[UCRT] Import Microsoft.Windows.SDK.CRTSource version 10.0.22621.3

Imported from https://www.nuget.org/packages/Microsoft.Windows.SDK.CRTSource/10.0.22621.3
License: MIT

sdk/lib/ucrt/string/strtok_s.cpp

@@ -0,0 +1,83 @@
+//
+// strtok_s.cpp
+//
+//      Copyright (c) Microsoft Corporation.  All rights reserved.
+//
+// Defines strtok_s(), which tokenizes a string via repeated calls.  See strtok()
+// for more details.  This more secure function uses a caller-provided context
+// instead of the thread-local tokenization state.
+//
+#include <string.h>
+#include <corecrt_internal_securecrt.h>
+
+
+
+// This common implementation is used by both strtok() and strtok_s()
+extern "C" char* __cdecl __acrt_strtok_s_novalidation(
+    _Inout_opt_z_                 char*       string,
+    _In_z_                        char const* control,
+    _Inout_ _Deref_prepost_opt_z_ char**      context
+    )
+{
+    // Clear control map.  The control characters are stored in a bitmap, one
+    // bit per character.  The null character is always a control character.
+    unsigned char map[32];
+    for (int count = 0; count < 32; count++)
+    {
+        map[count] = 0;
+    }
+
+    // Set bits in delimiter table
+    unsigned char const* unsigned_control = reinterpret_cast<unsigned char const*>(control);
+    do
+    {
+        map[*unsigned_control >> 3] |= (1 << (*unsigned_control & 7));
+    }
+    while (*unsigned_control++);
+
+    // If string is null, set the iterator to the saved pointer (i.e., continue
+    // breaking tokens out of the string from the last strtok call):
+    char* it = string != nullptr
+        ? string
+        : *context;
+
+    unsigned char*& unsigned_it = reinterpret_cast<unsigned char*&>(it);
+
+    // Find beginning of token (skip over leading delimiters). Note that
+    // there is no token iff this loop sets it to point to the terminal
+    // null (*it == '\0')
+    while ((map[*unsigned_it >> 3] & (1 << (*unsigned_it & 7))) && *it)
+    {
+        ++it;
+    }
+
+    char* const token_first = it;
+
+    // Find the end of the token. If it is not the end of the string,
+    // put a null there.
+    for (; *it; ++it)
+    {
+        if (map[*unsigned_it >> 3] & (1 << (*unsigned_it & 7)))
+        {
+            *it++ = '\0';
+            break;
+        }
+    }
+
+    // Update the saved pointer:
+    *context = it;
+
+    // Determine if a token has been found.
+    return it != token_first ? token_first : nullptr;
+}
+
+
+
+extern "C" char* __cdecl strtok_s(char* string, char const* control, char** context)
+{
+    _VALIDATE_POINTER_ERROR_RETURN(context, EINVAL, nullptr);
+    _VALIDATE_POINTER_ERROR_RETURN(control, EINVAL, nullptr);
+    _VALIDATE_CONDITION_ERROR_RETURN(string != nullptr || *context != nullptr, EINVAL, nullptr);
+
+    return __acrt_strtok_s_novalidation(string, control, context);
+}