StringCchCatN (Windows CE 5.0)
Developing an Application > Safe String Functions > Safe String Reference > StrSafe.h Character-Count Functions
This function is a replacement for strncat.
The size, in characters, of the destination buffer is provided to the function to ensure that StringCchCatN does not write past the end of this buffer.
HRESULT StringCchCatN( LPTSTR pszDest, size_t cchDest, LPCTSTR pszSrc, size_t cchMaxAppend);
Parameters
pszDest
[in, out] Pointer to a buffer containing the string that pszSrc is concatenated to, and which contains the entire resultant string.The string at pszSrc, up to cchMaxAppend characters, is added to the end of the string at pszDest.
cchDest
[in] Size of the destination buffer, in characters.This value must equal the length of pszSrc, plus the length of pszDest or cchMaxAppend (whichever is smaller).
To this sum, add 1 to account for the terminating null character.
The maximum number of characters allowed is STRSAFE_MAX_CCH.
pszSrc
[in] Pointer to a buffer containing the source string that is concatenated to the end of pszDest.This source string must be null-terminated.
cchMaxAppend
[in] The maximum number of characters to append to pszDest.
Return Value
This function returns an HRESULT, as opposed to strncat, which returns a pointer.
It is strongly recommended that you use the SUCCEEDED and FAILED macros to test the return value of this function.
| Value | Description |
|---|---|
| S_OK | Source data was present, the strings were concatenated without truncation, and the resultant destination buffer is null-terminated. |
| STRSAFE_E_INVALID_PARAMETER | The value in cchDest is larger than STRSAFE_MAX_CCH, or the destination buffer is already full. |
| STRSAFE_E_INSUFFICIENT_BUFFER | The concatenation operation failed due to insufficient buffer space.
The destination buffer contains a truncated, null-terminated version of the intended result. Where truncation is acceptable, this is not necessarily a failure condition. |
Remarks
StringCchCatN provides additional processing for proper buffer handling in your code.
Poor buffer handling is implicated in many security issues that involve buffer overruns. StringCchCatN always null-terminates a nonzero-length destination buffer.
StringCchCatN can be used in its generic form, or specifically as StringCchCatNA (for ANSI strings) or StringCchCatNW (for Unicode strings). The form to use is determined by your data.
| String data type | String literal | Function |
|---|---|---|
| char | "string" | StringCchCatNA |
| TCHAR | TEXT("string") | StringCchCatN |
| WCHAR | L"string" | StringCchCatNW |
StringCchCatN and its ANSI and Unicode variants are replacements for these functions:
Behavior is undefined if the strings pointed to by pszSrc and pszDest overlap.
Neither pszSrc nor pszDest should be NULL.
If you need the handling of null string pointer values, see StringCchCatNEx.
Requirements
OS Versions: Windows CE 5.0 and later.
Header: strsafe.h.
Link Library: strsafe.lib.
See Also
StringCbCatN | StringCchCatNEx | StringCchCat
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