BSD 4_4_Lite1 development

[unix-history] / usr / src / contrib / rc-1.4 / redir.c

/* redir.c: code for opening files and piping heredocs after fork but before exec. */

#include "rc.h"

/*
  Walk the redirection queue, and open files and dup2 to them. Also,
  here-documents are treated here by dumping them down a pipe. (this
  should make here-documents fast on systems with lots of memory which
  do pipes right. Under sh, a file is copied to /tmp, and then read
  out of /tmp again. I'm interested in knowing how much faster, say,
  shar runs when unpacking when invoked with rc instead of sh. On my
  sun4/280, it runs in about 60-75% of the time of sh for unpacking
  the rc source distribution.)
*/

extern void doredirs() {
       List *fname;
       int fd, p[2];
       Rq *r;
       for (r = redirq; r != NULL; r = r->n) {
               switch(r->r->type) {
               default:
                       panic("unexpected node in doredirs");
                       /* NOTREACHED */
               case nRedir:
                       if (r->r->u[0].i == rHerestring) {
                               fname = flatten(glom(r->r->u[2].p)); /* fname is really a string */
                               if (pipe(p) < 0) {
                                       uerror("pipe");
                                       rc_error(NULL);
                               }
                               if (rc_fork() == 0) { /* child writes to pipe */
                                       setsigdefaults(FALSE);
                                       close(p[0]);
                                       if (fname != NULL)
                                               writeall(p[1], fname->w, strlen(fname->w));
                                       exit(0);
                               } else {
                                       close(p[1]);
                                       if (mvfd(p[0], r->r->u[1].i) < 0)
                                               rc_error(NULL);
                               }
                       } else {
                               fname = glob(glom(r->r->u[2].p));
                               if (fname == NULL)
                                       rc_error("null filename in redirection");
                               if (fname->n != NULL)
                                       rc_error("multi-word filename in redirection");
                               switch (r->r->u[0].i) {
                               default:
                                       panic("unexpected node in doredirs");
                                       /* NOTREACHED */
                               case rCreate: case rAppend: case rFrom:
                                       fd = rc_open(fname->w, r->r->u[0].i);
                                       break;
                               }
                               if (fd < 0) {
                                       uerror(fname->w);
                                       rc_error(NULL);
                               }
                               if (mvfd(fd, r->r->u[1].i) < 0)
                                       rc_error(NULL);
                       }
                       break;
               case nDup:
                       if (r->r->u[2].i == -1)
                               close(r->r->u[1].i);
                       else if (r->r->u[2].i != r->r->u[1].i) {
                               if (dup2(r->r->u[2].i, r->r->u[1].i) < 0) {
                                       uerror("dup2");
                                       rc_error(NULL);
                               }
                       }
               }
       }
       redirq = NULL;
}