Bug in select()?

[Michele Bini]

The supposed bug can be easily shown with strace

$ echo|strace ./proggy;
[...]
select(1, [0], NULL, NULL, NULL)        = 1 (in [0])
read(0, "\n", 1)                        = 1
select(1, [0], NULL, NULL, NULL)        = 1 (in [0])
read(0, "", 1)                          = 0
select(1, [0], NULL, NULL, NULL)        = 1 (in [0])
read(0, "", 1)                          = 0
select(1, [0], NULL, NULL, NULL)        = 1 (in [0])
read(0, "", 1)                          = 0
[...]

How can it be? select() returns 1 (as if fd 0 had
some data pending, but read() returns 0 and doesn't
read any byte)

At the same time the process use almost 100% of
the CPU time (as shown by 'top').

This 'bug' however doesn't happen if I run
$ strace ./proggy

Here is a little proggy to reproduce it:

#include <sys/time.h>
#include <sys/types.h>
#include <unistd.h>
void main() {
        for(;;) {
                char c;
                fd_set fdset;
                FD_ZERO(&fdset);
                FD_SET(0, &fdset);
                select(1, &fdset, NULL, NULL, NULL);
                read(0, &c, 1);
        } }

Can someone explain the reason of this?
(I am using libc6 and Linux 2.1.131)

-Michele