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git-mirror/send-pack.c
Jeff King ad7a403268 send-pack: check remote ref status on pack-objects failure 
When we're pushing a pack and our local pack-objects fails, we enter an
error code path that does a few things:

  1. Set the status of every ref to REF_STATUS_NONE

  2. Call receive_unpack_status() to try to get an error report from
     the other side

  3. Return an error to the caller

If pack-objects failed because the connection to the server dropped,
there's not much more we can do than report the hangup. And indeed, step
2 will try to read a packet from the other side, which will die() in the
packet-reading code with "the remote end hung up unexpectedly".

But if the connection _didn't_ die, then the most common issue is that
the remote index-pack or unpack-objects complained about our pack (we
could also have a local pack-objects error, but this ends up being the
same; we'd send an incomplete pack and the remote side would complain).

In that case we do report the error from the other side (because of step
2), but we fail to say anything further about the refs. The issue is
two-fold:

  - in step 1, the "NONE" status is not "we saw an error, so we have no
    status". It generally means "this ref did not match our refspecs, so
    we didn't try to push it". So when we print out the push status
    table, we won't mention any refs at all!

    But even if we had a status enum for "pack-objects error", we
    wouldn't want to blindly set it for every ref. For example, in a
    non-atomic push we might have rejected some refs already on the
    client side (e.g., REF_STATUS_REJECT_NODELETE) and we'd want to
    report that.

  - in step 2, we read just the unpack status. But receive-pack will
    also tell us about each ref (usually that it rejected them because
    of the unpacker error).

So a much better strategy is to leave the ref status fields as they are
(usually EXPECTING_REPORT) and then actually receive (and print) the
full per-ref status.

This case is actually covered in the test suite, as t5504.8, which
writes a pack that will be rejected by the remote unpack-objects. But
it's racy. Because our pack is small, most of the time pack-objects
manages to write the whole thing before the remote rejects it, and so it
returns success and we print out the errors from the remote. But very
occasionally (or when run under --stress) it goes slow enough to see a
failure in writing, and git-push reports nothing for the refs.

With this patch, the test should behave consistently.

There shouldn't be any downside to this approach. If we really did see
the connection drop, we'd already die in receive_unpack_status(), and
we'll continue to do so. If the connection drops _after_ we get the
unpack status but before we see any ref status, we'll still print the
remote unpacker error, but will now say "remote end hung up" instead of
returning the error up the call-stack. But as discussed, we weren't
showing anything more useful than that with the current code. And
anyway, that case is quite unlikely (the connection dropping at that
point would have to be unrelated to the pack-objects error, because of
the ordering of events).

In the future we might want to handle packet-read errors ourself instead
of dying, which would print a full ref status table even for hangups.
But in the meantime, this patch should be a strict improvement.

Helped-by: SZEDER Gábor <szeder.dev@gmail.com>
Signed-off-by: Jeff King <peff@peff.net>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
2019-11-13 16:13:03 +09:00

628 lines
16 KiB
C
Raw Blame History

#include "builtin.h"
#include "config.h"
#include "commit.h"
#include "refs.h"
#include "object-store.h"
#include "pkt-line.h"
#include "sideband.h"
#include "run-command.h"
#include "remote.h"
#include "connect.h"
#include "send-pack.h"
#include "quote.h"
#include "transport.h"
#include "version.h"
#include "sha1-array.h"
#include "gpg-interface.h"
#include "cache.h"
int option_parse_push_signed(const struct option *opt,
const char *arg, int unset)
{
if (unset) {
*(int *)(opt->value) = SEND_PACK_PUSH_CERT_NEVER;
return 0;
}
switch (git_parse_maybe_bool(arg)) {
case 1:
*(int *)(opt->value) = SEND_PACK_PUSH_CERT_ALWAYS;
return 0;
case 0:
*(int *)(opt->value) = SEND_PACK_PUSH_CERT_NEVER;
return 0;
}
if (!strcasecmp("if-asked", arg)) {
*(int *)(opt->value) = SEND_PACK_PUSH_CERT_IF_ASKED;
return 0;
}
die("bad %s argument: %s", opt->long_name, arg);
}
static void feed_object(const struct object_id *oid, FILE *fh, int negative)
{
if (negative && !has_object_file(oid))
return;
if (negative)
putc('^', fh);
fputs(oid_to_hex(oid), fh);
putc('\n', fh);
}
/*
* Make a pack stream and spit it out into file descriptor fd
*/
static int pack_objects(int fd, struct ref *refs, struct oid_array *extra, struct send_pack_args *args)
{
/*
* The child becomes pack-objects --revs; we feed
* the revision parameters to it via its stdin and
* let its stdout go back to the other end.
*/
struct child_process po = CHILD_PROCESS_INIT;
FILE *po_in;
int i;
int rc;
argv_array_push(&po.args, "pack-objects");
argv_array_push(&po.args, "--all-progress-implied");
argv_array_push(&po.args, "--revs");
argv_array_push(&po.args, "--stdout");
if (args->use_thin_pack)
argv_array_push(&po.args, "--thin");
if (args->use_ofs_delta)
argv_array_push(&po.args, "--delta-base-offset");
if (args->quiet || !args->progress)
argv_array_push(&po.args, "-q");
if (args->progress)
argv_array_push(&po.args, "--progress");
if (is_repository_shallow(the_repository))
argv_array_push(&po.args, "--shallow");
po.in = -1;
po.out = args->stateless_rpc ? -1 : fd;
po.git_cmd = 1;
if (start_command(&po))
die_errno("git pack-objects failed");
/*
* We feed the pack-objects we just spawned with revision
* parameters by writing to the pipe.
*/
po_in = xfdopen(po.in, "w");
for (i = 0; i < extra->nr; i++)
feed_object(&extra->oid[i], po_in, 1);
while (refs) {
if (!is_null_oid(&refs->old_oid))
feed_object(&refs->old_oid, po_in, 1);
if (!is_null_oid(&refs->new_oid))
feed_object(&refs->new_oid, po_in, 0);
refs = refs->next;
}
fflush(po_in);
if (ferror(po_in))
die_errno("error writing to pack-objects");
fclose(po_in);
if (args->stateless_rpc) {
char *buf = xmalloc(LARGE_PACKET_MAX);
while (1) {
ssize_t n = xread(po.out, buf, LARGE_PACKET_MAX);
if (n <= 0)
break;
send_sideband(fd, -1, buf, n, LARGE_PACKET_MAX);
}
free(buf);
close(po.out);
po.out = -1;
}
rc = finish_command(&po);
if (rc) {
/*
* For a normal non-zero exit, we assume pack-objects wrote
* something useful to stderr. For death by signal, though,
* we should mention it to the user. The exception is SIGPIPE
* (141), because that's a normal occurrence if the remote end
* hangs up (and we'll report that by trying to read the unpack
* status).
*/
if (rc > 128 && rc != 141)
error("pack-objects died of signal %d", rc - 128);
return -1;
}
return 0;
}
static int receive_unpack_status(struct packet_reader *reader)
{
if (packet_reader_read(reader) != PACKET_READ_NORMAL)
return error(_("unexpected flush packet while reading remote unpack status"));
if (!skip_prefix(reader->line, "unpack ", &reader->line))
return error(_("unable to parse remote unpack status: %s"), reader->line);
if (strcmp(reader->line, "ok"))
return error(_("remote unpack failed: %s"), reader->line);
return 0;
}
static int receive_status(struct packet_reader *reader, struct ref *refs)
{
struct ref *hint;
int ret;
hint = NULL;
ret = receive_unpack_status(reader);
while (1) {
const char *refname;
char *msg;
if (packet_reader_read(reader) != PACKET_READ_NORMAL)
break;
if (!starts_with(reader->line, "ok ") && !starts_with(reader->line, "ng ")) {
error("invalid ref status from remote: %s", reader->line);
ret = -1;
break;
}
refname = reader->line + 3;
msg = strchr(refname, ' ');
if (msg)
*msg++ = '\0';
/* first try searching at our hint, falling back to all refs */
if (hint)
hint = find_ref_by_name(hint, refname);
if (!hint)
hint = find_ref_by_name(refs, refname);
if (!hint) {
warning("remote reported status on unknown ref: %s",
refname);
continue;
}
if (hint->status != REF_STATUS_EXPECTING_REPORT) {
warning("remote reported status on unexpected ref: %s",
refname);
continue;
}
if (reader->line[0] == 'o' && reader->line[1] == 'k')
hint->status = REF_STATUS_OK;
else {
hint->status = REF_STATUS_REMOTE_REJECT;
ret = -1;
}
hint->remote_status = xstrdup_or_null(msg);
/* start our next search from the next ref */
hint = hint->next;
}
return ret;
}
static int sideband_demux(int in, int out, void *data)
{
int *fd = data, ret;
if (async_with_fork())
close(fd[1]);
ret = recv_sideband("send-pack", fd[0], out);
close(out);
return ret;
}
static int advertise_shallow_grafts_cb(const struct commit_graft *graft, void *cb)
{
struct strbuf *sb = cb;
if (graft->nr_parent == -1)
packet_buf_write(sb, "shallow %s\n", oid_to_hex(&graft->oid));
return 0;
}
static void advertise_shallow_grafts_buf(struct strbuf *sb)
{
if (!is_repository_shallow(the_repository))
return;
for_each_commit_graft(advertise_shallow_grafts_cb, sb);
}
#define CHECK_REF_NO_PUSH -1
#define CHECK_REF_STATUS_REJECTED -2
#define CHECK_REF_UPTODATE -3
static int check_to_send_update(const struct ref *ref, const struct send_pack_args *args)
{
if (!ref->peer_ref && !args->send_mirror)
return CHECK_REF_NO_PUSH;
/* Check for statuses set by set_ref_status_for_push() */
switch (ref->status) {
case REF_STATUS_REJECT_NONFASTFORWARD:
case REF_STATUS_REJECT_ALREADY_EXISTS:
case REF_STATUS_REJECT_FETCH_FIRST:
case REF_STATUS_REJECT_NEEDS_FORCE:
case REF_STATUS_REJECT_STALE:
case REF_STATUS_REJECT_NODELETE:
return CHECK_REF_STATUS_REJECTED;
case REF_STATUS_UPTODATE:
return CHECK_REF_UPTODATE;
default:
return 0;
}
}
/*
* the beginning of the next line, or the end of buffer.
*
* NEEDSWORK: perhaps move this to git-compat-util.h or somewhere and
* convert many similar uses found by "git grep -A4 memchr".
*/
static const char *next_line(const char *line, size_t len)
{
const char *nl = memchr(line, '\n', len);
if (!nl)
return line + len; /* incomplete line */
return nl + 1;
}
static int generate_push_cert(struct strbuf *req_buf,
const struct ref *remote_refs,
struct send_pack_args *args,
const char *cap_string,
const char *push_cert_nonce)
{
const struct ref *ref;
struct string_list_item *item;
char *signing_key = xstrdup(get_signing_key());
const char *cp, *np;
struct strbuf cert = STRBUF_INIT;
int update_seen = 0;
strbuf_addstr(&cert, "certificate version 0.1\n");
strbuf_addf(&cert, "pusher %s ", signing_key);
datestamp(&cert);
strbuf_addch(&cert, '\n');
if (args->url && *args->url) {
char *anon_url = transport_anonymize_url(args->url);
strbuf_addf(&cert, "pushee %s\n", anon_url);
free(anon_url);
}
if (push_cert_nonce[0])
strbuf_addf(&cert, "nonce %s\n", push_cert_nonce);
if (args->push_options)
for_each_string_list_item(item, args->push_options)
strbuf_addf(&cert, "push-option %s\n", item->string);
strbuf_addstr(&cert, "\n");
for (ref = remote_refs; ref; ref = ref->next) {
if (check_to_send_update(ref, args) < 0)
continue;
update_seen = 1;
strbuf_addf(&cert, "%s %s %s\n",
oid_to_hex(&ref->old_oid),
oid_to_hex(&ref->new_oid),
ref->name);
}
if (!update_seen)
goto free_return;
if (sign_buffer(&cert, &cert, signing_key))
die(_("failed to sign the push certificate"));
packet_buf_write(req_buf, "push-cert%c%s", 0, cap_string);
for (cp = cert.buf; cp < cert.buf + cert.len; cp = np) {
np = next_line(cp, cert.buf + cert.len - cp);
packet_buf_write(req_buf,
"%.*s", (int)(np - cp), cp);
}
packet_buf_write(req_buf, "push-cert-end\n");
free_return:
free(signing_key);
strbuf_release(&cert);
return update_seen;
}
static int atomic_push_failure(struct send_pack_args *args,
struct ref *remote_refs,
struct ref *failing_ref)
{
struct ref *ref;
/* Mark other refs as failed */
for (ref = remote_refs; ref; ref = ref->next) {
if (!ref->peer_ref && !args->send_mirror)
continue;
switch (ref->status) {
case REF_STATUS_EXPECTING_REPORT:
ref->status = REF_STATUS_ATOMIC_PUSH_FAILED;
continue;
default:
break; /* do nothing */
}
}
return error("atomic push failed for ref %s. status: %d\n",
failing_ref->name, failing_ref->status);
}
#define NONCE_LEN_LIMIT 256
static void reject_invalid_nonce(const char *nonce, int len)
{
int i = 0;
if (NONCE_LEN_LIMIT <= len)
die("the receiving end asked to sign an invalid nonce <%.*s>",
len, nonce);
for (i = 0; i < len; i++) {
int ch = nonce[i] & 0xFF;
if (isalnum(ch) ||
ch == '-' || ch == '.' ||
ch == '/' || ch == '+' ||
ch == '=' || ch == '_')
continue;
die("the receiving end asked to sign an invalid nonce <%.*s>",
len, nonce);
}
}
int send_pack(struct send_pack_args *args,
int fd[], struct child_process *conn,
struct ref *remote_refs,
struct oid_array *extra_have)
{
int in = fd[0];
int out = fd[1];
struct strbuf req_buf = STRBUF_INIT;
struct strbuf cap_buf = STRBUF_INIT;
struct ref *ref;
int need_pack_data = 0;
int allow_deleting_refs = 0;
int status_report = 0;
int use_sideband = 0;
int quiet_supported = 0;
int agent_supported = 0;
int use_atomic = 0;
int atomic_supported = 0;
int use_push_options = 0;
int push_options_supported = 0;
unsigned cmds_sent = 0;
int ret;
struct async demux;
const char *push_cert_nonce = NULL;
struct packet_reader reader;
/* Does the other end support the reporting? */
if (server_supports("report-status"))
status_report = 1;
if (server_supports("delete-refs"))
allow_deleting_refs = 1;
if (server_supports("ofs-delta"))
args->use_ofs_delta = 1;
if (server_supports("side-band-64k"))
use_sideband = 1;
if (server_supports("quiet"))
quiet_supported = 1;
if (server_supports("agent"))
agent_supported = 1;
if (server_supports("no-thin"))
args->use_thin_pack = 0;
if (server_supports("atomic"))
atomic_supported = 1;
if (server_supports("push-options"))
push_options_supported = 1;
if (args->push_cert != SEND_PACK_PUSH_CERT_NEVER) {
int len;
push_cert_nonce = server_feature_value("push-cert", &len);
if (push_cert_nonce) {
reject_invalid_nonce(push_cert_nonce, len);
push_cert_nonce = xmemdupz(push_cert_nonce, len);
} else if (args->push_cert == SEND_PACK_PUSH_CERT_ALWAYS) {
die(_("the receiving end does not support --signed push"));
} else if (args->push_cert == SEND_PACK_PUSH_CERT_IF_ASKED) {
warning(_("not sending a push certificate since the"
" receiving end does not support --signed"
" push"));
}
}
if (!remote_refs) {
fprintf(stderr, "No refs in common and none specified; doing nothing.\n"
"Perhaps you should specify a branch such as 'master'.\n");
return 0;
}
if (args->atomic && !atomic_supported)
die(_("the receiving end does not support --atomic push"));
use_atomic = atomic_supported && args->atomic;
if (args->push_options && !push_options_supported)
die(_("the receiving end does not support push options"));
use_push_options = push_options_supported && args->push_options;
if (status_report)
strbuf_addstr(&cap_buf, " report-status");
if (use_sideband)
strbuf_addstr(&cap_buf, " side-band-64k");
if (quiet_supported && (args->quiet || !args->progress))
strbuf_addstr(&cap_buf, " quiet");
if (use_atomic)
strbuf_addstr(&cap_buf, " atomic");
if (use_push_options)
strbuf_addstr(&cap_buf, " push-options");
if (agent_supported)
strbuf_addf(&cap_buf, " agent=%s", git_user_agent_sanitized());
/*
* NEEDSWORK: why does delete-refs have to be so specific to
* send-pack machinery that set_ref_status_for_push() cannot
* set this bit for us???
*/
for (ref = remote_refs; ref; ref = ref->next)
if (ref->deletion && !allow_deleting_refs)
ref->status = REF_STATUS_REJECT_NODELETE;
if (!args->dry_run)
advertise_shallow_grafts_buf(&req_buf);
if (!args->dry_run && push_cert_nonce)
cmds_sent = generate_push_cert(&req_buf, remote_refs, args,
cap_buf.buf, push_cert_nonce);
/*
* Clear the status for each ref and see if we need to send
* the pack data.
*/
for (ref = remote_refs; ref; ref = ref->next) {
switch (check_to_send_update(ref, args)) {
case 0: /* no error */
break;
case CHECK_REF_STATUS_REJECTED:
/*
* When we know the server would reject a ref update if
* we were to send it and we're trying to send the refs
* atomically, abort the whole operation.
*/
if (use_atomic) {
strbuf_release(&req_buf);
strbuf_release(&cap_buf);
return atomic_push_failure(args, remote_refs, ref);
}
/* else fallthrough */
default:
continue;
}
if (!ref->deletion)
need_pack_data = 1;
if (args->dry_run || !status_report)
ref->status = REF_STATUS_OK;
else
ref->status = REF_STATUS_EXPECTING_REPORT;
}
/*
* Finally, tell the other end!
*/
for (ref = remote_refs; ref; ref = ref->next) {
char *old_hex, *new_hex;
if (args->dry_run || push_cert_nonce)
continue;
if (check_to_send_update(ref, args) < 0)
continue;
old_hex = oid_to_hex(&ref->old_oid);
new_hex = oid_to_hex(&ref->new_oid);
if (!cmds_sent) {
packet_buf_write(&req_buf,
"%s %s %s%c%s",
old_hex, new_hex, ref->name, 0,
cap_buf.buf);
cmds_sent = 1;
} else {
packet_buf_write(&req_buf, "%s %s %s",
old_hex, new_hex, ref->name);
}
}
if (use_push_options) {
struct string_list_item *item;
packet_buf_flush(&req_buf);
for_each_string_list_item(item, args->push_options)
packet_buf_write(&req_buf, "%s", item->string);
}
if (args->stateless_rpc) {
if (!args->dry_run && (cmds_sent || is_repository_shallow(the_repository))) {
packet_buf_flush(&req_buf);
send_sideband(out, -1, req_buf.buf, req_buf.len, LARGE_PACKET_MAX);
}
} else {
write_or_die(out, req_buf.buf, req_buf.len);
packet_flush(out);
}
strbuf_release(&req_buf);
strbuf_release(&cap_buf);
if (use_sideband && cmds_sent) {
memset(&demux, 0, sizeof(demux));
demux.proc = sideband_demux;
demux.data = fd;
demux.out = -1;
demux.isolate_sigpipe = 1;
if (start_async(&demux))
die("send-pack: unable to fork off sideband demultiplexer");
in = demux.out;
}
packet_reader_init(&reader, in, NULL, 0,
PACKET_READ_CHOMP_NEWLINE |
PACKET_READ_DIE_ON_ERR_PACKET);
if (need_pack_data && cmds_sent) {
if (pack_objects(out, remote_refs, extra_have, args) < 0) {
if (args->stateless_rpc)
close(out);
if (git_connection_is_socket(conn))
shutdown(fd[0], SHUT_WR);
/*
* Do not even bother with the return value; we know we
* are failing, and just want the error() side effects,
* as well as marking refs with their remote status (if
* we get one).
*/
if (status_report)
receive_status(&reader, remote_refs);
if (use_sideband) {
close(demux.out);
finish_async(&demux);
}
fd[1] = -1;
return -1;
}
if (!args->stateless_rpc)
/* Closed by pack_objects() via start_command() */
fd[1] = -1;
}
if (args->stateless_rpc && cmds_sent)
packet_flush(out);
if (status_report && cmds_sent)
ret = receive_status(&reader, remote_refs);
else
ret = 0;
if (args->stateless_rpc)
packet_flush(out);
if (use_sideband && cmds_sent) {
close(demux.out);
if (finish_async(&demux)) {
error("error in sideband demultiplexer");
ret = -1;
}
}
if (ret < 0)
return ret;
if (args->porcelain)
return 0;
for (ref = remote_refs; ref; ref = ref->next) {
switch (ref->status) {
case REF_STATUS_NONE:
case REF_STATUS_UPTODATE:
case REF_STATUS_OK:
break;
default:
return -1;
}
}
return 0;
}
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