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Annotation of 3BSD/libc/stdio/popen.c, revision 1.1.1.1

1.1       root        1: #include <stdio.h>
                      2: #include <signal.h>
                      3: #define        tst(a,b)        (*mode == 'r'? (b) : (a))
                      4: #define        RDR     0
                      5: #define        WTR     1
                      6: static int     popen_pid[20];
                      7: 
                      8: FILE *
                      9: popen(cmd,mode)
                     10: char   *cmd;
                     11: char   *mode;
                     12: {
                     13:        int p[2];
                     14:        register myside, hisside, pid;
                     15: 
                     16:        if(pipe(p) < 0)
                     17:                return NULL;
                     18:        myside = tst(p[WTR], p[RDR]);
                     19:        hisside = tst(p[RDR], p[WTR]);
                     20:        if((pid = vfork()) == 0) {
                     21:                /* myside and hisside reverse roles in child */
                     22:                close(myside);
                     23:                dup2(hisside, tst(0, 1));
                     24:                close(hisside);
                     25:                execl("/bin/sh", "sh", "-c", cmd, 0);
                     26:                _exit(1);
                     27:        }
                     28:        if(pid == -1)
                     29:                return NULL;
                     30:        popen_pid[myside] = pid;
                     31:        close(hisside);
                     32:        return(fdopen(myside, mode));
                     33: }
                     34: 
                     35: pclose(ptr)
                     36: FILE *ptr;
                     37: {
                     38:        register f, r, (*hstat)(), (*istat)(), (*qstat)();
                     39:        int status;
                     40: 
                     41:        f = fileno(ptr);
                     42:        fclose(ptr);
                     43:        istat = signal(SIGINT, SIG_IGN);
                     44:        qstat = signal(SIGQUIT, SIG_IGN);
                     45:        hstat = signal(SIGHUP, SIG_IGN);
                     46:        while((r = wait(&status)) != popen_pid[f] && r != -1)
                     47:                ;
                     48:        if(r == -1)
                     49:                status = -1;
                     50:        signal(SIGINT, istat);
                     51:        signal(SIGQUIT, qstat);
                     52:        signal(SIGHUP, hstat);
                     53:        return(status);
                     54: }

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