 advertised objects\&.
366 .fi
367 .if n \{\
368 .RE
369 .\}
370 .sp
371 .if n \{\
372 .RS 4
373 .\}
374 .nf
375 have <oid>
376 Indicates to the server an object which the client has locally\&.
377 This allows the server to make a packfile which only contains
378 the objects that the client needs\&. Multiple \(aqhave\(aq lines can be
379 supplied\&.
380 .fi
381 .if n \{\
382 .RE
383 .\}
384 .sp
385 .if n \{\
386 .RS 4
387 .\}
388 .nf
389 done
390 Indicates to the server that negotiation should terminate (or
391 not even begin if performing a clone) and that the server should
392 use the information supplied in the request to construct the
393 packfile\&.
394 .fi
395 .if n \{\
396 .RE
397 .\}
398 .sp
399 .if n \{\
400 .RS 4
401 .\}
402 .nf
403 thin\-pack
404 Request that a thin pack be sent, which is a pack with deltas
405 which reference base objects not contained within the pack (but
406 are known to exist at the receiving end)\&. This can reduce the
407 network traffic significantly, but it requires the receiving end
408 to know how to "thicken" these packs by adding the missing bases
409 to the pack\&.
410 .fi
411 .if n \{\
412 .RE
413 .\}
414 .sp
415 .if n \{\
416 .RS 4
417 .\}
418 .nf
419 no\-progress
420 Request that progress information that would normally be sent on
421 side\-band channel 2, during the packfile transfer, should not be
422 sent\&. However, the side\-band channel 3 is still used for error
423 responses\&.
424 .fi
425 .if n \{\
426 .RE
427 .\}
428 .sp
429 .if n \{\
430 .RS 4
431 .\}
432 .nf
433 include\-tag
434 Request that annotated tags should be sent if the objects they
435 point to are being sent\&.
436 .fi
437 .if n \{\
438 .RE
439 .\}
440 .sp
441 .if n \{\
442 .RS 4
443 .\}
444 .nf
445 ofs\-delta
446 Indicate that the client understands PACKv2 with delta referring
447 to its base by position in pack rather than by an oid\&. That is,
448 they can read OBJ_OFS_DELTA (aka type 6) in a packfile\&.
449 .fi
450 .if n \{\
451 .RE
452 .\}
453 .sp
454 If the \fIshallow\fR feature is advertised the following arguments can be included in the clients request as well as the potential addition of the \fIshallow\-info\fR section in the server\(cqs response as explained below\&.
455 .sp
456 .if n \{\
457 .RS 4
458 .\}
459 .nf
460 shallow <oid>
461 A client must notify the server of all commits for which it only
462 has shallow copies (meaning that it doesn\(aqt have the parents of
463 a commit) by supplying a \(aqshallow <oid>\(aq line for each such
464 object so that the server is aware of the limitations of the
465 client\(aqs history\&. This is so that the server is aware that the
466 client may not have all objects reachable from such commits\&.
467 .fi
468 .if n \{\
469 .RE
470 .\}
471 .sp
472 .if n \{\
473 .RS 4
474 .\}
475 .nf
476 deepen <depth>
477 Requests that the fetch/clone should be shallow having a commit
478 depth of <depth> relative to the remote side\&.
479 .fi
480 .if n \{\
481 .RE
482 .\}
483 .sp
484 .if n \{\
485 .RS 4
486 .\}
487 .nf
488 deepen\-relative
489 Requests that the semantics of the "deepen" command be changed
490 to indicate that the depth requested is relative to the client\(aqs
491 current shallow boundary, instead of relative to the requested
492 commits\&.
493 .fi
494 .if n \{\
495 .RE
496 .\}
497 .sp
498 .if n \{\
499 .RS 4
500 .\}
501 .nf
502 deepen\-since <timestamp>
503 Requests that the shallow clone/fetch should be cut at a
504 specific time, instead of depth\&. Internally it\(aqs equivalent to
505 doing "git rev\-list \-\-max\-age=<timestamp>"\&. Cannot be used with
506 "deepen"\&.
507 .fi
508 .if n \{\
509 .RE
510 .\}
511 .sp
512 .if n \{\
513 .RS 4
514 .\}
515 .nf
516 deepen\-not <rev>
517 Requests that the shallow clone/fetch should be cut at a
518 specific revision specified by \(aq<rev>\(aq, instead of a depth\&.
519 Internally it\(aqs equivalent of doing "git rev\-list \-\-not <rev>"\&.
520 Cannot be used with "deepen", but can be used with
521 "deepen\-since"\&.
522 .fi
523 .if n \{\
524 .RE
525 .\}
526 .sp
527 If the \fIfilter\fR feature is advertised, the following argument can be included in the client\(cqs request:
528 .sp
529 .if n \{\
530 .RS 4
531 .\}
532 .nf
533 filter <filter\-spec>
534 Request that various objects from the packfile be omitted
535 using one of several filtering techniques\&. These are intended
536 for use with partial clone and partial fetch operations\&. See
537 `rev\-list` for possible "filter\-spec" values\&. When communicating
538 with other processes, senders SHOULD translate scaled integers
539 (e\&.g\&. "1k") into a fully\-expanded form (e\&.g\&. "1024") to aid
540 interoperability with older receivers that may not understand
541 newly\-invented scaling suffixes\&. However, receivers SHOULD
542 accept the following suffixes: \(aqk\(aq, \(aqm\(aq, and \(aqg\(aq for 1024,
543 1048576, and 1073741824, respectively\&.
544 .fi
545 .if n \{\
546 .RE
547 .\}
548 .sp
549 If the \fIref\-in\-want\fR feature is advertised, the following argument can be included in the client\(cqs request as well as the potential addition of the \fIwanted\-refs\fR section in the server\(cqs response as explained below\&.
550 .sp
551 .if n \{\
552 .RS 4
553 .\}
554 .nf
555 want\-ref <ref>
556 Indicates to the server that the client wants to retrieve a
557 particular ref, where <ref> is the full name of a ref on the
558 server\&.
559 .fi
560 .if n \{\
561 .RE
562 .\}
563 .sp
564 If the \fIsideband\-all\fR feature is advertised, the following argument can be included in the client\(cqs request:
565 .sp
566 .if n \{\
567 .RS 4
568 .\}
569 .nf
570 sideband\-all
571 Instruct the server to send the whole response multiplexed, not just
572 the packfile section\&. All non\-flush and non\-delim PKT\-LINE in the
573 response (not only in the packfile section) will then start with a byte
574 indicating its sideband (1, 2, or 3), and the server may send "0005\e2"
575 (a PKT\-LINE of sideband 2 with no payload) as a keepalive packet\&.
576 .fi
577 .if n \{\
578 .RE
579 .\}
580 .sp
581 If the \fIpackfile\-uris\fR feature is advertised, the following argument can be included in the client\(cqs request as well as the potential addition of the \fIpackfile\-uris\fR section in the server\(cqs response as explained below\&.
582 .sp
583 .if n \{\
584 .RS 4
585 .\}
586 .nf
587 packfile\-uris <comma\-separated list of protocols>
588 Indicates to the server that the client is willing to receive
589 URIs of any of the given protocols in place of objects in the
590 sent packfile\&. Before performing the connectivity check, the
591 client should download from all given URIs\&. Currently, the
592 protocols supported are "http" and "https"\&.
593 .fi
594 .if n \{\
595 .RE
596 .\}
597 .sp
598 If the \fIwait\-for\-done\fR feature is advertised, the following argument can be included in the client\(cqs request\&.
599 .sp
600 .if n \{\
601 .RS 4
602 .\}
603 .nf
604 wait\-for\-done
605 Indicates to the server that it should never send "ready", but
606 should wait for the client to say "done" before sending the
607 packfile\&.
608 .fi
609 .if n \{\
610 .RE
611 .\}
612 .sp
613 The response of \fBfetch\fR is broken into a number of sections separated by delimiter packets (0001), with each section beginning with its section header\&. Most sections are sent only when the packfile is sent\&.
614 .sp
615 .if n \{\
616 .RS 4
617 .\}
618 .nf
619 output = acknowledgements flush\-pkt |
620 [acknowledgments delim\-pkt] [shallow\-info delim\-pkt]
621 [wanted\-refs delim\-pkt] [packfile\-uris delim\-pkt]
622 packfile flush\-pkt
623 .fi
624 .if n \{\
625 .RE
626 .\}
627 .sp
628 .if n \{\
629 .RS 4
630 .\}
631 .nf
632 acknowledgments = PKT\-LINE("acknowledgments" LF)
633 (nak | *ack)
634 (ready)
635 ready = PKT\-LINE("ready" LF)
636 nak = PKT\-LINE("NAK" LF)
637 ack = PKT\-LINE("ACK" SP obj\-id LF)
638 .fi
639 .if n \{\
640 .RE
641 .\}
642 .sp
643 .if n \{\
644 .RS 4
645 .\}
646 .nf
647 shallow\-info = PKT\-LINE("shallow\-info" LF)
648 *PKT\-LINE((shallow | unshallow) LF)
649 shallow = "shallow" SP obj\-id
650 unshallow = "unshallow" SP obj\-id
651 .fi
652 .if n \{\
653 .RE
654 .\}
655 .sp
656 .if n \{\
657 .RS 4
658 .\}
659 .nf
660 wanted\-refs = PKT\-LINE("wanted\-refs" LF)
661 *PKT\-LINE(wanted\-ref LF)
662 wanted\-ref = obj\-id SP refname
663 .fi
664 .if n \{\
665 .RE
666 .\}
667 .sp
668 .if n \{\
669 .RS 4
670 .\}
671 .nf
672 packfile\-uris = PKT\-LINE("packfile\-uris" LF) *packfile\-uri
673 packfile\-uri = PKT\-LINE(40*(HEXDIGIT) SP *%x20\-ff LF)
674 .fi
675 .if n \{\
676 .RE
677 .\}
678 .sp
679 .if n \{\
680 .RS 4
681 .\}
682 .nf
683 packfile = PKT\-LINE("packfile" LF)
684 *PKT\-LINE(%x01\-03 *%x00\-ff)
685 .fi
686 .if n \{\
687 .RE
688 .\}
689 .sp
690 .if n \{\
691 .RS 4
692 .\}
693 .nf
694 acknowledgments section
695 * If the client determines that it is finished with negotiations by
696 sending a "done" line (thus requiring the server to send a packfile),
697 the acknowledgments sections MUST be omitted from the server\(aqs
698 response\&.
699 .fi
700 .if n \{\
701 .RE
702 .\}
703 .sp
704 .RS 4
705 .ie n \{\
706 \h'-04'\(bu\h'+03'\c
707 .\}
708 .el \{\
709 .sp -1
710 .IP \(bu 2.3
711 .\}
712 Always begins with the section header "acknowledgments"
713 .RE
714 .sp
715 .RS 4
716 .ie n \{\
717 \h'-04'\(bu\h'+03'\c
718 .\}
719 .el \{\
720 .sp -1
721 .IP \(bu 2.3
722 .\}
723 The server will respond with "NAK" if none of the object ids sent as have lines were common\&.
724 .RE
725 .sp
726 .RS 4
727 .ie n \{\
728 \h'-04'\(bu\h'+03'\c
729 .\}
730 .el \{\
731 .sp -1
732 .IP \(bu 2.3
733 .\}
734 The server will respond with "ACK obj\-id" for all of the object ids sent as have lines which are common\&.
735 .RE
736 .sp
737 .RS 4
738 .ie n \{\
739 \h'-04'\(bu\h'+03'\c
740 .\}
741 .el \{\
742 .sp -1
743 .IP \(bu 2.3
744 .\}
745 A response cannot have both "ACK" lines as well as a "NAK" line\&.
746 .RE
747 .sp
748 .RS 4
749 .ie n \{\
750 \h'-04'\(bu\h'+03'\c
751 .\}
752 .el \{\
753 .sp -1
754 .IP \(bu 2.3
755 .\}
756 The server will respond with a "ready" line indicating that the server has found an acceptable common base and is ready to make and send a packfile (which will be found in the packfile section of the same response)
757 .RE
758 .sp
759 .RS 4
760 .ie n \{\
761 \h'-04'\(bu\h'+03'\c
762 .\}
763 .el \{\
764 .sp -1
765 .IP \(bu 2.3
766 .\}
767 If the server has found a suitable cut point and has decided to send a "ready" line, then the server can decide to (as an optimization) omit any "ACK" lines it would have sent during its response\&. This is because the server will have already determined the objects it plans to send to the client and no further negotiation is needed\&.
768 .sp
769 .if n \{\
770 .RS 4
771 .\}
772 .nf
773 shallow\-info section
774 * If the client has requested a shallow fetch/clone, a shallow
775 client requests a fetch or the server is shallow then the
776 server\(aqs response may include a shallow\-info section\&. The
777 shallow\-info section will be included if (due to one of the
778 above conditions) the server needs to inform the client of any
779 shallow boundaries or adjustments to the clients already
780 existing shallow boundaries\&.
781 .fi
782 .if n \{\
783 .RE
784 .\}
785 .RE
786 .sp
787 .RS 4
788 .ie n \{\
789 \h'-04'\(bu\h'+03'\c
790 .\}
791 .el \{\
792 .sp -1
793 .IP \(bu 2.3
794 .\}
795 Always begins with the section header "shallow\-info"
796 .RE
797 .sp
798 .RS 4
799 .ie n \{\
800 \h'-04'\(bu\h'+03'\c
801 .\}
802 .el \{\
803 .sp -1
804 .IP \(bu 2.3
805 .\}
806 If a positive depth is requested, the server will compute the set of commits which are no deeper than the desired depth\&.
807 .RE
808 .sp
809 .RS 4
810 .ie n \{\
811 \h'-04'\(bu\h'+03'\c
812 .\}
813 .el \{\
814 .sp -1
815 .IP \(bu 2.3
816 .\}
817 The server sends a "shallow obj\-id" line for each commit whose parents will not be sent in the following packfile\&.
818 .RE
819 .sp
820 .RS 4
821 .ie n \{\
822 \h'-04'\(bu\h'+03'\c
823 .\}
824 .el \{\
825 .sp -1
826 .IP \(bu 2.3
827 .\}
828 The server sends an "unshallow obj\-id" line for each commit which the client has indicated is shallow, but is no longer shallow as a result of the fetch (due to its parents being sent in the following packfile)\&.
829 .RE
830 .sp
831 .RS 4
832 .ie n \{\
833 \h'-04'\(bu\h'+03'\c
834 .\}
835 .el \{\
836 .sp -1
837 .IP \(bu 2.3
838 .\}
839 The server MUST NOT send any "unshallow" lines for anything which the client has not indicated was shallow as a part of its request\&.
840 .sp
841 .if n \{\
842 .RS 4
843 .\}
844 .nf
845 wanted\-refs section
846 * This section is only included if the client has requested a
847 ref using a \(aqwant\-ref\(aq line and if a packfile section is also
848 included in the response\&.
849 .fi
850 .if n \{\
851 .RE
852 .\}
853 .RE
854 .sp
855 .RS 4
856 .ie n \{\
857 \h'-04'\(bu\h'+03'\c
858 .\}
859 .el \{\
860 .sp -1
861 .IP \(bu 2.3
862 .\}
863 Always begins with the section header "wanted\-refs"\&.
864 .RE
865 .sp
866 .RS 4
867 .ie n \{\
868 \h'-04'\(bu\h'+03'\c
869 .\}
870 .el \{\
871 .sp -1
872 .IP \(bu 2.3
873 .\}
874 The server will send a ref listing ("<oid> <refname>") for each reference requested using
875 \fIwant\-ref\fR
876 lines\&.
877 .RE
878 .sp
879 .RS 4
880 .ie n \{\
881 \h'-04'\(bu\h'+03'\c
882 .\}
883 .el \{\
884 .sp -1
885 .IP \(bu 2.3
886 .\}
887 The server MUST NOT send any refs which were not requested using
888 \fIwant\-ref\fR
889 lines\&.
890 .sp
891 .if n \{\
892 .RS 4
893 .\}
894 .nf
895 packfile\-uris section
896 * This section is only included if the client sent
897 \(aqpackfile\-uris\(aq and the server has at least one such URI to
898 send\&.
899 .fi
900 .if n \{\
901 .RE
902 .\}
903 .RE
904 .sp
905 .RS 4
906 .ie n \{\
907 \h'-04'\(bu\h'+03'\c
908 .\}
909 .el \{\
910 .sp -1
911 .IP \(bu 2.3
912 .\}
913 Always begins with the section header "packfile\-uris"\&.
914 .RE
915 .sp
916 .RS 4
917 .ie n \{\
918 \h'-04'\(bu\h'+03'\c
919 .\}
920 .el \{\
921 .sp -1
922 .IP \(bu 2.3
923 .\}
924 For each URI the server sends, it sends a hash of the pack\(cqs contents (as output by git index\-pack) followed by the URI\&.
925 .RE
926 .sp
927 .RS 4
928 .ie n \{\
929 \h'-04'\(bu\h'+03'\c
930 .\}
931 .el \{\
932 .sp -1
933 .IP \(bu 2.3
934 .\}
935 The hashes are 40 hex characters long\&. When Git upgrades to a new hash algorithm, this might need to be updated\&. (It should match whatever index\-pack outputs after "pack\et" or "keep\et"\&.
936 .sp
937 .if n \{\
938 .RS 4
939 .\}
940 .nf
941 packfile section
942 * This section is only included if the client has sent \(aqwant\(aq
943 lines in its request and either requested that no more
944 negotiation be done by sending \(aqdone\(aq or if the server has
945 decided it has found a sufficient cut point to produce a
946 packfile\&.
947 .fi
948 .if n \{\
949 .RE
950 .\}
951 .RE
952 .sp
953 .RS 4
954 .ie n \{\
955 \h'-04'\(bu\h'+03'\c
956 .\}
957 .el \{\
958 .sp -1
959 .IP \(bu 2.3
960 .\}
961 Always begins with the section header "packfile"
962 .RE
963 .sp
964 .RS 4
965 .ie n \{\
966 \h'-04'\(bu\h'+03'\c
967 .\}
968 .el \{\
969 .sp -1
970 .IP \(bu 2.3
971 .\}
972 The transmission of the packfile begins immediately after the section header
973 .RE
974 .sp
975 .RS 4
976 .ie n \{\
977 \h'-04'\(bu\h'+03'\c
978 .\}
979 .el \{\
980 .sp -1
981 .IP \(bu 2.3
982 .\}
983 The data transfer of the packfile is always multiplexed, using the same semantics of the
984 \fIside\-band\-64k\fR
985 capability from protocol version 1\&. This means that each packet, during the packfile data stream, is made up of a leading 4\-byte pkt\-line length (typical of the pkt\-line format), followed by a 1\-byte stream code, followed by the actual data\&.
986 .sp
987 .if n \{\
988 .RS 4
989 .\}
990 .nf
991 The stream code can be one of:
992 1 \- pack data
993 2 \- progress messages
994 3 \- fatal error message just before stream aborts
995 .fi
996 .if n \{\
997 .RE
998 .\}
999 .RE
1000 .SS "server\-option"
1001 .sp
1002 If advertised, indicates that any number of server specific options can be included in a request\&. This is done by sending each option as a "server\-option=<option>" capability line in the capability\-list section of a request\&.
1003 .sp
1004 The provided options must not contain a NUL or LF character\&.
1005 .SS "object\-format"
1006 .sp
1007 The server can advertise the \fBobject\-format\fR capability with a value \fBX\fR (in the form \fBobject\-format=X\fR) to notify the client that the server is able to deal with objects using hash algorithm X\&. If not specified, the server is assumed to only handle SHA\-1\&. If the client would like to use a hash algorithm other than SHA\-1, it should specify its object\-format string\&.
1008 .SS "session\-id=<session id>"
1009 .sp
1010 The server may advertise a session ID that can be used to identify this process across multiple requests\&. The client may advertise its own session ID back to the server as well\&.
1011 .sp
1012 Session IDs should be unique to a given process\&. They must fit within a packet\-line, and must not contain non\-printable or whitespace characters\&. The current implementation uses trace2 session IDs (see \m[blue]\fBapi\-trace2\fR\m[]\&\s-2\u[1]\d\s+2 for details), but this may change and users of the session ID should not rely on this fact\&.
1013 .SS "object\-info"
1014 .sp
1015 \fBobject\-info\fR is the command to retrieve information about one or more objects\&. Its main purpose is to allow a client to make decisions based on this information without having to fully fetch objects\&. Object size is the only information that is currently supported\&.
1016 .sp
1017 An \fBobject\-info\fR request takes the following arguments:
1018 .sp
1019 .if n \{\
1020 .RS 4
1021 .\}
1022 .nf
1023 size
1024 Requests size information to be returned for each listed object id\&.
1025 .fi
1026 .if n \{\
1027 .RE
1028 .\}
1029 .sp
1030 .if n \{\
1031 .RS 4
1032 .\}
1033 .nf
1034 oid <oid>
1035 Indicates to the server an object which the client wants to obtain
1036 information for\&.
1037 .fi
1038 .if n \{\
1039 .RE
1040 .\}
1041 .sp
1042 The response of \fBobject\-info\fR is a list of the requested object ids and associated requested information, each separated by a single space\&.
1043 .sp
1044 .if n \{\
1045 .RS 4
1046 .\}
1047 .nf
1048 output = info flush\-pkt
1049 .fi
1050 .if n \{\
1051 .RE
1052 .\}
1053 .sp
1054 .if n \{\
1055 .RS 4
1056 .\}
1057 .nf
1058 info = PKT\-LINE(attrs) LF)
1059 *PKT\-LINE(obj\-info LF)
1060 .fi
1061 .if n \{\
1062 .RE
1063 .\}
1064 .sp
1065 .if n \{\
1066 .RS 4
1067 .\}
1068 .nf
1069 attrs = attr | attrs SP attrs
1070 .fi
1071 .if n \{\
1072 .RE
1073 .\}
1074 .sp
1075 .if n \{\
1076 .RS 4
1077 .\}
1078 .nf
1079 attr = "size"
1080 .fi
1081 .if n \{\
1082 .RE
1083 .\}
1084 .sp
1085 .if n \{\
1086 .RS 4
1087 .\}
1088 .nf
1089 obj\-info = obj\-id SP obj\-size
1090 .fi
1091 .if n \{\
1092 .RE
1093 .\}
1094 .SH "GIT"
1095 .sp
1096 Part of the \fBgit\fR(1) suite
1097 .SH "NOTES"
1098 .IP " 1." 4
1099 api-trace2
1100 .RS 4
1101 \%git-htmldocs/technical/api-trace2.html
1102 .RE