From: Junio C Hamano <gitster@pobox.com>
Date: Mon, 8 Aug 2016 21:21:35 +0000 (-0700)
Subject: Merge branch 'rs/notes-merge-no-toctou' into maint
X-Git-Tag: v2.9.3~40
X-Git-Url: https://git.lorimer.id.au/gitweb.git/diff_plain/743fba85f7dfb04eff4df55dc8d7aa08f3f8eaa3?hp=a52fb9b8f3e30b5b5e743cae91c3b2e1f729eb5d

Merge branch 'rs/notes-merge-no-toctou' into maint

"git notes merge" had a code to see if a path exists (and fails if
it does) and then open the path for writing (when it doesn't).
Replace it with open with O_EXCL.

* rs/notes-merge-no-toctou:
notes-merge: use O_EXCL to avoid overwriting existing files
---

diff --git a/notes-merge.c b/notes-merge.c
index 34bfac0c68..f00059520e 100644
--- a/notes-merge.c
+++ b/notes-merge.c
@@ -298,12 +298,8 @@ static void write_buf_to_worktree(const unsigned char *obj,
 	char *path = git_pathdup(NOTES_MERGE_WORKTREE "/%s", sha1_to_hex(obj));
 	if (safe_create_leading_directories_const(path))
 		die_errno("unable to create directory for '%s'", path);
-	if (file_exists(path))
-		die("found existing file at '%s'", path);
 
-	fd = open(path, O_WRONLY | O_TRUNC | O_CREAT, 0666);
-	if (fd < 0)
-		die_errno("failed to open '%s'", path);
+	fd = xopen(path, O_WRONLY | O_EXCL | O_CREAT, 0666);
 
 	while (size > 0) {
 		long ret = write_in_full(fd, buf, size);