Index: /trunk/include/iprt/string.h
===================================================================
--- /trunk/include/iprt/string.h	(revision 31220)
+++ /trunk/include/iprt/string.h	(revision 31221)
@@ -829,5 +829,5 @@
  * @param   psz         The string.
  */
-#define RTStrCalcLatin1Len(psz) RTStrUniLen(psz)
+RTDECL(size_t) RTStrCalcLatin1Len(const char *psz);
 
 /**
@@ -843,5 +843,5 @@
  *                      This is undefined on failure.
  */
-#define RTStrCalcLatin1LenEx(psz, cch, pcch) RTStrUniLenEx(psz, cch, pcch)
+RTDECL(int) RTStrCalcLatin1LenEx(const char *psz, size_t cch, size_t *pcwc);
 
 /**
Index: /trunk/src/VBox/Runtime/common/string/utf-8.cpp
===================================================================
--- /trunk/src/VBox/Runtime/common/string/utf-8.cpp	(revision 31220)
+++ /trunk/src/VBox/Runtime/common/string/utf-8.cpp	(revision 31221)
@@ -840,5 +840,5 @@
     while (cchIn > 0)
     {
-        char ch = *pszIn++; cchIn--;
+        unsigned char ch = (unsigned char) *pszIn++; cchIn--;
         if (!ch)
             break;
@@ -1000,10 +1000,128 @@
  * @param   cch     The max length of the string. (btw cch = cb)
  *                  Use RTSTR_MAX if all of the string is to be examined.
- * @param   pcwc    Where to store the length of the Latin-1 string in bytes.
+ * @param   pcch    Where to store the length of the Latin-1 string in bytes.
  */
 static int rtUtf8CalcLatin1Length(const char *psz, size_t cch, size_t *pcch)
 {
-    /* We re-encode to one byte per unicode code point. */
-    return RTStrUniLenEx(psz, cch, pcch);
+    const unsigned char *puch = (const unsigned char *)psz;
+    size_t cchOut = 0;
+    while (cch > 0)
+    {
+        const unsigned char uch = *puch;
+        if (!uch)
+            break;
+        if (!(uch & RT_BIT(7)))
+        {
+             /* one ASCII byte */
+            cchOut++;
+            puch++;
+            cch--;
+        }
+        else
+        {
+            /* figure sequence length and validate the first byte */
+            unsigned cb;
+            if ((uch & (RT_BIT(7) | RT_BIT(6) | RT_BIT(5))) == (RT_BIT(7) | RT_BIT(6)))
+                cb = 2;
+            else if ((uch & (RT_BIT(7) | RT_BIT(6) | RT_BIT(5) | RT_BIT(4))) == (RT_BIT(7) | RT_BIT(6) | RT_BIT(5)))
+                cb = 3;
+            else if ((uch & (RT_BIT(7) | RT_BIT(6) | RT_BIT(5) | RT_BIT(4) | RT_BIT(3))) == (RT_BIT(7) | RT_BIT(6) | RT_BIT(5) | RT_BIT(4)))
+                cb = 4;
+            else if ((uch & (RT_BIT(7) | RT_BIT(6) | RT_BIT(5) | RT_BIT(4) | RT_BIT(3) | RT_BIT(2))) == (RT_BIT(7) | RT_BIT(6) | RT_BIT(5) | RT_BIT(4) | RT_BIT(3)))
+                cb = 5;
+            else if ((uch & (RT_BIT(7) | RT_BIT(6) | RT_BIT(5) | RT_BIT(4) | RT_BIT(3) | RT_BIT(2) | RT_BIT(1))) == (RT_BIT(7) | RT_BIT(6) | RT_BIT(5) | RT_BIT(4) | RT_BIT(3) | RT_BIT(2)))
+                cb = 6;
+            else
+            {
+                RTStrAssertMsgFailed(("Invalid UTF-8 first byte: %.*Rhxs\n", RT_MIN(cch, 10), puch));
+                return VERR_INVALID_UTF8_ENCODING;
+            }
+
+            /* check length */
+            if (cb > cch)
+            {
+                RTStrAssertMsgFailed(("Invalid UTF-8 length: cb=%d cch=%d (%.*Rhxs)\n", cb, cch, RT_MIN(cch, 10), puch));
+                return VERR_INVALID_UTF8_ENCODING;
+            }
+
+            /* validate the rest */
+            switch (cb)
+            {
+                case 6:
+                    RTStrAssertMsgReturn((puch[5] & (RT_BIT(7) | RT_BIT(6))) == RT_BIT(7), ("6/%u: %.*Rhxs\n", cb, RT_MIN(cb + 10, cch), puch), VERR_INVALID_UTF8_ENCODING);
+                case 5:
+                    RTStrAssertMsgReturn((puch[4] & (RT_BIT(7) | RT_BIT(6))) == RT_BIT(7), ("5/%u: %.*Rhxs\n", cb, RT_MIN(cb + 10, cch), puch), VERR_INVALID_UTF8_ENCODING);
+                case 4:
+                    RTStrAssertMsgReturn((puch[3] & (RT_BIT(7) | RT_BIT(6))) == RT_BIT(7), ("4/%u: %.*Rhxs\n", cb, RT_MIN(cb + 10, cch), puch), VERR_INVALID_UTF8_ENCODING);
+                case 3:
+                    RTStrAssertMsgReturn((puch[2] & (RT_BIT(7) | RT_BIT(6))) == RT_BIT(7), ("3/%u: %.*Rhxs\n", cb, RT_MIN(cb + 10, cch), puch), VERR_INVALID_UTF8_ENCODING);
+                case 2:
+                    RTStrAssertMsgReturn((puch[1] & (RT_BIT(7) | RT_BIT(6))) == RT_BIT(7), ("2/%u: %.*Rhxs\n", cb, RT_MIN(cb + 10, cch), puch), VERR_INVALID_UTF8_ENCODING);
+                   break;
+            }
+
+            /* validate the code point. */
+            RTUNICP uc;
+            switch (cb)
+            {
+                case 6:
+                    uc =            (puch[5] & 0x3f)
+                        | ((RTUNICP)(puch[4] & 0x3f) << 6)
+                        | ((RTUNICP)(puch[3] & 0x3f) << 12)
+                        | ((RTUNICP)(puch[2] & 0x3f) << 18)
+                        | ((RTUNICP)(puch[1] & 0x3f) << 24)
+                        | ((RTUNICP)(uch     & 0x01) << 30);
+                    RTStrAssertMsgReturn(uc >= 0x04000000 && uc <= 0x7fffffff,
+                                         ("%u: cp=%#010RX32: %.*Rhxs\n", cb, uc, RT_MIN(cb + 10, cch), puch), VERR_INVALID_UTF8_ENCODING);
+                    break;
+                case 5:
+                    uc =            (puch[4] & 0x3f)
+                        | ((RTUNICP)(puch[3] & 0x3f) << 6)
+                        | ((RTUNICP)(puch[2] & 0x3f) << 12)
+                        | ((RTUNICP)(puch[1] & 0x3f) << 18)
+                        | ((RTUNICP)(uch     & 0x03) << 24);
+                    RTStrAssertMsgReturn(uc >= 0x00200000 && uc <= 0x03ffffff,
+                                         ("%u: cp=%#010RX32: %.*Rhxs\n", cb, uc, RT_MIN(cb + 10, cch), puch), VERR_INVALID_UTF8_ENCODING);
+                    break;
+                case 4:
+                    uc =            (puch[3] & 0x3f)
+                        | ((RTUNICP)(puch[2] & 0x3f) << 6)
+                        | ((RTUNICP)(puch[1] & 0x3f) << 12)
+                        | ((RTUNICP)(uch     & 0x07) << 18);
+                    RTStrAssertMsgReturn(uc >= 0x00010000 && uc <= 0x001fffff,
+                                         ("%u: cp=%#010RX32: %.*Rhxs\n", cb, uc, RT_MIN(cb + 10, cch), puch), VERR_INVALID_UTF8_ENCODING);
+                    break;
+                case 3:
+                    uc =            (puch[2] & 0x3f)
+                        | ((RTUNICP)(puch[1] & 0x3f) << 6)
+                        | ((RTUNICP)(uch     & 0x0f) << 12);
+                    RTStrAssertMsgReturn(uc >= 0x00000800 && uc <= 0x0000fffd,
+                                         ("%u: cp=%#010RX32: %.*Rhxs\n", cb, uc, RT_MIN(cb + 10, cch), puch),
+                                         uc == 0xffff || uc == 0xfffe ? VERR_CODE_POINT_ENDIAN_INDICATOR : VERR_INVALID_UTF8_ENCODING);
+                    RTStrAssertMsgReturn(uc < 0xd800 || uc > 0xdfff,
+                                         ("%u: cp=%#010RX32: %.*Rhxs\n", cb, uc, RT_MIN(cb + 10, cch), puch), VERR_CODE_POINT_SURROGATE);
+                    break;
+                case 2:
+                    uc =            (puch[1] & 0x3f)
+                        | ((RTUNICP)(uch     & 0x1f) << 6);
+                    RTStrAssertMsgReturn(uc >= 0x00000080 && uc <= 0x000007ff,
+                                         ("%u: cp=%#010RX32: %.*Rhxs\n", cb, uc, RT_MIN(cb + 10, cch), puch), VERR_INVALID_UTF8_ENCODING);
+                    break;
+            }
+
+            /* does this code point have a Latin-1 translation? */
+            if (cb > 2 || uch > 0xC3)
+                return VERR_NO_TRANSLATION;
+
+            /* advance */
+            cch -= cb;
+            puch += cb;
+            cchOut++;
+        }
+    }
+
+    /* done */
+    *pcch = cchOut;
+    return VINF_SUCCESS;
 }
 
@@ -1174,4 +1292,24 @@
 }
 RT_EXPORT_SYMBOL(RTStrToLatin1Tag);
+
+
+RTDECL(size_t) RTStrCalcLatin1Len(const char *psz)
+{
+    size_t cch;
+    int rc = rtUtf8CalcLatin1Length(psz, RTSTR_MAX, &cch);
+    return RT_SUCCESS(rc) ? cch : 0;
+}
+RT_EXPORT_SYMBOL(RTStrCalcLatin1Len);
+
+
+RTDECL(int) RTStrCalcLatin1LenEx(const char *psz, size_t cchIn, size_t *pcch)
+{
+    size_t cch;
+    int rc = rtUtf8CalcLatin1Length(psz, cchIn, &cch);
+    if (pcch)
+        *pcch = RT_SUCCESS(rc) ? cch : ~(size_t)0;
+    return rc;
+}
+RT_EXPORT_SYMBOL(RTStrCalcLatin1LenEx);