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#include "stdio_impl.h"
#include <fcntl.h>
#include <unistd.h>
/* The basic idea of this implementation is to open a new FILE,
* hack the necessary parts of the new FILE into the old one, then
* close the new FILE. */
/* Locking IS necessary because another thread may provably hold the
* lock, via flockfile or otherwise, when freopen is called, and in that
* case, freopen cannot act until the lock is released. */
FILE *freopen(const char *restrict filename, const char *restrict mode, FILE *restrict f)
{
int fl = __fmodeflags(mode);
FILE *f2;
FLOCK(f);
fflush(f);
if (!filename) {
if (fl&O_CLOEXEC)
__syscall(SYS_fcntl, f->fd, F_SETFD, FD_CLOEXEC);
fl &= ~(O_CREAT|O_EXCL|O_CLOEXEC);
if (syscall(SYS_fcntl, f->fd, F_SETFL, fl) < 0)
goto fail;
} else {
f2 = fopen(filename, mode);
if (!f2) goto fail;
if (f2->fd == f->fd) f2->fd = -1; /* avoid closing in fclose */
else if (__dup3(f2->fd, f->fd, fl&O_CLOEXEC)<0) goto fail2;
f->flags = (f->flags & F_PERM) | f2->flags;
f->read = f2->read;
f->write = f2->write;
f->seek = f2->seek;
f->close = f2->close;
fclose(f2);
}
f->mode = 0;
f->locale = 0;
FUNLOCK(f);
return f;
fail2:
fclose(f2);
fail:
fclose(f);
return NULL;
}
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