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Re: segfault by emacs -nw
From: |
Kenichi Handa |
Subject: |
Re: segfault by emacs -nw |
Date: |
Thu, 21 Aug 2003 20:41:32 +0900 (JST) |
User-agent: |
SEMI/1.14.3 (Ushinoya) FLIM/1.14.2 (Yagi-Nishiguchi) APEL/10.2 Emacs/21.2.92 (sparc-sun-solaris2.6) MULE/5.0 (SAKAKI) |
Terje Rosten <address@hidden> writes:
> | With today's CVS HEAD, emacs -nw always crashes as below:
> Reverting this patch seems to fix it here:
> <URL:
> http://savannah.gnu.org/cgi-bin/viewcvs/emacs/emacs/src/term.c.diff?r1=1.146&r2=1.147&sortby=date>
> The change is from:
> 2003-08-19 Gerd Moellmann <address@hidden>
> * s/freebsd.h [__FreeBSD_version >= 400000]: Define TERMINFO,
> use -lncurses.
> * term.c (term_init): Use a buffer of size 4096 for tgetent since
> FreeBSD returns something longer than 2044. Abort if the end of
> the buffer is overwritten.
Thank you for the info. I think I found what is wrong with
the above patch.
The current code is like this:
----------------------------------------------------------------------
buffer = (char *) xmalloc (buffer_size);
status = tgetent (buffer, terminal_type);
[...]
if (strlen (buffer) >= buffer_size)
abort ();
area = (char *) xmalloc (strlen (buffer));
----------------------------------------------------------------------
But, on GNU/Linux, the argument `buffer' of tgetent is
ignored. This is the man page for tgetent.
SYNOPSIS
[...]
int tgetent(char *bp, const char *name);
[...]
These routines are included as a conversion aid for pro-
grams that use the termcap library. Their parameters are
the same and the routines are emulated using the terminfo
database. Thus, they can only be used to query the capa-
bilities of entries for which a terminfo entry has been
compiled.
The tgetent routine loads the entry for name. It returns
1 on success, 0 if there is no such entry, and -1 if the
terminfo database could not be found. The emulation
ignores the buffer pointer bp.
^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
So, in my environment, the memory allocated for `area' is
too small which leads to buffer overrun. I've just
installed the attached change.
---
Ken'ichi HANDA
address@hidden
2003-08-21 Kenichi Handa <address@hidden>
* term.c (term_init): Fix previous change; don't rely on the
length of `buffer' if TERMINFO is defined.
Index: term.c
===================================================================
RCS file: /cvsroot/emacs/emacs/src/term.c,v
retrieving revision 1.147
diff -u -c -r1.147 term.c
cvs server: conflicting specifications of output style
*** term.c 19 Aug 2003 23:47:22 -0000 1.147
--- term.c 21 Aug 2003 11:34:21 -0000
***************
*** 2229,2238 ****
#endif
}
if (strlen (buffer) >= buffer_size)
abort ();
!
! area = (char *) xmalloc (strlen (buffer));
TS_ins_line = tgetstr ("al", address);
TS_ins_multi_lines = tgetstr ("AL", address);
--- 2229,2240 ----
#endif
}
+ #ifndef TERMINFO
if (strlen (buffer) >= buffer_size)
abort ();
! buffer_size = strlen (buffer);
! #endif
! area = (char *) xmalloc (buffer_size);
TS_ins_line = tgetstr ("al", address);
TS_ins_multi_lines = tgetstr ("AL", address);