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annotate lib/full-write.c @ 5159:a535859efd14

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Merge from coreutils.
author Paul Eggert <eggert@cs.ucla.edu>
date Sat, 07 Aug 2004 00:09:38 +0000
parents 96e52fc820a5
children a48fb0e98c8c
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1 /* An interface to read and write that retries (if necessary) until complete.
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2
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3 Copyright (C) 1993, 1994, 1997, 1998, 1999, 2000, 2001, 2002, 2003,
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4 2004 Free Software Foundation, Inc.
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5
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6 This program is free software; you can redistribute it and/or modify
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7 it under the terms of the GNU General Public License as published by
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8 the Free Software Foundation; either version 2, or (at your option)
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9 any later version.
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10
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11 This program is distributed in the hope that it will be useful,
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12 but WITHOUT ANY WARRANTY; without even the implied warranty of
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13 MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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14 GNU General Public License for more details.
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15
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16 You should have received a copy of the GNU General Public License
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17 along with this program; if not, write to the Free Software Foundation,
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18 Inc., 59 Temple Place - Suite 330, Boston, MA 02111-1307, USA. */
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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 /* Specification. */
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25 #ifdef FULL_READ
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26 # include "full-read.h"
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27 #else
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28 # include "full-write.h"
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29 #endif
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30
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31 #include <errno.h>
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32
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33 #ifdef FULL_READ
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34 # include "safe-read.h"
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35 # define safe_rw safe_read
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36 # define full_rw full_read
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37 # undef const
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38 # define const /* empty */
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39 #else
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40 # include "safe-write.h"
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41 # define safe_rw safe_write
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42 # define full_rw full_write
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43 #endif
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44
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45 #ifdef FULL_READ
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46 /* Set errno to zero upon EOF. */
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47 # define ZERO_BYTE_TRANSFER_ERRNO 0
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48 #else
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49 /* Some buggy drivers return 0 when one tries to write beyond
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50 a device's end. (Example: Linux 1.2.13 on /dev/fd0.)
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51 Set errno to ENOSPC so they get a sensible diagnostic. */
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52 # define ZERO_BYTE_TRANSFER_ERRNO ENOSPC
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53 #endif
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54
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55 /* Write(read) COUNT bytes at BUF to(from) descriptor FD, retrying if
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56 interrupted or if a partial write(read) occurs. Return the number
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57 of bytes transferred.
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58 When writing, set errno if fewer than COUNT bytes are written.
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59 When reading, if fewer than COUNT bytes are read, you must examine
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60 errno to distinguish failure from EOF (errno == 0). */
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61 size_t
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62 full_rw (int fd, const void *buf, size_t count)
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63 {
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64 size_t total = 0;
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65 const char *ptr = buf;
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66
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67 while (count > 0)
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68 {
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69 size_t n_rw = safe_rw (fd, ptr, count);
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70 if (n_rw == (size_t) -1)
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71 break;
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72 if (n_rw == 0)
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73 {
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74 errno = ZERO_BYTE_TRANSFER_ERRNO;
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75 break;
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76 }
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77 total += n_rw;
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78 ptr += n_rw;
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79 count -= n_rw;
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80 }
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81
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82 return total;
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83 }