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refs file backend: move raceproof_create_file() here
Move the raceproof_create_file() API added to cache.h and
object-file.c in 177978f56a (raceproof_create_file(): new function,
2017-01-06) to its only user, refs/files-backend.c.
Signed-off-by: Ævar Arnfjörð Bjarmason <avarab@gmail.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
This commit is contained in:
Ævar Arnfjörð Bjarmason
Junio C Hamano
parent
48cdcd9ca0
commit
3fa2e91d17
43
cache.h
43
cache.h
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@ -1202,49 +1202,6 @@ enum scld_error safe_create_leading_directories(char *path);
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enum scld_error safe_create_leading_directories_const(const char *path);
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enum scld_error safe_create_leading_directories_no_share(char *path);
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/*
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* Callback function for raceproof_create_file(). This function is
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* expected to do something that makes dirname(path) permanent despite
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* the fact that other processes might be cleaning up empty
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* directories at the same time. Usually it will create a file named
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* path, but alternatively it could create another file in that
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* directory, or even chdir() into that directory. The function should
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* return 0 if the action was completed successfully. On error, it
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* should return a nonzero result and set errno.
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* raceproof_create_file() treats two errno values specially:
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*
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* - ENOENT -- dirname(path) does not exist. In this case,
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* raceproof_create_file() tries creating dirname(path)
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* (and any parent directories, if necessary) and calls
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* the function again.
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*
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* - EISDIR -- the file already exists and is a directory. In this
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* case, raceproof_create_file() removes the directory if
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* it is empty (and recursively any empty directories that
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* it contains) and calls the function again.
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*
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* Any other errno causes raceproof_create_file() to fail with the
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* callback's return value and errno.
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*
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* Obviously, this function should be OK with being called again if it
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* fails with ENOENT or EISDIR. In other scenarios it will not be
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* called again.
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*/
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typedef int create_file_fn(const char *path, void *cb);
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/*
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* Create a file in dirname(path) by calling fn, creating leading
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* directories if necessary. Retry a few times in case we are racing
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* with another process that is trying to clean up the directory that
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* contains path. See the documentation for create_file_fn for more
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* details.
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*
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* Return the value and set the errno that resulted from the most
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* recent call of fn. fn is always called at least once, and will be
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* called more than once if it returns ENOENT or EISDIR.
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*/
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int raceproof_create_file(const char *path, create_file_fn fn, void *cb);
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int mkdir_in_gitdir(const char *path);
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char *expand_user_path(const char *path, int real_home);
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const char *enter_repo(const char *path, int strict);
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@ -414,74 +414,6 @@ enum scld_error safe_create_leading_directories_const(const char *path)
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return result;
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}
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int raceproof_create_file(const char *path, create_file_fn fn, void *cb)
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{
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/*
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* The number of times we will try to remove empty directories
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* in the way of path. This is only 1 because if another
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* process is racily creating directories that conflict with
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* us, we don't want to fight against them.
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*/
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int remove_directories_remaining = 1;
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/*
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* The number of times that we will try to create the
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* directories containing path. We are willing to attempt this
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* more than once, because another process could be trying to
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* clean up empty directories at the same time as we are
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* trying to create them.
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*/
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int create_directories_remaining = 3;
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/* A scratch copy of path, filled lazily if we need it: */
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struct strbuf path_copy = STRBUF_INIT;
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int ret, save_errno;
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/* Sanity check: */
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assert(*path);
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retry_fn:
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ret = fn(path, cb);
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save_errno = errno;
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if (!ret)
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goto out;
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if (errno == EISDIR && remove_directories_remaining-- > 0) {
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/*
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* A directory is in the way. Maybe it is empty; try
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* to remove it:
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*/
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if (!path_copy.len)
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strbuf_addstr(&path_copy, path);
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if (!remove_dir_recursively(&path_copy, REMOVE_DIR_EMPTY_ONLY))
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goto retry_fn;
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} else if (errno == ENOENT && create_directories_remaining-- > 0) {
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/*
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* Maybe the containing directory didn't exist, or
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* maybe it was just deleted by a process that is
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* racing with us to clean up empty directories. Try
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* to create it:
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*/
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enum scld_error scld_result;
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if (!path_copy.len)
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strbuf_addstr(&path_copy, path);
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do {
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scld_result = safe_create_leading_directories(path_copy.buf);
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if (scld_result == SCLD_OK)
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goto retry_fn;
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} while (scld_result == SCLD_VANISHED && create_directories_remaining-- > 0);
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}
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out:
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strbuf_release(&path_copy);
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errno = save_errno;
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return ret;
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}
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static void fill_loose_path(struct strbuf *buf, const struct object_id *oid)
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{
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int i;
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@ -852,6 +852,115 @@ static struct ref_iterator *files_ref_iterator_begin(
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return ref_iterator;
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}
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/*
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* Callback function for raceproof_create_file(). This function is
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* expected to do something that makes dirname(path) permanent despite
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* the fact that other processes might be cleaning up empty
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* directories at the same time. Usually it will create a file named
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* path, but alternatively it could create another file in that
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* directory, or even chdir() into that directory. The function should
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* return 0 if the action was completed successfully. On error, it
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* should return a nonzero result and set errno.
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* raceproof_create_file() treats two errno values specially:
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*
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* - ENOENT -- dirname(path) does not exist. In this case,
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* raceproof_create_file() tries creating dirname(path)
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* (and any parent directories, if necessary) and calls
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* the function again.
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*
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* - EISDIR -- the file already exists and is a directory. In this
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* case, raceproof_create_file() removes the directory if
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* it is empty (and recursively any empty directories that
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* it contains) and calls the function again.
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*
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* Any other errno causes raceproof_create_file() to fail with the
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* callback's return value and errno.
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*
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* Obviously, this function should be OK with being called again if it
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* fails with ENOENT or EISDIR. In other scenarios it will not be
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* called again.
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*/
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typedef int create_file_fn(const char *path, void *cb);
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/*
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* Create a file in dirname(path) by calling fn, creating leading
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* directories if necessary. Retry a few times in case we are racing
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* with another process that is trying to clean up the directory that
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* contains path. See the documentation for create_file_fn for more
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* details.
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*
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* Return the value and set the errno that resulted from the most
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* recent call of fn. fn is always called at least once, and will be
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* called more than once if it returns ENOENT or EISDIR.
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*/
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static int raceproof_create_file(const char *path, create_file_fn fn, void *cb)
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{
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/*
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* The number of times we will try to remove empty directories
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* in the way of path. This is only 1 because if another
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* process is racily creating directories that conflict with
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* us, we don't want to fight against them.
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*/
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int remove_directories_remaining = 1;
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/*
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* The number of times that we will try to create the
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* directories containing path. We are willing to attempt this
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* more than once, because another process could be trying to
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* clean up empty directories at the same time as we are
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* trying to create them.
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*/
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int create_directories_remaining = 3;
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/* A scratch copy of path, filled lazily if we need it: */
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struct strbuf path_copy = STRBUF_INIT;
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int ret, save_errno;
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/* Sanity check: */
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assert(*path);
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retry_fn:
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ret = fn(path, cb);
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save_errno = errno;
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if (!ret)
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goto out;
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if (errno == EISDIR && remove_directories_remaining-- > 0) {
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/*
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* A directory is in the way. Maybe it is empty; try
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* to remove it:
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*/
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if (!path_copy.len)
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strbuf_addstr(&path_copy, path);
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if (!remove_dir_recursively(&path_copy, REMOVE_DIR_EMPTY_ONLY))
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goto retry_fn;
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} else if (errno == ENOENT && create_directories_remaining-- > 0) {
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/*
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* Maybe the containing directory didn't exist, or
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* maybe it was just deleted by a process that is
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* racing with us to clean up empty directories. Try
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* to create it:
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*/
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enum scld_error scld_result;
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if (!path_copy.len)
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strbuf_addstr(&path_copy, path);
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do {
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scld_result = safe_create_leading_directories(path_copy.buf);
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if (scld_result == SCLD_OK)
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goto retry_fn;
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} while (scld_result == SCLD_VANISHED && create_directories_remaining-- > 0);
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}
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out:
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strbuf_release(&path_copy);
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errno = save_errno;
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return ret;
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}
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static int remove_empty_directories(struct strbuf *path)
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{
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/*
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