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bug#62009: 29.0.60; Emacs crashes on setf symbol-name
From: |
Po Lu |
Subject: |
bug#62009: 29.0.60; Emacs crashes on setf symbol-name |
Date: |
Sat, 11 Mar 2023 15:07:56 +0800 |
User-agent: |
Gnus/5.13 (Gnus v5.13) |
Robert Pluim <rpluim@gmail.com> writes:
>>>>>> On Fri, 10 Mar 2023 12:09:59 +0100, Daniel Mendler
>>>>>> <mail@daniel-mendler.de> said:
>
> Daniel> One could check if the string is located in read-only memory. Or
> one
> Daniel> could add a flag bit to the string data structure (and possibly
> to other
> Daniel> data structures too). Freezing data structures such that they
> become
> Daniel> read-only is a generally useful feature. There won't be any
> performance
> Daniel> overhead of the check since a branch not taken is fast thanks to
> the
> Daniel> branch predictor.
>
> We already have such a flag:
>
> /* Number of characters in string; MSB is used as the mark bit. */
> ptrdiff_t size;
> /* If nonnegative, number of bytes in the string (which is multibyte).
> If negative, the string is unibyte:
> -1 for data normally allocated
> -2 for data in rodata (C string constants)
> -3 for data that must be immovable (used for bytecode) */
> ptrdiff_t size_byte;
>
> Try this:
>
> diff --git a/src/lisp.h b/src/lisp.h
> index 1276285e2f2..80bbb047824 100644
> --- a/src/lisp.h
> +++ b/src/lisp.h
> @@ -1685,6 +1685,8 @@ SREF (Lisp_Object string, ptrdiff_t index)
> INLINE void
> SSET (Lisp_Object string, ptrdiff_t index, unsigned char new)
> {
> + if (XSTRING (string)->u.s.size_byte == -2)
> + Fsignal (Qsetting_constant, string);
> SDATA (string)[index] = new;
> }
> INLINE ptrdiff_t
>
> Robert
Why does this have to be in SSET and not in PURE_P?
- bug#62009: 29.0.60; Emacs crashes on setf symbol-name, (continued)
- bug#62009: 29.0.60; Emacs crashes on setf symbol-name, Robert Pluim, 2023/03/10
- bug#62009: 29.0.60; Emacs crashes on setf symbol-name, Daniel Mendler, 2023/03/10
- bug#62009: 29.0.60; Emacs crashes on setf symbol-name, Eli Zaretskii, 2023/03/10
- bug#62009: 29.0.60; Emacs crashes on setf symbol-name, Daniel Mendler, 2023/03/10
- bug#62009: 29.0.60; Emacs crashes on setf symbol-name, Dmitry Gutov, 2023/03/10
- bug#62009: 29.0.60; Emacs crashes on setf symbol-name, Gregory Heytings, 2023/03/10
- bug#62009: 29.0.60; Emacs crashes on setf symbol-name, Eli Zaretskii, 2023/03/10
- bug#62009: 29.0.60; Emacs crashes on setf symbol-name, Robert Pluim, 2023/03/10
- bug#62009: 29.0.60; Emacs crashes on setf symbol-name,
Po Lu <=
- bug#62009: 29.0.60; Emacs crashes on setf symbol-name, Robert Pluim, 2023/03/13
- bug#62009: 29.0.60; Emacs crashes on setf symbol-name, Po Lu, 2023/03/13
- bug#62009: 29.0.60; Emacs crashes on setf symbol-name, Eli Zaretskii, 2023/03/13
- bug#62009: 29.0.60; Emacs crashes on setf symbol-name, Po Lu, 2023/03/13
- bug#62009: 29.0.60; Emacs crashes on setf symbol-name, Eli Zaretskii, 2023/03/13
- bug#62009: 29.0.60; Emacs crashes on setf symbol-name, Eli Zaretskii, 2023/03/10
- bug#62009: 29.0.60; Emacs crashes on setf symbol-name, Eli Zaretskii, 2023/03/10
- bug#62009: 29.0.60; Emacs crashes on setf symbol-name, Gregory Heytings, 2023/03/10
- bug#62009: 29.0.60; Emacs crashes on setf symbol-name, Po Lu, 2023/03/11
- bug#62009: 29.0.60; Emacs crashes on setf symbol-name, Eli Zaretskii, 2023/03/11