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git/fetch-pack.h
Jonathan Tan cf1e7c0770 fetch-pack: write shallow, then check connectivity
When fetching, connectivity is checked after the shallow file is
updated. There are 2 issues with this: (1) the connectivity check is
only performed up to ancestors of existing refs (which is not thorough
enough if we were deepening an existing ref in the first place), and (2)
there is no rollback of the shallow file if the connectivity check
fails.

To solve (1), update the connectivity check to check the ancestry chain
completely in the case of a deepening fetch by refraining from passing
"--not --all" when invoking rev-list in connected.c.

To solve (2), have fetch_pack() perform its own connectivity check
before updating the shallow file. To support existing use cases in which
"git fetch-pack" is used to download objects without much regard as to
the connectivity of the resulting objects with respect to the existing
repository, the connectivity check is only done if necessary (that is,
the fetch is not a clone, and the fetch involves shallow/deepen
functionality). "git fetch" still performs its own connectivity check,
preserving correctness but sometimes performing redundant work. This
redundancy is mitigated by the fact that fetch_pack() reports if it has
performed a connectivity check itself, and if the transport supports
connect or stateless-connect, it will bubble up that report so that "git
fetch" knows not to perform the connectivity check in such a case.

This was noticed when a user tried to deepen an existing repository by
fetching with --no-shallow from a server that did not send all necessary
objects - the connectivity check as run by "git fetch" succeeded, but a
subsequent "git fsck" failed.

Signed-off-by: Jonathan Tan <jonathantanmy@google.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
2018-07-03 14:57:44 -07:00

83 lines
2.4 KiB
C

#ifndef FETCH_PACK_H
#define FETCH_PACK_H
#include "string-list.h"
#include "run-command.h"
#include "protocol.h"
#include "list-objects-filter-options.h"
struct oid_array;
struct fetch_pack_args {
const char *uploadpack;
int unpacklimit;
int depth;
const char *deepen_since;
const struct string_list *deepen_not;
struct list_objects_filter_options filter_options;
const struct string_list *server_options;
unsigned deepen_relative:1;
unsigned quiet:1;
unsigned keep_pack:1;
unsigned lock_pack:1;
unsigned use_thin_pack:1;
unsigned fetch_all:1;
unsigned stdin_refs:1;
unsigned diag_url:1;
unsigned verbose:1;
unsigned no_progress:1;
unsigned include_tag:1;
unsigned stateless_rpc:1;
unsigned check_self_contained_and_connected:1;
unsigned self_contained_and_connected:1;
unsigned cloning:1;
unsigned update_shallow:1;
unsigned deepen:1;
unsigned from_promisor:1;
/*
* If 1, fetch_pack() will also not modify any object flags.
* This allows fetch_pack() to safely be called by any function,
* regardless of which object flags it uses (if any).
*/
unsigned no_dependents:1;
/*
* Because fetch_pack() overwrites the shallow file upon a
* successful deepening non-clone fetch, if this struct
* specifies such a fetch, fetch_pack() needs to perform a
* connectivity check before deciding if a fetch is successful
* (and overwriting the shallow file). fetch_pack() sets this
* field to 1 if such a connectivity check was performed.
*
* This is different from check_self_contained_and_connected
* in that the former allows existing objects in the
* repository to satisfy connectivity needs, whereas the
* latter doesn't.
*/
unsigned connectivity_checked:1;
};
/*
* sought represents remote references that should be updated from.
* On return, the names that were found on the remote will have been
* marked as such.
*/
struct ref *fetch_pack(struct fetch_pack_args *args,
int fd[], struct child_process *conn,
const struct ref *ref,
const char *dest,
struct ref **sought,
int nr_sought,
struct oid_array *shallow,
char **pack_lockfile,
enum protocol_version version);
/*
* Print an appropriate error message for each sought ref that wasn't
* matched. Return 0 if all sought refs were matched, otherwise 1.
*/
int report_unmatched_refs(struct ref **sought, int nr_sought);
#endif