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#include <assert.h>
#include <errno.h>
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <sys/types.h>
#include <sys/time.h>
#include <unistd.h>
#define nil ((void*) 0)
enum
{
BUFSZ = (1<<15)
};
static void
fatal(char *s)
{
fprintf(stderr, "%s: %s\n", s, strerror(errno));
exit(1);
}
static int
writen(int fd, char *buf, int n)
{
int m, k = 0;
while(n > 0){
if((m = write(fd, buf, n)) < 0){
if(errno == EINTR)
continue;
fatal("write");
}
buf += m;
n -= m;
k += m;
}
return k;
}
static int
copy(int from, int to, int w)
{
int n;
char tmp[6];
static char buf[BUFSZ+5];
if((n = read(from, buf+5, BUFSZ)) > 0){
sprintf(tmp, "%c%.4X", w?'e':'o', n);
memmove(buf, tmp, 5);
if(writen(to, buf, n+5) != n+5)
fatal("writen");
}
return n;
}
static void
merge(int a, int b)
{
int ao=1, bo=1, m = 1 + ((a>b)?a:b);
fd_set rdset;
while(ao || bo){
FD_ZERO(&rdset);
if(ao)
FD_SET(a, &rdset);
if(bo)
FD_SET(b, &rdset);
if(select(m, &rdset, nil, nil, nil) == -1){
if(errno == EINTR)
continue;
fatal("select");
}
if(ao && FD_ISSET(a, &rdset))
ao = (copy(a, 1, 0) != 0);
if(bo && FD_ISSET(b, &rdset))
bo = (copy(b, 1, 1) != 0);
}
return;
}
static void
usage(void)
{
fprintf(stderr, "usage: stdmerge cmd ...\n");
}
int
main(int argc, char *argv[])
{
int ps[2], pe[2];
if(argc <= 1){
usage();
return 1;
}
if((pipe(ps) < 0) || (pipe(pe) < 0))
fatal("pipe");
switch(fork()){
case -1:
fatal("fork");
case 0:
close(ps[0]); close(pe[0]);
if(dup2(ps[1], 1) < 0 || dup2(pe[1], 2) < 0)
fatal("dup2");
execvp(argv[1], argv+1);
fatal("exec");
default:
close(ps[1]); close(pe[1]);
merge(ps[0], pe[0]);
}
return 0;
}
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