freebsd-skq/bin/sh/main.c
Jilles Tjoelker 960da93430 Avoid leaving unnecessary waiting shells in many forms of sh -c COMMAND.
This change only affects strings passed to -c, when the -s
option is not used.

The approach is to check if there may be additional data
in the string after parsing each command. If there is none,
use the EV_EXIT flag so that a fork may be omitted in
specific cases.

If there are empty lines after the command, the check will
not see the end and forks will not be omitted. The same
thing seems to happen in bash.

Example:
  sh -c 'ps lT'
No longer shows a shell process waiting for ps to finish.

PR:		bin/113860
Reviewed by:	stefanf
Approved by:	ed (mentor)
2009-06-13 21:17:45 +00:00

353 lines
7.4 KiB
C

/*-
* Copyright (c) 1991, 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.
* 4. 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
static char const copyright[] =
"@(#) Copyright (c) 1991, 1993\n\
The Regents of the University of California. All rights reserved.\n";
#endif /* not lint */
#ifndef lint
#if 0
static char sccsid[] = "@(#)main.c 8.6 (Berkeley) 5/28/95";
#endif
#endif /* not lint */
#include <sys/cdefs.h>
__FBSDID("$FreeBSD$");
#include <stdio.h>
#include <signal.h>
#include <sys/stat.h>
#include <unistd.h>
#include <fcntl.h>
#include <locale.h>
#include <errno.h>
#include "shell.h"
#include "main.h"
#include "mail.h"
#include "options.h"
#include "output.h"
#include "parser.h"
#include "nodes.h"
#include "expand.h"
#include "eval.h"
#include "jobs.h"
#include "input.h"
#include "trap.h"
#include "var.h"
#include "show.h"
#include "memalloc.h"
#include "error.h"
#include "init.h"
#include "mystring.h"
#include "exec.h"
#include "cd.h"
int rootpid;
int rootshell;
STATIC void read_profile(char *);
STATIC char *find_dot_file(char *);
/*
* Main routine. We initialize things, parse the arguments, execute
* profiles if we're a login shell, and then call cmdloop to execute
* commands. The setjmp call sets up the location to jump to when an
* exception occurs. When an exception occurs the variable "state"
* is used to figure out how far we had gotten.
*/
int
main(int argc, char *argv[])
{
struct jmploc jmploc;
struct stackmark smark;
volatile int state;
char *shinit;
(void) setlocale(LC_ALL, "");
state = 0;
if (setjmp(jmploc.loc)) {
/*
* When a shell procedure is executed, we raise the
* exception EXSHELLPROC to clean up before executing
* the shell procedure.
*/
switch (exception) {
case EXSHELLPROC:
rootpid = getpid();
rootshell = 1;
minusc = NULL;
state = 3;
break;
case EXEXEC:
exitstatus = exerrno;
break;
case EXERROR:
exitstatus = 2;
break;
default:
break;
}
if (exception != EXSHELLPROC) {
if (state == 0 || iflag == 0 || ! rootshell)
exitshell(exitstatus);
}
reset();
if (exception == EXINT) {
out2c('\n');
flushout(&errout);
}
popstackmark(&smark);
FORCEINTON; /* enable interrupts */
if (state == 1)
goto state1;
else if (state == 2)
goto state2;
else if (state == 3)
goto state3;
else
goto state4;
}
handler = &jmploc;
#ifdef DEBUG
opentrace();
trputs("Shell args: "); trargs(argv);
#endif
rootpid = getpid();
rootshell = 1;
init();
setstackmark(&smark);
procargs(argc, argv);
if (getpwd() == NULL && iflag)
out2str("sh: cannot determine working directory\n");
if (getpwd() != NULL)
setvar ("PWD", getpwd(), VEXPORT);
if (argv[0] && argv[0][0] == '-') {
state = 1;
read_profile("/etc/profile");
state1:
state = 2;
if (privileged == 0)
read_profile(".profile");
else
read_profile("/etc/suid_profile");
}
state2:
state = 3;
if (!privileged && iflag) {
if ((shinit = lookupvar("ENV")) != NULL && *shinit != '\0') {
state = 3;
read_profile(shinit);
}
}
state3:
state = 4;
if (minusc) {
evalstring(minusc, sflag ? 0 : EV_EXIT);
}
if (sflag || minusc == NULL) {
state4: /* XXX ??? - why isn't this before the "if" statement */
cmdloop(1);
}
exitshell(exitstatus);
/*NOTREACHED*/
return 0;
}
/*
* Read and execute commands. "Top" is nonzero for the top level command
* loop; it turns on prompting if the shell is interactive.
*/
void
cmdloop(int top)
{
union node *n;
struct stackmark smark;
int inter;
int numeof = 0;
TRACE(("cmdloop(%d) called\n", top));
setstackmark(&smark);
for (;;) {
if (pendingsigs)
dotrap();
inter = 0;
if (iflag && top) {
inter++;
showjobs(1, SHOWJOBS_DEFAULT);
chkmail(0);
flushout(&output);
}
n = parsecmd(inter);
/* showtree(n); DEBUG */
if (n == NEOF) {
if (!top || numeof >= 50)
break;
if (!stoppedjobs()) {
if (!Iflag)
break;
out2str("\nUse \"exit\" to leave shell.\n");
}
numeof++;
} else if (n != NULL && nflag == 0) {
job_warning = (job_warning == 2) ? 1 : 0;
numeof = 0;
evaltree(n, 0);
}
popstackmark(&smark);
setstackmark(&smark);
if (evalskip == SKIPFILE) {
evalskip = 0;
break;
}
}
popstackmark(&smark);
}
/*
* Read /etc/profile or .profile. Return on error.
*/
STATIC void
read_profile(char *name)
{
int fd;
INTOFF;
if ((fd = open(name, O_RDONLY)) >= 0)
setinputfd(fd, 1);
INTON;
if (fd < 0)
return;
cmdloop(0);
popfile();
}
/*
* Read a file containing shell functions.
*/
void
readcmdfile(char *name)
{
int fd;
INTOFF;
if ((fd = open(name, O_RDONLY)) >= 0)
setinputfd(fd, 1);
else
error("Can't open %s: %s", name, strerror(errno));
INTON;
cmdloop(0);
popfile();
}
/*
* Take commands from a file. To be compatible we should do a path
* search for the file, which is necessary to find sub-commands.
*/
STATIC char *
find_dot_file(char *basename)
{
static char localname[FILENAME_MAX+1];
char *fullname;
char *path = pathval();
struct stat statb;
/* don't try this for absolute or relative paths */
if( strchr(basename, '/'))
return basename;
while ((fullname = padvance(&path, basename)) != NULL) {
strcpy(localname, fullname);
stunalloc(fullname);
if ((stat(fullname, &statb) == 0) && S_ISREG(statb.st_mode))
return localname;
}
return basename;
}
int
dotcmd(int argc, char **argv)
{
struct strlist *sp;
char *fullname;
if (argc < 2)
error("missing filename");
exitstatus = 0;
for (sp = cmdenviron; sp ; sp = sp->next)
setvareq(savestr(sp->text), VSTRFIXED|VTEXTFIXED);
fullname = find_dot_file(argv[1]);
setinputfile(fullname, 1);
commandname = fullname;
cmdloop(0);
popfile();
return exitstatus;
}
int
exitcmd(int argc, char **argv)
{
extern int oexitstatus;
if (stoppedjobs())
return 0;
if (argc > 1)
exitstatus = number(argv[1]);
else
exitstatus = oexitstatus;
exitshell(exitstatus);
/*NOTREACHED*/
return 0;
}