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tty: the grid was 80x24 on a 160x50 screen, and wrapping was eager

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Three symptoms, two causes, both in the terminal layer.

**The grid and TIOCGWINSZ disagreed about the size.** vt_init() sizes every
grid from gfx_cols()/gfx_rows(), and it runs at main.c:75 -- while the display
driver attaches its scanout from the PCI bus walk at main.c:99. So the grids
were the 80x24 fallback, and TIOCGWINSZ, which computed its own answer live,
said 160x50.

That one disagreement produced all three things visible in the report: text
stopped two thirds of the way down the screen, `ls` laid out 160 columns into
an 80-column grid so words split across the wrap ("vers" / "ion"), and zsh's
cursor tracking was wrong on every line.

Fixed in two places, because either alone would leave the trap set:
gfx_attach_scanout() now calls vt_resize(), so the grids learn the real screen
the moment there is one; and TIOCGWINSZ reports v->cols/v->rows rather than
measuring again. One number, from the terminal being asked.

**Wrapping was eager.** A glyph printed in the last column moved the cursor to
the next line immediately. Real terminals set a pending-wrap flag and wrap when
the *next* glyph arrives -- which is why a line exactly as wide as the screen
takes one row and not two, and why a program can write the bottom-right cell
without scrolling.

zsh's partial-line marker depends on that rule directly: it writes exactly
COLUMNS-1 spaces and expects to still be on the line. With eager wrap it left a
reverse-video '#' above every prompt, which is the hashtag in the report. Both
are gone.

Verified by screendump: `ls /proc` now fits one line with "version" intact, no
markers, and output fills the screen to the last row. schfs-check passes.

Co-Authored-By: Claude Opus 5 <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_01VQ7Qx8E1q1M1bbCq8QLHS2
This commit is contained in:
Nexoniarz 2026-09-13 12:49:13 +02:00
commit a5b0d5a0ef
5 changed files with 137 additions and 25 deletions
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30
kernel/sys/sys_fs.c
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@ -1061,22 +1061,24 @@ addr_t sys_ioctl(void)
if (request == TIOCGWINSZ) {
struct winsize *ws = (struct winsize*)user_ptr(argp, sizeof(*ws));
if (!ws) return -EFAULT;
// The console's real geometry, not a VT100's.
// The terminal's own grid, and nothing else.
//
// This used to answer 24x80 unconditionally -- the size of a terminal
// SchOS has never drawn. Every program that lays out a screen asks
// this one question first: a line editor to decide where to wrap, `ls`
// to pick a column count, fastfetch to place its logo beside the text.
// At 1024x768 with the 8x16 font the console is 128x48, so all of them
// were formatting for a screen a third the area of the real one, and
// each looked like a separate bug in a separate program.
int cols = gfx_cols(), rows = gfx_rows();
// Serial-only boot, with no framebuffer attached: 80x24 is then a
// stated default rather than a wrong measurement.
ws->ws_col = cols > 0 ? (uint16)cols : 80;
ws->ws_row = rows > 0 ? (uint16)rows : 24;
ws->ws_xpixel = (uint16)gfx_width();
ws->ws_ypixel = (uint16)gfx_height();
// SchOS has never drawn -- and was then fixed to compute the answer
// live from gfx_cols()/gfx_rows(). That was a second source of truth,
// and it disagreed with the first: the grids are sized once at
// vt_init(), which runs before the display driver is found on the PCI
// bus, so they were 80x24 while this reported 160x50. Programs
// formatted for a screen the grid did not have -- `ls` split words
// across the wrap, text stopped two thirds of the way down, and zsh's
// cursor tracking was wrong on every line.
//
// One number, from the terminal being asked. They cannot disagree.
struct vt *v = vt_for_minor(f->ip->minor);
ws->ws_col = (uint16)v->cols;
ws->ws_row = (uint16)v->rows;
ws->ws_xpixel = (uint16)(v->cols * gfx_char_w());
ws->ws_ypixel = (uint16)(v->rows * gfx_char_h());
return 0;
}
// The console's size is a property of the framebuffer, so a request to