Option to override cols/rows of the recorded process

This adds `--cols <n>` / `--rows <n>` options to `rec` command. This disables
autodection of terminal size, and reports fake fixed number of columns/rows to
the recorded process.

README.md

@@ -228,6 +228,8 @@ Available options:
   to `SHELL,TERM`
 - `-t, --title=<title>` - Specify the title of the asciicast
 - `-i, --idle-time-limit=<sec>` - Limit recorded terminal inactivity to max `<sec>` seconds
+- `--cols=<n>` - Override terminal columns for recorded process
+- `--rows=<n>` - Override terminal rows for recorded process
 - `-y, --yes` - Answer "yes" to all prompts (e.g. upload confirmation)
 - `-q, --quiet` - Be quiet, suppress all notices/warnings (implies -y)
 

asciinema/__main__.py

@@ -12,6 +12,14 @@ from .commands.record import RecordCommand
 from .commands.upload import UploadCommand
 
 
+def positive_int(value: str) -> int:
+    _value = int(value)
+    if _value <= 0:
+        raise argparse.ArgumentTypeError("must be positive")
+
+    return _value
+
+
 def positive_float(value: str) -> float:
     _value = float(value)
     if _value <= 0.0:
@@ -120,6 +128,18 @@ For help on a specific command run:
         type=positive_float,
         default=maybe_str(cfg.record_idle_time_limit),
     )
+    parser_rec.add_argument(
+        "--cols",
+        help="override terminal columns for recorded process",
+        type=positive_int,
+        default=None,
+    )
+    parser_rec.add_argument(
+        "--rows",
+        help="override terminal rows for recorded process",
+        type=positive_int,
+        default=None,
+    )
     parser_rec.add_argument(
         "-y",
         "--yes",

asciinema/commands/record.py

@@ -21,6 +21,8 @@ class RecordCommand(Command):  # pylint: disable=too-many-instance-attributes
         self.title = args.title
         self.assume_yes = args.yes or args.quiet
         self.idle_time_limit = args.idle_time_limit
+        self.cols_override = args.cols
+        self.rows_override = args.rows
         self.append = args.append
         self.overwrite = args.overwrite
         self.raw = args.raw
@@ -109,6 +111,8 @@ class RecordCommand(Command):  # pylint: disable=too-many-instance-attributes
                 writer=self.writer,
                 notifier=self.notifier,
                 key_bindings=self.key_bindings,
+                cols_override=self.cols_override,
+                rows_override=self.rows_override,
             )
         except v2.LoadError:
             self.print_error(

asciinema/pty_.py

@@ -8,7 +8,7 @@ import signal
 import struct
 import termios
 import time
-from typing import Any, Dict, List, Optional, Tuple
+from typing import Any, Callable, Dict, List, Optional, Tuple
 
 from .term import raw
 
@@ -17,11 +17,14 @@ from .term import raw
 def record(
     command: Any,
     writer: Any,
+    get_tty_size: Callable[[], Tuple[int, int]],
     env: Any = None,
     rec_stdin: bool = False,
     time_offset: float = 0,
     notifier: Any = None,
     key_bindings: Optional[Dict[str, Any]] = None,
+    tty_stdin_fd: int = pty.STDIN_FILENO,
+    tty_stdout_fd: int = pty.STDOUT_FILENO,
 ) -> None:
     if env is None:
         env = os.environ
@@ -46,18 +49,15 @@ def record(
 
         # 1. Get the terminal size of the real terminal.
         # 2. Set the same size on the pseudoterminal.
-        if os.isatty(pty.STDOUT_FILENO):
-            buf = array.array("h", [0, 0, 0, 0])
-            fcntl.ioctl(pty.STDOUT_FILENO, termios.TIOCGWINSZ, buf, True)
-        else:
-            buf = array.array("h", [24, 80, 0, 0])
 
+        cols, rows = get_tty_size()
+        buf = array.array("h", [rows, cols, 0, 0])
         fcntl.ioctl(master_fd, termios.TIOCSWINSZ, buf)
 
     def _write_stdout(data: Any) -> None:
         """Writes to stdout as if the child process had written the data."""
 
-        os.write(pty.STDOUT_FILENO, data)
+        os.write(tty_stdout_fd, data)
 
     def _handle_master_read(data: Any) -> None:
         """Handles new data on child process stdout."""
@@ -120,7 +120,7 @@ def record(
         when new data arrives.
         """
 
-        fds = [master_fd, pty.STDIN_FILENO, signal_fd]
+        fds = [master_fd, tty_stdin_fd, signal_fd]
 
         while True:
             try:
@@ -136,10 +136,10 @@ def record(
                 else:
                     _handle_master_read(data)
 
-            if pty.STDIN_FILENO in rfds:
-                data = os.read(pty.STDIN_FILENO, 1024)
+            if tty_stdin_fd in rfds:
+                data = os.read(tty_stdin_fd, 1024)
                 if not data:
-                    fds.remove(pty.STDIN_FILENO)
+                    fds.remove(tty_stdin_fd)
                 else:
                     _handle_stdin_read(data)
 
@@ -188,7 +188,7 @@ def record(
 
     start_time = time.time() - time_offset
 
-    with raw(pty.STDIN_FILENO):
+    with raw(tty_stdin_fd):
         try:
             _copy(pipe_r)
         except (IOError, OSError):

asciinema/recorder.py

@@ -3,7 +3,6 @@ import time
 from typing import Any, Callable, Dict, Optional, Tuple, Type
 
 from . import pty_ as pty  # avoid collisions with standard library `pty`
-from . import term
 from .asciicast import v2
 from .asciicast.v2 import writer as w2
 from .async_worker import async_worker
@@ -23,6 +22,8 @@ def record(  # pylint: disable=too-many-arguments,too-many-locals
     record_: Callable[..., None] = pty.record,
     notifier: Any = None,
     key_bindings: Optional[Dict[str, Any]] = None,
+    cols_override: Optional[int] = None,
+    rows_override: Optional[int] = None,
 ) -> None:
     if command is None:
         command = os.environ.get("SHELL", "sh")
@@ -38,11 +39,16 @@ def record(  # pylint: disable=too-many-arguments,too-many-locals
     if capture_env is None:
         capture_env = ["SHELL", "TERM"]
 
-    w, h = term.get_size()
+    tty_stdin_fd = 0
+    tty_stdout_fd = 1
+
+    get_tty_size = _get_tty_size(tty_stdout_fd, cols_override, rows_override)
+
+    cols, rows = get_tty_size()
 
     full_metadata: Dict[str, Any] = {
-        "width": w,
-        "height": h,
+        "width": cols,
+        "height": rows,
         "timestamp": int(time.time()),
     }
 
@@ -75,11 +81,14 @@ def record(  # pylint: disable=too-many-arguments,too-many-locals
             record_(
                 ["sh", "-c", command],
                 _writer,
+                get_tty_size,
                 command_env,
                 rec_stdin,
                 time_offset,
                 _notifier,
                 key_bindings,
+                tty_stdin_fd=tty_stdin_fd,
+                tty_stdout_fd=tty_stdout_fd,
             )
 
 
@@ -143,3 +152,27 @@ class async_notifier(async_worker):
             # we catch *ALL* exceptions here because we don't want failed
             # notification to crash the recording session
             pass
+
+
+def _get_tty_size(
+    fd: int, cols_override: Optional[int], rows_override: Optional[int]
+) -> Callable[[], Tuple[int, int]]:
+    if cols_override is not None and rows_override is not None:
+
+        def fixed_size() -> Tuple[int, int]:
+            return (cols_override, rows_override)  # type: ignore
+
+        return fixed_size
+
+    if not os.isatty(fd):
+
+        def fallback_size() -> Tuple[int, int]:
+            return (cols_override or 80, rows_override or 24)
+
+        return fallback_size
+
+    def size() -> Tuple[int, int]:
+        cols, rows = os.get_terminal_size(fd)
+        return (cols_override or cols, rows_override or rows)
+
+    return size

asciinema/term.py

@@ -1,10 +1,9 @@
 import os
 import select
-import subprocess
 import termios as tty  # avoid `Module "tty" has no attribute ...` errors
 from time import sleep
 from tty import setraw
-from typing import IO, Any, List, Optional, Tuple, Union
+from typing import IO, Any, List, Optional, Union
 
 
 class raw:
@@ -33,13 +32,3 @@ def read_blocking(fd: int, timeout: Any) -> bytes:
         return os.read(fd, 1024)
 
     return b""
-
-
-def get_size() -> Tuple[int, int]:
-    try:
-        return os.get_terminal_size()
-    except:  # pylint: disable=bare-except  # noqa: E722
-        return (
-            int(subprocess.check_output(["tput", "cols"])),
-            int(subprocess.check_output(["tput", "lines"])),
-        )

man/asciinema.1.md

@@ -93,6 +93,12 @@ Available options:
     `-i, --idle-time-limit=<sec>`
     :   Limit recorded terminal inactivity to max `<sec>` seconds
 
+    `--cols=<n>`
+    :   Override terminal columns for recorded process
+
+    `--rows=<n>`
+    :   Override terminal rows for recorded process
+
     `-y, --yes`
     :   Answer "yes" to all prompts (e.g. upload confirmation)
 

tests/pty_test.py

@@ -44,6 +44,6 @@ class TestRecord(Test):
                 "; sys.stdout.write('bar')"
             ),
         ]
-        asciinema.pty_.record(command, output)
+        asciinema.pty_.record(command, output, lambda: (80, 24))
 
         assert output.data == [b"foo", b"bar"]