From 0829fce079dae45737330114c27886cb8af85043 Mon Sep 17 00:00:00 2001 From: Denys Vlasenko Date: Fri, 12 Jul 2024 21:58:04 +0200 Subject: ash: do not abort interactive mode on >&9999 redirect With very large fd#, the error code path is different from one for closed but small fd#. Make it not abort if we are interactive: $ echo text >&99 # this wasn't buggy ash: dup2(9,1): Bad file descriptor $ echo text >&9999 # this was ash: fcntl(1,F_DUPFD,10000): Invalid argument function old new delta .rodata 105637 105661 +24 dup2_or_raise 35 38 +3 redirect 1084 1044 -40 ------------------------------------------------------------------------------ (add/remove: 0/0 grow/shrink: 2/1 up/down: 27/-40) Total: -13 bytes Signed-off-by: Denys Vlasenko --- shell/ash.c | 20 ++++++++++++++++---- 1 file changed, 16 insertions(+), 4 deletions(-) diff --git a/shell/ash.c b/shell/ash.c index 094a87390..39455c7c5 100644 --- a/shell/ash.c +++ b/shell/ash.c @@ -5621,10 +5621,13 @@ dup2_or_raise(int from, int to) newfd = (from != to) ? dup2(from, to) : to; if (newfd < 0) { /* Happens when source fd is not open: try "echo >&99" */ - ash_msg_and_raise_perror("%d", from); + ash_msg_and_raise_perror("dup2(%d,%d)", from, to); } return newfd; } +/* The only possible error return is EBADF (fd wasn't open). + * Transient errors retry, other errors raise exception. + */ static int dup_CLOEXEC(int fd, int avoid_fd) { @@ -5639,6 +5642,16 @@ dup_CLOEXEC(int fd, int avoid_fd) goto repeat; if (errno == EINTR) goto repeat; + if (errno != EBADF) { + /* "echo >&9999" gets EINVAL trying to save fd 1 to above 9999. + * We could try saving it _below_ 9999 instead (how?), but + * this probably means that dup2(9999,1) to effectuate >&9999 + * would also not work: fd 9999 can't exist. Gracefully bail out. + * (This differs from "echo >&99" where saving works, but + * subsequent dup2(99,1) fails if fd 99 is not open). + */ + ash_msg_and_raise_perror("fcntl(%d,F_DUPFD,%d)", fd, avoid_fd + 1); + } } return newfd; } @@ -5754,7 +5767,7 @@ save_fd_on_redirect(int fd, int avoid_fd, struct redirtab *sq) 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? */ + if (new_fd < 0) /* EBADF? what? */ xfunc_die(); return 0; /* "we did not close fd" */ } @@ -5769,8 +5782,7 @@ save_fd_on_redirect(int fd, int avoid_fd, struct redirtab *sq) 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) - xfunc_die(); + /* EBADF (fd is not open) */ /* new_fd = CLOSED; - already is -1 */ } sq->two_fd[i].moved_to = new_fd; -- cgit v1.2.3-55-g6feb