git/transport.h
Junio C Hamano b26ed4305f fetch: work around "transport-take-over" hack
A Git-aware "connect" transport allows the "transport_take_over" to
redirect generic transport requests like fetch(), push_refs() and
get_refs_list() to the native Git transport handling methods.  The
take-over process replaces transport->data with a fake data that
these method implementations understand.

While this hack works OK for a single request, it breaks when the
transport needs to make more than one requests.  transport->data
that used to hold necessary information for the specific helper to
work correctly is destroyed during the take-over process.

One codepath that this matters is "git fetch" in auto-follow mode;
when it does not get all the tags that ought to point at the history
it got (which can be determined by looking at the peeled tags in the
initial advertisement) from the primary transfer, it internally
makes a second request to complete the fetch.  Because "take-over"
hack has already destroyed the data necessary to talk to the
transport helper by the time this happens, the second request cannot
make a request to the helper to make another connection to fetch
these additional tags.

Mark such a transport as "cannot_reuse", and use a separate
transport to perform the backfill fetch in order to work around
this breakage.

Note that this problem does not manifest itself when running t5802,
because our upload-pack gives you all the necessary auto-followed
tags during the primary transfer.  You would need to step through
"git fetch" in a debugger, stop immediately after the primary
transfer finishes and writes these auto-followed tags, remove the
tag references and repack/prune the repository to convince the
"find-non-local-tags" procedure that the primary transfer failed to
give us all the necessary tags, and then let it continue, in order
to trigger the bug in the secondary transfer this patch fixes.

Signed-off-by: Junio C Hamano <gitster@pobox.com>
2013-08-07 16:24:30 -07:00

198 lines
6.6 KiB
C

#ifndef TRANSPORT_H
#define TRANSPORT_H
#include "cache.h"
#include "remote.h"
struct git_transport_options {
unsigned thin : 1;
unsigned keep : 1;
unsigned followtags : 1;
unsigned check_self_contained_and_connected : 1;
unsigned self_contained_and_connected : 1;
int depth;
const char *uploadpack;
const char *receivepack;
};
struct transport {
struct remote *remote;
const char *url;
void *data;
const struct ref *remote_refs;
/**
* Indicates whether we already called get_refs_list(); set by
* transport.c::transport_get_remote_refs().
*/
unsigned got_remote_refs : 1;
/*
* Transports that call take-over destroys the data specific to
* the transport type while doing so, and cannot be reused.
*/
unsigned cannot_reuse : 1;
/**
* Returns 0 if successful, positive if the option is not
* recognized or is inapplicable, and negative if the option
* is applicable but the value is invalid.
**/
int (*set_option)(struct transport *connection, const char *name,
const char *value);
/**
* Returns a list of the remote side's refs. In order to allow
* the transport to try to share connections, for_push is a
* hint as to whether the ultimate operation is a push or a fetch.
*
* If the transport is able to determine the remote hash for
* the ref without a huge amount of effort, it should store it
* in the ref's old_sha1 field; otherwise it should be all 0.
**/
struct ref *(*get_refs_list)(struct transport *transport, int for_push);
/**
* Fetch the objects for the given refs. Note that this gets
* an array, and should ignore the list structure.
*
* If the transport did not get hashes for refs in
* get_refs_list(), it should set the old_sha1 fields in the
* provided refs now.
**/
int (*fetch)(struct transport *transport, int refs_nr, struct ref **refs);
/**
* Push the objects and refs. Send the necessary objects, and
* then, for any refs where peer_ref is set and
* peer_ref->new_sha1 is different from old_sha1, tell the
* remote side to update each ref in the list from old_sha1 to
* peer_ref->new_sha1.
*
* Where possible, set the status for each ref appropriately.
*
* The transport must modify new_sha1 in the ref to the new
* value if the remote accepted the change. Note that this
* could be a different value from peer_ref->new_sha1 if the
* process involved generating new commits.
**/
int (*push_refs)(struct transport *transport, struct ref *refs, int flags);
int (*push)(struct transport *connection, int refspec_nr, const char **refspec, int flags);
int (*connect)(struct transport *connection, const char *name,
const char *executable, int fd[2]);
/** get_refs_list(), fetch(), and push_refs() can keep
* resources (such as a connection) reserved for further
* use. disconnect() releases these resources.
**/
int (*disconnect)(struct transport *connection);
char *pack_lockfile;
signed verbose : 3;
/**
* Transports should not set this directly, and should use this
* value without having to check isatty(2), -q/--quiet
* (transport->verbose < 0), etc. - checking has already been done
* in transport_set_verbosity().
**/
unsigned progress : 1;
/*
* If transport is at least potentially smart, this points to
* git_transport_options structure to use in case transport
* actually turns out to be smart.
*/
struct git_transport_options *smart_options;
};
#define TRANSPORT_PUSH_ALL 1
#define TRANSPORT_PUSH_FORCE 2
#define TRANSPORT_PUSH_DRY_RUN 4
#define TRANSPORT_PUSH_MIRROR 8
#define TRANSPORT_PUSH_PORCELAIN 16
#define TRANSPORT_PUSH_SET_UPSTREAM 32
#define TRANSPORT_RECURSE_SUBMODULES_CHECK 64
#define TRANSPORT_PUSH_PRUNE 128
#define TRANSPORT_RECURSE_SUBMODULES_ON_DEMAND 256
#define TRANSPORT_PUSH_NO_HOOK 512
#define TRANSPORT_PUSH_FOLLOW_TAGS 1024
#define TRANSPORT_SUMMARY_WIDTH (2 * DEFAULT_ABBREV + 3)
#define TRANSPORT_SUMMARY(x) (int)(TRANSPORT_SUMMARY_WIDTH + strlen(x) - gettext_width(x)), (x)
/* Returns a transport suitable for the url */
struct transport *transport_get(struct remote *, const char *);
/* Transport options which apply to git:// and scp-style URLs */
/* The program to use on the remote side to send a pack */
#define TRANS_OPT_UPLOADPACK "uploadpack"
/* The program to use on the remote side to receive a pack */
#define TRANS_OPT_RECEIVEPACK "receivepack"
/* Transfer the data as a thin pack if not null */
#define TRANS_OPT_THIN "thin"
/* Keep the pack that was transferred if not null */
#define TRANS_OPT_KEEP "keep"
/* Limit the depth of the fetch if not null */
#define TRANS_OPT_DEPTH "depth"
/* Aggressively fetch annotated tags if possible */
#define TRANS_OPT_FOLLOWTAGS "followtags"
/**
* Returns 0 if the option was used, non-zero otherwise. Prints a
* message to stderr if the option is not used.
**/
int transport_set_option(struct transport *transport, const char *name,
const char *value);
void transport_set_verbosity(struct transport *transport, int verbosity,
int force_progress);
#define REJECT_NON_FF_HEAD 0x01
#define REJECT_NON_FF_OTHER 0x02
#define REJECT_ALREADY_EXISTS 0x04
#define REJECT_FETCH_FIRST 0x08
#define REJECT_NEEDS_FORCE 0x10
int transport_push(struct transport *connection,
int refspec_nr, const char **refspec, int flags,
unsigned int * reject_reasons);
const struct ref *transport_get_remote_refs(struct transport *transport);
int transport_fetch_refs(struct transport *transport, struct ref *refs);
void transport_unlock_pack(struct transport *transport);
int transport_disconnect(struct transport *transport);
char *transport_anonymize_url(const char *url);
void transport_take_over(struct transport *transport,
struct child_process *child);
int transport_connect(struct transport *transport, const char *name,
const char *exec, int fd[2]);
/* Transport methods defined outside transport.c */
int transport_helper_init(struct transport *transport, const char *name);
int bidirectional_transfer_loop(int input, int output);
/* common methods used by transport.c and builtin/send-pack.c */
void transport_verify_remote_names(int nr_heads, const char **heads);
void transport_update_tracking_ref(struct remote *remote, struct ref *ref, int verbose);
int transport_refs_pushed(struct ref *ref);
void transport_print_push_status(const char *dest, struct ref *refs,
int verbose, int porcelain, unsigned int *reject_reasons);
typedef void alternate_ref_fn(const struct ref *, void *);
extern void for_each_alternate_ref(alternate_ref_fn, void *);
struct send_pack_args;
extern int send_pack(struct send_pack_args *args,
int fd[], struct child_process *conn,
struct ref *remote_refs,
struct extra_have_objects *extra_have);
#endif