Reject invalid arguments instead of ignoring them

term_feed() returns bool and rejects a NULL terminal, a NULL buffer with
a nonzero length, and any flag bit it does not know. Unknown bits are
rejected now so that later flags can be added without changing what the
old calls mean.

term_new() returns NULL for a negative size component, columns above
TERM_MAX_COLS, a negative scrollback, or a cursor style outside the enum.
Zero still selects the default size and scrollback. It no longer clamps
bad values silently.

term_resize() rejects columns above TERM_MAX_COLS instead of clamping
them, which matches how it already rejects a size below 1.

Co-Authored-By: Claude Haiku 5.5 <noreply@anthropic.com>

1 files changed, 9 insertions, 10 deletions

diff --git a/src/screen.c b/src/screen.c
index 87d6f2c..697e08a 100644
--- a/src/screen.c
+++ b/src/screen.c
@@ -808,12 +808,11 @@ void term_screen_set_alternate(struct term *t, bool enabled)
     }
 }
 
+/* The caller has checked that requested is not negative. */
 static int scrollback_lines(int requested)
 {
     if (requested == 0)
         return TERM_SCROLLBACK_DEFAULT;
-    if (requested < 0)
-        return 0;
     return requested > 1000000 ? 1000000 : requested;
 }
 
@@ -847,10 +846,12 @@ struct term *term_new(const struct term_options *opt)
     static const struct term_options defaults;
     if (!opt)
         opt = &defaults;
-    int cols = opt->size.x < 1 ? 80 : opt->size.x;
-    int rows = opt->size.y < 1 ? 24 : opt->size.y;
-    if (cols > TERM_MAX_COLS)
-        cols = TERM_MAX_COLS;
+    if (opt->size.x < 0 || opt->size.y < 0 || opt->size.x > TERM_MAX_COLS)
+        return NULL;
+    if (opt->scrollback < 0 || (unsigned)opt->cursor_style > TERM_CURSOR_BAR)
+        return NULL;
+    int cols = opt->size.x == 0 ? 80 : opt->size.x;
+    int rows = opt->size.y == 0 ? 24 : opt->size.y;
 
     static _Atomic uint64_t next_serial = 1;
     struct term *t = calloc(1, sizeof(*t));
@@ -895,7 +896,7 @@ struct term *term_new(const struct term_options *opt)
     t->cur_fg = TERM_COLOR_FG;
     t->cur_bg = TERM_COLOR_BG;
     t->cursor_visible = true;
-    t->default_cursor_style = opt->cursor_style > TERM_CURSOR_BAR ? TERM_CURSOR_BLOCK : opt->cursor_style;
+    t->default_cursor_style = opt->cursor_style;
     t->default_cursor_blink = !opt->cursor_steady;
     t->cursor_style = t->default_cursor_style;
     t->cursor_blink = t->default_cursor_blink;
@@ -1523,10 +1524,8 @@ bool term_resize(struct term *t, struct term_vector2i size)
         return false;
     int cols = size.x;
     int rows = size.y;
-    if (cols < 1 || rows < 1)
+    if (cols < 1 || rows < 1 || cols > TERM_MAX_COLS)
         return false;
-    if (cols > TERM_MAX_COLS)
-        cols = TERM_MAX_COLS;
     term_write_begin(t);
     if (cols == t->cols && rows == t->rows) {
         term_write_end(t);