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1234 | cejka | 1 | /* |
2 | * Copyright (C) 2006 Josef Cejka |
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3 | * All rights reserved. |
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4 | * |
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5 | * Redistribution and use in source and binary forms, with or without |
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6 | * modification, are permitted provided that the following conditions |
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7 | * are met: |
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8 | * |
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9 | * - Redistributions of source code must retain the above copyright |
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10 | * notice, this list of conditions and the following disclaimer. |
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11 | * - Redistributions in binary form must reproduce the above copyright |
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12 | * notice, this list of conditions and the following disclaimer in the |
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13 | * documentation and/or other materials provided with the distribution. |
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14 | * - The name of the author may not be used to endorse or promote products |
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15 | * derived from this software without specific prior written permission. |
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16 | * |
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17 | * THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR |
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18 | * IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES |
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19 | * OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED. |
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20 | * IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT, |
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21 | * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT |
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22 | * NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, |
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23 | * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY |
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24 | * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT |
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25 | * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF |
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26 | * THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE. |
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27 | */ |
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28 | |||
29 | #include <stdarg.h> |
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30 | #include <stdio.h> |
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31 | #include <string.h> |
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32 | #include <io/printf_core.h> |
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33 | |||
34 | |||
35 | struct vsnprintf_data { |
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36 | size_t size; /* total space for string */ |
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37 | size_t len; /* count of currently used characters */ |
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38 | char *string; /* destination string */ |
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39 | }; |
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40 | |||
41 | int vsnprintf_write(const char *str, size_t count, struct vsnprintf_data *data); |
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42 | |||
43 | /** Write string to given buffer. |
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44 | * Write at most data->size characters including trailing zero. According to C99 has snprintf to return number |
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45 | * of characters that would have been written if enough space had been available. Hence the return value is not |
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46 | * number of really printed characters but size of input string. Number of really used characters |
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47 | * is stored in data->len. |
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48 | * @param str source string to print |
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49 | * @param count size of source string |
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50 | * @param data structure with destination string, counter of used space and total string size. |
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51 | * @return number of characters to print (not characters really printed!) |
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52 | */ |
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53 | int vsnprintf_write(const char *str, size_t count, struct vsnprintf_data *data) |
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54 | { |
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1617 | cejka | 55 | size_t i; |
1234 | cejka | 56 | i = data->size - data->len; |
57 | |||
1617 | cejka | 58 | if (i == 0) { |
59 | return count; |
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1234 | cejka | 60 | } |
61 | |||
1617 | cejka | 62 | if (i == 1) { |
63 | /* We have only one free byte left in buffer => write there trailing zero */ |
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64 | data->string[data->size - 1] = 0; |
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65 | data->len = data->size; |
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66 | return count; |
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67 | } |
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68 | |||
69 | if (i <= count) { |
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70 | /* We have not enought space for whole string with the trailing zero => print only a part of string */ |
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71 | memcpy((void *)(data->string + data->len), (void *)str, i - 1); |
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72 | data->string[data->size - 1] = 0; |
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73 | data->len = data->size; |
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74 | return count; |
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75 | } |
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76 | |||
77 | /* Buffer is big enought to print whole string */ |
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78 | memcpy((void *)(data->string + data->len), (void *)str, count); |
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79 | data->len += count; |
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80 | /* Put trailing zero at end, but not count it into data->len so it could be rewritten next time */ |
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81 | data->string[data->len] = 0; |
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82 | |||
1234 | cejka | 83 | return count; |
84 | } |
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85 | |||
86 | int vsnprintf(char *str, size_t size, const char *fmt, va_list ap) |
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87 | { |
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88 | struct vsnprintf_data data = {size, 0, str}; |
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89 | struct printf_spec ps = {(int(*)(void *, size_t, void *))vsnprintf_write, &data}; |
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90 | |||
91 | /* Print 0 at end of string - fix the case that nothing will be printed */ |
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92 | if (size > 0) |
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93 | str[0] = 0; |
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94 | |||
95 | /* vsnprintf_write ensures that str will be terminated by zero. */ |
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96 | return printf_core(fmt, &ps, ap); |
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97 | } |
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98 | |||
99 |