hush: fix "redirects can close script fd" bug
Signed-off-by: Denys Vlasenko <vda.linux@googlemail.com>
This commit is contained in:
Denys Vlasenko
parent
d8e61bbf13
commit
aa3576a29b
@ -189,20 +189,28 @@ int klogctl(int type, char *b, int len);
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# undef getchar
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# define getchar() getchar_unlocked()
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# undef putc
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# define putc(c, stream) putc_unlocked(c, stream)
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# define putc(c,stream) putc_unlocked(c,stream)
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# undef putchar
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# define putchar(c) putchar_unlocked(c)
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# undef fgetc
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# define fgetc(stream) getc_unlocked(stream)
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# undef fputc
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# define fputc(c, stream) putc_unlocked(c, stream)
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# define fputc(c,stream) putc_unlocked(c,stream)
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#endif
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/* Above functions are required by POSIX.1-2008, below ones are extensions */
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#ifdef HAVE_UNLOCKED_LINE_OPS
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# undef fgets
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# define fgets(s, n, stream) fgets_unlocked(s, n, stream)
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# define fgets(s,n,stream) fgets_unlocked(s,n,stream)
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# undef fputs
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# define fputs(s, stream) fputs_unlocked(s, stream)
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# define fputs(s,stream) fputs_unlocked(s,stream)
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# undef fflush
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# define fflush(stream) fflush_unlocked(stream)
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# undef feof
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# define feof(stream) feof_unlocked(stream)
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# undef ferror
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# define ferror(stream) ferror_unlocked(stream)
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# undef fileno
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# define fileno(stream) fileno_unlocked(stream)
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#endif
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199
shell/hush.c
199
shell/hush.c
@ -103,6 +103,9 @@
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#else
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# define CLEAR_RANDOM_T(rnd) ((void)0)
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#endif
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#ifndef F_DUPFD_CLOEXEC
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# define F_DUPFD_CLOEXEC F_DUPFD
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#endif
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#ifndef PIPE_BUF
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# define PIPE_BUF 4096 /* amount of buffering in a pipe */
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#endif
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@ -711,10 +714,10 @@ enum {
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};
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/* Can be extended to handle a FIXME in setup_redirects about not saving script fds */
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struct FILE_list {
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struct FILE_list *next;
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FILE *fp;
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int fd;
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};
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@ -809,9 +812,7 @@ struct globals {
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unsigned handled_SIGCHLD;
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smallint we_have_children;
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#endif
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#if ENABLE_FEATURE_SH_STANDALONE
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struct FILE_list *FILE_list;
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#endif
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/* Which signals have non-DFL handler (even with no traps set)?
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* Set at the start to:
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* (SIGQUIT + maybe SPECIAL_INTERACTIVE_SIGS + maybe SPECIAL_JOBSTOP_SIGS)
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@ -1262,35 +1263,34 @@ static void free_strings(char **strings)
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}
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static int xdup_and_close(int fd, int F_DUPFD_maybe_CLOEXEC)
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{
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/* We avoid taking stdio fds. Mimicking ash: use fds above 9 */
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int newfd = fcntl(fd, F_DUPFD_maybe_CLOEXEC, 10);
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if (newfd < 0) {
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/* fd was not open? */
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if (errno == EBADF)
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return fd;
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xfunc_die();
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}
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close(fd);
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return newfd;
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}
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/* Manipulating the list of open FILEs */
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static FILE *remember_FILE(FILE *fp)
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{
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if (fp) {
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#if ENABLE_FEATURE_SH_STANDALONE
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struct FILE_list *n = xmalloc(sizeof(*n));
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n->fp = fp;
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n->next = G.FILE_list;
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G.FILE_list = n;
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#endif
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close_on_exec_on(fileno(fp));
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n->fp = fp;
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n->fd = fileno(fp);
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close_on_exec_on(n->fd);
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}
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return fp;
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}
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#if ENABLE_FEATURE_SH_STANDALONE
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static void close_all_FILE_list(void)
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{
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struct FILE_list *fl = G.FILE_list;
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while (fl) {
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/* fclose would also free FILE object.
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* It is disastrous if we share memory with a vforked parent.
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* I'm not sure we never come here after vfork.
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* Therefore just close fd, nothing more.
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*/
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/*fclose(fl->fp); - unsafe */
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close(fileno(fl->fp));
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fl = fl->next;
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}
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}
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static void fclose_and_forget(FILE *fp)
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{
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struct FILE_list **pp = &G.FILE_list;
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@ -1305,8 +1305,46 @@ static void fclose_and_forget(FILE *fp)
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}
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fclose(fp);
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}
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#else
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# define fclose_and_forget(fp) fclose(fp);
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static int save_FILEs_on_redirect(int fd)
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{
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struct FILE_list *fl = G.FILE_list;
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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);
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return 1;
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}
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fl = fl->next;
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}
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return 0;
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}
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static void restore_redirected_FILEs(void)
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{
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struct FILE_list *fl = G.FILE_list;
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while (fl) {
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int should_be = fileno(fl->fp);
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if (fl->fd != should_be) {
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xmove_fd(fl->fd, should_be);
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fl->fd = should_be;
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}
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fl = fl->next;
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}
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}
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#if ENABLE_FEATURE_SH_STANDALONE
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static void close_all_FILE_list(void)
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{
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struct FILE_list *fl = G.FILE_list;
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while (fl) {
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/* fclose would also free FILE object.
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* It is disastrous if we share memory with a vforked parent.
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* I'm not sure we never come here after vfork.
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* Therefore just close fd, nothing more.
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*/
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/*fclose(fl->fp); - unsafe */
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close(fl->fd);
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fl = fl->next;
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}
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}
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#endif
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@ -6147,6 +6185,74 @@ static void setup_heredoc(struct redir_struct *redir)
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wait(NULL); /* wait till child has died */
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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 squirrel[3])
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{
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if (squirrel) {
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/* Handle redirects of fds 0,1,2 */
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/* If we collide with an already moved stdio fd... */
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if (fd == squirrel[0]) {
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squirrel[0] = xdup_and_close(squirrel[0], F_DUPFD);
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return 1;
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}
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if (fd == squirrel[1]) {
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squirrel[1] = xdup_and_close(squirrel[1], F_DUPFD);
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return 1;
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}
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if (fd == squirrel[2]) {
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squirrel[2] = xdup_and_close(squirrel[2], F_DUPFD);
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return 1;
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}
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/* If we are about to redirect stdio fd, and did not yet move it... */
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if (fd <= 2 && squirrel[fd] < 0) {
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/* We avoid taking stdio fds */
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squirrel[fd] = fcntl(fd, F_DUPFD, 10);
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if (squirrel[fd] < 0 && errno != EBADF)
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xfunc_die();
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return 0; /* "we did not close fd" */
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}
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}
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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);
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return 1;
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}
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#endif
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/* Are we called from setup_redirects(squirrel==NULL)? Two cases:
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* (1) Redirect in a forked child. No need to save FILEs' fds,
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* we aren't going to use them anymore, ok to trash.
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* (2) "exec 3>FILE". Bummer. We can save FILEs' fds,
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* but how are we doing to use them?
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* "fileno(fd) = new_fd" can't be done.
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*/
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if (!squirrel)
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return 0;
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return save_FILEs_on_redirect(fd);
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}
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static void restore_redirects(int squirrel[3])
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{
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int i, fd;
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for (i = 0; i <= 2; i++) {
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fd = squirrel[i];
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if (fd != -1) {
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/* We simply die on error */
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xmove_fd(fd, i);
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}
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}
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/* Moved G.interactive_fd stays on new fd, not doing anything for it */
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restore_redirected_FILEs();
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}
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/* squirrel != NULL means we squirrel away copies of stdin, stdout,
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* and stderr if they are redirected. */
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static int setup_redirects(struct command *prog, int squirrel[])
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@ -6157,13 +6263,7 @@ static int setup_redirects(struct command *prog, int squirrel[])
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for (redir = prog->redirects; redir; redir = redir->next) {
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if (redir->rd_type == REDIRECT_HEREDOC2) {
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/* "rd_fd<<HERE" case */
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if (redir->rd_fd <= 2
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&& squirrel
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&& squirrel[redir->rd_fd] < 0
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) {
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/* Save old fds 0..2 if redirect uses them */
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squirrel[redir->rd_fd] = dup(redir->rd_fd);
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}
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save_fds_on_redirect(redir->rd_fd, squirrel);
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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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@ -6199,47 +6299,26 @@ static int setup_redirects(struct command *prog, int squirrel[])
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}
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if (openfd != redir->rd_fd) {
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if (redir->rd_fd <= 2
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&& squirrel
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&& squirrel[redir->rd_fd] < 0
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) {
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/* Save old fds 0..2 if redirect uses them */
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//FIXME: script fd's also need this! "sh SCRIPT" and SCRIPT has "echo FOO 3>&-":
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// open("SCRIPT", O_RDONLY) = 3
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// fcntl(3, F_SETFD, FD_CLOEXEC) = 0
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// read(3, "echo FOO 3>&-\n....", 4096) = N
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// close(3) = 0
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// write(1, "FOO\n", 4) = 4
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// ...
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// read(3, 0x205f8e0, 4096) = -1 EBADF <== BUG
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//
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squirrel[redir->rd_fd] = dup(redir->rd_fd);
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}
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int closed = save_fds_on_redirect(redir->rd_fd, squirrel);
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if (openfd == REDIRFD_CLOSE) {
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/* "n>-" means "close me" */
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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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}
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}
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}
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return 0;
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}
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static void restore_redirects(int squirrel[])
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{
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int i, fd;
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for (i = 0; i <= 2; i++) {
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fd = squirrel[i];
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if (fd != -1) {
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/* We simply die on error */
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xmove_fd(fd, i);
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}
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}
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}
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static char *find_in_path(const char *arg)
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{
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char *ret = NULL;
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1
shell/hush_test/hush-misc/redir_script.right
Normal file
1
shell/hush_test/hush-misc/redir_script.right
Normal file
@ -0,0 +1 @@
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Ok: script fd is not closed
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29
shell/hush_test/hush-misc/redir_script.tests
Executable file
29
shell/hush_test/hush-misc/redir_script.tests
Executable file
@ -0,0 +1,29 @@
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# Builds a " 3>&- 4>&-" string.
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# Note: one of these fds is a directory opened to /proc/self/fd
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# for globbing. It is unwanted, but I don't know how to filter it out.
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find_fds() {
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fds=""
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for f in /proc/self/fd/*; do
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test "$f" = "/proc/self/fd/0" && continue
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test "$f" = "/proc/self/fd/1" && continue
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test "$f" = "/proc/self/fd/2" && continue
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fds="$fds ${f##*/}>&-"
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done
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}
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find_fds
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fds1="$fds"
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# One of the fds is open to the script body
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# Close it while executing something.
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eval "find_fds $fds"
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# Shell should not lose that fd. Did it?
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find_fds
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test x"$fds1" = x"$fds" && { echo "Ok: script fd is not closed"; exit 0; }
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echo "Bug: script fd is closed"
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echo "fds1:$fds1"
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echo "fds2:$fds"
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exit 1
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