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Unix Plink: fix tight loop after EOF on stdin.

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When Plink saw EOF on stdin, it would continue to put stdin in its
list of poll fds, so that the poll loop would always terminate
instantly with stdin readable. Plink would read from it, see EOF
again, go back to the poll loop, and keep spinning like that.

This was supposed to be fixed by the 'sending' flag, which was set to
false on seeing EOF to indicate that we were no longer interested in
reading stdin data to send to the SSH server. But that flag was
ineffective, because it turns out it was _always_ set to false -
nothing in the code ever set it to true! And the reason why that
didn't totally prevent reading from stdin at all is because it was
also tested with the wrong sense. How embarrassing.

Changed the flag name to 'seen_stdin_eof', and made it behave
sensibly.
This commit is contained in:
Simon Tatham 2021-02-02 18:19:56 +00:00
parent 9e1ec093fd
commit af278ac870
1 changed files with 3 additions and 4 deletions
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7
unix/uxplink.c
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@ -572,13 +572,13 @@ const unsigned cmdline_tooltype =
TOOLTYPE_HOST_ARG_PROTOCOL_PREFIX |
TOOLTYPE_HOST_ARG_FROM_LAUNCHABLE_LOAD;
static bool sending;
static bool seen_stdin_eof = false;
static bool plink_pw_setup(void *vctx, pollwrapper *pw)
{
pollwrap_add_fd_rwx(pw, signalpipe[0], SELECT_R);
if (!sending &&
if (!seen_stdin_eof &&
backend_connected(backend) &&
backend_sendok(backend) &&
backend_sendbuffer(backend) < MAX_STDIN_BACKLOG) {
@ -623,7 +623,7 @@ static void plink_pw_check(void *vctx, pollwrapper *pw)
exit(1);
} else if (ret == 0) {
backend_special(backend, SS_EOF, 0);
sending = false; /* send nothing further after this */
seen_stdin_eof = true;
} else {
if (local_tty)
from_tty(buf, ret);
@ -948,7 +948,6 @@ int main(int argc, char **argv)
local_tty = (tcgetattr(STDIN_FILENO, &orig_termios) == 0);
atexit(cleanup_termios);
seat_echoedit_update(plink_seat, 1, 1);
sending = false;
cli_main_loop(plink_pw_setup, plink_pw_check, plink_continue, NULL);