/* Compare two open file descriptors to see if they refer to the same file.
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/* Compare two open file descriptors to see if they refer to the same file.
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Copyright (C) 1991 Free Software Foundation, Inc.
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Copyright (C) 1991 Free Software Foundation, Inc.
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This file is part of the libiberty library.
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This file is part of the libiberty library.
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Libiberty is free software; you can redistribute it and/or
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Libiberty is free software; you can redistribute it and/or
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modify it under the terms of the GNU Library General Public
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modify it under the terms of the GNU Library General Public
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License as published by the Free Software Foundation; either
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License as published by the Free Software Foundation; either
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version 2 of the License, or (at your option) any later version.
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version 2 of the License, or (at your option) any later version.
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Libiberty is distributed in the hope that it will be useful,
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Libiberty is distributed in the hope that it will be useful,
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but WITHOUT ANY WARRANTY; without even the implied warranty of
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but WITHOUT ANY WARRANTY; without even the implied warranty of
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MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
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MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
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Library General Public License for more details.
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Library General Public License for more details.
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You should have received a copy of the GNU Library General Public
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You should have received a copy of the GNU Library General Public
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License along with libiberty; see the file COPYING.LIB. If
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License along with libiberty; see the file COPYING.LIB. If
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not, write to the Free Software Foundation, Inc., 59 Temple Place - Suite 330,
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not, write to the Free Software Foundation, Inc., 59 Temple Place - Suite 330,
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Boston, MA 02111-1307, USA. */
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Boston, MA 02111-1307, USA. */
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/*
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/*
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NAME
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NAME
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fdmatch -- see if two file descriptors refer to same file
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fdmatch -- see if two file descriptors refer to same file
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SYNOPSIS
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SYNOPSIS
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int fdmatch (int fd1, int fd2)
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int fdmatch (int fd1, int fd2)
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DESCRIPTION
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DESCRIPTION
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Check to see if two open file descriptors refer to the same file.
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Check to see if two open file descriptors refer to the same file.
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This is useful, for example, when we have an open file descriptor
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This is useful, for example, when we have an open file descriptor
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for an unnamed file, and the name of a file that we believe to
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for an unnamed file, and the name of a file that we believe to
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correspond to that fd. This can happen when we are exec'd with
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correspond to that fd. This can happen when we are exec'd with
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an already open file (stdout for example) or from the SVR4 /proc
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an already open file (stdout for example) or from the SVR4 /proc
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calls that return open file descriptors for mapped address spaces.
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calls that return open file descriptors for mapped address spaces.
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All we have to do is open the file by name and check the two file
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All we have to do is open the file by name and check the two file
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descriptors for a match, which is done by comparing major&minor
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descriptors for a match, which is done by comparing major&minor
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device numbers and inode numbers.
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device numbers and inode numbers.
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BUGS
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BUGS
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(FIXME: does this work for networks?)
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(FIXME: does this work for networks?)
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It works for NFS, which assigns a device number to each mount.
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It works for NFS, which assigns a device number to each mount.
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*/
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*/
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#include "ansidecl.h"
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#include "ansidecl.h"
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#include "libiberty.h"
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#include "libiberty.h"
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#include <sys/types.h>
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#include <sys/types.h>
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#include <sys/stat.h>
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#include <sys/stat.h>
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int fdmatch (fd1, fd2)
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int fdmatch (fd1, fd2)
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int fd1;
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int fd1;
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int fd2;
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int fd2;
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{
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{
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struct stat sbuf1;
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struct stat sbuf1;
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struct stat sbuf2;
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struct stat sbuf2;
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if ((fstat (fd1, &sbuf1) == 0) &&
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if ((fstat (fd1, &sbuf1) == 0) &&
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(fstat (fd2, &sbuf2) == 0) &&
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(fstat (fd2, &sbuf2) == 0) &&
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(sbuf1.st_dev == sbuf2.st_dev) &&
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(sbuf1.st_dev == sbuf2.st_dev) &&
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(sbuf1.st_ino == sbuf2.st_ino))
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(sbuf1.st_ino == sbuf2.st_ino))
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{
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{
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return (1);
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return (1);
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}
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}
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else
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else
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{
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{
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return (0);
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return (0);
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}
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}
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}
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}
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