usr/src/lib/libbc/libc/gen/common/popen.c

   1 /*
   2  * Copyright (c) 1995, by Sun Microsystems, Inc.
   3  * All rights reserved.
   4  */
   5
   6 #pragma ident   "%Z%%M% %I%     %E% SMI"
   7           /* from UCB 5.2 85/06/05 */
   8
   9 /*
  10  * Copyright (c) 1980 Regents of the University of California.
  11  * All rights reserved.  The Berkeley software License Agreement
  12  * specifies the terms and conditions for redistribution.
  13  */
  14
  15 #include <stdio.h>
  16 #include <signal.h>
  17 #include <vfork.h>
  18
  19 #define tst(a,b)        (*mode == 'r'? (b) : (a))
  20 #define RDR     0
  21 #define WTR     1
  22
  23 extern  char *malloc();
  24 extern  int execl(), vfork(), pipe(), close(), fcntl();
  25
  26 static  int *popen_pid;
  27 static  int nfiles;
  28
  29 FILE *
  30 popen(cmd,mode)
  31         char *cmd;
  32         char *mode;
  33 {
  34         int p[2];
  35         register int *poptr;
  36         register int myside, hisside, pid;
  37
  38         if (nfiles <= 0)
  39                 nfiles = getdtablesize();
  40         if (popen_pid == NULL) {
  41                 popen_pid = (int *)malloc(nfiles * sizeof *popen_pid);
  42                 if (popen_pid == NULL)
  43                         return (NULL);
  44                 for (pid = 0; pid < nfiles; pid++)
  45                         popen_pid[pid] = -1;
  46         }
  47         if (pipe(p) < 0)
  48                 return (NULL);
  49         myside = tst(p[WTR], p[RDR]);
  50         hisside = tst(p[RDR], p[WTR]);
  51         if ((pid = vfork()) == 0) {
  52                 /* myside and hisside reverse roles in child */
  53                 int     stdio;
  54
  55                 /* close all pipes from other popen's */
  56                 for (poptr = popen_pid; poptr < popen_pid+nfiles; poptr++) {
  57                         if(*poptr >= 0)
  58                                 close(poptr - popen_pid);
  59                 }
  60                 stdio = tst(0, 1);
  61                 (void) close(myside);
  62                 if (hisside != stdio) {
  63                         (void) dup2(hisside, stdio);
  64                         (void) close(hisside);
  65                 }
  66                 (void) execl("/bin/sh", "sh", "-c", cmd, (char *)NULL);
  67                 _exit(127);
  68         }
  69         if (pid == -1) {
  70                 close(myside);
  71                 close(hisside);
  72                 return (NULL);
  73         }
  74         popen_pid[myside] = pid;
  75         close(hisside);
  76         return (fdopen(myside, mode));
  77 }
  78
  79 int
  80 pclose(ptr)
  81         FILE *ptr;
  82 {
  83         int child = -1;
  84         int pid, status, omask;
  85
  86         if (popen_pid != NULL) {
  87                 child = popen_pid[fileno(ptr)];
  88                 popen_pid[fileno(ptr)] = -1;
  89         }
  90         fclose(ptr);
  91         if (child == -1)
  92                 return (-1);
  93         omask = sigblock(sigmask(SIGINT)|sigmask(SIGQUIT)|sigmask(SIGHUP));
  94         while ((pid = waitpid(child, &status, 0)) != child && pid != -1)
  95                 ;
  96         (void) sigsetmask(omask);
  97         return (pid == -1 ? -1 : status);
  98 }