/*
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* Copyright (c) 2018 Google, Inc.
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*
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* This program is free software: you can redistribute it and/or modify
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* it under the terms of the GNU General Public License as published by
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* the Free Software Foundation, either version 2 of the License, or
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* (at your option) any later version.
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*
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* This program is distributed in the hope that it will be useful,
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* but WITHOUT ANY WARRANTY; without even the implied warranty of
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* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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* GNU General Public License for more details.
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*
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* You should have received a copy of the GNU General Public License
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* along with this program, if not, see <http://www.gnu.org/licenses/>.
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*/
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/*
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* Regression test for commit 966031f340185 ("n_tty: fix EXTPROC vs ICANON
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* interaction with TIOCINQ (aka FIONREAD)"). The test reproduces a hang
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* (infinite loop in the kernel) after a pseudoterminal is put in both canonical
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* (ICANON) and external processing (EXTPROC) mode, some data is written to the
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* master and read from the slave, and the FIONREAD ioctl is called on the
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* slave. This is simplified from a syzkaller-generated reproducer.
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*/
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#include <stdlib.h>
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#include <errno.h>
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#include <termio.h>
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#include "tst_test.h"
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#include "lapi/termbits.h"
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static void do_test(void)
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{
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struct termios io;
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int ptmx, pts;
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char c = 'A';
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int nbytes;
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ptmx = SAFE_OPEN("/dev/ptmx", O_WRONLY);
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if (tcgetattr(ptmx, &io) != 0)
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tst_brk(TBROK | TERRNO, "tcgetattr() failed");
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io.c_lflag = EXTPROC | ICANON;
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TEST(tcsetattr(ptmx, TCSANOW, &io));
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if (TST_RET == -1) {
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if (TST_ERR == EINVAL)
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tst_brk(TCONF, "tcsetattr(, , EXTPROC | ICANON) is not supported");
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tst_brk(TBROK | TERRNO, "tcsetattr() failed");
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}
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if (unlockpt(ptmx) != 0)
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tst_brk(TBROK | TERRNO, "unlockpt() failed");
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pts = SAFE_OPEN(ptsname(ptmx), O_RDONLY);
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/* write newline to ptmx to avoid read() on pts to block */
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SAFE_WRITE(1, ptmx, "A\n", 2);
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SAFE_READ(1, pts, &c, 1);
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tst_res(TINFO, "Calling FIONREAD, this will hang in n_tty_ioctl() if the bug is present...");
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SAFE_IOCTL(pts, FIONREAD, &nbytes);
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SAFE_CLOSE(ptmx);
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SAFE_CLOSE(pts);
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tst_res(TPASS, "Got to the end without hanging");
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}
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static struct tst_test test = {
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.test_all = do_test,
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};
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