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/* $snafu: stdfiles.c,v 1.3 2003/02/03 21:22:26 marc Exp $ */
/* PUBLIC DOMAIN Oct 2002 <marc@snafu.org> */
#include <assert.h>
#include <fcntl.h>
#include <stdio.h>
#include <unistd.h>
/*
* test what happens to blocking/non-blocking mode on stdout/stderr when
* it is changed on stdin. A comment in the pthreads code implies that
* all three files are linked. Check it out.
*/
int
main(int argc, char *argv[])
{
int dup_stdout;
int stdin_flags;
int stdout_flags;
int dup_flags;
int stderr_flags;
int new_flags;
int new_fd;
/* dup stdout for the fun of it. */
dup_stdout = dup(STDOUT_FILENO);
/* read std in/out/err flags */
stdin_flags = fcntl(STDIN_FILENO, F_GETFL, 0);
assert(stdin_flags != -1);
stdout_flags = fcntl(STDOUT_FILENO, F_GETFL, 0);
assert(stdout_flags != -1);
dup_flags = fcntl(dup_stdout, F_GETFL, 0);
assert(dup_flags != -1);
stderr_flags = fcntl(STDERR_FILENO, F_GETFL, 0);
assert(stderr_flags != -1);
printf("starting flags: in = %x, out = %x, dup = %x, err = %x\n",
stdin_flags, stdout_flags, dup_flags, stderr_flags);
/* set stdin to non-blocking mode and see if stdout/stderr change */
new_flags = stdin_flags | O_NONBLOCK;
printf("forcing stdin to O_NONBLOCK (flags %x)\n", new_flags);
assert(fcntl(STDIN_FILENO, F_SETFL, new_flags) != -1);
new_flags = fcntl(STDIN_FILENO, F_GETFL, 0);
assert(new_flags != -1);
if (new_flags != stdin_flags) {
printf("stdin flags changed %x -> %x\n", stdin_flags,
new_flags);
stdin_flags = new_flags;
}
new_flags = fcntl(STDOUT_FILENO, F_GETFL, 0);
assert(new_flags != -1);
if (new_flags != stdout_flags) {
printf("stdout flags changed %x -> %x\n", stdout_flags,
new_flags);
stdout_flags = new_flags;
}
new_flags = fcntl(dup_stdout, F_GETFL, 0);
assert(new_flags != -1);
if (new_flags != dup_flags) {
printf("dup_stdout flags changed %x -> %x\n", dup_flags,
new_flags);
dup_flags = new_flags;
}
new_flags = fcntl(STDERR_FILENO, F_GETFL, 0);
assert(new_flags != -1);
if (new_flags != stderr_flags) {
printf("stderr flags changed %x -> %x\n", stderr_flags,
new_flags);
stderr_flags = new_flags;
}
/*
* Close stderr and open /dev/tty. See what it's flags
* are. Set the file to non blocking.
*/
printf("close stderr and open /dev/tty\n");
assert(close(STDERR_FILENO) != -1);
new_fd = open("/dev/tty", O_RDWR|O_CREAT, 0666);
assert(new_fd == STDERR_FILENO);
new_flags = fcntl(STDERR_FILENO, F_GETFL, 0);
assert(new_flags != -1);
printf("/dev/tty [STDERR_FILENO] flags are %x\n", new_flags);
stderr_flags = new_flags | O_NONBLOCK;
printf("forcing /dev/tty to O_NONBLOCK (flags %x)\n", stderr_flags);
assert(fcntl(STDERR_FILENO, F_SETFL, stdin_flags) != -1);
/* now turn off non blocking mode on stdin */
stdin_flags &= ~O_NONBLOCK;
printf("turning off O_NONBLOCK on stdin (flags %x)\n", stdin_flags);
assert(fcntl(STDIN_FILENO, F_SETFL, stdin_flags) != -1);
new_flags = fcntl(STDIN_FILENO, F_GETFL, 0);
assert(new_flags != -1);
assert(new_flags == stdin_flags);
new_flags = fcntl(STDOUT_FILENO, F_GETFL, 0);
assert(new_flags != -1);
if (new_flags != stdout_flags) {
printf("stdout flags changed %x -> %x\n", stdout_flags,
new_flags);
stdout_flags = new_flags;
}
new_flags = fcntl(dup_stdout, F_GETFL, 0);
assert(new_flags != -1);
if (new_flags != dup_flags) {
printf("dup_stdout flags changed %x -> %x\n", dup_flags,
new_flags);
dup_flags = new_flags;
}
new_flags = fcntl(STDERR_FILENO, F_GETFL, 0);
assert(new_flags != -1);
if (new_flags != stderr_flags) {
printf("stderr flags changed %x -> %x\n", stderr_flags,
new_flags);
stderr_flags = new_flags;
}
return 0;
}
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