regex: add/document missing offset param (#1175)

* Regex Little Changes

* Prevented to triple and double call `strlen`.
* More informative message on `if (offset >= len)`.
* Add missing parametr in navite `MatchRegex`.

* Regex Little Changes v2

* Using `strdup` instead `strcpy`.
* Replaced NULL to nullptr.
* Removed note about MatchOffset.

Co-Authored-By: Headline <headline@users.noreply.github.com>

* Removed padding.

Co-Authored-By: Headline <headline@users.noreply.github.com>

* Removed more padding.

Co-Authored-By: Headline <headline@users.noreply.github.com>

Co-authored-by: Headline <michaelwflaherty@me.com>

extensions/regex/CRegEx.cpp

@@ -39,25 +39,25 @@ RegEx::RegEx()
 {
 	mErrorOffset = 0;
 	mErrorCode = 0;
-	mError = NULL;
-	re = NULL;
+	mError = nullptr;
+	re = nullptr;
 	mFree = true;
-	subject = NULL;
+	subject = nullptr;
 	mMatchCount = 0;
 }
 
 void RegEx::Clear ()
 {
 	mErrorOffset = 0;
 	mErrorCode = 0;
-	mError = NULL;
+	mError = nullptr;
 	if (re)
 		pcre_free(re);
-	re = NULL;
+	re = nullptr;
 	mFree = true;
 	if (subject)
 		delete [] subject;
-	subject = NULL;
+	subject = nullptr;
 	mMatchCount = 0;
 }
 
@@ -82,9 +82,9 @@ int RegEx::Compile(const char *pattern, int iFlags)
 	if (!mFree)
 		Clear();
 
-	re = pcre_compile2(pattern, iFlags, &mErrorCode, &mError, &mErrorOffset, NULL);
+	re = pcre_compile2(pattern, iFlags, &mErrorCode, &mError, &mErrorOffset, nullptr);
 
-	if (re == NULL)
+	if (re == nullptr)
 	{
 		return 0;
 	}
@@ -94,22 +94,19 @@ int RegEx::Compile(const char *pattern, int iFlags)
 	return 1;
 }
 
-int RegEx::Match(const char *str, unsigned int offset)
+int RegEx::Match(const char *const str, const size_t offset)
 {
 	int rc = 0;
 
-	if (mFree || re == NULL)
+	if (mFree || re == nullptr)
 		return -1;
 
 	this->ClearMatch();
 
 	//save str
-	subject = new char[strlen(str)+1];
-	strcpy(subject, str);
+	subject = strdup(str);
 
-	unsigned int len = strlen(subject);
-
-	rc = pcre_exec(re, NULL, subject, len, offset, 0, mMatches[0].mVector, MAX_CAPTURES);
+	rc = pcre_exec(re, nullptr, subject, strlen(subject), offset, 0, mMatches[0].mVector, MAX_CAPTURES);
 
 	if (rc < 0)
 	{
@@ -132,17 +129,16 @@ int RegEx::MatchAll(const char *str)
 {
 	int rc = 0;
 
-	if (mFree || re == NULL)
+	if (mFree || re == nullptr)
 		return -1;
 
 	this->ClearMatch();
 
 	//save str
-	subject = new char[strlen(str) + 1];
-	strcpy(subject, str);
+	subject = strdup(str);
+	size_t len = strlen(subject);
 
-	unsigned int offset = 0;
-	unsigned int len = strlen(subject);
+	size_t offset = 0;
 	unsigned int matches = 0;
 
 	while (matches < MAX_MATCHES && offset < len && (rc = pcre_exec(re, 0, subject, len, offset, 0, mMatches[matches].mVector, MAX_CAPTURES)) >= 0)
@@ -175,10 +171,10 @@ void RegEx::ClearMatch()
 	// Clears match results
 	mErrorOffset = 0;
 	mErrorCode = 0;
-	mError = NULL;
+	mError = nullptr;
 	if (subject)
 		delete [] subject;
-	subject = NULL;
+	subject = nullptr;
 	mMatchCount = 0;
 }
 

extensions/regex/CRegEx.h

@@ -51,7 +51,7 @@ class RegEx
 	void Clear();
 
 	int Compile(const char *pattern, int iFlags);
-	int Match(const char *str, unsigned int offset);
+	int Match(const char *const str, const size_t offset);
 	int MatchAll(const char *str);
 	void ClearMatch();
 	bool GetSubstring(int s, char buffer[], int max, int match);

extensions/regex/extension.cpp

@@ -114,35 +114,33 @@ static cell_t MatchRegex(IPluginContext *pCtx, const cell_t *params)
 	sec.pOwner = NULL;
 	sec.pIdentity = myself->GetIdentity();
 
-	unsigned int offset = 0;
-
-	if (params[0] >= 4)
-	{
-		offset = (unsigned int)params[4];
-	}
-
 	RegEx *x;
-
 	if ((err=g_pHandleSys->ReadHandle(hndl, g_RegexHandle, &sec, (void **)&x)) != HandleError_None)
 	{
 		return pCtx->ThrowNativeError("Invalid regex handle %x (error %d)", hndl, err);
 	}
-
 	if (!x)
 	{
 		pCtx->ThrowNativeError("Regex data not found\n");
-
 		return 0;
 	}
 
+	size_t offset = 0;
+	if (params[0] >= 4)
+	{
+		offset = static_cast<size_t>(params[4]);
+	}
+
 	char *str;
 	pCtx->LocalToString(params[2], &str);
 
-	if(offset >= strlen(str))
-		return pCtx->ThrowNativeError("Invalid string index\n");
+	size_t len = strlen(str);
+	if (offset >= len)
+	{
+		return pCtx->ThrowNativeError("Offset greater or equal than string length\n");
+	}
 
 	int e = x->Match(str, offset);
-
 	if (e == -1)
 	{
 		/* there was a match error.  move on. */

plugins/include/regex.inc

@@ -199,12 +199,13 @@ native Regex CompileRegex(const char[] pattern, int flags = 0, char[] error="",
  * @param regex         Regex Handle from CompileRegex()
  * @param str           The string to check.
  * @param ret           Error code, if applicable.
+ * @param offset        Offset in the string to start searching from.
  * @return              Number of captures found or -1 on failure.
  *
  * @note Use the regex handle passed to this function to extract
  *       matches with GetRegexSubString().
  */
-native int MatchRegex(Handle regex, const char[] str, RegexError &ret = REGEX_ERROR_NONE);
+native int MatchRegex(Handle regex, const char[] str, RegexError &ret = REGEX_ERROR_NONE, int offset = 0);
 
 /**
  * Returns a matched substring from a regex handle.