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![Emily Shaffer](/assets/img/avatar_default.png)
Previously, when promisor_remote_move_to_tail() is called for a promisor_remote which is currently the final element in promisors, a cycle is created in the promisors linked list. This cycle leads to a double free later on in promisor_remote_clear() when the final element of the promisors list is removed: promisors is set to promisors->next (a no-op, as promisors->next == promisors); the previous value of promisors is free()'d; then the new value of promisors (which is equal to the previous value of promisors) is also free()'d. This double-free error was unrecoverable for the user without removing the filter or re-cloning the repo and hoping to miss this edge case. Now, when promisor_remote_move_to_tail() would be a no-op, just do a no-op. In cases of promisor_remote_move_to_tail() where r is not already at the tail of the list, it works as before. Helped-by: Jeff King <peff@peff.net> Signed-off-by: Emily Shaffer <emilyshaffer@google.com> Acked-by: Christian Couder <christian.couder@gmail.com> Signed-off-by: Junio C Hamano <gitster@pobox.com>
269 lines
5.6 KiB
C
269 lines
5.6 KiB
C
#include "cache.h"
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#include "object-store.h"
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#include "promisor-remote.h"
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#include "config.h"
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#include "transport.h"
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static char *repository_format_partial_clone;
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static const char *core_partial_clone_filter_default;
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void set_repository_format_partial_clone(char *partial_clone)
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{
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repository_format_partial_clone = xstrdup_or_null(partial_clone);
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}
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static int fetch_refs(const char *remote_name, struct ref *ref)
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{
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struct remote *remote;
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struct transport *transport;
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int original_fetch_if_missing = fetch_if_missing;
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int res;
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fetch_if_missing = 0;
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remote = remote_get(remote_name);
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if (!remote->url[0])
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die(_("Remote with no URL"));
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transport = transport_get(remote, remote->url[0]);
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transport_set_option(transport, TRANS_OPT_FROM_PROMISOR, "1");
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transport_set_option(transport, TRANS_OPT_NO_DEPENDENTS, "1");
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res = transport_fetch_refs(transport, ref);
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fetch_if_missing = original_fetch_if_missing;
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return res;
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}
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static int fetch_objects(const char *remote_name,
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const struct object_id *oids,
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int oid_nr)
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{
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struct ref *ref = NULL;
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int i;
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for (i = 0; i < oid_nr; i++) {
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struct ref *new_ref = alloc_ref(oid_to_hex(&oids[i]));
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oidcpy(&new_ref->old_oid, &oids[i]);
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new_ref->exact_oid = 1;
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new_ref->next = ref;
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ref = new_ref;
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}
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return fetch_refs(remote_name, ref);
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}
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static struct promisor_remote *promisors;
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static struct promisor_remote **promisors_tail = &promisors;
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static struct promisor_remote *promisor_remote_new(const char *remote_name)
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{
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struct promisor_remote *r;
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if (*remote_name == '/') {
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warning(_("promisor remote name cannot begin with '/': %s"),
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remote_name);
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return NULL;
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}
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FLEX_ALLOC_STR(r, name, remote_name);
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*promisors_tail = r;
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promisors_tail = &r->next;
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return r;
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}
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static struct promisor_remote *promisor_remote_lookup(const char *remote_name,
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struct promisor_remote **previous)
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{
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struct promisor_remote *r, *p;
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for (p = NULL, r = promisors; r; p = r, r = r->next)
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if (!strcmp(r->name, remote_name)) {
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if (previous)
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*previous = p;
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return r;
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}
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return NULL;
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}
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static void promisor_remote_move_to_tail(struct promisor_remote *r,
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struct promisor_remote *previous)
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{
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if (r->next == NULL)
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return;
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if (previous)
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previous->next = r->next;
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else
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promisors = r->next ? r->next : r;
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r->next = NULL;
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*promisors_tail = r;
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promisors_tail = &r->next;
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}
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static int promisor_remote_config(const char *var, const char *value, void *data)
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{
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const char *name;
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int namelen;
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const char *subkey;
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if (!strcmp(var, "core.partialclonefilter"))
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return git_config_string(&core_partial_clone_filter_default,
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var, value);
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if (parse_config_key(var, "remote", &name, &namelen, &subkey) < 0)
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return 0;
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if (!strcmp(subkey, "promisor")) {
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char *remote_name;
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if (!git_config_bool(var, value))
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return 0;
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remote_name = xmemdupz(name, namelen);
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if (!promisor_remote_lookup(remote_name, NULL))
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promisor_remote_new(remote_name);
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free(remote_name);
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return 0;
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}
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if (!strcmp(subkey, "partialclonefilter")) {
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struct promisor_remote *r;
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char *remote_name = xmemdupz(name, namelen);
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r = promisor_remote_lookup(remote_name, NULL);
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if (!r)
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r = promisor_remote_new(remote_name);
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free(remote_name);
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if (!r)
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return 0;
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return git_config_string(&r->partial_clone_filter, var, value);
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}
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return 0;
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}
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static int initialized;
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static void promisor_remote_init(void)
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{
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if (initialized)
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return;
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initialized = 1;
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git_config(promisor_remote_config, NULL);
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if (repository_format_partial_clone) {
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struct promisor_remote *o, *previous;
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o = promisor_remote_lookup(repository_format_partial_clone,
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&previous);
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if (o)
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promisor_remote_move_to_tail(o, previous);
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else
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promisor_remote_new(repository_format_partial_clone);
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}
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}
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static void promisor_remote_clear(void)
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{
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while (promisors) {
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struct promisor_remote *r = promisors;
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promisors = promisors->next;
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free(r);
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}
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promisors_tail = &promisors;
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}
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void promisor_remote_reinit(void)
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{
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initialized = 0;
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promisor_remote_clear();
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promisor_remote_init();
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}
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struct promisor_remote *promisor_remote_find(const char *remote_name)
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{
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promisor_remote_init();
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if (!remote_name)
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return promisors;
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return promisor_remote_lookup(remote_name, NULL);
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}
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int has_promisor_remote(void)
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{
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return !!promisor_remote_find(NULL);
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}
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static int remove_fetched_oids(struct repository *repo,
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struct object_id **oids,
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int oid_nr, int to_free)
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{
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int i, remaining_nr = 0;
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int *remaining = xcalloc(oid_nr, sizeof(*remaining));
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struct object_id *old_oids = *oids;
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struct object_id *new_oids;
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for (i = 0; i < oid_nr; i++)
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if (oid_object_info_extended(repo, &old_oids[i], NULL,
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OBJECT_INFO_SKIP_FETCH_OBJECT)) {
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remaining[i] = 1;
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remaining_nr++;
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}
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if (remaining_nr) {
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int j = 0;
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new_oids = xcalloc(remaining_nr, sizeof(*new_oids));
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for (i = 0; i < oid_nr; i++)
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if (remaining[i])
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oidcpy(&new_oids[j++], &old_oids[i]);
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*oids = new_oids;
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if (to_free)
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free(old_oids);
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}
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free(remaining);
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return remaining_nr;
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}
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int promisor_remote_get_direct(struct repository *repo,
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const struct object_id *oids,
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int oid_nr)
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{
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struct promisor_remote *r;
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struct object_id *remaining_oids = (struct object_id *)oids;
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int remaining_nr = oid_nr;
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int to_free = 0;
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int res = -1;
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promisor_remote_init();
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for (r = promisors; r; r = r->next) {
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if (fetch_objects(r->name, remaining_oids, remaining_nr) < 0) {
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if (remaining_nr == 1)
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continue;
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remaining_nr = remove_fetched_oids(repo, &remaining_oids,
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remaining_nr, to_free);
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if (remaining_nr) {
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to_free = 1;
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continue;
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}
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}
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res = 0;
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break;
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}
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if (to_free)
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free(remaining_oids);
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return res;
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}
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