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| Rev | Author | Line No. | Line |
|---|---|---|---|
| 212 | dhylands | 1 | /**************************************************************************** |
| 2 | * |
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| 3 | * Copyright (c) 2003 Dave Hylands |
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| 4 | * All Rights Reserved |
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| 5 | * |
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| 6 | * Permission is granted to any individual or institution to use, copy, or |
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| 7 | * redistribute this software so long as it is not sold for profit, and that |
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| 8 | * this copyright notice is retained. |
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| 9 | * |
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| 10 | ****************************************************************************/ |
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| 11 | /** |
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| 12 | * |
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| 13 | * @file StrMaxCpy.cpp |
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| 14 | * |
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| 15 | * @brief Implements StrMaxCpy, a bounded string copy routine. |
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| 16 | * |
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| 17 | ****************************************************************************/ |
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| 18 | |||
| 19 | /* ---- Include Files ---------------------------------------------------- */ |
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| 20 | |||
| 21 | #include "Str.h" |
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| 22 | #include <string.h> |
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| 23 | |||
| 24 | /* ---- Public Variables ------------------------------------------------- */ |
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| 25 | /* ---- Private Constants and Types -------------------------------------- */ |
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| 26 | /* ---- Private Variables ------------------------------------------------ */ |
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| 27 | /* ---- Private Function Prototypes -------------------------------------- */ |
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| 28 | /* ---- Functions -------------------------------------------------------- */ |
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| 29 | |||
| 30 | /** |
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| 31 | * @addtogroup Str |
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| 32 | * @{ |
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| 33 | */ |
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| 34 | |||
| 35 | /***************************************************************************/ |
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| 36 | /** |
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| 37 | * Copies the source to the destination, but makes sure that the |
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| 38 | * destination string (including terminating null), doesn't exceed |
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| 39 | * maxLen. |
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| 40 | * |
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| 41 | * @param dst (out) Place to store the string copy. |
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| 42 | * @param src (in) String to copy. |
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| 43 | * @param maxLen (in) Maximum number of characters to copy into @a dst. |
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| 44 | * |
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| 45 | * @return A pointer to the destination string. |
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| 46 | */ |
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| 47 | |||
| 48 | char *StrMaxCpy( char *dst, const char *src, size_t maxLen ) |
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| 49 | { |
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| 50 | if ( maxLen < 1 ) |
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| 51 | { |
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| 52 | /* |
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| 53 | * There's no room in the buffer? |
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| 54 | */ |
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| 55 | |||
| 56 | return ""; |
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| 57 | } |
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| 58 | |||
| 59 | if ( maxLen == 1 ) |
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| 60 | { |
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| 61 | /* |
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| 62 | * There's only room for the terminating null character |
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| 63 | */ |
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| 64 | |||
| 65 | dst[ 0 ] = '\0'; |
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| 66 | return dst; |
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| 67 | } |
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| 68 | |||
| 69 | /* |
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| 70 | * The Visual C++ version of strncpy writes to every single character |
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| 71 | * of the destination buffer, so we use a length one character smaller |
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| 72 | * and write in our own null (if required). |
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| 73 | * |
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| 74 | * This allows the caller to store a sentinel in the last byte of the |
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| 75 | * buffer to detect overflows (if desired). |
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| 76 | */ |
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| 77 | |||
| 78 | strncpy( dst, src, maxLen - 1 ); |
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| 79 | if (( strlen( src ) + 1 ) >= maxLen ) |
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| 80 | { |
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| 81 | /* |
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| 82 | * The string exactly fits, or probably overflows the buffer. |
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| 83 | * Write in the terminating null character since strncpy doesn't in |
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| 84 | * this particular case. |
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| 85 | * |
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| 86 | * We don't do this arbitrarily so that the caller can use a sentinel |
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| 87 | * in the very end of the buffer to detect buffer overflows. |
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| 88 | */ |
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| 89 | |||
| 90 | dst[ maxLen - 1 ] = '\0'; |
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| 91 | } |
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| 92 | |||
| 93 | return dst; |
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| 94 | |||
| 95 | } /* StrMaxCpy */ |
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| 96 | |||
| 97 | /** @} */ |
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| 98 |