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Annotation of GNUtools/libg++/libiberty/fdmatch.c, revision 1.1

1.1     ! root        1: /* Compare two open file descriptors to see if they refer to the same file.
        !             2:    Copyright (C) 1991 Free Software Foundation, Inc.
        !             3: 
        !             4: This file is part of the libiberty library.
        !             5: Libiberty is free software; you can redistribute it and/or
        !             6: modify it under the terms of the GNU Library General Public
        !             7: License as published by the Free Software Foundation; either
        !             8: version 2 of the License, or (at your option) any later version.
        !             9: 
        !            10: Libiberty is distributed in the hope that it will be useful,
        !            11: but WITHOUT ANY WARRANTY; without even the implied warranty of
        !            12: MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
        !            13: Library General Public License for more details.
        !            14: 
        !            15: You should have received a copy of the GNU Library General Public
        !            16: License along with libiberty; see the file COPYING.LIB.  If
        !            17: not, write to the Free Software Foundation, Inc., 675 Mass Ave,
        !            18: Cambridge, MA 02139, USA.  */
        !            19: 
        !            20: 
        !            21: /*
        !            22: 
        !            23: NAME
        !            24: 
        !            25:        fdmatch -- see if two file descriptors refer to same file
        !            26: 
        !            27: SYNOPSIS
        !            28: 
        !            29:        int fdmatch (int fd1, int fd2)
        !            30: 
        !            31: DESCRIPTION
        !            32: 
        !            33:        Check to see if two open file descriptors refer to the same file.
        !            34:        This is useful, for example, when we have an open file descriptor
        !            35:        for an unnamed file, and the name of a file that we believe to 
        !            36:        correspond to that fd.  This can happen when we are exec'd with
        !            37:        an already open file (stdout for example) or from the SVR4 /proc
        !            38:        calls that return open file descriptors for mapped address spaces.
        !            39:        All we have to do is open the file by name and check the two file
        !            40:        descriptors for a match, which is done by comparing major&minor
        !            41:        device numbers and inode numbers.
        !            42: 
        !            43: BUGS
        !            44: 
        !            45:        (FIXME: does this work for networks?)
        !            46:        It works for NFS, which assigns a device number to each mount.
        !            47: 
        !            48: */
        !            49: 
        !            50: #include <sys/types.h>
        !            51: #include <sys/stat.h>
        !            52: 
        !            53: int fdmatch (fd1, fd2)
        !            54:        int fd1;
        !            55:        int fd2;
        !            56: {
        !            57:   struct stat sbuf1;
        !            58:   struct stat sbuf2;
        !            59: 
        !            60:   if ((fstat (fd1, &sbuf1) == 0) &&
        !            61:       (fstat (fd2, &sbuf2) == 0) &&
        !            62:       (sbuf1.st_dev == sbuf2.st_dev) &&
        !            63:       (sbuf1.st_ino == sbuf2.st_ino))
        !            64:     {
        !            65:       return (1);
        !            66:     }
        !            67:   else
        !            68:     {
        !            69:       return (0);
        !            70:     }
        !            71: }

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