Return to popen.c CVS log

Up to [CSRG BSD Unix] / 43BSD / ucb / Mail

Annotation of 43BSD/ucb/Mail/popen.c, revision 1.1.1.1

1.1       root        1: /*
                      2:  * Copyright (c) 1980 Regents of the University of California.
                      3:  * All rights reserved.  The Berkeley software License Agreement
                      4:  * specifies the terms and conditions for redistribution.
                      5:  */
                      6: 
                      7: #ifndef lint
                      8: static char *sccsid = "@(#)popen.c     5.2 (Berkeley) 6/21/85";
                      9: #endif not lint
                     10: 
                     11: #include <stdio.h>
                     12: #include <signal.h>
                     13: #include <errno.h>
                     14: #define        tst(a,b)        (*mode == 'r'? (b) : (a))
                     15: #define        RDR     0
                     16: #define        WTR     1
                     17: static int     popen_pid[20];
                     18: 
                     19: #ifndef VMUNIX
                     20: #define vfork  fork
                     21: #endif VMUNIX
                     22: #ifndef        SIGRETRO
                     23: #define        sigchild()
                     24: #endif
                     25: 
                     26: FILE *
                     27: popen(cmd,mode)
                     28: char   *cmd;
                     29: char   *mode;
                     30: {
                     31:        int p[2];
                     32:        register myside, hisside, pid;
                     33: 
                     34:        if(pipe(p) < 0)
                     35:                return NULL;
                     36:        myside = tst(p[WTR], p[RDR]);
                     37:        hisside = tst(p[RDR], p[WTR]);
                     38:        if((pid = vfork()) == 0) {
                     39:                /* myside and hisside reverse roles in child */
                     40:                sigchild();
                     41:                close(myside);
                     42:                dup2(hisside, tst(0, 1));
                     43:                close(hisside);
                     44:                execl("/bin/csh", "sh", "-c", cmd, 0);
                     45:                _exit(1);
                     46:        }
                     47:        if(pid == -1)
                     48:                return NULL;
                     49:        popen_pid[myside] = pid;
                     50:        close(hisside);
                     51:        return(fdopen(myside, mode));
                     52: }
                     53: 
                     54: pclose(ptr)
                     55: FILE *ptr;
                     56: {
                     57:        register f, r;
                     58:        int status, omask;
                     59:        extern int errno;
                     60: 
                     61:        f = fileno(ptr);
                     62:        fclose(ptr);
                     63: # ifdef VMUNIX
                     64:        omask = sigblock(sigmask(SIGINT)|sigmask(SIGQUIT)|sigmask(SIGHUP));
                     65: # endif VMUNIX
                     66:        while((r = wait(&status)) != popen_pid[f] && r != -1 && errno != EINTR)
                     67:                ;
                     68:        if(r == -1)
                     69:                status = -1;
                     70: # ifdef VMUNIX
                     71:        sigsetmask(omask);
                     72: # endif VMUNIX
                     73:        return(status);
                     74: }

This archive runs on limited infrastructure. Preserving old code on modern bandwidth. Automated agents are requested to crawl responsibly.