ref: bf645afaac246967b9590ae7463f243c11d97480
dir: /sys/src/cmd/rc/havefork.c/
#include "rc.h" #include "getflags.h" #include "exec.h" #include "io.h" #include "fns.h" static int *waitpids; static int nwaitpids; void addwaitpid(int pid) { waitpids = erealloc(waitpids, (nwaitpids+1)*sizeof waitpids[0]); waitpids[nwaitpids++] = pid; } void delwaitpid(int pid) { int r, w; for(r=w=0; r<nwaitpids; r++) if(waitpids[r] != pid) waitpids[w++] = waitpids[r]; nwaitpids = w; } void clearwaitpids(void) { nwaitpids = 0; } int havewaitpid(int pid) { int i; for(i=0; i<nwaitpids; i++) if(waitpids[i] == pid) return 1; return 0; } void Xasync(void) { int pid; char npid[10]; switch(pid = Fork()){ case -1: Xerror2("try again", Errstr()); break; case 0: clearwaitpids(); start(runq->code, runq->pc+1, runq->local, runq->redir); runq->ret = 0; break; default: addwaitpid(pid); runq->pc = runq->code[runq->pc].i; inttoascii(npid, pid); setvar("apid", newword(npid, (word *)0)); break; } } void Xpipe(void) { thread *p = runq; int pid, pc = p->pc; int lfd = p->code[pc++].i; int rfd = p->code[pc++].i; int pfd[2]; if(pipe(pfd)<0){ Xerror2("can't get pipe", Errstr()); return; } switch(pid = Fork()){ case -1: Xerror2("try again", Errstr()); break; case 0: clearwaitpids(); Close(pfd[PRD]); start(p->code, pc+2, runq->local, runq->redir); runq->ret = 0; pushredir(ROPEN, pfd[PWR], lfd); break; default: addwaitpid(pid); Close(pfd[PWR]); start(p->code, p->code[pc].i, runq->local, runq->redir); pushredir(ROPEN, pfd[PRD], rfd); p->pc = p->code[pc+1].i; p->pid = pid; break; } } /* * Who should wait for the exit from the fork? */ void Xbackq(void) { int pid, pfd[2]; char *s, *split; word *end, **link; io *f; if(pipe(pfd)<0){ Xerror2("can't make pipe", Errstr()); return; } switch(pid = Fork()){ case -1: Xerror2("try again", Errstr()); Close(pfd[PRD]); Close(pfd[PWR]); return; case 0: clearwaitpids(); Close(pfd[PRD]); start(runq->code, runq->pc+1, runq->local, runq->redir); pushredir(ROPEN, pfd[PWR], 1); return; default: addwaitpid(pid); Close(pfd[PWR]); split = Popword(); poplist(); f = openiofd(pfd[PRD]); end = runq->argv->words; link = &runq->argv->words; while((s = rstr(f, split)) != 0){ *link = Newword(s, (word*)0); link = &(*link)->next; } *link = end; closeio(f); free(split); Waitfor(pid); runq->pc = runq->code[runq->pc].i; return; } } void Xpipefd(void) { thread *p = runq; int pid, pc = p->pc; char name[40]; int pfd[2]; int sidefd, mainfd; if(pipe(pfd)<0){ Xerror2("can't get pipe", Errstr()); return; } if(p->code[pc].i==READ){ sidefd = pfd[PWR]; mainfd = pfd[PRD]; } else{ sidefd = pfd[PRD]; mainfd = pfd[PWR]; } switch(pid = Fork()){ case -1: Xerror2("try again", Errstr()); break; case 0: clearwaitpids(); Close(mainfd); start(p->code, pc+2, runq->local, runq->redir); pushredir(ROPEN, sidefd, p->code[pc].i==READ?1:0); runq->ret = 0; break; default: addwaitpid(pid); Close(sidefd); pushredir(ROPEN, mainfd, mainfd); shuffleredir(); /* shuffle redir to bottom of stack for Xpopredir() */ strcpy(name, Fdprefix); inttoascii(name+strlen(name), mainfd); pushword(name); p->pc = p->code[pc+1].i; break; } } void Xsubshell(void) { int pid; switch(pid = Fork()){ case -1: Xerror2("try again", Errstr()); break; case 0: clearwaitpids(); start(runq->code, runq->pc+1, runq->local, runq->redir); runq->ret = 0; break; default: addwaitpid(pid); while(Waitfor(pid) < 0) ; runq->pc = runq->code[runq->pc].i; break; } } int execforkexec(void) { int pid; switch(pid = Fork()){ case -1: return -1; case 0: clearwaitpids(); pushword("exec"); execexec(); /* does not return */ } addwaitpid(pid); return pid; }