tcsh/tcsh-6.19.00-history-file-locking-order.patch

---
 sh.c |   57 +++++++++++++++++++++++++++++++++------------------------
 1 file changed, 33 insertions(+), 24 deletions(-)

--- sh.c
+++ sh.c	2016-11-25 08:05:00.501610199 +0000
@@ -1540,18 +1540,18 @@ int
 #endif /*WINNT_NATIVE*/
 srcfile(const char *f, int onlyown, int flg, Char **av)
 {
-    int *unit;
+    int unit, *hd = NULL;
 
-    unit = xmalloc(sizeof(*unit));
-    cleanup_push(unit, xfree);
-    *unit = xopen(f, O_LARGEFILE |
+    unit = xopen(f, O_LARGEFILE |
 		    ((flg & HIST_FILE_WRLCK) ? (O_CREAT|O_RDWR) : O_RDONLY), 0600);
-    if (*unit == -1)
+    if (unit < 0)
 	return 0; /* Error. */
 
-    cleanup_push(unit, open_cleanup);
-    *unit = dmove(*unit, -1);
-    (void) close_on_exec(*unit, 1);
+    cleanup_push(&unit, open_cleanup);
+    unit = dmove(unit, -1);
+    cleanup_ignore(&unit);
+    cleanup_until(&unit);
+    (void) close_on_exec(unit, 1);
 
     if (flg & (HIST_FILE_WRLCK | HIST_FILE_RDLCK)) {
 	struct flock fl;
@@ -1561,26 +1561,35 @@ srcfile(const char *f, int onlyown, int
 	fl.l_start = 0;
 	fl.l_len = 0;
 
-	cleanup_push(unit, fcntl_cleanup);
-	if (fcntl(*unit, F_SETLKW, &fl) == -1)
-	    cleanup_ignore(unit);
-    }
+	hd = xmalloc(sizeof(*hd));
+	cleanup_push(hd, xfree);
 
-    srcunit(*unit, onlyown, flg, av);
+	*hd = fcntl(unit, F_DUPFD_CLOEXEC, FSAFE+1);
+	cleanup_push(hd, open_cleanup);
 
-    /* Unlock the unit, if we don't want to leave it locked (or open). */
-    if ((flg & (HIST_FILE_WRLCK | HIST_FILE_RDLCK)) &&
-        (!(flg & HIST_FILE_LOCK) || !(flg & HIST_FILE_OPEN)))
-	cleanup_until(unit); /* fcntl_cleanup */
-
-    /* Close the unit, if we don't want to leave it open. */
-    if (!(flg & HIST_FILE_OPEN)) {
-	cleanup_until(unit); /* open_cleanup */
-	cleanup_until(unit); /* xfree */
-	return -1; /* Not error but invalid file descriptor. */
+	fcntl(*hd, F_SETLKW, &fl);
+	cleanup_push(hd, fcntl_cleanup);
     }
 
-    return *unit; /* File descriptor (fd > FSAFE). */
+    cleanup_push(&unit, open_cleanup);
+    /*
+     * This one *does* do a cleanup_until() hence a open_cleanup()
+     * therefore use a duplicated fd to lock/unlock the history file
+     */
+    srcunit(unit, onlyown, flg, av);
+    cleanup_until(&unit);	/* Close the official unit. */
+
+    if (!hd)
+	return -1;		/* Not error but invalid file descriptor. */
+
+    if ((flg & HIST_FILE_OPEN) && (flg & HIST_FILE_LOCK))
+	return -1;
+
+    cleanup_until(hd);		/* fcntl_cleanup */
+    cleanup_until(hd);		/* open_cleanup */
+    cleanup_until(hd);		/* xfree */
+
+    return unit;		/* File descriptor (fd > FSAFE). */
 }