Merge branch 'mh/safe-create-leading-directories'

Code clean-up and protection against concurrent write access to the
ref namespace.

* mh/safe-create-leading-directories:
  rename_tmp_log(): on SCLD_VANISHED, retry
  rename_tmp_log(): limit the number of remote_empty_directories() attempts
  rename_tmp_log(): handle a possible mkdir/rmdir race
  rename_ref(): extract function rename_tmp_log()
  remove_dir_recurse(): handle disappearing files and directories
  remove_dir_recurse(): tighten condition for removing unreadable dir
  lock_ref_sha1_basic(): if locking fails with ENOENT, retry
  lock_ref_sha1_basic(): on SCLD_VANISHED, retry
  safe_create_leading_directories(): add new error value SCLD_VANISHED
  cmd_init_db(): when creating directories, handle errors conservatively
  safe_create_leading_directories(): introduce enum for return values
  safe_create_leading_directories(): always restore slash at end of loop
  safe_create_leading_directories(): split on first of multiple slashes
  safe_create_leading_directories(): rename local variable
  safe_create_leading_directories(): add explicit "slash" pointer
  safe_create_leading_directories(): reduce scope of local variable
  safe_create_leading_directories(): fix format of "if" chaining

1 files changed, 20 insertions, 7 deletions

diff --git a/dir.c b/dir.c
index d10a63f..b35b633 100644
--- a/dir.c
+++ b/dir.c
@@ -1511,8 +1511,13 @@ static int remove_dir_recurse(struct strbuf *path, int flag, int *kept_up)
 	flag &= ~REMOVE_DIR_KEEP_TOPLEVEL;
 	dir = opendir(path->buf);
 	if (!dir) {
-		/* an empty dir could be removed even if it is unreadble */
-		if (!keep_toplevel)
+		if (errno == ENOENT)
+			return keep_toplevel ? -1 : 0;
+		else if (errno == EACCES && !keep_toplevel)
+			/*
+			 * An empty dir could be removable even if it
+			 * is unreadable:
+			 */
 			return rmdir(path->buf);
 		else
 			return -1;
@@ -1528,13 +1533,21 @@ static int remove_dir_recurse(struct strbuf *path, int flag, int *kept_up)
 
 		strbuf_setlen(path, len);
 		strbuf_addstr(path, e->d_name);
-		if (lstat(path->buf, &st))
-			; /* fall thru */
-		else if (S_ISDIR(st.st_mode)) {
+		if (lstat(path->buf, &st)) {
+			if (errno == ENOENT)
+				/*
+				 * file disappeared, which is what we
+				 * wanted anyway
+				 */
+				continue;
+			/* fall thru */
+		} else if (S_ISDIR(st.st_mode)) {
 			if (!remove_dir_recurse(path, flag, &kept_down))
 				continue; /* happy */
-		} else if (!only_empty && !unlink(path->buf))
+		} else if (!only_empty &&
+			   (!unlink(path->buf) || errno == ENOENT)) {
 			continue; /* happy, too */
+		}
 
 		/* path too long, stat fails, or non-directory still exists */
 		ret = -1;
@@ -1544,7 +1557,7 @@ static int remove_dir_recurse(struct strbuf *path, int flag, int *kept_up)
 
 	strbuf_setlen(path, original_len);
 	if (!ret && !keep_toplevel && !kept_down)
-		ret = rmdir(path->buf);
+		ret = (!rmdir(path->buf) || errno == ENOENT) ? 0 : -1;
 	else if (kept_up)
 		/*
 		 * report the uplevel that it is not an error that we