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Fix reuse of pty slave devices #2449

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Fix reuse of pty slave devices #2449

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e781ef0
Copy ish-lld.lldb to build dir
cgull Aug 31, 2024
6b0856c
Support pty slave reuse and behave more like Linux
cgull Aug 31, 2024
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6 changes: 6 additions & 0 deletions fs/pty.c
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Original file line number Diff line number Diff line change
Expand Up @@ -66,6 +66,12 @@ static int pty_slave_open(struct tty *tty) {
return _EIO;
if (tty->pty.locked)
return _EIO;
// If userland's reference count on the pty slave is now 1, clear
// hang_up on the pty master. But the session leader may have a
// reference, and the pty master always has a reference.
if (tty->refcount - 1 == (tty->session ? 2 : 1)) {
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I found this check a bit unsettling in the last PR but figured it could be fixed later. Seeing it again, I'm thinking much the same thing... Ideally we would define explicitly which references count for this and which ones don't, and with that knowledge the likely solution is to create a second refcount field for tracking just those.

tty->pty.other->hung_up = false;
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This needs locking, right?

}
return 0;
}

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1 change: 1 addition & 0 deletions fs/tty.c
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Expand Up @@ -446,6 +446,7 @@ static ssize_t tty_read(struct fd *fd, void *buf, size_t bufsize) {
lock(&tty->lock);
if (tty->hung_up || pty_is_half_closed_master(tty)) {
unlock(&pids_lock);
err = -1;
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This should be an errno constant

goto error;
}

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4 changes: 2 additions & 2 deletions meson.build
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Expand Up @@ -181,8 +181,8 @@ endif

subdir('tools')

gdb_scripts = ['ish-gdb.gdb']
foreach script : gdb_scripts
debugger_scripts = ['ish-gdb.gdb', 'ish-lldb.lldb']
foreach script : debugger_scripts
custom_target(script,
output: script, input: script,
command: ['ln', '-sf', '@INPUT@', '@OUTPUT@'],
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