SysIII/usr/src/cmd/sh/xec.c
#
/*
* UNIX shell
*
* S. R. Bourne
* Bell Telephone Laboratories
*
*/
#include "defs.h"
#include <errno.h>
#include "sym.h"
LOCAL INT parent;
SYSTAB commands;
SYSTAB xcmds;
/* ======== command execution ========*/
execute(argt, execflg, pf1, pf2)
TREPTR argt;
INT *pf1, *pf2;
{
/* `stakbot' is preserved by this routine */
REG TREPTR t;
STKPTR sav=savstak();
INT bltflg=0;
sigchk();
IF (t=argt) ANDF execbrk==0
THEN REG INT treeflgs;
INT oldexit, type;
REG STRING *com;
treeflgs = t->tretyp; type = treeflgs&COMMSK;
oldexit=exitval; exitval=0;
SWITCH type IN
case TCOM:
BEGIN
STRING a1;
INT argn, internal;
ARGPTR schain=gchain;
IOPTR io=t->treio;
gchain=0;
argn = getarg(t);
com=scan(argn);
a1=com[1]; gchain=schain;
IF (internal=syslook(com[0],commands)) ORF argn==0
THEN setlist(((COMPTR) t)->comset, 0);
FI
IF argn ANDF (flags&noexec)==0
THEN /* print command if execpr */
IF flags&execpr
THEN argn=0; prs(execpmsg);
WHILE com[argn]!=ENDARGS
DO prs(com[argn++]); blank() OD
newline();
FI
SWITCH internal IN
case SYSDOT:
IF a1
THEN REG INT f;
IF (f=pathopen(getpath(a1), a1)) < 0
THEN failed(a1,notfound);
ELSE execexp(0,f);
FI
FI
break;
case SYSTIMES:
{
L_INT t[4]; times(t);
prt(t[2]); blank(); prt(t[3]); newline();
}
break;
case SYSEXIT:
flags |= forked; /* force exit */
exitsh(a1?stoi(a1):oldexit);
case SYSNULL:
io=0;
break;
case SYSCONT:
IF (execbrk = -loopcnt) ANDF a1
THEN breakcnt = stoi(a1);
FI
break;
case SYSBREAK:
IF (execbrk=loopcnt) ANDF a1
THEN breakcnt=stoi(a1);
FI
break;
case SYSTRAP:
IF a1
THEN BOOL clear;
IF (clear=digit(*a1))==0
THEN ++com;
FI
WHILE *++com
DO INT i;
IF (i=stoi(*com))>=MAXTRAP ORF i<MINTRAP
THEN failed(*com,badtrap);
ELIF clear
THEN clrsig(i);
ELSE replace(&trapcom[i],a1);
IF *a1
THEN getsig(i);
ELSE ignsig(i);
FI
FI
OD
ELSE /* print out current traps */
INT i;
FOR i=0; i<MAXTRAP; i++
DO IF trapcom[i]
THEN prn(i); prs(colon); prs(trapcom[i]); newline();
FI
OD
FI
break;
case SYSEXEC:
com++;
initio(io); ioset=0; io=0;
IF a1==0 THEN break FI
#ifdef RES /* Research includes login as part of shell */
case SYSLOGIN:
oldsigs(); execa(com); done();
#else
case SYSNEWGRP:
IF flags&rshflg
THEN
failed(com[0],restricted);
ELSE
flags |= forked; /* force bad exec to terminate shell */
oldsigs(); execa(com); done();
FI
#endif
case SYSCD:
IF flags&rshflg
THEN failed(com[0],restricted);
ELIF (argn >2) THEN failed(com[0], "argument count");
ELIF (a1==0 ANDF (a1=homenod.namval)==0) ORF chdir(a1)<0
THEN failed(a1,baddir);
FI
break;
case SYSSHFT:
IF dolc<1
THEN error(badshift);
ELSE dolv++; dolc--;
FI
assnum(&dolladr, dolc);
break;
case SYSWAIT:
/*
await(-1);
*/
await(a1?stoi(a1):-1,1);
break;
case SYSREAD:
rwait=1;
exitval=readvar(&com[1]);
rwait=0;
break;
case SYSSET:
IF a1
THEN INT argc;
argc = options(argn,com);
IF argc>1
THEN setargs(com+argn-argc);
FI
ELIF ((COMPTR) t)->comset==0
THEN /*scan name chain and print*/
namscan(printnam);
FI
break;
case SYSRDONLY:
exitval=N_RDONLY;
case SYSXPORT:
IF exitval==0 THEN exitval=N_EXPORT; FI
IF a1
THEN WHILE *++com
DO attrib(lookup(*com), exitval) OD
ELSE namscan(printflg);
FI
exitval=0;
break;
case SYSEVAL:
IF a1
THEN execexp(a1,&com[2]);
FI
break;
case SYSUMASK:
IF a1
THEN INT c, i;
i = 0;
WHILE (c = *a1++) >= '0' && c<= '7'
DO i= (i << 3) + c - '0'
OD
umask(i);
ELSE
INT i, j;
umask(i= umask(0));
prc('0');
FOR j=6;j>=0;j-=3
DO prc(((i>>j)&07) +'0');
OD
newline();
FI
break;
default:
IF (internal=syslook(com[0],xcmds)) >0
THEN builtin(internal, argn, com);
bltflg=1;
FI
ENDSW
IF internal
THEN IF io ANDF !bltflg THEN error(illegal) FI
chktrap();
break;
FI
ELIF t->treio==0
THEN chktrap();
break;
FI
END
case TFORK:
IF execflg ANDF (treeflgs&(FAMP|FPOU))==0
THEN parent=0;
ELSE BEGIN
/* FORKLIM is the max period between forks -
power of 2 usually. Currently shell tries after
2,4,8,16, and 32 seconds and then quits */
INT forkcnt=1;
WHILE (parent=fork()) == -1
DO IF (forkcnt=(forkcnt*2)) > FORKLIM /* 32 */
THEN SWITCH errno IN
case ENOMEM: error(noswap);
break;
default:
case EAGAIN: error(nofork);
break;
ENDSW
FI
sigchk(); alarm(forkcnt);
pause();
OD
END
FI
IF parent
THEN /* This is the parent branch of fork; */
/* it may or may not wait for the child. */
IF treeflgs&FPRS ANDF flags&ttyflg
THEN prn(parent); newline();
FI
IF treeflgs&FPCL THEN closepipe(pf1) FI
IF (treeflgs&(FAMP|FPOU))==0
THEN await(parent,0);
ELIF (treeflgs&FAMP)==0
THEN post(parent);
ELSE assnum(&pcsadr, parent);
FI
chktrap();
break;
ELSE /* this is the forked branch (child) of execute */
flags |= forked; iotemp=0;
postclr();
settmp();
/* Turn off INTR and QUIT if `FINT' */
/* Reset ramaining signals to parent */
/* except for those `lost' by trap */
oldsigs();
IF treeflgs&FINT
THEN signal(INTR,1); signal(QUIT,1);
FI
/* pipe in or out */
IF treeflgs&FPIN
THEN rename(pf1[INPIPE],0);
close(pf1[OTPIPE]);
FI
IF treeflgs&FPOU
THEN rename(pf2[OTPIPE],1);
close(pf2[INPIPE]);
FI
/* default std input for & */
IF treeflgs&FINT ANDF ioset==0
THEN rename(chkopen(devnull),0);
FI
/* io redirection */
initio(t->treio);
IF type!=TCOM
THEN execute(((FORKPTR) t)->forktre,1);
ELIF com[0]!=ENDARGS
THEN setlist(((COMPTR) t)->comset,N_EXPORT);
execa(com);
FI
done();
FI
case TPAR:
rename(dup(2),output);
execute(((PARPTR) t)->partre,execflg);
done();
case TFIL:
BEGIN
INT pv[2]; chkpipe(pv);
IF execute(((LSTPTR) t)->lstlef, 0, pf1, pv)==0
THEN execute(((LSTPTR) t)->lstrit, execflg, pv, pf2);
ELSE closepipe(pv);
FI
END
break;
case TLST:
execute(((LSTPTR) t)->lstlef,0);
execute(((LSTPTR) t)->lstrit,execflg);
break;
case TAND:
IF execute(((LSTPTR) t)->lstlef,0)==0
THEN execute(((LSTPTR) t)->lstrit,execflg);
FI
break;
case TORF:
IF execute(((LSTPTR) t)->lstlef,0)!=0
THEN execute(((LSTPTR) t)->lstrit,execflg);
FI
break;
case TFOR:
BEGIN
NAMPTR n = lookup(((FORPTR) t)->fornam);
STRING *args;
DOLPTR argsav=0;
IF ((FORPTR) t)->forlst==0
THEN args=dolv+1;
argsav=useargs();
ELSE ARGPTR schain=gchain;
gchain=0;
trim((args=scan(getarg(((FORPTR) t)->forlst)))[0]);
gchain=schain;
FI
loopcnt++;
WHILE *args != ENDARGS ANDF execbrk <= 0
DO
assign(n, *args++);
execute(((FORPTR) t)->fortre,0);
IF execbrk
THEN IF breakcnt > 1 ORF execbrk > 0
THEN break;
ELSE execbrk = breakcnt = 0;
FI
FI
OD
IF breakcnt THEN breakcnt-- FI
execbrk = (execbrk < 0 ? -breakcnt : breakcnt);
loopcnt--;
argfor=(DOLPTR)freeargs(argsav);
END
break;
case TWH:
case TUN:
BEGIN
INT i=0;
loopcnt++;
WHILE execbrk<=0 ANDF (execute(((WHPTR) t)->whtre,0)==0)==(type==TWH)
DO
i = execute(((WHPTR) t)->dotre, 0);
IF execbrk
THEN IF breakcnt > 1 ORF execbrk > 0
THEN break;
ELSE execbrk = breakcnt = 0;
FI
FI
OD
IF breakcnt THEN breakcnt-- FI
execbrk=(execbrk < 0 ? -breakcnt : breakcnt);
loopcnt--; exitval= i;
END
break;
case TIF:
IF execute(((IFPTR) t)->iftre,0)==0
THEN execute(((IFPTR) t)->thtre,execflg);
ELIF ((IFPTR) t)->eltre
THEN execute(((IFPTR) t)->eltre, execflg);
ELSE exitval=0; /* force zero exit for if-then-fi */
FI
break;
case TSW:
BEGIN
REG STRING r = mactrim(((SWPTR) t)->swarg);
t=(TREPTR)((SWPTR) t)->swlst;
WHILE t
DO ARGPTR rex=(ARGPTR)((REGPTR) t)->regptr;
WHILE rex
DO REG STRING s;
IF gmatch(r,s=macro(((ARGPTR) rex)->argval)) ORF (trim(s), eq(r,s))
THEN execute(((REGPTR) t)->regcom,0);
t=0; break;
ELSE rex=rex->argnxt;
FI
OD
IF t THEN t=(TREPTR)((REGPTR) t)->regnxt FI
OD
END
break;
ENDSW
exitset();
FI
sigchk();
tdystak(sav);
return(exitval);
}
execexp(s,f)
STRING s;
UFD f;
{
FILEBLK fb;
push(&fb);
IF s
THEN estabf(s); fb.feval=(STRING *)(f);
ELIF f>=0
THEN initf(f);
FI
execute(cmd(NL, NLFLG|MTFLG),0);
pop();
}