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Annotation of 43BSD/lib/libc/gen/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: #if defined(LIBC_SCCS) && !defined(lint)
                      8: static char sccsid[] = "@(#)popen.c    5.4 (Berkeley) 3/26/86";
                      9: #endif LIBC_SCCS and not lint
                     10: 
                     11: #include <stdio.h>
                     12: #include <signal.h>
                     13: 
                     14: #define        tst(a,b)        (*mode == 'r'? (b) : (a))
                     15: #define        RDR     0
                     16: #define        WTR     1
                     17: 
                     18: extern char *malloc();
                     19: 
                     20: static int *popen_pid;
                     21: static int nfiles;
                     22: 
                     23: FILE *
                     24: popen(cmd,mode)
                     25:        char *cmd;
                     26:        char *mode;
                     27: {
                     28:        int p[2];
                     29:        int myside, hisside, pid;
                     30: 
                     31:        if (nfiles <= 0)
                     32:                nfiles = getdtablesize();
                     33:        if (popen_pid == NULL) {
                     34:                popen_pid = (int *)malloc(nfiles * sizeof *popen_pid);
                     35:                if (popen_pid == NULL)
                     36:                        return (NULL);
                     37:                for (pid = 0; pid < nfiles; pid++)
                     38:                        popen_pid[pid] = -1;
                     39:        }
                     40:        if (pipe(p) < 0)
                     41:                return (NULL);
                     42:        myside = tst(p[WTR], p[RDR]);
                     43:        hisside = tst(p[RDR], p[WTR]);
                     44:        if ((pid = vfork()) == 0) {
                     45:                /* myside and hisside reverse roles in child */
                     46:                close(myside);
                     47:                if (hisside != tst(0, 1)) {
                     48:                        dup2(hisside, tst(0, 1));
                     49:                        close(hisside);
                     50:                }
                     51:                execl("/bin/sh", "sh", "-c", cmd, (char *)NULL);
                     52:                _exit(127);
                     53:        }
                     54:        if (pid == -1) {
                     55:                close(myside);
                     56:                close(hisside);
                     57:                return (NULL);
                     58:        }
                     59:        popen_pid[myside] = pid;
                     60:        close(hisside);
                     61:        return (fdopen(myside, mode));
                     62: }
                     63: 
                     64: pclose(ptr)
                     65:        FILE *ptr;
                     66: {
                     67:        int child, pid, status, omask;
                     68: 
                     69:        child = popen_pid[fileno(ptr)];
                     70:        popen_pid[fileno(ptr)] = -1;
                     71:        fclose(ptr);
                     72:        if (child == -1)
                     73:                return (-1);
                     74:        omask = sigblock(sigmask(SIGINT)|sigmask(SIGQUIT)|sigmask(SIGHUP));
                     75:        while ((pid = wait(&status)) != child && pid != -1)
                     76:                ;
                     77:        (void) sigsetmask(omask);
                     78:        return (pid == -1 ? -1 : status);
                     79: }

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