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Fix segfault on Windows when stdout is not a real console handle #125

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Fix segfault on Windows when stdout is not a real console handle #125

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28 changes: 18 additions & 10 deletions src/lTerm.ml
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Original file line number Diff line number Diff line change
Expand Up @@ -210,16 +210,24 @@ let create
term.input_stream <- Lwt_stream.from (fun () -> Lwt_io.read_char_opt term.ic);
(* Setup initial size and size updater. *)
if term.outgoing_is_a_tty then begin
let check_size () =
let size = get_size_from_fd term.outgoing_fd in
if size <> term.size then begin
term.size <- size;
Lwt_condition.signal term.notify (LTerm_event.Resize size)
end
in
term.size <- get_size_from_fd term.outgoing_fd;
term.last_reported_size <- term.size;
term.event <- E.map check_size resize_event
try
let check_size () =
try
let size = get_size_from_fd term.outgoing_fd in
if size <> term.size then begin
term.size <- size;
Lwt_condition.signal term.notify (LTerm_event.Resize size)
end
with Unix.Unix_error _ -> ()
in
term.size <- get_size_from_fd term.outgoing_fd;
term.last_reported_size <- term.size;
term.event <- E.map check_size resize_event
with Unix.Unix_error _ ->
(* If we can't get the terminal size (e.g. on Windows when the
handle passes isatty but is not a real console), fall back to
treating it as a non-tty. *)
term.outgoing_is_a_tty <- false
end;
return term)
Lwt.fail
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27 changes: 23 additions & 4 deletions src/lTerm_term_stubs.c
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Original file line number Diff line number Diff line change
Expand Up @@ -23,10 +23,22 @@

CAMLprim value lt_term_get_size_from_fd(value fd)
{
HANDLE h = Handle_val(fd);
CONSOLE_SCREEN_BUFFER_INFO info;
DWORD mode;
value result;

if (!GetConsoleScreenBufferInfo(Handle_val(fd), &info)) {
/* Validate that the handle is a usable console handle before calling
GetConsoleScreenBufferInfo. On some Windows environments (e.g. GitHub
Actions runners using ConPTY), _isatty() may return true for handles
that are not real console screen buffers, causing
GetConsoleScreenBufferInfo to crash with an access violation. */
if (h == INVALID_HANDLE_VALUE || h == NULL || !GetConsoleMode(h, &mode)) {
win32_maperr(ERROR_INVALID_HANDLE);
uerror("GetConsoleScreenBufferInfo", Nothing);
}

if (!GetConsoleScreenBufferInfo(h, &info)) {
win32_maperr(GetLastError());
uerror("GetConsoleScreenBufferInfo", Nothing);
}
Expand All @@ -39,21 +51,28 @@ CAMLprim value lt_term_get_size_from_fd(value fd)

CAMLprim value lt_term_set_size_from_fd(value fd, value val_size)
{
HANDLE h = Handle_val(fd);
CONSOLE_SCREEN_BUFFER_INFO info;
SMALL_RECT rect;
DWORD mode;

/* Validate that the handle is a usable console handle. */
if (h == INVALID_HANDLE_VALUE || h == NULL || !GetConsoleMode(h, &mode)) {
win32_maperr(ERROR_INVALID_HANDLE);
uerror("SetConsoleWindowInfo", Nothing);
}

if (!GetConsoleScreenBufferInfo(Handle_val(fd), &info)) {
if (!GetConsoleScreenBufferInfo(h, &info)) {
win32_maperr(GetLastError());
uerror("GetConsoleScreenBufferInfo", Nothing);
}

rect;
rect.Top = info.srWindow.Top;
rect.Left = info.srWindow.Left;
rect.Bottom = rect.Top + Int_val(Field(val_size, 0)) - 1;
rect.Right = rect.Left + Int_val(Field(val_size, 1)) - 1;

if (!SetConsoleWindowInfo(Handle_val(fd), TRUE, &rect)) {
if (!SetConsoleWindowInfo(h, TRUE, &rect)) {
win32_maperr(GetLastError());
uerror("SetConsoleWindowInfo", Nothing);
}
Expand Down