static int packed_transaction_prepare(struct ref_store *ref_store,
struct ref_transaction *transaction,
struct strbuf *err)
{
struct packed_ref_store *refs = packed_downcast(
ref_store,
REF_STORE_READ | REF_STORE_WRITE | REF_STORE_ODB,
"ref_transaction_prepare");
struct packed_transaction_backend_data *data;
size_t i;
int ret = TRANSACTION_GENERIC_ERROR;
/*
* Note that we *don't* skip transactions with zero updates,
* because such a transaction might be executed for the side
* effect of ensuring that all of the references are peeled or
* ensuring that the `packed-refs` file is sorted. If the
* caller wants to optimize away empty transactions, it should
* do so itself.
*/
data = xcalloc(1, sizeof(*data));
string_list_init(&data->updates, 0);
transaction->backend_data = data;
/*
* Stick the updates in a string list by refname so that we
* can sort them:
*/
for (i = 0; i < transaction->nr; i++) {
struct ref_update *update = transaction->updates[i];
struct string_list_item *item =
string_list_append(&data->updates, update->refname);
/* Store a pointer to update in item->util: */
item->util = update;
}
string_list_sort(&data->updates);
if (ref_update_reject_duplicates(&data->updates, err))
goto failure;
if (!is_lock_file_locked(&refs->lock)) {
if (packed_refs_lock(ref_store, 0, err))
goto failure;
data->own_lock = 1;
}
if (write_with_updates(refs, &data->updates, err))
goto failure;
transaction->state = REF_TRANSACTION_PREPARED;
return 0;
failure:
packed_transaction_cleanup(refs, transaction);
return ret;
}
int packed_refs_is_locked(struct ref_store *ref_store)
{
struct packed_ref_store *refs = packed_downcast(
ref_store,
REF_STORE_READ | REF_STORE_WRITE,
"packed_refs_is_locked");
return is_lock_file_locked(&refs->lock);
}
/*
* Get the `snapshot` for the specified packed_ref_store, creating and
* populating it if it hasn't been read before or if the file has been
* changed (according to its `validity` field) since it was last read.
* On the other hand, if we hold the lock, then assume that the file
* hasn't been changed out from under us, so skip the extra `stat()`
* call in `stat_validity_check()`. This function does *not* increase
* the snapshot's reference count on behalf of the caller.
*/
static struct snapshot *get_snapshot(struct packed_ref_store *refs)
{
if (!is_lock_file_locked(&refs->lock))
validate_snapshot(refs);
if (!refs->snapshot)
refs->snapshot = create_snapshot(refs);
return refs->snapshot;
}
void packed_refs_unlock(struct ref_store *ref_store)
{
struct packed_ref_store *refs = packed_downcast(
ref_store,
REF_STORE_READ | REF_STORE_WRITE,
"packed_refs_unlock");
if (!is_lock_file_locked(&refs->lock))
die("BUG: packed_refs_unlock() called when not locked");
rollback_lock_file(&refs->lock);
}
static void packed_transaction_cleanup(struct packed_ref_store *refs,
struct ref_transaction *transaction)
{
struct packed_transaction_backend_data *data = transaction->backend_data;
if (data) {
string_list_clear(&data->updates, 0);
if (is_tempfile_active(refs->tempfile))
delete_tempfile(&refs->tempfile);
if (data->own_lock && is_lock_file_locked(&refs->lock)) {
packed_refs_unlock(&refs->base);
data->own_lock = 0;
}
free(data);
transaction->backend_data = NULL;
}
transaction->state = REF_TRANSACTION_CLOSED;
}
int is_packed_transaction_needed(struct ref_store *ref_store,
struct ref_transaction *transaction)
{
struct packed_ref_store *refs = packed_downcast(
ref_store,
REF_STORE_READ,
"is_packed_transaction_needed");
struct strbuf referent = STRBUF_INIT;
size_t i;
int ret;
if (!is_lock_file_locked(&refs->lock))
BUG("is_packed_transaction_needed() called while unlocked");
/*
* We're only going to bother returning false for the common,
* trivial case that references are only being deleted, their
* old values are not being checked, and the old `packed-refs`
* file doesn't contain any of those reference(s). This gives
* false positives for some other cases that could
* theoretically be optimized away:
*
* 1. It could be that the old value is being verified without
* setting a new value. In this case, we could verify the
* old value here and skip the update if it agrees. If it
* disagrees, we could either let the update go through
* (the actual commit would re-detect and report the
* problem), or come up with a way of reporting such an
* error to *our* caller.
*
* 2. It could be that a new value is being set, but that it
* is identical to the current packed value of the
* reference.
*
* Neither of these cases will come up in the current code,
* because the only caller of this function passes to it a
* transaction that only includes `delete` updates with no
* `old_id`. Even if that ever changes, false positives only
* cause an optimization to be missed; they do not affect
* correctness.
*/
/*
* Start with the cheap checks that don't require old
* reference values to be read:
*/
for (i = 0; i < transaction->nr; i++) {
struct ref_update *update = transaction->updates[i];
if (update->flags & REF_HAVE_OLD)
/* Have to check the old value -> needed. */
return 1;
if ((update->flags & REF_HAVE_NEW) && !is_null_oid(&update->new_oid))
/* Have to set a new value -> needed. */
return 1;
}
/*
* The transaction isn't checking any old values nor is it
* setting any nonzero new values, so it still might be able
* to be skipped. Now do the more expensive check: the update
* is needed if any of the updates is a delete, and the old
* `packed-refs` file contains a value for that reference.
*/
ret = 0;
for (i = 0; i < transaction->nr; i++) {
struct ref_update *update = transaction->updates[i];
unsigned int type;
struct object_id oid;
if (!(update->flags & REF_HAVE_NEW))
/*
* This reference isn't being deleted -> not
* needed.
*/
continue;
if (!refs_read_raw_ref(ref_store, update->refname,
&oid, &referent, &type) ||
errno != ENOENT) {
/*
* We have to actually delete that reference
* -> this transaction is needed.
*/
ret = 1;
break;
}
}
strbuf_release(&referent);
return ret;
}
/*
* Write the packed refs from the current snapshot to the packed-refs
* tempfile, incorporating any changes from `updates`. `updates` must
* be a sorted string list whose keys are the refnames and whose util
* values are `struct ref_update *`. On error, rollback the tempfile,
* write an error message to `err`, and return a nonzero value.
*
* The packfile must be locked before calling this function and will
* remain locked when it is done.
*/
static int write_with_updates(struct packed_ref_store *refs,
struct string_list *updates,
struct strbuf *err)
{
struct ref_iterator *iter = NULL;
size_t i;
int ok;
FILE *out;
struct strbuf sb = STRBUF_INIT;
char *packed_refs_path;
if (!is_lock_file_locked(&refs->lock))
die("BUG: write_with_updates() called while unlocked");
/*
* If packed-refs is a symlink, we want to overwrite the
* symlinked-to file, not the symlink itself. Also, put the
* staging file next to it:
*/
packed_refs_path = get_locked_file_path(&refs->lock);
strbuf_addf(&sb, "%s.new", packed_refs_path);
free(packed_refs_path);
refs->tempfile = create_tempfile(sb.buf);
if (!refs->tempfile) {
strbuf_addf(err, "unable to create file %s: %s",
sb.buf, strerror(errno));
strbuf_release(&sb);
return -1;
}
strbuf_release(&sb);
out = fdopen_tempfile(refs->tempfile, "w");
if (!out) {
strbuf_addf(err, "unable to fdopen packed-refs tempfile: %s",
strerror(errno));
goto error;
}
if (fprintf(out, "%s", PACKED_REFS_HEADER) < 0)
goto write_error;
/*
* We iterate in parallel through the current list of refs and
* the list of updates, processing an entry from at least one
* of the lists each time through the loop. When the current
* list of refs is exhausted, set iter to NULL. When the list
* of updates is exhausted, leave i set to updates->nr.
*/
iter = packed_ref_iterator_begin(&refs->base, "",
DO_FOR_EACH_INCLUDE_BROKEN);
if ((ok = ref_iterator_advance(iter)) != ITER_OK)
iter = NULL;
i = 0;
while (iter || i < updates->nr) {
struct ref_update *update = NULL;
int cmp;
if (i >= updates->nr) {
cmp = -1;
} else {
update = updates->items[i].util;
if (!iter)
cmp = +1;
else
cmp = strcmp(iter->refname, update->refname);
}
if (!cmp) {
/*
* There is both an old value and an update
* for this reference. Check the old value if
* necessary:
*/
if ((update->flags & REF_HAVE_OLD)) {
if (is_null_oid(&update->old_oid)) {
strbuf_addf(err, "cannot update ref '%s': "
"reference already exists",
update->refname);
goto error;
} else if (oidcmp(&update->old_oid, iter->oid)) {
strbuf_addf(err, "cannot update ref '%s': "
"is at %s but expected %s",
update->refname,
oid_to_hex(iter->oid),
oid_to_hex(&update->old_oid));
goto error;
}
}
/* Now figure out what to use for the new value: */
if ((update->flags & REF_HAVE_NEW)) {
/*
* The update takes precedence. Skip
* the iterator over the unneeded
* value.
*/
if ((ok = ref_iterator_advance(iter)) != ITER_OK)
iter = NULL;
cmp = +1;
} else {
/*
* The update doesn't actually want to
* change anything. We're done with it.
*/
i++;
cmp = -1;
}
} else if (cmp > 0) {
/*
* There is no old value but there is an
* update for this reference. Make sure that
* the update didn't expect an existing value:
*/
if ((update->flags & REF_HAVE_OLD) &&
!is_null_oid(&update->old_oid)) {
strbuf_addf(err, "cannot update ref '%s': "
"reference is missing but expected %s",
update->refname,
oid_to_hex(&update->old_oid));
goto error;
}
}
if (cmp < 0) {
/* Pass the old reference through. */
struct object_id peeled;
int peel_error = ref_iterator_peel(iter, &peeled);
if (write_packed_entry(out, iter->refname,
iter->oid,
peel_error ? NULL : &peeled))
goto write_error;
if ((ok = ref_iterator_advance(iter)) != ITER_OK)
iter = NULL;
} else if (is_null_oid(&update->new_oid)) {
/*
* The update wants to delete the reference,
* and the reference either didn't exist or we
* have already skipped it. So we're done with
* the update (and don't have to write
* anything).
*/
i++;
} else {
struct object_id peeled;
int peel_error = peel_object(&update->new_oid,
&peeled);
if (write_packed_entry(out, update->refname,
&update->new_oid,
peel_error ? NULL : &peeled))
goto write_error;
i++;
}
}
if (ok != ITER_DONE) {
strbuf_addstr(err, "unable to write packed-refs file: "
"error iterating over old contents");
goto error;
}
if (close_tempfile_gently(refs->tempfile)) {
strbuf_addf(err, "error closing file %s: %s",
get_tempfile_path(refs->tempfile),
strerror(errno));
strbuf_release(&sb);
delete_tempfile(&refs->tempfile);
return -1;
}
return 0;
write_error:
strbuf_addf(err, "error writing to %s: %s",
get_tempfile_path(refs->tempfile), strerror(errno));
error:
if (iter)
ref_iterator_abort(iter);
delete_tempfile(&refs->tempfile);
return -1;
}
int cmd_checkout_index(int argc, const char **argv, const char *prefix)
{
int i;
struct lock_file lock_file = LOCK_INIT;
int all = 0;
int read_from_stdin = 0;
int prefix_length;
int force = 0, quiet = 0, not_new = 0;
int index_opt = 0;
struct option builtin_checkout_index_options[] = {
OPT_BOOL('a', "all", &all,
N_("check out all files in the index")),
OPT__FORCE(&force, N_("force overwrite of existing files"), 0),
OPT__QUIET(&quiet,
N_("no warning for existing files and files not in index")),
OPT_BOOL('n', "no-create", ¬_new,
N_("don't checkout new files")),
OPT_BOOL('u', "index", &index_opt,
N_("update stat information in the index file")),
OPT_BOOL('z', NULL, &nul_term_line,
N_("paths are separated with NUL character")),
OPT_BOOL(0, "stdin", &read_from_stdin,
N_("read list of paths from the standard input")),
OPT_BOOL(0, "temp", &to_tempfile,
N_("write the content to temporary files")),
OPT_STRING(0, "prefix", &state.base_dir, N_("string"),
N_("when creating files, prepend <string>")),
{ OPTION_CALLBACK, 0, "stage", NULL, "(1|2|3|all)",
N_("copy out the files from named stage"),
PARSE_OPT_NONEG, option_parse_stage },
OPT_END()
};
if (argc == 2 && !strcmp(argv[1], "-h"))
usage_with_options(builtin_checkout_index_usage,
builtin_checkout_index_options);
git_config(git_default_config, NULL);
prefix_length = prefix ? strlen(prefix) : 0;
if (read_cache() < 0) {
die("invalid cache");
}
argc = parse_options(argc, argv, prefix, builtin_checkout_index_options,
builtin_checkout_index_usage, 0);
state.istate = &the_index;
state.force = force;
state.quiet = quiet;
state.not_new = not_new;
if (!state.base_dir)
state.base_dir = "";
state.base_dir_len = strlen(state.base_dir);
/*
* when --prefix is specified we do not want to update cache.
*/
if (index_opt && !state.base_dir_len && !to_tempfile) {
state.refresh_cache = 1;
state.istate = &the_index;
hold_locked_index(&lock_file, LOCK_DIE_ON_ERROR);
}
/* Check out named files first */
for (i = 0; i < argc; i++) {
const char *arg = argv[i];
char *p;
if (all)
die("git checkout-index: don't mix '--all' and explicit filenames");
if (read_from_stdin)
die("git checkout-index: don't mix '--stdin' and explicit filenames");
p = prefix_path(prefix, prefix_length, arg);
checkout_file(p, prefix);
free(p);
}
if (read_from_stdin) {
struct strbuf buf = STRBUF_INIT;
struct strbuf unquoted = STRBUF_INIT;
strbuf_getline_fn getline_fn;
if (all)
die("git checkout-index: don't mix '--all' and '--stdin'");
getline_fn = nul_term_line ? strbuf_getline_nul : strbuf_getline_lf;
while (getline_fn(&buf, stdin) != EOF) {
char *p;
if (!nul_term_line && buf.buf[0] == '"') {
strbuf_reset(&unquoted);
if (unquote_c_style(&unquoted, buf.buf, NULL))
die("line is badly quoted");
strbuf_swap(&buf, &unquoted);
}
p = prefix_path(prefix, prefix_length, buf.buf);
checkout_file(p, prefix);
free(p);
}
strbuf_release(&unquoted);
strbuf_release(&buf);
}
if (all)
checkout_all(prefix, prefix_length);
if (is_lock_file_locked(&lock_file) &&
write_locked_index(&the_index, &lock_file, COMMIT_LOCK))
die("Unable to write new index file");
return 0;
}
