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Merge pull request #9 from mcci-catena/issue8
Add McciAdkLib_SafeCopyString()
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/* | ||
Module: mcciadklib_safecopystring.c | ||
Function: | ||
Home for McciAdkLib_SafeCopyString() | ||
Copyright notice: | ||
See accompanying LICENSE file | ||
Author: | ||
ChaeHee Won, MCCI Corporation November 2013 | ||
*/ | ||
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#include "mcciadk_baselib.h" | ||
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/****************************************************************************\ | ||
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| Manifest constants & typedefs. | ||
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\****************************************************************************/ | ||
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/****************************************************************************\ | ||
| | ||
| Read-only data. | ||
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\****************************************************************************/ | ||
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/****************************************************************************\ | ||
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| Variables. | ||
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\****************************************************************************/ | ||
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/* | ||
Name: McciAdkLib_SafeCopyString() | ||
Function: | ||
String copy rotuine that is reasonably safe to use. | ||
Definition: | ||
size_t | ||
McciAdkLib_SafeCopyString( | ||
char *pBuffer, | ||
size_t nBuffer, | ||
size_t iBuffer, | ||
const char *pString | ||
); | ||
Description: | ||
This routine copyies memory from the input string to the given | ||
offset in the buffer, and appends a '\0', taking into account | ||
the size of the buffer. | ||
pBuffer is a buffer that has nBuffer bytes allocated to it. | ||
pString points to a '\0'-terminated string (ANSI, UTF-8, etc -- | ||
encoding is not critical as long as '\0' always designates the | ||
end of the string. | ||
Bytes from pString are copied to pBuffer + iBuffer. In no case | ||
will data be written outside the range of bytes pBuffer[0..nBuffer). | ||
The resulting string at pBuffer+iBuffer is guaranteed to be '\0'- | ||
terminated. Therefore, the maximum string size that can be handled | ||
without truncation is (nBuffer - iBuffer - 1) bytes long. | ||
We can consider boundary conditions without loss of generality by | ||
considering only the case where iBuffer == 0. | ||
If pBuffer == NULL, pString == NULL or nBuffer == 0, then the result | ||
is always 0. | ||
if nBuffer == 1, then the result is also always 0, but pBuffer[0] | ||
will be set to '\0'. | ||
If nBuffer > strlen(pString), then the entire string will be copied | ||
to pBuffer, and a trailing '\0' is provided. | ||
If nBuffer == strlen(pString), then all but the last byte is copied, | ||
a trailing '\0' is provided, and the result is (nBuffer - 1), or | ||
equivalently strlen(pString)-1. | ||
Returns: | ||
Number of bytes of pString placed into the buffer. | ||
The result + iBuffer will always be less than nBuffer (in order | ||
to guarantee a trailing '\0'), unless nBuffer is zero. | ||
Notes: | ||
If (iBuffer + the result) >= nBuffer, then you should assume | ||
that one or more bytes of the string was truncated. If nBuffer>0, | ||
and iBuffer + the result == nBuffer-1, then the string may have | ||
been truncated. | ||
This implementation favors simplicity and correctness over raw | ||
speed. | ||
*/ | ||
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size_t | ||
McciAdkLib_SafeCopyString( | ||
char *pBuffer, | ||
size_t nBuffer, | ||
size_t iBuffer, | ||
const char *pString | ||
) | ||
{ | ||
char *p; | ||
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if (pBuffer == NULL || nBuffer == 0) | ||
return 0; | ||
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if (iBuffer >= nBuffer-1) | ||
{ | ||
pBuffer[nBuffer-1] = '\0'; | ||
return 0; | ||
} | ||
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pBuffer += iBuffer; | ||
nBuffer -= iBuffer; | ||
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for (p = pBuffer; nBuffer > 1; --nBuffer) | ||
{ | ||
const char c = *pString++; | ||
if (c == 0) | ||
break; | ||
*p++ = c; | ||
} | ||
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*p = '\0'; | ||
return p - pBuffer; | ||
} | ||
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/**** end of mcciadklib_safecopystring.c ****/ |
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