225 lines
6.2 KiB
C
225 lines
6.2 KiB
C
/* C support for scsh select call.
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** Copyright (c) 1995 by Olin Shivers.
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*/
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#include "sysdep.h"
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#include <sys/types.h>
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#if defined(HAVE_SYS_SELECT_H)
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# include <sys/select.h>
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#endif
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#include <sys/time.h>
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#include <errno.h>
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#include <stdio.h>
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#include "cstuff.h"
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#include "fdports.h" /* Accessors for Scheme I/O port internals. */
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#include "machine/stdio_dep.h" /* Import stdio buf-peeking ops. */
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/* Make sure our exports match up w/the implementation: */
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#include "select1.h"
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/* the traditional sleazy max non-function. */
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#define max(a,b) (((a) > (b)) ? (a) : (b))
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extern int errno;
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static void or2_fdset(fd_set *x, fd_set *y, int max_elt);
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static int copyback_fdvec(s48_value portvec, fd_set *fdset);
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/* RVEC, WVEC, and EVEC are Scheme vectors of integer file descriptors,
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** I/O ports, and #f's. NSECS is an integer timeout value, or #f for
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** infinite wait. Do the select() call, returning result fd_sets in the
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** passed pointers. Return 0 for OK, otherwise error is in errno.
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*/
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int do_select(s48_value rvec, s48_value wvec,
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s48_value evec, s48_value nsecs,
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fd_set *rset_ans, fd_set *wset_ans, fd_set *eset_ans)
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{
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struct timeval timeout, *tptr;
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fd_set rset_bufrdy, wset_bufrdy, eset_bufrdy; /* Buffered port hits. */
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int rbuf_rdy=0, wbuf_rdy=0, bufrdy; /* Set if we find buffered I/O hits. */
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int max_fd = -1; /* Max fdes in the sets. */
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int nelts, i;
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int nfound;
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FD_ZERO(rset_ans); FD_ZERO(wset_ans); FD_ZERO(eset_ans);
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FD_ZERO(&rset_bufrdy); FD_ZERO(&wset_bufrdy); FD_ZERO(&eset_bufrdy);
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/* Scan the readvec elts. */
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nelts = S48_VECTOR_LENGTH(rvec);
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for(i=nelts; --i >= 0; ) {
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s48_value elt = S48_VECTOR_REF(rvec,i);
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int fd;
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fd = s48_extract_fixnum(elt);
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FD_SET(fd, rset_ans);
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max_fd = max(max_fd, fd);
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}
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/* Scan the writevec elts. */
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nelts = S48_VECTOR_LENGTH(wvec);
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for(i=nelts; --i >= 0; ) {
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s48_value elt = S48_VECTOR_REF(wvec,i);
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int fd;
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fd = s48_extract_fixnum(elt);
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FD_SET(fd, wset_ans);
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max_fd = max(max_fd, fd);
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}
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/* Scan the exception-vec elts. */
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nelts = S48_VECTOR_LENGTH(evec);
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for(i=nelts; --i >= 0; ) {
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s48_value elt = S48_VECTOR_REF(evec,i);
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int fd;
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fd = s48_extract_fixnum(elt);
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FD_SET(fd, eset_ans);
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max_fd = max(max_fd, fd);
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}
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bufrdy = rbuf_rdy || wbuf_rdy;
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if( bufrdy ) { /* Already have some hits on buffered ports, */
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timeout.tv_sec = 0; /* so we only poll the others. */
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timeout.tv_usec = 0;
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tptr = &timeout;
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}
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else if ( S48_FIXNUM_P(nsecs) ) {
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timeout.tv_sec = s48_extract_fixnum(nsecs); /* Wait n seconds. */
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timeout.tv_usec = 0;
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tptr = &timeout;
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}
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else tptr = NULL; /* #f => Infinite wait. */
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/* select1() is defined in sysdep.h -- bogus compatibility macro. */
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nfound = select(max_fd+1, rset_ans, wset_ans, eset_ans, tptr); /* Do it.*/
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/* EINTR is not an error return if we have hits on buffered ports
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** to report.
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*/
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if( nfound < 0 )
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if ( errno != EINTR || !bufrdy ) return -1;
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else { /* EINTR, but we have hits on buffered ports to report. */
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FD_ZERO(rset_ans); /* This should never happen -- */
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FD_ZERO(wset_ans); /* EINTR on a zero-sec select() */
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FD_ZERO(eset_ans); /* -- but I'm paranoid. */
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}
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/* OR together the buffered-io ready sets and the fd ready sets. */
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if( rbuf_rdy ) or2_fdset(rset_ans, &rset_bufrdy, max_fd);
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if( wbuf_rdy ) or2_fdset(wset_ans, &wset_bufrdy, max_fd);
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return 0;
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}
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/* x = x or y */
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static void or2_fdset(fd_set *x, fd_set *y, int max_elt)
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{
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int i;
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for(i=max_elt+1; --i >= 0;)
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if( FD_ISSET(i,y) ) FD_SET(i,x);
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}
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/* PORTVEC is a vector of integer file descriptors and Scheme ports.
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** Scan over the vector, and copy any elt whose file descriptor is in FDSET
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** to the front of the vector. Return the number of elts thus copied.
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*/
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static int copyback_fdvec(s48_value portvec, fd_set *fdset)
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{
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int vlen = S48_VECTOR_LENGTH(portvec);
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int i, j=0;
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for( i = -1; ++i < vlen; ) {
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s48_value elt = S48_VECTOR_REF(portvec, i);
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int fd = s48_extract_fixnum((S48_FIXNUM_P(elt)) ? elt : (1 / 0));
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//JMG *PortFd(elt));
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if( FD_ISSET(fd,fdset) ) {
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FD_CLR(fd,fdset); /* In case luser put elt in multiple times. */
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S48_VECTOR_SET(portvec, j, elt);
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j++;
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}
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}
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return j;
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}
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/* Overwrite every inactive element in the vector with #f;
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** Return count of active elements.
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*/
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static int clobber_inactives(s48_value portvec, fd_set *fdset)
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{
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int count = 0;
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int i = S48_VECTOR_LENGTH(portvec);
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while( --i >= 0 ) {
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s48_value elt = S48_VECTOR_REF(portvec, i);
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if( elt != S48_FALSE ) {
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int fd = s48_extract_fixnum((S48_FIXNUM_P(elt)) ? elt : (1/0)); //JMG *PortFd(elt));
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if( FD_ISSET(fd,fdset) ) {
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FD_CLR(fd,fdset); /* In case luser put elt in multiple times. */
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++count;
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}
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else S48_VECTOR_SET(portvec, i, S48_FALSE); /* Clobber. */
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}
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}
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return count;
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}
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/* These two functions are the entry points to this file.
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*********************************************************
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*/
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/* Copy active elts back to the front of their vector;
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** Return error indicator & number of hits for each vector.
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*/
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s48_value select_copyback(s48_value rvec, s48_value wvec,
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s48_value evec, s48_value nsecs,
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int *r_numrdy, int *w_numrdy, int *e_numrdy)
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{
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fd_set rset, wset, eset;
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if( do_select(rvec, wvec, evec, nsecs, &rset, &wset, &eset) ) {
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*r_numrdy = *w_numrdy = *e_numrdy = 0;
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return s48_enter_fixnum(errno);
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}
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*r_numrdy = copyback_fdvec(rvec, &rset);
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*w_numrdy = copyback_fdvec(wvec, &wset);
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*e_numrdy = copyback_fdvec(evec, &eset);
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return S48_FALSE;
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}
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/* Overwrite non-active elements in the vectors with #f;
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** return error indicator & number of hits for each vector.
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*/
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s48_value select_filter(s48_value rvec, s48_value wvec,
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s48_value evec, s48_value nsecs,
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int *r_numrdy, int *w_numrdy, int *e_numrdy)
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{
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fd_set rset, wset, eset;
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if( do_select(rvec, wvec, evec, nsecs, &rset, &wset, &eset) ) {
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*r_numrdy = *w_numrdy = *e_numrdy = 0;
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return s48_enter_fixnum(errno);
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}
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*r_numrdy = clobber_inactives(rvec, &rset);
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*w_numrdy = clobber_inactives(wvec, &wset);
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*e_numrdy = clobber_inactives(evec, &eset);
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return S48_FALSE;
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}
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