t3508: add check_head_differs_from() helper function and use it

diff --git a/refs.c b/refs.c
index 6f486ae62d8b4605520e75286ca36217d0715363..b5400674d7a1fcf4cc16dd630b8671b2ad7b9f7b 100644 (file)
--- a/refs.c
+++ b/refs.c
@@ -1090,6 +1090,15 @@ int delete_ref(const char *refname, const unsigned char *sha1, int delopt)
        return ret;
 }
 
+/*
+ * People using contrib's git-new-workdir have .git/logs/refs ->
+ * /some/other/path/.git/logs/refs, and that may live on another device.
+ *
+ * IOW, to avoid cross device rename errors, the temporary renamed log must
+ * live into logs/refs.
+ */
+#define TMP_RENAMED_LOG  "logs/refs/.tmp-renamed-log"
+
 int rename_ref(const char *oldref, const char *newref, const char *logmsg)
 {
        static const char renamed_ref[] = "RENAMED-REF";
@@ -1123,8 +1132,8 @@ int rename_ref(const char *oldref, const char *newref, const char *logmsg)
        if (write_ref_sha1(lock, orig_sha1, logmsg))
                return error("unable to save current sha1 in %s", renamed_ref);
 
-       if (log && rename(git_path("logs/%s", oldref), git_path("tmp-renamed-log")))
-               return error("unable to move logfile logs/%s to tmp-renamed-log: %s",
+       if (log && rename(git_path("logs/%s", oldref), git_path(TMP_RENAMED_LOG)))
+               return error("unable to move logfile logs/%s to "TMP_RENAMED_LOG": %s",
                        oldref, strerror(errno));
 
        if (delete_ref(oldref, orig_sha1, REF_NODEREF)) {
@@ -1150,7 +1159,7 @@ int rename_ref(const char *oldref, const char *newref, const char *logmsg)
        }
 
  retry:
-       if (log && rename(git_path("tmp-renamed-log"), git_path("logs/%s", newref))) {
+       if (log && rename(git_path(TMP_RENAMED_LOG), git_path("logs/%s", newref))) {
                if (errno==EISDIR || errno==ENOTDIR) {
                        /*
                         * rename(a, b) when b is an existing
@@ -1163,7 +1172,7 @@ int rename_ref(const char *oldref, const char *newref, const char *logmsg)
                        }
                        goto retry;
                } else {
-                       error("unable to move logfile tmp-renamed-log to logs/%s: %s",
+                       error("unable to move logfile "TMP_RENAMED_LOG" to logs/%s: %s",
                                newref, strerror(errno));
                        goto rollback;
                }
@@ -1203,8 +1212,8 @@ int rename_ref(const char *oldref, const char *newref, const char *logmsg)
                error("unable to restore logfile %s from %s: %s",
                        oldref, newref, strerror(errno));
        if (!logmoved && log &&
-           rename(git_path("tmp-renamed-log"), git_path("logs/%s", oldref)))
-               error("unable to restore logfile %s from tmp-renamed-log: %s",
+           rename(git_path(TMP_RENAMED_LOG), git_path("logs/%s", oldref)))
+               error("unable to restore logfile %s from "TMP_RENAMED_LOG": %s",
                        oldref, strerror(errno));
 
        return 1;