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![Lars Schneider](/assets/img/avatar_default.png)
In 2841e8f
("convert: add "status=delayed" to filter process protocol",
2017-06-30) we taught the filter process protocol to delay responses.
That means an external filter might answer in the first write_entry()
call on a file that requires filtering "I got your request, but I
can't answer right now. Ask again later!". As Git got no answer, we do
not write anything to the filesystem. Consequently, the lstat() call in
the finish block of the function writes garbage to the cache entry.
The garbage is eventually overwritten when the filter answers with
the final file content in a subsequent write_entry() call.
Fix the brief time window of garbage in the cache entry by adding a
special finish block that does nothing for delayed responses. The cache
entry is written properly in a subsequent write_entry() call where
the filter responds with the final file content.
Reported-by: Jeff King <peff@peff.net>
Signed-off-by: Lars Schneider <larsxschneider@gmail.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
447 lines
12 KiB
C
447 lines
12 KiB
C
#include "cache.h"
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#include "blob.h"
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#include "dir.h"
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#include "streaming.h"
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#include "submodule.h"
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static void create_directories(const char *path, int path_len,
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const struct checkout *state)
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{
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char *buf = xmallocz(path_len);
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int len = 0;
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while (len < path_len) {
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do {
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buf[len] = path[len];
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len++;
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} while (len < path_len && path[len] != '/');
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if (len >= path_len)
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break;
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buf[len] = 0;
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/*
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* For 'checkout-index --prefix=<dir>', <dir> is
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* allowed to be a symlink to an existing directory,
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* and we set 'state->base_dir_len' below, such that
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* we test the path components of the prefix with the
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* stat() function instead of the lstat() function.
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*/
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if (has_dirs_only_path(buf, len, state->base_dir_len))
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continue; /* ok, it is already a directory. */
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/*
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* If this mkdir() would fail, it could be that there
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* is already a symlink or something else exists
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* there, therefore we then try to unlink it and try
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* one more time to create the directory.
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*/
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if (mkdir(buf, 0777)) {
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if (errno == EEXIST && state->force &&
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!unlink_or_warn(buf) && !mkdir(buf, 0777))
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continue;
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die_errno("cannot create directory at '%s'", buf);
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}
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}
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free(buf);
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}
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static void remove_subtree(struct strbuf *path)
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{
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DIR *dir = opendir(path->buf);
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struct dirent *de;
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int origlen = path->len;
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if (!dir)
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die_errno("cannot opendir '%s'", path->buf);
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while ((de = readdir(dir)) != NULL) {
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struct stat st;
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if (is_dot_or_dotdot(de->d_name))
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continue;
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strbuf_addch(path, '/');
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strbuf_addstr(path, de->d_name);
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if (lstat(path->buf, &st))
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die_errno("cannot lstat '%s'", path->buf);
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if (S_ISDIR(st.st_mode))
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remove_subtree(path);
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else if (unlink(path->buf))
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die_errno("cannot unlink '%s'", path->buf);
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strbuf_setlen(path, origlen);
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}
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closedir(dir);
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if (rmdir(path->buf))
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die_errno("cannot rmdir '%s'", path->buf);
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}
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static int create_file(const char *path, unsigned int mode)
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{
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mode = (mode & 0100) ? 0777 : 0666;
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return open(path, O_WRONLY | O_CREAT | O_EXCL, mode);
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}
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static void *read_blob_entry(const struct cache_entry *ce, unsigned long *size)
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{
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enum object_type type;
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void *new = read_sha1_file(ce->oid.hash, &type, size);
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if (new) {
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if (type == OBJ_BLOB)
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return new;
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free(new);
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}
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return NULL;
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}
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static int open_output_fd(char *path, const struct cache_entry *ce, int to_tempfile)
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{
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int symlink = (ce->ce_mode & S_IFMT) != S_IFREG;
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if (to_tempfile) {
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xsnprintf(path, TEMPORARY_FILENAME_LENGTH, "%s",
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symlink ? ".merge_link_XXXXXX" : ".merge_file_XXXXXX");
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return mkstemp(path);
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} else {
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return create_file(path, !symlink ? ce->ce_mode : 0666);
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}
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}
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static int fstat_output(int fd, const struct checkout *state, struct stat *st)
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{
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/* use fstat() only when path == ce->name */
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if (fstat_is_reliable() &&
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state->refresh_cache && !state->base_dir_len) {
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fstat(fd, st);
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return 1;
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}
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return 0;
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}
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static int streaming_write_entry(const struct cache_entry *ce, char *path,
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struct stream_filter *filter,
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const struct checkout *state, int to_tempfile,
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int *fstat_done, struct stat *statbuf)
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{
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int result = 0;
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int fd;
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fd = open_output_fd(path, ce, to_tempfile);
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if (fd < 0)
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return -1;
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result |= stream_blob_to_fd(fd, &ce->oid, filter, 1);
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*fstat_done = fstat_output(fd, state, statbuf);
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result |= close(fd);
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if (result)
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unlink(path);
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return result;
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}
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void enable_delayed_checkout(struct checkout *state)
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{
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if (!state->delayed_checkout) {
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state->delayed_checkout = xmalloc(sizeof(*state->delayed_checkout));
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state->delayed_checkout->state = CE_CAN_DELAY;
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string_list_init(&state->delayed_checkout->filters, 0);
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string_list_init(&state->delayed_checkout->paths, 0);
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}
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}
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static int remove_available_paths(struct string_list_item *item, void *cb_data)
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{
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struct string_list *available_paths = cb_data;
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struct string_list_item *available;
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available = string_list_lookup(available_paths, item->string);
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if (available)
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available->util = (void *)item->string;
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return !available;
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}
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int finish_delayed_checkout(struct checkout *state)
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{
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int errs = 0;
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struct string_list_item *filter, *path;
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struct delayed_checkout *dco = state->delayed_checkout;
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if (!state->delayed_checkout)
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return errs;
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dco->state = CE_RETRY;
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while (dco->filters.nr > 0) {
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for_each_string_list_item(filter, &dco->filters) {
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struct string_list available_paths = STRING_LIST_INIT_NODUP;
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if (!async_query_available_blobs(filter->string, &available_paths)) {
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/* Filter reported an error */
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errs = 1;
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filter->string = "";
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continue;
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}
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if (available_paths.nr <= 0) {
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/*
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* Filter responded with no entries. That means
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* the filter is done and we can remove the
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* filter from the list (see
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* "string_list_remove_empty_items" call below).
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*/
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filter->string = "";
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continue;
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}
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/*
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* In dco->paths we store a list of all delayed paths.
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* The filter just send us a list of available paths.
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* Remove them from the list.
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*/
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filter_string_list(&dco->paths, 0,
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&remove_available_paths, &available_paths);
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for_each_string_list_item(path, &available_paths) {
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struct cache_entry* ce;
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if (!path->util) {
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error("external filter '%s' signaled that '%s' "
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"is now available although it has not been "
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"delayed earlier",
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filter->string, path->string);
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errs |= 1;
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/*
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* Do not ask the filter for available blobs,
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* again, as the filter is likely buggy.
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*/
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filter->string = "";
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continue;
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}
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ce = index_file_exists(state->istate, path->string,
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strlen(path->string), 0);
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errs |= (ce ? checkout_entry(ce, state, NULL) : 1);
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}
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}
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string_list_remove_empty_items(&dco->filters, 0);
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}
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string_list_clear(&dco->filters, 0);
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/* At this point we should not have any delayed paths anymore. */
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errs |= dco->paths.nr;
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for_each_string_list_item(path, &dco->paths) {
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error("'%s' was not filtered properly", path->string);
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}
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string_list_clear(&dco->paths, 0);
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free(dco);
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state->delayed_checkout = NULL;
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return errs;
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}
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static int write_entry(struct cache_entry *ce,
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char *path, const struct checkout *state, int to_tempfile)
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{
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unsigned int ce_mode_s_ifmt = ce->ce_mode & S_IFMT;
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int fd, ret, fstat_done = 0;
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char *new;
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struct strbuf buf = STRBUF_INIT;
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unsigned long size;
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size_t wrote, newsize = 0;
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struct stat st;
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const struct submodule *sub;
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if (ce_mode_s_ifmt == S_IFREG) {
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struct stream_filter *filter = get_stream_filter(ce->name,
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ce->oid.hash);
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if (filter &&
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!streaming_write_entry(ce, path, filter,
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state, to_tempfile,
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&fstat_done, &st))
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goto finish;
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}
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switch (ce_mode_s_ifmt) {
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case S_IFREG:
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case S_IFLNK:
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new = read_blob_entry(ce, &size);
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if (!new)
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return error("unable to read sha1 file of %s (%s)",
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path, oid_to_hex(&ce->oid));
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if (ce_mode_s_ifmt == S_IFLNK && has_symlinks && !to_tempfile) {
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ret = symlink(new, path);
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free(new);
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if (ret)
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return error_errno("unable to create symlink %s",
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path);
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break;
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}
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/*
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* Convert from git internal format to working tree format
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*/
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if (ce_mode_s_ifmt == S_IFREG) {
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struct delayed_checkout *dco = state->delayed_checkout;
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if (dco && dco->state != CE_NO_DELAY) {
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/* Do not send the blob in case of a retry. */
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if (dco->state == CE_RETRY) {
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new = NULL;
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size = 0;
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}
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ret = async_convert_to_working_tree(
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ce->name, new, size, &buf, dco);
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if (ret && string_list_has_string(&dco->paths, ce->name)) {
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free(new);
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goto delayed;
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}
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} else
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ret = convert_to_working_tree(
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ce->name, new, size, &buf);
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if (ret) {
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free(new);
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new = strbuf_detach(&buf, &newsize);
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size = newsize;
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}
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/*
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* No "else" here as errors from convert are OK at this
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* point. If the error would have been fatal (e.g.
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* filter is required), then we would have died already.
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*/
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}
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fd = open_output_fd(path, ce, to_tempfile);
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if (fd < 0) {
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free(new);
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return error_errno("unable to create file %s", path);
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}
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wrote = write_in_full(fd, new, size);
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if (!to_tempfile)
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fstat_done = fstat_output(fd, state, &st);
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close(fd);
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free(new);
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if (wrote != size)
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return error("unable to write file %s", path);
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break;
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case S_IFGITLINK:
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if (to_tempfile)
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return error("cannot create temporary submodule %s", path);
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if (mkdir(path, 0777) < 0)
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return error("cannot create submodule directory %s", path);
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sub = submodule_from_ce(ce);
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if (sub)
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return submodule_move_head(ce->name,
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NULL, oid_to_hex(&ce->oid),
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state->force ? SUBMODULE_MOVE_HEAD_FORCE : 0);
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break;
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default:
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return error("unknown file mode for %s in index", path);
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}
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finish:
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if (state->refresh_cache) {
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assert(state->istate);
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if (!fstat_done)
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lstat(ce->name, &st);
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fill_stat_cache_info(ce, &st);
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ce->ce_flags |= CE_UPDATE_IN_BASE;
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state->istate->cache_changed |= CE_ENTRY_CHANGED;
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}
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delayed:
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return 0;
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}
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/*
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* This is like 'lstat()', except it refuses to follow symlinks
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* in the path, after skipping "skiplen".
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*/
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static int check_path(const char *path, int len, struct stat *st, int skiplen)
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{
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const char *slash = path + len;
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while (path < slash && *slash != '/')
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slash--;
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if (!has_dirs_only_path(path, slash - path, skiplen)) {
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errno = ENOENT;
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return -1;
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}
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return lstat(path, st);
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}
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/*
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* Write the contents from ce out to the working tree.
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*
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* When topath[] is not NULL, instead of writing to the working tree
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* file named by ce, a temporary file is created by this function and
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* its name is returned in topath[], which must be able to hold at
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* least TEMPORARY_FILENAME_LENGTH bytes long.
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*/
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int checkout_entry(struct cache_entry *ce,
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const struct checkout *state, char *topath)
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{
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static struct strbuf path = STRBUF_INIT;
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struct stat st;
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if (topath)
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return write_entry(ce, topath, state, 1);
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strbuf_reset(&path);
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strbuf_add(&path, state->base_dir, state->base_dir_len);
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strbuf_add(&path, ce->name, ce_namelen(ce));
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if (!check_path(path.buf, path.len, &st, state->base_dir_len)) {
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const struct submodule *sub;
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unsigned changed = ce_match_stat(ce, &st, CE_MATCH_IGNORE_VALID|CE_MATCH_IGNORE_SKIP_WORKTREE);
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/*
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* Needs to be checked before !changed returns early,
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* as the possibly empty directory was not changed
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*/
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sub = submodule_from_ce(ce);
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if (sub) {
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int err;
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if (!is_submodule_populated_gently(ce->name, &err)) {
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struct stat sb;
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if (lstat(ce->name, &sb))
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die(_("could not stat file '%s'"), ce->name);
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if (!(st.st_mode & S_IFDIR))
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unlink_or_warn(ce->name);
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return submodule_move_head(ce->name,
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NULL, oid_to_hex(&ce->oid), 0);
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} else
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return submodule_move_head(ce->name,
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"HEAD", oid_to_hex(&ce->oid),
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state->force ? SUBMODULE_MOVE_HEAD_FORCE : 0);
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}
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if (!changed)
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return 0;
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if (!state->force) {
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if (!state->quiet)
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fprintf(stderr,
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"%s already exists, no checkout\n",
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path.buf);
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return -1;
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}
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/*
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* We unlink the old file, to get the new one with the
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* right permissions (including umask, which is nasty
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* to emulate by hand - much easier to let the system
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* just do the right thing)
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*/
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if (S_ISDIR(st.st_mode)) {
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/* If it is a gitlink, leave it alone! */
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if (S_ISGITLINK(ce->ce_mode))
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return 0;
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if (!state->force)
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return error("%s is a directory", path.buf);
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remove_subtree(&path);
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} else if (unlink(path.buf))
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return error_errno("unable to unlink old '%s'", path.buf);
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} else if (state->not_new)
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return 0;
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create_directories(path.buf, path.len, state);
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return write_entry(ce, path.buf, state, 0);
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}
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