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#include "stdio_impl.h"
FILE *popen(const char *cmd, const char *mode)
{
int p[2];
int op;
pid_t pid;
FILE *f;
const char *modes = "rw", *mi = strchr(modes, *mode);
if (mi) {
op = mi-modes;
} else {
errno = EINVAL;
return 0;
}
if (pipe(p)) return NULL;
f = fdopen(p[op], mode);
if (!f) {
close(p[0]);
close(p[1]);
return NULL;
}
pid = fork();
switch (pid) {
case -1:
fclose(f);
close(p[0]);
close(p[1]);
return NULL;
case 0:
dup2(p[1-op], 1-op);
close(p[0]);
close(p[1]);
execl("/bin/sh", "sh", "-c", cmd, (char *)0);
_exit(127);
}
close(p[1-op]);
f->pipe_pid = pid;
return f;
}
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