1 | /* Convert Inet number to ASCII representation. |
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2 | Copyright (C) 1997, 1998, 2000, 2001 Free Software Foundation, Inc. |
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3 | This file is part of the GNU C Library. |
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4 | Contributed by Ulrich Drepper <drepper@cygnus.com>, 1997. |
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5 | |
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6 | The GNU C Library is free software; you can redistribute it and/or |
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7 | modify it under the terms of the GNU Lesser General Public |
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8 | License as published by the Free Software Foundation; either |
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9 | version 2.1 of the License, or (at your option) any later version. |
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10 | |
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11 | The GNU C Library 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 GNU |
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14 | Lesser 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 Lesser General Public |
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17 | License along with the GNU C Library; if not, write to the Free |
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18 | Software Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA |
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19 | 02111-1307 USA. */ |
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20 | |
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21 | #include <stdio.h> |
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22 | #include <stdlib.h> |
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23 | #include <arpa/inet.h> |
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24 | #include <bits/libc-lock.h> |
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25 | |
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26 | /* The interface of this function is completely stupid, it requires a |
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27 | static buffer. We relax this a bit in that we allow at least one |
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28 | buffer for each thread. */ |
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29 | |
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30 | /* This is the key for the thread specific memory. */ |
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31 | static __libc_key_t key; |
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32 | |
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33 | /* If nonzero the key allocation failed and we should better use a |
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34 | static buffer than fail. */ |
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35 | static char local_buf[18]; |
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36 | static char *static_buf; |
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37 | |
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38 | /* Destructor for the thread-specific data. */ |
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39 | static void init (void); |
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40 | static void free_key_mem (void *mem); |
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41 | |
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42 | |
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43 | char * |
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44 | inet_ntoa (struct in_addr in) |
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45 | { |
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46 | __libc_once_define (static, once); |
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47 | char *buffer; |
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48 | unsigned char *bytes; |
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49 | |
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50 | /* If we have not yet initialized the buffer do it now. */ |
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51 | __libc_once (once, init); |
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52 | |
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53 | if (static_buf != NULL) |
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54 | buffer = static_buf; |
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55 | else |
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56 | { |
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57 | /* We don't use the static buffer and so we have a key. Use it |
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58 | to get the thread-specific buffer. */ |
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59 | buffer = __libc_getspecific (key); |
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60 | if (buffer == NULL) |
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61 | { |
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62 | /* No buffer allocated so far. */ |
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63 | buffer = malloc (18); |
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64 | if (buffer == NULL) |
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65 | /* No more memory available. We use the static buffer. */ |
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66 | buffer = local_buf; |
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67 | else |
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68 | __libc_setspecific (key, buffer); |
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69 | } |
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70 | } |
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71 | |
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72 | bytes = (unsigned char *) ∈ |
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73 | snprintf (buffer, 18, "%d.%d.%d.%d", |
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74 | bytes[0], bytes[1], bytes[2], bytes[3]); |
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75 | |
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76 | return buffer; |
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77 | } |
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78 | |
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79 | |
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80 | /* Initialize buffer. */ |
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81 | static void |
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82 | init (void) |
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83 | { |
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84 | if (__libc_key_create (&key, free_key_mem)) |
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85 | /* Creating the key failed. This means something really went |
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86 | wrong. In any case use a static buffer which is better than |
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87 | nothing. */ |
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88 | static_buf = local_buf; |
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89 | } |
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90 | |
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91 | |
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92 | /* Free the thread specific data, this is done if a thread terminates. */ |
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93 | static void |
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94 | free_key_mem (void *mem) |
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95 | { |
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96 | free (mem); |
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97 | __libc_setspecific (key, NULL); |
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98 | } |
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