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1 /* Compare two open file descriptors to see if they refer to the same file.
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2 Copyright (C) 1991 Free Software Foundation, Inc.
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3
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4 This file is part of the libiberty library.
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5 Libiberty is free software; you can redistribute it and/or
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6 modify it under the terms of the GNU Library General Public
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7 License as published by the Free Software Foundation; either
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8 version 2 of the License, or (at your option) any later version.
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9
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10 Libiberty is distributed in the hope that it will be useful,
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11 but WITHOUT ANY WARRANTY; without even the implied warranty of
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12 MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
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13 Library General Public License for more details.
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14
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15 You should have received a copy of the GNU Library General Public
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16 License along with libiberty; see the file COPYING.LIB. If
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17 not, write to the Free Software Foundation, Inc., 51 Franklin Street - Fifth Floor,
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18 Boston, MA 02110-1301, USA. */
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19
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20
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21 /*
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22
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23 @deftypefn Extension int fdmatch (int @var{fd1}, int @var{fd2})
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24
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25 Check to see if two open file descriptors refer to the same file.
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26 This is useful, for example, when we have an open file descriptor for
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27 an unnamed file, and the name of a file that we believe to correspond
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28 to that fd. This can happen when we are exec'd with an already open
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29 file (@code{stdout} for example) or from the SVR4 @file{/proc} calls
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30 that return open file descriptors for mapped address spaces. All we
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31 have to do is open the file by name and check the two file descriptors
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32 for a match, which is done by comparing major and minor device numbers
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33 and inode numbers.
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34
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35 @end deftypefn
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36
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37 BUGS
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38
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39 (FIXME: does this work for networks?)
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40 It works for NFS, which assigns a device number to each mount.
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41
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42 */
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43
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44 #ifdef HAVE_CONFIG_H
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45 #include "config.h"
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46 #endif
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47 #include "ansidecl.h"
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48 #include "libiberty.h"
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49 #include <sys/types.h>
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50 #include <sys/stat.h>
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51
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52 int fdmatch (int fd1, int fd2)
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53 {
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54 struct stat sbuf1;
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55 struct stat sbuf2;
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56
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57 if ((fstat (fd1, &sbuf1) == 0) &&
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58 (fstat (fd2, &sbuf2) == 0) &&
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59 (sbuf1.st_dev == sbuf2.st_dev) &&
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60 (sbuf1.st_ino == sbuf2.st_ino))
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61 {
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62 return (1);
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63 }
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64 else
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65 {
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66 return (0);
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67 }
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68 }
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