kathyv@tektools.UUCP (Kathy Vineyard) (12/01/86)
Index: /usr/src/usr.lib/libcurses/cr_tty.c 4.3BSD
Description:
When running a program that uses curses, the user environment
was sometimes getting stepped on. This resulted in getting the
famed "x: is not an identifier" from /bin/sh when it was
exec'd. This happened only when using a termcap which had
multiple names ( > 2 ) for the termcap entry, the third name of
the entry was the one being used by the user, and the length of
that third name was at least 2 less than the length of the
second name.
Repeat-By:
Use a termcap which has it's names set up like:
Mc|aaa-c|aaa|aaa with separate scrolling and editing areas:\
The way I found it was to use initscr() (which calls the
functions in cr_tty.c) and print out the environment just
before and after the initscr. With a termcap entry set up as
above (with the setups, of course) and your TERM variable set
to the third name (in this case, the "aaa"), you can run this
little program to duplicate the bug and see how it messes up
the environment:
#include <stdio.h>
#include <curses.h>
extern char **environ;
printenv()
{
int n=1;
char **c;
c= environ;
while (*c) {
printf("%d. %s\n",n, *c);
n++;
*c++;
}
}
main()
{
printenv();
initscr();
refresh();
printenv();
printf("\n");
execl("/bin/sh","sh","-c","ls");
}
( compile with "cc foo.c -lcurses -ltermlib" )
Fix:
A fix is to send longname() a copy of the TERM variable, not
the TERM variable itself, as longname replaces the variable it
was sent with the second field of the termcap name. A context
diff is included, numbering may be a few off:
*** cr_tty.c.old Mon Dec 1 11:25:35 1986
--- cr_tty.c.new Mon Dec 1 11:25:09 1986
***************
*** 77,82
reg int unknown;
static char genbuf[1024];
# ifdef TIOCGWINSZ
struct winsize win;
# endif
--- 77,84 -----
reg int unknown;
static char genbuf[1024];
+ static char xtype[1024]; /* xtype should be the same size
+ as genbuf for longname(). */
# ifdef TIOCGWINSZ
struct winsize win;
# endif
***************
*** 137,143
PC = _PC ? _PC[0] : FALSE;
aoftspace = _tspace;
! strncpy(ttytype, longname(genbuf, type), sizeof(ttytype) - 1);
ttytype[sizeof(ttytype) - 1] = '\0';
if (unknown)
return ERR;
--- 139,150 -----
PC = _PC ? _PC[0] : FALSE;
aoftspace = _tspace;
! /*
! * longname() steps on the second variable it is passed, so copy type
! * into xtype so it isn't stepped on when you are least suspecting it.
! */
! strcpy(xtype,type);
! strncpy(ttytype, longname(genbuf, xtype), sizeof(ttytype) - 1);
ttytype[sizeof(ttytype) - 1] = '\0';
if (unknown)
return ERR;
-------------------------------------------------------------------------------
Kathy Vineyard
kathyv@tektools.tek.com
Unix Systems Support, Tektronix Inc.