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bug#57211: 29.0.50; generate-new-buffer-name sprintf format overflow war
From: |
Basil L. Contovounesios |
Subject: |
bug#57211: 29.0.50; generate-new-buffer-name sprintf format overflow warning |
Date: |
Sun, 14 Aug 2022 19:50:03 +0300 |
User-agent: |
Gnus/5.13 (Gnus v5.13) Emacs/29.0.50 (gnu/linux) |
Severity: minor
Compiling with gcc (Debian 12.1.0-7) 12.1.0 and -Og, I get the following
-Wformat-overflow warning:
In file included from buffer.c:33:
buffer.c: In function ‘Fgenerate_new_buffer_name’:
buffer.c:1167:46: warning: ‘sprintf’ may write a terminating nul past the end
of the destination [-Wformat-overflow=]
1167 | AUTO_STRING_WITH_LEN (lnumber, number, sprintf (number, "-%d",
i));
| ^~~~~~~~~~~~~~~~~~~~~~~~~~
lisp.h:5493:36: note: in definition of macro ‘AUTO_STRING_WITH_LEN’
5493 | ((&(struct Lisp_String) {{{len, -1, 0, (unsigned char *)
(str)}}}), \
| ^~~
buffer.c:1167:46: note: ‘sprintf’ output between 3 and 9 bytes into a
destination of size 8
1167 | AUTO_STRING_WITH_LEN (lnumber, number, sprintf (number, "-%d",
i));
| ^~~~~~~~~~~~~~~~~~~~~~~~~~
lisp.h:5493:36: note: in definition of macro ‘AUTO_STRING_WITH_LEN’
5493 | ((&(struct Lisp_String) {{{len, -1, 0, (unsigned char *)
(str)}}}), \
| ^~~
Can the upper bound 9 ever be achieved? If so, how? If not, is this a
GCC bug? Either way, is there a way to pacify the warning?
I tried
snprintf (number, sizeof number, ...)
but got the same warning.
BTW, in the preceding
int i = r % 1000000;
can the result of % ever exceed INT_MAX? And do we care either way?
Thanks,
--
Basil
In GNU Emacs 29.0.50 (build 1, x86_64-pc-linux-gnu, X toolkit, cairo version
1.16.0, Xaw3d scroll bars)
of 2022-08-14 built on tia
Repository revision: 1d3fe256907d5e78a4acedd194e55db8ab952952
Repository branch: master
Windowing system distributor 'The X.Org Foundation', version 11.0.12101004
System Description: Debian GNU/Linux bookworm/sid
Configured using:
'configure CC=gcc-12 'CFLAGS=-Og -ggdb3' --config-cache
--prefix=/home/blc/.local --enable-checking=structs
--with-file-notification=yes --with-x-toolkit=lucid --with-x'
Configured features:
ACL CAIRO DBUS FREETYPE GIF GLIB GMP GNUTLS GPM GSETTINGS HARFBUZZ JPEG
JSON LCMS2 LIBOTF LIBSELINUX LIBSYSTEMD LIBXML2 M17N_FLT MODULES NOTIFY
INOTIFY PDUMPER PNG RSVG SECCOMP SOUND SQLITE3 THREADS TIFF
TOOLKIT_SCROLL_BARS WEBP X11 XAW3D XDBE XIM XINPUT2 XPM LUCID ZLIB
Important settings:
value of $LANG: en_IE.UTF-8
value of $XMODIFIERS: @im=ibus
locale-coding-system: utf-8-unix
- bug#57211: 29.0.50; generate-new-buffer-name sprintf format overflow warning,
Basil L. Contovounesios <=