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annotate lib/areadlink-with-size.c @ 15727:144db791c6fa

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Ensure EBADF returns for socket functions on mingw. * lib/accept.c (rpl_accept): Fail with error EBADF if the file descriptor is invalid. * lib/bind.c (rpl_bind): Likewise. * lib/connect.c (rpl_connect): Likewise. * lib/getpeername.c (rpl_getpeername): Likewise. * lib/getsockname.c (rpl_getsockname): Likewise. * lib/getsockopt.c (rpl_getsockopt): Likewise. * lib/listen.c (rpl_listen): Likewise. * lib/recv.c (rpl_recv): Likewise. * lib/recvfrom.c (rpl_recvfrom): Likewise. * lib/send.c (rpl_send): Likewise. * lib/sendto.c (rpl_sendto): Likewise. * lib/setsockopt.c (rpl_setsockopt): Likewise. * lib/shutdown.c (rpl_shutdown): Likewise.
author Bruno Haible <bruno@clisp.org>
date Wed, 21 Sep 2011 00:20:59 +0200
parents 97fc9a21a8fb
children 8250f2777afc
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1 /* readlink wrapper to return the link name in malloc'd storage.
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2 Unlike xreadlink and xreadlink_with_size, don't ever call exit.
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3
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4 Copyright (C) 2001, 2003-2007, 2009-2011 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 3 of the License, or
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9 (at your option) 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, see <http://www.gnu.org/licenses/>. */
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18
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19 /* Written by Jim Meyering <jim@meyering.net> */
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20
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21 #include <config.h>
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22
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23 #include "areadlink.h"
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24
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25 #include <errno.h>
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26 #include <limits.h>
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27 #include <stdint.h>
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28 #include <stdlib.h>
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29 #include <unistd.h>
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30
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31 #ifndef SSIZE_MAX
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32 # define SSIZE_MAX ((ssize_t) (SIZE_MAX / 2))
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33 #endif
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34
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35 /* SYMLINK_MAX is used only for an initial memory-allocation sanity
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36 check, so it's OK to guess too small on hosts where there is no
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37 arbitrary limit to symbolic link length. */
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38 #ifndef SYMLINK_MAX
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39 # define SYMLINK_MAX 1024
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40 #endif
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41
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42 #define MAXSIZE (SIZE_MAX < SSIZE_MAX ? SIZE_MAX : SSIZE_MAX)
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43
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44 /* Call readlink to get the symbolic link value of FILE.
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45 SIZE is a hint as to how long the link is expected to be;
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46 typically it is taken from st_size. It need not be correct.
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47 Return a pointer to that NUL-terminated string in malloc'd storage.
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48 If readlink fails, malloc fails, or if the link value is longer
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49 than SSIZE_MAX, return NULL (caller may use errno to diagnose). */
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50
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51 char *
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52 areadlink_with_size (char const *file, size_t size)
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53 {
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54 /* Some buggy file systems report garbage in st_size. Defend
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55 against them by ignoring outlandish st_size values in the initial
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56 memory allocation. */
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57 size_t symlink_max = SYMLINK_MAX;
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58 size_t INITIAL_LIMIT_BOUND = 8 * 1024;
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59 size_t initial_limit = (symlink_max < INITIAL_LIMIT_BOUND
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60 ? symlink_max + 1
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61 : INITIAL_LIMIT_BOUND);
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62
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63 /* The initial buffer size for the link value. */
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64 size_t buf_size = size < initial_limit ? size + 1 : initial_limit;
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65
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66 while (1)
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67 {
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68 ssize_t r;
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69 size_t link_length;
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70 char *buffer = malloc (buf_size);
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71
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72 if (buffer == NULL)
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73 return NULL;
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74 r = readlink (file, buffer, buf_size);
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75 link_length = r;
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76
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77 /* On AIX 5L v5.3 and HP-UX 11i v2 04/09, readlink returns -1
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78 with errno == ERANGE if the buffer is too small. */
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79 if (r < 0 && errno != ERANGE)
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80 {
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81 int saved_errno = errno;
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82 free (buffer);
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83 errno = saved_errno;
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84 return NULL;
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85 }
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86
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87 if (link_length < buf_size)
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88 {
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89 buffer[link_length] = 0;
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90 return buffer;
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91 }
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92
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93 free (buffer);
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94 if (buf_size <= MAXSIZE / 2)
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95 buf_size *= 2;
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96 else if (buf_size < MAXSIZE)
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97 buf_size = MAXSIZE;
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98 else
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99 {
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100 errno = ENOMEM;
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101 return NULL;
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102 }
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103 }
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104 }