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[PATCH v3 2/2] setup: don't fail if commondir reference is deleted.

From
Michal Suchanek <msuchanek@suse.de>
Date
Feb 20, 2019, 16:16 UTC
Message-ID
<37df7fd81c3dee990bd7723f18c94713a0d842b6.1550679076.git.msuchanek@suse.de>
In-Reply-To
<cover.1550508544.git.msuchanek@suse.de>

Apparently it can happen that stat() claims there is a commondir file but when trying to open the file it is missing.

Another even rarer issue is that the file might be zero size because another process initializing a worktree opened the file but has not written is content yet.

When any of this happnes git aborts failing to perform perfectly valid command because unrelated worktree is not yet fully initialized.

Rather than testing if the file exists before reading it handle ENOENT and ENOTDIR.

Signed-off-by: Michal Suchanek <msuchanek@suse.de>
---
v2:
- do not test file existence first, just read it and handle ENOENT.
- handle zero size file correctly
v3:
- handle ENOTDIR as well
- add more details to commit message
---
 setup.c | 16 +++++++++++-----
 1 file changed, 11 insertions(+), 5 deletions(-)
diff --git a/setup.c b/setup.c
index ca9e8a949ed8..49306e36990d 100644
--- a/setup.c
+++ b/setup.c
@@ -270,12 +270,20 @@ int get_common_dir_noenv(struct strbuf *sb, const char *gitdir)
 {
 	struct strbuf data = STRBUF_INIT;
 	struct strbuf path = STRBUF_INIT;
-	int ret = 0;
+	int ret;
 
 	strbuf_addf(&path, "%s/commondir", gitdir);
-	if (file_exists(path.buf)) {
-		if (strbuf_read_file(&data, path.buf, 0) <= 0)
+	ret = strbuf_read_file(&data, path.buf, 0);
+	if (ret <= 0) {
+		/*
+		 * if file is missing or zero size (just being written)
+		 * assume default, bail otherwise
+		 */
+		if (ret && errno != ENOENT && errno != ENOTDIR)
 			die_errno(_("failed to read %s"), path.buf);
+		strbuf_addstr(sb, gitdir);
+		ret = 0;
+	} else {
 		while (data.len && (data.buf[data.len - 1] == '\n' ||
 				    data.buf[data.len - 1] == '\r'))
 			data.len--;
@@ -286,8 +294,6 @@ int get_common_dir_noenv(struct strbuf *sb, const char *gitdir)
 		strbuf_addbuf(&path, &data);
 		strbuf_add_real_path(sb, path.buf);
 		ret = 1;
-	} else {
-		strbuf_addstr(sb, gitdir);
 	}
 
 	strbuf_release(&data);
-- 
2.20.1
Previous: Junio C HamanoNext: Eric Sunshine
Message 21 of 27 in “worktree add race fix”
  1. 0/2 worktree add race fixMichal Suchanek, Feb 18, 2019
  2. 1/2 worktree: fix worktree add race.Michal Suchanek, Feb 18, 2019
  3. 2/2 setup: don't fail if commondir reference is deleted.Michal Suchanek, Feb 18, 2019
  4. Eric SunshineFeb 18, 2019
  5. Duy NguyenFeb 21, 2019
  6. Michal SuchánekFeb 21, 2019
  7. Phillip WoodFeb 21, 2019
  8. Eric SunshineFeb 21, 2019
  9. Phillip WoodFeb 21, 2019
  10. Michal SuchánekMar 4, 2019
  11. Michal SuchánekFeb 21, 2019
  12. Duy NguyenFeb 22, 2019
  13. Phillip WoodFeb 22, 2019
  14. Duy NguyenFeb 22, 2019
  15. 1/2 worktree: fix worktree add race.Michal Suchanek, Feb 20, 2019
  16. Eric SunshineFeb 20, 2019
  17. Michal SuchánekFeb 20, 2019
  18. Duy NguyenMar 8, 2019
  19. Eric SunshineMar 8, 2019
  20. Junio C HamanoMar 11, 2019
  21. 2/2 setup: don't fail if commondir reference is deleted.Michal Suchanek, Feb 20, 2019
  22. Eric SunshineFeb 20, 2019
  23. Michal SuchánekFeb 20, 2019
  24. Eric SunshineFeb 20, 2019
  25. Eric SunshineFeb 21, 2019
  26. Michal SuchánekFeb 21, 2019
  27. Michal SuchánekFeb 21, 2019

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