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Annotation of 43BSD/ucb/window/wwrint.c, revision 1.1.1.1

1.1       root        1: #ifndef lint
                      2: static char sccsid[] = "@(#)wwrint.c   3.4 4/24/85";
                      3: #endif
                      4: 
                      5: /*
                      6:  * Copyright (c) 1983 Regents of the University of California,
                      7:  * All rights reserved.  Redistribution permitted subject to
                      8:  * the terms of the Berkeley Software License Agreement.
                      9:  */
                     10: 
                     11: #include "ww.h"
                     12: #include <fcntl.h>
                     13: #include <sys/signal.h>
                     14: 
                     15: /*
                     16:  * Tty input interrupt handler.
                     17:  * (1) Read input into buffer (wwib*).
                     18:  * (2) If the flag wwsetjmp is true, do longjmp(wwjmpbuf) for asyncronous
                     19:  *     actions, and to avoid race conditions, clear wwsetjmp.
                     20:  * Currently, the last is used to get out of the blocking
                     21:  * select() in wwiomux().
                     22:  * To avoid race conditions, we only modify wwibq in here, except
                     23:  * when the buffer is empty; and everywhere else, we only change wwibp.
                     24:  * It should be completely safe.
                     25:  */
                     26: wwrint()
                     27: {
                     28:        register n;
                     29: 
                     30:        if (wwibp == wwibq)
                     31:                wwibp = wwibq = wwib;
                     32:        wwnread++;
                     33:        (void) fcntl(0, F_SETFL, FNDELAY|wwnewtty.ww_fflags);
                     34:        n = read(0, wwibq, wwibe - wwibq);
                     35:        (void) fcntl(0, F_SETFL, wwnewtty.ww_fflags);
                     36:        if (n > 0) {
                     37:                wwibq += n;
                     38:                wwnreadc += n;
                     39:        } else if (n == 0)
                     40:                wwnreadz++;
                     41:        else
                     42:                wwnreade++;
                     43:        if (wwinterrupt() && wwsetjmp) {
                     44:                wwsetjmp = 0;
                     45:                (void) sigsetmask(sigblock(0) & ~sigmask(SIGIO));
                     46:                longjmp(wwjmpbuf, 1);
                     47:        }
                     48: }

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