static mksh_uari_t
rndsetup(void)
{
register uint32_t h;
struct {
ALLOC_ITEM alloc_INT;
void *dataptr, *stkptr, *mallocptr;
#if defined(__GLIBC__) && (__GLIBC__ >= 2)
sigjmp_buf jbuf;
#endif
struct timeval tv;
} *bufptr;
char *cp;
cp = alloc(sizeof(*bufptr) - sizeof(ALLOC_ITEM), APERM);
/* clear the allocated space, for valgrind and to avoid UB */
memset(cp, 0, sizeof(*bufptr) - sizeof(ALLOC_ITEM));
/* undo what alloc() did to the malloc result address */
bufptr = (void *)(cp - sizeof(ALLOC_ITEM));
/* PIE or something similar provides us with deltas here */
bufptr->dataptr = &rndsetupstate;
/* ASLR in at least Windows, Linux, some BSDs */
bufptr->stkptr = &bufptr;
/* randomised malloc in BSD (and possibly others) */
bufptr->mallocptr = bufptr;
#if defined(__GLIBC__) && (__GLIBC__ >= 2)
/* glibc pointer guard */
sigsetjmp(bufptr->jbuf, 1);
#endif
/* introduce variation (and yes, second arg MBZ for portability) */
mksh_TIME(bufptr->tv);
#ifdef MKSH_ALLOC_CATCH_UNDERRUNS
mprotect(((char *)bufptr) + 4096, 4096, PROT_READ | PROT_WRITE);
#endif
h = chvt_rndsetup(bufptr, sizeof(*bufptr));
afree(cp, APERM);
return ((mksh_uari_t)h);
}
static void
setspec(struct tbl *vp)
{
mksh_ari_u num;
char *s;
int st;
switch ((st = special(vp->name))) {
#if HAVE_PERSISTENT_HISTORY
case V_HISTFILE:
sethistfile(str_val(vp));
return;
#endif
case V_IFS:
setctypes(s = str_val(vp), C_IFS);
ifs0 = *s;
return;
case V_PATH:
if (path)
afree(path, APERM);
s = str_val(vp);
strdupx(path, s, APERM);
/* clear tracked aliases */
flushcom(true);
return;
case V_TMPDIR:
if (tmpdir) {
afree(tmpdir, APERM);
tmpdir = NULL;
}
/*
* Use tmpdir iff it is an absolute path, is writable
* and searchable and is a directory...
*/
{
struct stat statb;
s = str_val(vp);
/* LINTED use of access */
if (mksh_abspath(s) && access(s, W_OK|X_OK) == 0 &&
stat(s, &statb) == 0 && S_ISDIR(statb.st_mode))
strdupx(tmpdir, s, APERM);
}
return;
/* common sub-cases */
case V_COLUMNS:
case V_LINES:
if (vp->flag & IMPORT) {
/* do not touch */
unspecial(vp->name);
vp->flag &= ~SPECIAL;
return;
}
/* FALLTHROUGH */
case V_HISTSIZE:
case V_LINENO:
case V_OPTIND:
case V_RANDOM:
case V_SECONDS:
case V_TMOUT:
vp->flag &= ~SPECIAL;
if (getint(vp, &num, false) == -1) {
s = str_val(vp);
if (st != V_RANDOM)
errorf("%s: %s: %s", vp->name, "bad number", s);
num.u = hash(s);
}
vp->flag |= SPECIAL;
break;
default:
/* do nothing, do not touch vp at all */
return;
}
/* process the singular parts of the common cases */
switch (st) {
case V_COLUMNS:
if (num.i >= MIN_COLS)
x_cols = num.i;
break;
case V_HISTSIZE:
sethistsize(num.i);
break;
case V_LINENO:
/* The -1 is because line numbering starts at 1. */
user_lineno = num.u - (mksh_uari_t)current_lineno - 1;
break;
case V_LINES:
if (num.i >= MIN_LINS)
x_lins = num.i;
break;
case V_OPTIND:
getopts_reset((int)num.i);
break;
case V_RANDOM:
/*
* mksh R39d+ no longer has the traditional repeatability
* of $RANDOM sequences, but always retains state
*/
rndset((unsigned long)num.u);
break;
case V_SECONDS:
{
struct timeval tv;
mksh_TIME(tv);
seconds = tv.tv_sec - num.i;
}
break;
case V_TMOUT:
ksh_tmout = num.i >= 0 ? num.i : 0;
break;
}
}
static void
getspec(struct tbl *vp)
{
mksh_ari_u num;
int st;
struct timeval tv;
switch ((st = special(vp->name))) {
case V_COLUMNS:
case V_LINES:
/*
* Do NOT export COLUMNS/LINES. Many applications
* check COLUMNS/LINES before checking ws.ws_col/row,
* so if the app is started with C/L in the environ
* and the window is then resized, the app won't
* see the change cause the environ doesn't change.
*/
if (got_winch)
change_winsz();
break;
}
switch (st) {
case V_BASHPID:
num.u = (mksh_uari_t)procpid;
break;
case V_COLUMNS:
num.i = x_cols;
break;
case V_HISTSIZE:
num.i = histsize;
break;
case V_LINENO:
num.u = (mksh_uari_t)current_lineno + user_lineno;
break;
case V_LINES:
num.i = x_lins;
break;
case V_EPOCHREALTIME: {
/* 10(%u) + 1(.) + 6 + NUL */
char buf[18];
vp->flag &= ~SPECIAL;
mksh_TIME(tv);
shf_snprintf(buf, sizeof(buf), "%u.%06u",
(unsigned)tv.tv_sec, (unsigned)tv.tv_usec);
setstr(vp, buf, KSH_RETURN_ERROR | 0x4);
vp->flag |= SPECIAL;
return;
}
case V_OPTIND:
num.i = user_opt.uoptind;
break;
case V_RANDOM:
num.i = rndget();
break;
case V_SECONDS:
/*
* On start up the value of SECONDS is used before
* it has been set - don't do anything in this case
* (see initcoms[] in main.c).
*/
if (vp->flag & ISSET) {
mksh_TIME(tv);
num.i = tv.tv_sec - seconds;
} else
return;
break;
default:
/* do nothing, do not touch vp at all */
return;
}
vp->flag &= ~SPECIAL;
setint_n(vp, num.i, 0);
vp->flag |= SPECIAL;
}
