2.9BSD - /usr/src/ucb/Mail/popen.c

   1: #include <stdio.h>
   2: #include <signal.h>
   3: #include <errno.h>
   4: #define tst(a,b)    (*mode == 'r'? (b) : (a))
   5: #define RDR 0
   6: #define WTR 1
   7: static  int popen_pid[20];
   8: static  char    *sccsid = "@(#)popen.c	1.6 6/12/83";
   9: 
  10: # ifndef VMUNIX
  11: # define vfork  fork
  12: # endif VMUNIX
  13: #ifndef SIGRETRO
  14: #define sigchild()
  15: #endif
  16: 
  17: FILE *
  18: popen(cmd,mode)
  19: char    *cmd;
  20: char    *mode;
  21: {
  22:     int p[2];
  23:     register myside, hisside, pid;
  24: 
  25:     if(pipe(p) < 0)
  26:         return NULL;
  27:     myside = tst(p[WTR], p[RDR]);
  28:     hisside = tst(p[RDR], p[WTR]);
  29:     if((pid = vfork()) == 0) {
  30:         /* myside and hisside reverse roles in child */
  31:         sigchild();
  32:         close(myside);
  33:         dup2(hisside, tst(0, 1));
  34:         close(hisside);
  35:         execl("/bin/csh", "sh", "-c", cmd, 0);
  36:         _exit(1);
  37:     }
  38:     if(pid == -1)
  39:         return NULL;
  40:     popen_pid[myside] = pid;
  41:     close(hisside);
  42:     return(fdopen(myside, mode));
  43: }
  44: 
  45: pclose(ptr)
  46: FILE *ptr;
  47: {
  48:     register f, r;
  49:     int status;
  50:     extern int errno;
  51: 
  52:     f = fileno(ptr);
  53:     fclose(ptr);
  54: # ifdef VMUNIX
  55:     sighold(SIGINT);
  56:     sighold(SIGQUIT);
  57:     sighold(SIGHUP);
  58: # endif VMUNIX
  59:     while((r = wait(&status)) != popen_pid[f] && r != -1 && errno != EINTR)
  60:         ;
  61:     if(r == -1)
  62:         status = -1;
  63: # ifdef VMUNIX
  64:     sigrelse(SIGINT);
  65:     sigrelse(SIGQUIT);
  66:     sigrelse(SIGHUP);
  67: # endif VMUNIX
  68:     return(status);
  69: }

Defined functions

Defined variables

Defined macros