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1822
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1 /* Duplicate an open file descriptor to a specified file descriptor. |
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2 Copyright 1999 Free Software Foundation, Inc. |
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3 |
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4 This program is free software; you can redistribute it and/or modify |
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5 it under the terms of the GNU General Public License as published by |
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6 the Free Software Foundation; either version 2, or (at your option) |
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7 any later version. |
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8 |
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9 This program is distributed in the hope that it will be useful, |
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10 but WITHOUT ANY WARRANTY; without even the implied warranty of |
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11 MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the |
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12 GNU General Public License for more details. |
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13 |
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14 You should have received a copy of the GNU General Public License |
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15 along with this program; if not, write to the Free Software Foundation, |
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16 Inc., 59 Temple Place - Suite 330, Boston, MA 02111-1307, USA. */ |
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17 |
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18 /* written by Paul Eggert */ |
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19 |
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20 #if HAVE_CONFIG_H |
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21 # include <config.h> |
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22 #endif |
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23 |
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24 #include <errno.h> |
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25 #ifndef errno |
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26 extern int errno; |
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27 #endif |
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28 |
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29 #if HAVE_FCNTL_H |
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30 # include <fcntl.h> |
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31 #endif |
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32 |
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33 #if HAVE_UNISTD_H |
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34 # include <unistd.h> |
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35 #endif |
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36 |
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37 #ifndef F_DUPFD |
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38 static int |
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39 dupfd (int fd, int desired_fd) |
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40 { |
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41 int duplicated_fd = dup (fd); |
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42 if (duplicated_fd < 0 || duplicated_fd == desired_fd) |
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43 return duplicated_fd; |
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44 else |
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45 { |
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46 int r = dupfd (fd, desired_fd); |
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47 int e = errno; |
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48 close (duplicated_fd); |
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49 errno = e; |
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50 return r; |
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51 } |
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52 } |
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53 #endif |
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54 |
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55 int |
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56 dup2 (int fd, int desired_fd) |
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57 { |
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58 if (fd == desired_fd) |
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59 return fd; |
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60 close (desired_fd); |
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61 #ifdef F_DUPFD |
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62 return fcntl (fd, F_DUPFD, desired_fd); |
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63 #else |
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64 return dupfd (fd, desired_fd); |
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65 #endif |
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66 } |
