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#include <err.h>
#include <fcntl.h>
#include <stdio.h>
#include <string.h>
#include <sys/select.h>
#include <unistd.h>
#define MAXBUF 2048
int
main()
{
char bufin[MAXBUF], bufout[MAXBUF], *bi, *bo;
fd_set rfds0, rfds1;
int c, fdin, fdout, flags, i, nin, nout, state;
struct timeval tv;
if(!(fdin = open("/var/tmp/r.in", O_WRONLY)))
err(1, "open");
if(!(fdout = open("/var/tmp/r.out", O_RDONLY)))
err(1, "open");
FD_ZERO(&rfds0);
FD_ZERO(&rfds1);
tv.tv_sec = 0;
tv.tv_usec = 1;
for(;;){
/*
* User input is read from standard in and copied the
* input pipe. It is saved in bufin for later use.
*/
FD_SET(0, &rfds0);
if(select(0+1, &rfds0, NULL, NULL, &tv) > 0){
nout = read(0, bufin, MAXBUF);
bufin[nout] = 0;
dprintf(fdin, "%s", bufin);
fflush(stdout);
}
/*
* System output is read from the output pipe and copied
* to standard out for the user to see.
*/
FD_SET(fdout, &rfds1);
if(select(fdout+1, &rfds1, NULL, NULL, &tv) > 0){
nout = read(fdout, bufout, MAXBUF);
if(!nout) continue;
bufout[nout] = 0;
/*
* Bufin and bufout are copied to the temporary
* pointers bi and bo. Bo is incremented in order
* to skip any potential repetition of the command
* given by the user on standard in. (It is assumed
* that the typed command fits in bufin, i.e. is
* not larger than MAXBUF.)
*/
bi = bufin;
bo = bufout;
for(;;){
if(*bo == '\n'){
bo++;
break;
}
if(*bo == 13){
bo++;
continue;
}
if(*bi != *bo){
bo = bufout;
break;
}
bi++; bo++;
}
/*
* Bo is printed and bufin is cleared, so as not
* to perform the skip again, incorrectly.
*/
printf("%s", bo);
fflush(stdout);
bufin[0] = 0;
}
}
}
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