tar: handle the case when opened created tarball happens to have fd#0
Reproducer:
exec 0>&-
exec 1>&-
tar czf z.tar.gz FILE
function old new delta
vfork_compressor 229 257 +28
Signed-off-by: Denys Vlasenko <vda.linux@googlemail.com>
diff --git a/archival/tar.c b/archival/tar.c
index 9239d8e..120c77f 100644
--- a/archival/tar.c
+++ b/archival/tar.c
@@ -611,6 +611,7 @@
if (xvfork() == 0) {
/* child */
+ int tfd;
/* NB: close _first_, then move fds! */
close(data.wr);
# if WAIT_FOR_CHILD
@@ -619,8 +620,23 @@
* parent waits for this close to happen */
fcntl(status.wr, F_SETFD, FD_CLOEXEC);
# endif
+ /* copy it: parent's tar_fd variable must not change */
+ tfd = tar_fd;
+ if (tfd == 0) {
+ /* Output tar fd may be zero.
+ * xmove_fd(data.rd, 0) would destroy it.
+ * Reproducer:
+ * exec 0>&-
+ * exec 1>&-
+ * tar czf Z.tar.gz FILE
+ * Swapping move_fd's order wouldn't work:
+ * data.rd is 1 and _it_ would be destroyed.
+ */
+ xmove_fd(tfd, 3);
+ tfd = 3;
+ }
xmove_fd(data.rd, 0);
- xmove_fd(tar_fd, 1);
+ xmove_fd(tfd, 1);
/* exec gzip/bzip2 program/applet */
BB_EXECLP(gzip, gzip, "-f", (char *)0);
vfork_exec_errno = errno;
@@ -715,11 +731,7 @@
return errorFlag;
}
-#else /* !FEATURE_TAR_CREATE */
-
-# define writeTarFile(...) 0
-
-#endif
+#endif /* FEATURE_TAR_CREATE */
#if ENABLE_FEATURE_TAR_FROM
static llist_t *append_file_list_to_list(llist_t *list)