hush: massage redirect code to be slightly more like ash
function old new delta save_fd_on_redirect - 203 +203 xdup_CLOEXEC_and_close - 75 +75 setup_redirects 245 250 +5 xdup_and_close 72 - -72 save_fds_on_redirect 221 - -221 ------------------------------------------------------------------------------ (add/remove: 2/2 grow/shrink: 1/0 up/down: 283/-293) Total: -10 bytes Signed-off-by: Denys Vlasenko <vda.linux@googlemail.com>
This commit is contained in:
Denys Vlasenko
parent
d07a15bd1b
commit
657e9005a9
103
shell/hush.c
103
shell/hush.c
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@ -1454,11 +1454,11 @@ static int fcntl_F_DUPFD(int fd, int avoid_fd)
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return newfd;
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}
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static int xdup_and_close(int fd, int F_DUPFD_maybe_CLOEXEC, int avoid_fd)
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static int xdup_CLOEXEC_and_close(int fd, int avoid_fd)
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{
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int newfd;
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repeat:
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newfd = fcntl(fd, F_DUPFD_maybe_CLOEXEC, avoid_fd + 1);
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newfd = fcntl(fd, F_DUPFD_CLOEXEC, avoid_fd + 1);
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if (newfd < 0) {
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if (errno == EBUSY)
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goto repeat;
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@ -1469,6 +1469,8 @@ static int xdup_and_close(int fd, int F_DUPFD_maybe_CLOEXEC, int avoid_fd)
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return fd;
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xfunc_die();
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}
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if (F_DUPFD_CLOEXEC == F_DUPFD) /* if old libc (w/o F_DUPFD_CLOEXEC) */
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fcntl(newfd, F_SETFD, FD_CLOEXEC);
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close(fd);
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return newfd;
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}
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@ -1507,7 +1509,7 @@ static int save_FILEs_on_redirect(int fd, int avoid_fd)
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while (fl) {
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if (fd == fl->fd) {
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/* We use it only on script files, they are all CLOEXEC */
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fl->fd = xdup_and_close(fd, F_DUPFD_CLOEXEC, avoid_fd);
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fl->fd = xdup_CLOEXEC_and_close(fd, avoid_fd);
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debug_printf_redir("redirect_fd %d: matches a script fd, moving it to %d\n", fd, fl->fd);
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return 1;
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}
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@ -6711,18 +6713,42 @@ static struct squirrel *add_squirrel(struct squirrel *sq, int fd, int avoid_fd)
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return append_squirrel(sq, i, fd, moved_to);
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}
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static struct squirrel *add_squirrel_closed(struct squirrel *sq, int fd)
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{
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int i;
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i = 0;
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if (sq) while (sq[i].orig_fd >= 0) {
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/* If we collide with an already moved fd... */
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if (fd == sq[i].orig_fd) {
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/* Examples:
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* "echo 3>FILE 3>&- 3>FILE"
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* "echo 3>&- 3>FILE"
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* No need for last redirect to insert
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* another "need to close 3" indicator.
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*/
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debug_printf_redir("redirect_fd %d: already moved or closed\n", fd);
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return sq;
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}
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i++;
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}
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debug_printf_redir("redirect_fd %d: previous fd was closed\n", fd);
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return append_squirrel(sq, i, fd, -1);
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}
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/* fd: redirect wants this fd to be used (e.g. 3>file).
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* Move all conflicting internally used fds,
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* and remember them so that we can restore them later.
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*/
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static int save_fds_on_redirect(int fd, int avoid_fd, struct squirrel **sqp)
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static int save_fd_on_redirect(int fd, int avoid_fd, struct squirrel **sqp)
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{
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if (avoid_fd < 9) /* the important case here is that it can be -1 */
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avoid_fd = 9;
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#if ENABLE_HUSH_INTERACTIVE
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if (fd != 0 && fd == G.interactive_fd) {
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G.interactive_fd = xdup_and_close(G.interactive_fd, F_DUPFD_CLOEXEC, avoid_fd);
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G.interactive_fd = xdup_CLOEXEC_and_close(G.interactive_fd, avoid_fd);
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debug_printf_redir("redirect_fd %d: matches interactive_fd, moving it to %d\n", fd, G.interactive_fd);
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return 1; /* "we closed fd" */
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}
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@ -6748,7 +6774,6 @@ static int save_fds_on_redirect(int fd, int avoid_fd, struct squirrel **sqp)
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static void restore_redirects(struct squirrel *sq)
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{
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if (sq) {
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int i = 0;
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while (sq[i].orig_fd >= 0) {
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@ -6775,13 +6800,15 @@ static void restore_redirects(struct squirrel *sq)
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* and stderr if they are redirected. */
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static int setup_redirects(struct command *prog, struct squirrel **sqp)
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{
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int openfd, mode;
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struct redir_struct *redir;
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for (redir = prog->redirects; redir; redir = redir->next) {
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int newfd;
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int closed;
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if (redir->rd_type == REDIRECT_HEREDOC2) {
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/* "rd_fd<<HERE" case */
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save_fds_on_redirect(redir->rd_fd, /*avoid:*/ 0, sqp);
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save_fd_on_redirect(redir->rd_fd, /*avoid:*/ 0, sqp);
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/* for REDIRECT_HEREDOC2, rd_filename holds _contents_
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* of the heredoc */
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debug_printf_parse("set heredoc '%s'\n",
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@ -6793,6 +6820,8 @@ static int setup_redirects(struct command *prog, struct squirrel **sqp)
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if (redir->rd_dup == REDIRFD_TO_FILE) {
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/* "rd_fd<*>file" case (<*> is <,>,>>,<>) */
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char *p;
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int mode;
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if (redir->rd_filename == NULL) {
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/*
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* Examples:
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@ -6804,9 +6833,9 @@ static int setup_redirects(struct command *prog, struct squirrel **sqp)
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}
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mode = redir_table[redir->rd_type].mode;
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p = expand_string_to_string(redir->rd_filename, /*unbackslash:*/ 1);
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openfd = open_or_warn(p, mode);
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newfd = open_or_warn(p, mode);
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free(p);
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if (openfd < 0) {
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if (newfd < 0) {
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/* Error message from open_or_warn can be lost
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* if stderr has been redirected, but bash
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* and ash both lose it as well
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@ -6814,40 +6843,46 @@ static int setup_redirects(struct command *prog, struct squirrel **sqp)
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*/
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return 1;
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}
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if (openfd == redir->rd_fd && sqp) {
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if (newfd == redir->rd_fd && sqp) {
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/* open() gave us precisely the fd we wanted.
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* This means that this fd was not busy
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* (not opened to anywhere).
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* Remember to close it on restore:
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*/
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struct squirrel *sq = *sqp;
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int i = 0;
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if (sq) while (sq[i].orig_fd >= 0)
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i++;
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*sqp = append_squirrel(sq, i, openfd, -1); /* -1 = "it was closed" */
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debug_printf_redir("redir to previously closed fd %d\n", openfd);
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*sqp = add_squirrel_closed(*sqp, newfd);
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debug_printf_redir("redir to previously closed fd %d\n", newfd);
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}
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} else {
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/* "rd_fd<*>rd_dup" or "rd_fd<*>-" cases */
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openfd = redir->rd_dup;
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/* "rd_fd>&rd_dup" or "rd_fd>&-" case */
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newfd = redir->rd_dup;
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}
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if (openfd != redir->rd_fd) {
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int closed = save_fds_on_redirect(redir->rd_fd, /*avoid:*/ openfd, sqp);
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if (openfd == REDIRFD_CLOSE) {
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/* "rd_fd >&-" means "close me" */
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if (!closed) {
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/* ^^^ optimization: saving may already
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* have closed it. If not... */
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close(redir->rd_fd);
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}
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} else {
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xdup2(openfd, redir->rd_fd);
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if (redir->rd_dup == REDIRFD_TO_FILE)
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/* "rd_fd > FILE" */
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close(openfd);
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/* else: "rd_fd > rd_dup" */
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if (newfd == redir->rd_fd)
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continue;
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/* if "N>FILE": move newfd to redir->rd_fd */
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/* if "N>&M": dup newfd to redir->rd_fd */
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/* if "N>&-": close redir->rd_fd (newfd is REDIRFD_CLOSE) */
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closed = save_fd_on_redirect(redir->rd_fd, /*avoid:*/ newfd, sqp);
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if (newfd == REDIRFD_CLOSE) {
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/* "N>&-" means "close me" */
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if (!closed) {
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/* ^^^ optimization: saving may already
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* have closed it. If not... */
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close(redir->rd_fd);
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}
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/* Sometimes we do another close on restore, getting EBADF.
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* Consider "echo 3>FILE 3>&-"
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* first redirect remembers "need to close 3",
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* and second redirect closes 3! Restore code then closes 3 again.
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*/
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} else {
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xdup2(newfd, redir->rd_fd);
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if (redir->rd_dup == REDIRFD_TO_FILE)
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/* "rd_fd > FILE" */
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close(newfd);
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/* else: "rd_fd > rd_dup" */
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}
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}
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return 0;
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