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authorDenys Vlasenko <vda.linux@googlemail.com>2018-08-04 18:15:19 +0200
committerDenys Vlasenko <vda.linux@googlemail.com>2018-08-04 18:15:19 +0200
commit037759bb4f57b0cb9b0daf6ffed43f90b62b8cb4 (patch)
tree64a7f3b7d8ca50d3e622c9f1a1bb2b91198723d9
parent45d68c3749d29339494eb38bb4d5fe3ea189ac77 (diff)
downloadbusybox-037759bb4f57b0cb9b0daf6ffed43f90b62b8cb4.tar.gz
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>
-rw-r--r--archival/tar.c24
1 files changed, 18 insertions, 6 deletions
diff --git a/archival/tar.c b/archival/tar.c
index 9239d8ee4..120c77f3b 100644
--- a/archival/tar.c
+++ b/archival/tar.c
@@ -611,6 +611,7 @@ static void NOINLINE vfork_compressor(int tar_fd, const char *gzip)
if (xvfork() == 0) {
/* child */
+ int tfd;
/* NB: close _first_, then move fds! */
close(data.wr);
# if WAIT_FOR_CHILD
@@ -619,8 +620,23 @@ static void NOINLINE vfork_compressor(int tar_fd, const char *gzip)
* 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 @@ static NOINLINE int writeTarFile(
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)