gh-154855: Ask non-ncurses curses for one more character - #154870
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serhiy-storchaka merged 3 commits intoAug 23, 2026
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Passing n to the library is ncurses' reading of n: it stores n characters and adds a terminator. NetBSD curses counts the terminator in n. Ask a library that is neither ncurses nor PDCurses for n + 1, and read again if it stored more than asked; truncating could split a multibyte character. This is not possible for input, so getstr() and get_wstr() are left as they are. instr() now takes the length from the value returned by winnstr(), as X/Open specifies, instead of searching for a terminator which it does not.
serhiy-storchaka
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needs backport to 3.13
# Conflicts: # Modules/_cursesmodule.c
serhiy-storchaka
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August 23, 2026 12:15
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Thanks @serhiy-storchaka for the PR 🌮🎉.. I'm working now to backport this PR to: 3.13, 3.14, 3.15. |
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Sorry, @serhiy-storchaka, I could not cleanly backport this to |
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Sorry, @serhiy-storchaka, I could not cleanly backport this to |
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Sorry, @serhiy-storchaka, I could not cleanly backport this to |
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GH-156283 is a backport of this pull request to the 3.15 branch. |
bedevere-app
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the
needs backport to 3.15
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GH-156284 is a backport of this pull request to the 3.14 branch. |
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GH-156285 is a backport of this pull request to the 3.13 branch. |
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Aug 23, 2026
…54870) (GH-156285) Passing n to the library is ncurses' reading of n: it stores n characters and adds a terminator. NetBSD curses counts the terminator in n. Ask a library that is neither ncurses nor PDCurses for n + 1, and read again if it stored more than asked; truncating could split a multibyte character. This is not possible for input, so getstr() is left as it is. instr() now takes the length from the value returned by winnstr(), as X/Open specifies, instead of searching for a terminator which it does not. (cherry picked from commit 43a1869)
serhiy-storchaka
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Aug 23, 2026
…54870) (GH-156284) Passing n to the library is ncurses' reading of n: it stores n characters and adds a terminator. NetBSD curses counts the terminator in n. Ask a library that is neither ncurses nor PDCurses for n + 1, and read again if it stored more than asked; truncating could split a multibyte character. This is not possible for input, so getstr() is left as it is. instr() now takes the length from the value returned by winnstr(), as X/Open specifies, instead of searching for a terminator which it does not. (cherry picked from commit 43a1869)
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instr(),in_wstr()andin_wchstr()passnto the library, which is ncurses' reading ofn: it storesncharacters and adds a terminator. NetBSD curses counts the terminator inn, so these methods return one character too few there. X/Open does not settle the point: "at mostnbytes in the string", with no mention of a terminator.Such a library is asked for
n + 1, and the read is repeated for the requested length if it stored more than asked -- truncating could split a multibyte character. That is not possible for input, where the extra character is consumed and echoed before we see it, sogetstr()andget_wstr()are left as they are.instr()now takes the length from the value returned bywinnstr(), as X/Open specifies, likein_wstr()since GH-154782.Against NetBSD 10.1 native curses (
--with-curses=curses),test_cursesgoes from 34 failures to 22, with nothing newly broken. Builds against ncurses are unchanged, the macro being 0; forcing it to 1 there makes 12 tests fail without the repeated read and pass with it.