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ash,hush: fix "saved" redirected fds still visible in children

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Based on a patch by Mark Marshall <mark.marshall@omicronenergy.com>

function                                             old     new   delta
dup_CLOEXEC                                            -      49     +49
fcntl_F_DUPFD                                         46       -     -46

Signed-off-by: Denys Vlasenko <vda.linux@googlemail.com>
This commit is contained in:
Denys Vlasenko
2018-03-28 18:35:07 +02:00
parent e4defe826b
commit 9acd63c92c
14 changed files with 92 additions and 13 deletions
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16
shell/ash.c
View File

@@ -255,6 +255,9 @@ typedef long arith_t;
# define IF_NOT_FEATURE_SH_STANDALONE(...) __VA_ARGS__
#endif
#ifndef F_DUPFD_CLOEXEC
# define F_DUPFD_CLOEXEC F_DUPFD
#endif
#ifndef PIPE_BUF
# define PIPE_BUF 4096 /* amount of buffering in a pipe */
#endif
@@ -5448,12 +5451,15 @@ dup2_or_raise(int from, int to)
return newfd;
}
static int
fcntl_F_DUPFD(int fd, int avoid_fd)
dup_CLOEXEC(int fd, int avoid_fd)
{
int newfd;
repeat:
newfd = fcntl(fd, F_DUPFD, avoid_fd + 1);
if (newfd < 0) {
newfd = fcntl(fd, F_DUPFD_CLOEXEC, avoid_fd + 1);
if (newfd >= 0) {
if (F_DUPFD_CLOEXEC == F_DUPFD) /* if old libc (w/o F_DUPFD_CLOEXEC) */
fcntl(newfd, F_SETFD, FD_CLOEXEC);
} else { /* newfd < 0 */
if (errno == EBUSY)
goto repeat;
if (errno == EINTR)
@@ -5569,7 +5575,7 @@ save_fd_on_redirect(int fd, int avoid_fd, struct redirtab *sq)
for (i = 0; sq->two_fd[i].orig_fd != EMPTY; i++) {
/* If we collide with an already moved fd... */
if (fd == sq->two_fd[i].moved_to) {
new_fd = fcntl_F_DUPFD(fd, avoid_fd);
new_fd = dup_CLOEXEC(fd, avoid_fd);
sq->two_fd[i].moved_to = new_fd;
TRACE(("redirect_fd %d: already busy, moving to %d\n", fd, new_fd));
if (new_fd < 0) /* what? */
@@ -5584,7 +5590,7 @@ save_fd_on_redirect(int fd, int avoid_fd, struct redirtab *sq)
}
/* If this fd is open, we move and remember it; if it's closed, new_fd = CLOSED (-1) */
new_fd = fcntl_F_DUPFD(fd, avoid_fd);
new_fd = dup_CLOEXEC(fd, avoid_fd);
TRACE(("redirect_fd %d: previous fd is moved to %d (-1 if it was closed)\n", fd, new_fd));
if (new_fd < 0) {
if (errno != EBADF)