[31485] in CVS-changelog-for-Kerberos-V5
krb5 commit: Make atomic ccache replacement work on Windows
daemon@ATHENA.MIT.EDU (ghudson@mit.edu)
Wed Nov 12 00:27:56 2025
From: ghudson@mit.edu
To: cvs-krb5@mit.edu
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Date: Wed, 12 Nov 2025 00:27:50 -0500 (EST)
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https://github.com/krb5/krb5/commit/04816024aadbfd64b5306942e2dfbd757cb05f93
commit 04816024aadbfd64b5306942e2dfbd757cb05f93
Author: YUBI LEE <eubnara@gmail.com>
Date: Fri Oct 31 20:26:05 2025 +0900
Make atomic ccache replacement work on Windows
Commit 371f09d4bf4ca0c7ba15c5ef909bc35307ed9cc3 relies on POSIX
rename() semantics for atomic ccache replacement. Windows rename()
fails if the destination file exists. Add a fallback to ReplaceFile()
when this happens. We may be able to do better using
FILE_RENAME_FLAG_POSIX_SEMANTICS (added in Windows 10 update 1067) but
this should generally suffice.
[ghudson@mit.edu: simplified code slightly; rewrote commit message]
ticket: 9190 (new)
tags: pullup
target_version: 1.22-next
src/lib/krb5/ccache/cc_file.c | 8 ++++++++
1 file changed, 8 insertions(+)
diff --git a/src/lib/krb5/ccache/cc_file.c b/src/lib/krb5/ccache/cc_file.c
index 198152a9e..f34c0f106 100644
--- a/src/lib/krb5/ccache/cc_file.c
+++ b/src/lib/krb5/ccache/cc_file.c
@@ -1311,6 +1311,14 @@ fcc_replace(krb5_context context, krb5_ccache id, krb5_principal princ,
goto errno_cleanup;
st = rename(tmpname, data->filename);
+#ifdef _WIN32
+ /* Windows cannot rename over an existing file under most circumstances.
+ * Try ReplaceFile() (which only works if the destination file exists). */
+ if (st != 0) {
+ if (ReplaceFile(data->filename, tmpname, NULL, 0, NULL, NULL))
+ st = 0;
+ }
+#endif
if (st != 0)
goto errno_cleanup;
tmpfile_exists = FALSE;
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