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| author | Denys Vlasenko <vda.linux@googlemail.com> | 2018-08-04 18:15:19 +0200 |
|---|---|---|
| committer | Denys Vlasenko <vda.linux@googlemail.com> | 2018-08-04 18:15:19 +0200 |
| commit | 037759bb4f57b0cb9b0daf6ffed43f90b62b8cb4 (patch) | |
| tree | 64a7f3b7d8ca50d3e622c9f1a1bb2b91198723d9 | |
| parent | 45d68c3749d29339494eb38bb4d5fe3ea189ac77 (diff) | |
| download | busybox-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.c | 24 |
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) |