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eval.c
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eval.c
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/*-
* Copyright (c) 1993
* The Regents of the University of California. All rights reserved.
*
* This code is derived from software contributed to Berkeley by
* Kenneth Almquist.
*
* Redistribution and use in source and binary forms, with or without
* modification, are permitted provided that the following conditions
* are met:
* 1. Redistributions of source code must retain the above copyright
* notice, this list of conditions and the following disclaimer.
* 2. Redistributions in binary form must reproduce the above copyright
* notice, this list of conditions and the following disclaimer in the
* documentation and/or other materials provided with the distribution.
* 3. Neither the name of the University nor the names of its contributors
* may be used to endorse or promote products derived from this software
* without specific prior written permission.
*
* THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
* ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
* IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
* ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
* FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
* DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
* OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
* HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
* LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
* OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
* SUCH DAMAGE.
*/
#ifndef lint
#if 0
static char sccsid[] = "@(#)eval.c 8.9 (Berkeley) 6/8/95";
#endif
#endif /* not lint */
#include <sys/cdefs.h>
__FBSDID("$FreeBSD$");
#include <paths.h>
#include <signal.h>
#include <stdlib.h>
#include <unistd.h>
#include <sys/resource.h>
#include <errno.h>
/*
* Evaluate a command.
*/
#include "shell.h"
#include "nodes.h"
#include "syntax.h"
#include "expand.h"
#include "parser.h"
#include "jobs.h"
#include "eval.h"
#include "builtins.h"
#include "options.h"
#include "exec.h"
#include "redir.h"
#include "input.h"
#include "output.h"
#include "trap.h"
#include "var.h"
#include "memalloc.h"
#include "error.h"
#include "show.h"
#include "mystring.h"
#ifndef NO_HISTORY
#include "myhistedit.h"
#endif
int evalskip; /* set if we are skipping commands */
int skipcount; /* number of levels to skip */
static int loopnest; /* current loop nesting level */
int funcnest; /* depth of function calls */
static int builtin_flags; /* evalcommand flags for builtins */
char *commandname;
struct arglist *cmdenviron;
int exitstatus; /* exit status of last command */
int oexitstatus; /* saved exit status */
static void evalloop(union node *, int);
static void evalfor(union node *, int);
static union node *evalcase(union node *);
static void evalsubshell(union node *, int);
static void evalredir(union node *, int);
static void exphere(union node *, struct arglist *);
static void expredir(union node *);
static void evalpipe(union node *);
static int is_valid_fast_cmdsubst(union node *n);
static void evalcommand(union node *, int, struct backcmd *);
static void prehash(union node *);
/*
* Called to reset things after an exception.
*/
void
reseteval(void)
{
evalskip = 0;
loopnest = 0;
}
/*
* The eval command.
*/
int
evalcmd(int argc, char **argv)
{
char *p;
char *concat;
char **ap;
if (argc > 1) {
p = argv[1];
if (argc > 2) {
STARTSTACKSTR(concat);
ap = argv + 2;
for (;;) {
STPUTS(p, concat);
if ((p = *ap++) == NULL)
break;
STPUTC(' ', concat);
}
STPUTC('\0', concat);
p = grabstackstr(concat);
}
evalstring(p, builtin_flags);
} else
exitstatus = 0;
return exitstatus;
}
/*
* Execute a command or commands contained in a string.
*/
void
evalstring(const char *s, int flags)
{
union node *n;
struct stackmark smark;
int flags_exit;
int any;
flags_exit = flags & EV_EXIT;
flags &= ~EV_EXIT;
any = 0;
setstackmark(&smark);
setinputstring(s, 1);
while ((n = parsecmd(0)) != NEOF) {
if (n != NULL && !nflag) {
if (flags_exit && preadateof())
evaltree(n, flags | EV_EXIT);
else
evaltree(n, flags);
any = 1;
if (evalskip)
break;
}
popstackmark(&smark);
setstackmark(&smark);
}
popfile();
popstackmark(&smark);
if (!any)
exitstatus = 0;
if (flags_exit)
exraise(EXEXIT);
}
/*
* Evaluate a parse tree. The value is left in the global variable
* exitstatus.
*/
void
evaltree(union node *n, int flags)
{
int do_etest;
union node *next;
struct stackmark smark;
setstackmark(&smark);
do_etest = 0;
if (n == NULL) {
TRACE(("evaltree(NULL) called\n"));
exitstatus = 0;
goto out;
}
do {
next = NULL;
#ifndef NO_HISTORY
displayhist = 1; /* show history substitutions done with fc */
#endif
TRACE(("evaltree(%p: %d) called\n", (void *)n, n->type));
switch (n->type) {
case NSEMI:
evaltree(n->nbinary.ch1, flags & ~EV_EXIT);
if (evalskip)
goto out;
next = n->nbinary.ch2;
break;
case NAND:
evaltree(n->nbinary.ch1, EV_TESTED);
if (evalskip || exitstatus != 0) {
goto out;
}
next = n->nbinary.ch2;
break;
case NOR:
evaltree(n->nbinary.ch1, EV_TESTED);
if (evalskip || exitstatus == 0)
goto out;
next = n->nbinary.ch2;
break;
case NREDIR:
evalredir(n, flags);
break;
case NSUBSHELL:
evalsubshell(n, flags);
do_etest = !(flags & EV_TESTED);
break;
case NBACKGND:
evalsubshell(n, flags);
break;
case NIF: {
evaltree(n->nif.test, EV_TESTED);
if (evalskip)
goto out;
if (exitstatus == 0)
next = n->nif.ifpart;
else if (n->nif.elsepart)
next = n->nif.elsepart;
else
exitstatus = 0;
break;
}
case NWHILE:
case NUNTIL:
evalloop(n, flags & ~EV_EXIT);
break;
case NFOR:
evalfor(n, flags & ~EV_EXIT);
break;
case NCASE:
next = evalcase(n);
break;
case NCLIST:
next = n->nclist.body;
break;
case NCLISTFALLTHRU:
if (n->nclist.body) {
evaltree(n->nclist.body, flags & ~EV_EXIT);
if (evalskip)
goto out;
}
next = n->nclist.next;
break;
case NDEFUN:
defun(n->narg.text, n->narg.next);
exitstatus = 0;
break;
case NNOT:
evaltree(n->nnot.com, EV_TESTED);
if (evalskip)
goto out;
exitstatus = !exitstatus;
break;
case NPIPE:
evalpipe(n);
do_etest = !(flags & EV_TESTED);
break;
case NCMD:
evalcommand(n, flags, (struct backcmd *)NULL);
do_etest = !(flags & EV_TESTED);
break;
default:
out1fmt("Node type = %d\n", n->type);
flushout(&output);
break;
}
n = next;
popstackmark(&smark);
setstackmark(&smark);
} while (n != NULL);
out:
popstackmark(&smark);
if (pendingsig)
dotrap();
if (eflag && exitstatus != 0 && do_etest)
exitshell(exitstatus);
if (flags & EV_EXIT)
exraise(EXEXIT);
}
static void
evalloop(union node *n, int flags)
{
int status;
loopnest++;
status = 0;
for (;;) {
if (!evalskip)
evaltree(n->nbinary.ch1, EV_TESTED);
if (evalskip) {
if (evalskip == SKIPCONT && --skipcount <= 0) {
evalskip = 0;
continue;
}
if (evalskip == SKIPBREAK && --skipcount <= 0)
evalskip = 0;
if (evalskip == SKIPRETURN)
status = exitstatus;
break;
}
if (n->type == NWHILE) {
if (exitstatus != 0)
break;
} else {
if (exitstatus == 0)
break;
}
evaltree(n->nbinary.ch2, flags);
status = exitstatus;
}
loopnest--;
exitstatus = status;
}
static void
evalfor(union node *n, int flags)
{
struct arglist arglist;
union node *argp;
int i;
int status;
emptyarglist(&arglist);
for (argp = n->nfor.args ; argp ; argp = argp->narg.next) {
oexitstatus = exitstatus;
expandarg(argp, &arglist, EXP_FULL | EXP_TILDE);
}
loopnest++;
status = 0;
for (i = 0; i < arglist.count; i++) {
setvar(n->nfor.var, arglist.args[i], 0);
evaltree(n->nfor.body, flags);
status = exitstatus;
if (evalskip) {
if (evalskip == SKIPCONT && --skipcount <= 0) {
evalskip = 0;
continue;
}
if (evalskip == SKIPBREAK && --skipcount <= 0)
evalskip = 0;
break;
}
}
loopnest--;
exitstatus = status;
}
/*
* Evaluate a case statement, returning the selected tree.
*
* The exit status needs care to get right.
*/
static union node *
evalcase(union node *n)
{
union node *cp;
union node *patp;
struct arglist arglist;
emptyarglist(&arglist);
oexitstatus = exitstatus;
expandarg(n->ncase.expr, &arglist, EXP_TILDE);
for (cp = n->ncase.cases ; cp ; cp = cp->nclist.next) {
for (patp = cp->nclist.pattern ; patp ; patp = patp->narg.next) {
if (casematch(patp, arglist.args[0])) {
while (cp->nclist.next &&
cp->type == NCLISTFALLTHRU &&
cp->nclist.body == NULL)
cp = cp->nclist.next;
if (cp->nclist.next &&
cp->type == NCLISTFALLTHRU)
return (cp);
if (cp->nclist.body == NULL)
exitstatus = 0;
return (cp->nclist.body);
}
}
}
exitstatus = 0;
return (NULL);
}
/*
* Kick off a subshell to evaluate a tree.
*/
static void
evalsubshell(union node *n, int flags)
{
struct job *jp;
int backgnd = (n->type == NBACKGND);
oexitstatus = exitstatus;
expredir(n->nredir.redirect);
if ((!backgnd && flags & EV_EXIT && !have_traps()) ||
forkshell(jp = makejob(n, 1), n, backgnd) == 0) {
if (backgnd)
flags &=~ EV_TESTED;
redirect(n->nredir.redirect, 0);
evaltree(n->nredir.n, flags | EV_EXIT); /* never returns */
} else if (! backgnd) {
INTOFF;
exitstatus = waitforjob(jp, (int *)NULL);
INTON;
} else
exitstatus = 0;
}
/*
* Evaluate a redirected compound command.
*/
static void
evalredir(union node *n, int flags)
{
struct jmploc jmploc;
struct jmploc *savehandler;
volatile int in_redirect = 1;
oexitstatus = exitstatus;
expredir(n->nredir.redirect);
savehandler = handler;
if (setjmp(jmploc.loc)) {
int e;
handler = savehandler;
e = exception;
popredir();
if (e == EXERROR && in_redirect) {
FORCEINTON;
return;
}
longjmp(handler->loc, 1);
} else {
INTOFF;
handler = &jmploc;
redirect(n->nredir.redirect, REDIR_PUSH);
in_redirect = 0;
INTON;
evaltree(n->nredir.n, flags);
}
INTOFF;
handler = savehandler;
popredir();
INTON;
}
static void
exphere(union node *redir, struct arglist *fn)
{
struct jmploc jmploc;
struct jmploc *savehandler;
struct localvar *savelocalvars;
int need_longjmp = 0;
unsigned char saveoptreset;
redir->nhere.expdoc = "";
savelocalvars = localvars;
localvars = NULL;
saveoptreset = shellparam.reset;
forcelocal++;
savehandler = handler;
if (setjmp(jmploc.loc))
need_longjmp = exception != EXERROR;
else {
handler = &jmploc;
expandarg(redir->nhere.doc, fn, 0);
redir->nhere.expdoc = fn->args[0];
INTOFF;
}
handler = savehandler;
forcelocal--;
poplocalvars();
localvars = savelocalvars;
shellparam.reset = saveoptreset;
if (need_longjmp)
longjmp(handler->loc, 1);
INTON;
}
/*
* Compute the names of the files in a redirection list.
*/
static void
expredir(union node *n)
{
union node *redir;
for (redir = n ; redir ; redir = redir->nfile.next) {
struct arglist fn;
emptyarglist(&fn);
switch (redir->type) {
case NFROM:
case NTO:
case NFROMTO:
case NAPPEND:
case NCLOBBER:
expandarg(redir->nfile.fname, &fn, EXP_TILDE);
redir->nfile.expfname = fn.args[0];
break;
case NFROMFD:
case NTOFD:
if (redir->ndup.vname) {
expandarg(redir->ndup.vname, &fn, EXP_TILDE);
fixredir(redir, fn.args[0], 1);
}
break;
case NXHERE:
exphere(redir, &fn);
break;
}
}
}
/*
* Evaluate a pipeline. All the processes in the pipeline are children
* of the process creating the pipeline. (This differs from some versions
* of the shell, which make the last process in a pipeline the parent
* of all the rest.)
*/
static void
evalpipe(union node *n)
{
struct job *jp;
struct nodelist *lp;
int pipelen;
int prevfd;
int pip[2];
TRACE(("evalpipe(%p) called\n", (void *)n));
pipelen = 0;
for (lp = n->npipe.cmdlist ; lp ; lp = lp->next)
pipelen++;
INTOFF;
jp = makejob(n, pipelen);
prevfd = -1;
for (lp = n->npipe.cmdlist ; lp ; lp = lp->next) {
prehash(lp->n);
pip[1] = -1;
if (lp->next) {
if (pipe(pip) < 0) {
if (prevfd >= 0)
close(prevfd);
error("Pipe call failed: %s", strerror(errno));
}
}
if (forkshell(jp, lp->n, n->npipe.backgnd) == 0) {
INTON;
if (prevfd > 0) {
dup2(prevfd, 0);
close(prevfd);
}
if (pip[1] >= 0) {
if (!(prevfd >= 0 && pip[0] == 0))
close(pip[0]);
if (pip[1] != 1) {
dup2(pip[1], 1);
close(pip[1]);
}
}
evaltree(lp->n, EV_EXIT);
}
if (prevfd >= 0)
close(prevfd);
prevfd = pip[0];
if (pip[1] != -1)
close(pip[1]);
}
INTON;
if (n->npipe.backgnd == 0) {
INTOFF;
exitstatus = waitforjob(jp, (int *)NULL);
TRACE(("evalpipe: job done exit status %d\n", exitstatus));
INTON;
} else
exitstatus = 0;
}
static int
is_valid_fast_cmdsubst(union node *n)
{
return (n->type == NCMD);
}
/*
* Execute a command inside back quotes. If it's a builtin command, we
* want to save its output in a block obtained from malloc. Otherwise
* we fork off a subprocess and get the output of the command via a pipe.
* Should be called with interrupts off.
*/
void
evalbackcmd(union node *n, struct backcmd *result)
{
int pip[2];
struct job *jp;
struct stackmark smark;
struct jmploc jmploc;
struct jmploc *savehandler;
struct localvar *savelocalvars;
unsigned char saveoptreset;
result->fd = -1;
result->buf = NULL;
result->nleft = 0;
result->jp = NULL;
if (n == NULL) {
exitstatus = 0;
return;
}
setstackmark(&smark);
exitstatus = oexitstatus;
if (is_valid_fast_cmdsubst(n)) {
savelocalvars = localvars;
localvars = NULL;
saveoptreset = shellparam.reset;
forcelocal++;
savehandler = handler;
if (setjmp(jmploc.loc)) {
if (exception == EXERROR)
/* nothing */;
else if (exception != 0) {
handler = savehandler;
forcelocal--;
poplocalvars();
localvars = savelocalvars;
shellparam.reset = saveoptreset;
longjmp(handler->loc, 1);
}
} else {
handler = &jmploc;
evalcommand(n, EV_BACKCMD, result);
}
handler = savehandler;
forcelocal--;
poplocalvars();
localvars = savelocalvars;
shellparam.reset = saveoptreset;
} else {
if (pipe(pip) < 0)
error("Pipe call failed: %s", strerror(errno));
jp = makejob(n, 1);
if (forkshell(jp, n, FORK_NOJOB) == 0) {
FORCEINTON;
close(pip[0]);
if (pip[1] != 1) {
dup2(pip[1], 1);
close(pip[1]);
}
evaltree(n, EV_EXIT);
}
close(pip[1]);
result->fd = pip[0];
result->jp = jp;
}
popstackmark(&smark);
TRACE(("evalbackcmd done: fd=%d buf=%p nleft=%d jp=%p\n",
result->fd, result->buf, result->nleft, result->jp));
}
static int
mustexpandto(const char *argtext, const char *mask)
{
for (;;) {
if (*argtext == CTLQUOTEMARK || *argtext == CTLQUOTEEND) {
argtext++;
continue;
}
if (*argtext == CTLESC)
argtext++;
else if (BASESYNTAX[(int)*argtext] == CCTL)
return (0);
if (*argtext != *mask)
return (0);
if (*argtext == '\0')
return (1);
argtext++;
mask++;
}
}
static int
isdeclarationcmd(struct narg *arg)
{
int have_command = 0;
if (arg == NULL)
return (0);
while (mustexpandto(arg->text, "command")) {
have_command = 1;
arg = &arg->next->narg;
if (arg == NULL)
return (0);
/*
* To also allow "command -p" and "command --" as part of
* a declaration command, add code here.
* We do not do this, as ksh does not do it either and it
* is not required by POSIX.
*/
}
return (mustexpandto(arg->text, "export") ||
mustexpandto(arg->text, "readonly") ||
(mustexpandto(arg->text, "local") &&
(have_command || !isfunc("local"))));
}
static void
xtracecommand(struct arglist *varlist, int argc, char **argv)
{
char sep = 0;
const char *text, *p, *ps4;
int i;
ps4 = expandstr(ps4val());
out2str(ps4 != NULL ? ps4 : ps4val());
for (i = 0; i < varlist->count; i++) {
text = varlist->args[i];
if (sep != 0)
out2c(' ');
p = strchr(text, '=');
if (p != NULL) {
p++;
outbin(text, p - text, out2);
out2qstr(p);
} else
out2qstr(text);
sep = ' ';
}
for (i = 0; i < argc; i++) {
text = argv[i];
if (sep != 0)
out2c(' ');
out2qstr(text);
sep = ' ';
}
out2c('\n');
flushout(&errout);
}
/*
* Check if a builtin can safely be executed in the same process,
* even though it should be in a subshell (command substitution).
* Note that jobid, jobs, times and trap can show information not
* available in a child process; this is deliberate.
* The arguments should already have been expanded.
*/
static int
safe_builtin(int idx, int argc, char **argv)
{
/* Generated from builtins.def. */
if (safe_builtin_always(idx))
return (1);
if (idx == EXPORTCMD || idx == TRAPCMD || idx == ULIMITCMD ||
idx == UMASKCMD)
return (argc <= 1 || (argc == 2 && argv[1][0] == '-'));
if (idx == SETCMD)
return (argc <= 1 || (argc == 2 && (argv[1][0] == '-' ||
argv[1][0] == '+') && argv[1][1] == 'o' &&
argv[1][2] == '\0'));
return (0);
}
/*
* Execute a simple command.
* Note: This may or may not return if (flags & EV_EXIT).
*/
static void
evalcommand(union node *cmd, int flags, struct backcmd *backcmd)
{
union node *argp;
struct arglist arglist;
struct arglist varlist;
char **argv;
int argc;
char **envp;
int varflag;
int mode;
int pip[2];
struct cmdentry cmdentry;
struct job *jp;
struct jmploc jmploc;
struct jmploc *savehandler;
char *savecmdname;
struct shparam saveparam;
struct localvar *savelocalvars;
struct parsefile *savetopfile;
volatile int e;
char *lastarg;
int signaled;
int do_clearcmdentry;
const char *path = pathval();
int i;
/* First expand the arguments. */
TRACE(("evalcommand(%p, %d) called\n", (void *)cmd, flags));
emptyarglist(&arglist);
emptyarglist(&varlist);
varflag = 1;
jp = NULL;
do_clearcmdentry = 0;
oexitstatus = exitstatus;
exitstatus = 0;
/* Add one slot at the beginning for tryexec(). */
appendarglist(&arglist, nullstr);
for (argp = cmd->ncmd.args ; argp ; argp = argp->narg.next) {
if (varflag && isassignment(argp->narg.text)) {
expandarg(argp, varflag == 1 ? &varlist : &arglist,
EXP_VARTILDE);
continue;
} else if (varflag == 1)
varflag = isdeclarationcmd(&argp->narg) ? 2 : 0;
expandarg(argp, &arglist, EXP_FULL | EXP_TILDE);
}
appendarglist(&arglist, nullstr);
expredir(cmd->ncmd.redirect);
argc = arglist.count - 2;
argv = &arglist.args[1];
argv[argc] = NULL;
lastarg = NULL;
if (iflag && funcnest == 0 && argc > 0)
lastarg = argv[argc - 1];
/* Print the command if xflag is set. */
if (xflag)
xtracecommand(&varlist, argc, argv);
/* Now locate the command. */
if (argc == 0) {
/* Variable assignment(s) without command */
cmdentry.cmdtype = CMDBUILTIN;
cmdentry.u.index = BLTINCMD;
cmdentry.special = 0;
} else {
static const char PATH[] = "PATH=";
int cmd_flags = 0, bltinonly = 0;
/*
* Modify the command lookup path, if a PATH= assignment
* is present
*/
for (i = 0; i < varlist.count; i++)
if (strncmp(varlist.args[i], PATH, sizeof(PATH) - 1) == 0) {
path = varlist.args[i] + sizeof(PATH) - 1;
/*
* On `PATH=... command`, we need to make
* sure that the command isn't using the
* non-updated hash table of the outer PATH
* setting and we need to make sure that
* the hash table isn't filled with items
* from the temporary setting.
*
* It would be better to forbit using and
* updating the table while this command
* runs, by the command finding mechanism
* is heavily integrated with hash handling,
* so we just delete the hash before and after
* the command runs. Partly deleting like
* changepatch() does doesn't seem worth the
* bookinging effort, since most such runs add
* directories in front of the new PATH.
*/
clearcmdentry();
do_clearcmdentry = 1;
}
for (;;) {
if (bltinonly) {
cmdentry.u.index = find_builtin(*argv, &cmdentry.special);
if (cmdentry.u.index < 0) {
cmdentry.u.index = BLTINCMD;
argv--;
argc++;
break;
}
} else
find_command(argv[0], &cmdentry, cmd_flags, path);
/* implement the bltin and command builtins here */
if (cmdentry.cmdtype != CMDBUILTIN)
break;
if (cmdentry.u.index == BLTINCMD) {
if (argc == 1)
break;
argv++;
argc--;
bltinonly = 1;
} else if (cmdentry.u.index == COMMANDCMD) {
if (argc == 1)
break;
if (!strcmp(argv[1], "-p")) {
if (argc == 2)
break;
if (argv[2][0] == '-') {
if (strcmp(argv[2], "--"))
break;
if (argc == 3)
break;
argv += 3;
argc -= 3;
} else {
argv += 2;
argc -= 2;
}
path = _PATH_STDPATH;
clearcmdentry();
do_clearcmdentry = 1;
} else if (!strcmp(argv[1], "--")) {
if (argc == 2)
break;
argv += 2;
argc -= 2;
} else if (argv[1][0] == '-')
break;
else {
argv++;
argc--;
}
cmd_flags |= DO_NOFUNC;
bltinonly = 0;
} else
break;
}
/*
* Special builtins lose their special properties when
* called via 'command'.
*/
if (cmd_flags & DO_NOFUNC)
cmdentry.special = 0;
}
/* Fork off a child process if necessary. */
if (((cmdentry.cmdtype == CMDNORMAL || cmdentry.cmdtype == CMDUNKNOWN)
&& ((flags & EV_EXIT) == 0 || have_traps()))
|| ((flags & EV_BACKCMD) != 0
&& (cmdentry.cmdtype != CMDBUILTIN ||
!safe_builtin(cmdentry.u.index, argc, argv)))) {
jp = makejob(cmd, 1);
mode = FORK_FG;
if (flags & EV_BACKCMD) {
mode = FORK_NOJOB;
if (pipe(pip) < 0)
error("Pipe call failed: %s", strerror(errno));
}
if (cmdentry.cmdtype == CMDNORMAL &&
cmd->ncmd.redirect == NULL &&
varlist.count == 0 &&
(mode == FORK_FG || mode == FORK_NOJOB) &&
!disvforkset() && !iflag && !mflag) {
vforkexecshell(jp, argv, environment(), path,
cmdentry.u.index, flags & EV_BACKCMD ? pip : NULL);