hle: Improve safety (#2778)

* timezone: Make timezone implementation safe

* hle: Do not use TrimEnd to parse ASCII strings

This adds an util that handle reading an ASCII string in a safe way.
Previously it was possible to read malformed data that could cause
various undefined behaviours in multiple services.

* hid: Remove an useless unsafe modifier on keyboard update

* Address gdkchan's comment

* Address gdkchan's comment

Ryujinx.HLE/FileSystem/Content/SystemVersion.cs

@@ -1,3 +1,4 @@
+using Ryujinx.HLE.Utilities;
 using System.IO;
 using System.Text;
 
@@ -30,10 +31,10 @@ namespace Ryujinx.HLE.FileSystem.Content
 
                 reader.ReadBytes(2); // Padding
 
-                PlatformString = Encoding.ASCII.GetString(reader.ReadBytes(0x20)).TrimEnd('\0');
-                Hex            = Encoding.ASCII.GetString(reader.ReadBytes(0x40)).TrimEnd('\0');
-                VersionString  = Encoding.ASCII.GetString(reader.ReadBytes(0x18)).TrimEnd('\0');
-                VersionTitle   = Encoding.ASCII.GetString(reader.ReadBytes(0x80)).TrimEnd('\0');
+                PlatformString = StringUtils.ReadInlinedAsciiString(reader, 0x20);
+                Hex            = StringUtils.ReadInlinedAsciiString(reader, 0x40);
+                VersionString  = StringUtils.ReadInlinedAsciiString(reader, 0x18);
+                VersionTitle   = StringUtils.ReadInlinedAsciiString(reader, 0x80);
             }
         }
     }

Ryujinx.HLE/HOS/Services/Hid/HidDevices/KeyboardDevice.cs

@@ -8,7 +8,7 @@ namespace Ryujinx.HLE.HOS.Services.Hid
     {
         public KeyboardDevice(Switch device, bool active) : base(device, active) { }
 
-        public unsafe void Update(KeyboardInput keyState)
+        public void Update(KeyboardInput keyState)
         {
             ref RingLifo<KeyboardState> lifo = ref _device.Hid.SharedMemory.Keyboard;
 

Ryujinx.HLE/HOS/Services/Sockets/Sfdnsres/IResolver.cs

@@ -218,11 +218,7 @@ namespace Ryujinx.HLE.HOS.Services.Sockets.Sfdnsres
 
         private ResultCode GetHostByNameRequestImpl(ServiceCtx context, ulong inputBufferPosition, ulong inputBufferSize, ulong outputBufferPosition, ulong outputBufferSize, ulong optionsBufferPosition, ulong optionsBufferSize)
         {
-            byte[] rawName = new byte[inputBufferSize];
-
-            context.Memory.Read(inputBufferPosition, rawName);
-
-            string name = Encoding.ASCII.GetString(rawName).TrimEnd('\0');
+            string name = MemoryHelper.ReadAsciiString(context.Memory, inputBufferPosition, (int)inputBufferSize);
 
             // TODO: Use params.
             bool  enableNsdResolve = (context.RequestData.ReadInt32() & 1) != 0;

Ryujinx.HLE/HOS/Services/Time/ITimeServiceManager.cs

@@ -116,7 +116,7 @@ namespace Ryujinx.HLE.HOS.Services.Time
         // SetupTimeZoneManager(nn::time::LocationName location_name, nn::time::SteadyClockTimePoint timezone_update_timepoint, u32 total_location_name_count, nn::time::TimeZoneRuleVersion timezone_rule_version, buffer<nn::time::TimeZoneBinary, 0x21> timezone_binary)
         public ResultCode SetupTimeZoneManager(ServiceCtx context)
         {
-            string               locationName            = Encoding.ASCII.GetString(context.RequestData.ReadBytes(0x24)).TrimEnd('\0');
+            string               locationName            = StringUtils.ReadInlinedAsciiString(context.RequestData, 0x24);
             SteadyClockTimePoint timeZoneUpdateTimePoint = context.RequestData.ReadStruct<SteadyClockTimePoint>();
             uint                 totalLocationNameCount  = context.RequestData.ReadUInt32();
             UInt128              timeZoneRuleVersion     = context.RequestData.ReadStruct<UInt128>();

Ryujinx.HLE/HOS/Services/Time/StaticService/ITimeZoneServiceForGlue.cs

@@ -1,6 +1,7 @@
 using Ryujinx.Common.Logging;
 using Ryujinx.Cpu;
 using Ryujinx.HLE.HOS.Services.Time.TimeZone;
+using Ryujinx.HLE.Utilities;
 using System;
 using System.Text;
 
@@ -35,7 +36,7 @@ namespace Ryujinx.HLE.HOS.Services.Time.StaticService
                 return ResultCode.PermissionDenied;
             }
 
-            string locationName = Encoding.ASCII.GetString(context.RequestData.ReadBytes(0x24)).TrimEnd('\0');
+            string locationName = StringUtils.ReadInlinedAsciiString(context.RequestData, 0x24);
 
             return _timeZoneContentManager.SetDeviceLocationName(locationName);
         }
@@ -97,7 +98,7 @@ namespace Ryujinx.HLE.HOS.Services.Time.StaticService
                 throw new InvalidOperationException();
             }
 
-            string locationName = Encoding.ASCII.GetString(context.RequestData.ReadBytes(0x24)).TrimEnd('\0');
+            string locationName = StringUtils.ReadInlinedAsciiString(context.RequestData, 0x24);
 
             ResultCode resultCode = _timeZoneContentManager.LoadTimeZoneRule(out TimeZoneRule rules, locationName);
 

Ryujinx.HLE/HOS/Services/Time/StaticService/ITimeZoneServiceForPsc.cs

@@ -125,7 +125,7 @@ namespace Ryujinx.HLE.HOS.Services.Time.StaticService
 
             (ulong bufferPosition, ulong bufferSize) = context.Request.GetBufferType0x21();
 
-            string locationName = Encoding.ASCII.GetString(context.RequestData.ReadBytes(0x24)).TrimEnd('\0');
+            string locationName = StringUtils.ReadInlinedAsciiString(context.RequestData, 0x24);
 
             ResultCode result;
 

Ryujinx.HLE/HOS/Services/Time/TimeZone/TimeZone.cs

@@ -2,6 +2,7 @@
 using Ryujinx.Common.Utilities;
 using Ryujinx.HLE.Utilities;
 using System;
+using System.Buffers.Binary;
 using System.IO;
 using System.Runtime.InteropServices;
 using System.Text;
@@ -107,40 +108,24 @@ namespace Ryujinx.HLE.HOS.Services.Time.TimeZone
             public int      TransitionTime;
         }
 
-        private static int Detzcode32(byte[] bytes)
+        private static int Detzcode32(ReadOnlySpan<byte> bytes)
         {
-            if (BitConverter.IsLittleEndian)
-            {
-                Array.Reverse(bytes, 0, bytes.Length);
-            }
-
-            return BitConverter.ToInt32(bytes, 0);
+            return BinaryPrimitives.ReadInt32BigEndian(bytes);
         }
 
-        private static unsafe int Detzcode32(int* data)
+        private static int Detzcode32(int value)
         {
-            int result = *data;
             if (BitConverter.IsLittleEndian)
             {
-                byte[] bytes = BitConverter.GetBytes(result);
-                Array.Reverse(bytes, 0, bytes.Length);
-                result = BitConverter.ToInt32(bytes, 0);
+                return BinaryPrimitives.ReverseEndianness(value);
             }
 
-            return result;
+            return value;
         }
 
-        private static unsafe long Detzcode64(long* data)
+        private static long Detzcode64(ReadOnlySpan<byte> bytes)
         {
-            long result = *data;
-            if (BitConverter.IsLittleEndian)
-            {
-                byte[] bytes = BitConverter.GetBytes(result);
-                Array.Reverse(bytes, 0, bytes.Length);
-                result = BitConverter.ToInt64(bytes, 0);
-            }
-
-            return result;
+            return BinaryPrimitives.ReadInt64BigEndian(bytes);
         }
 
         private static bool DifferByRepeat(long t1, long t0)
@@ -148,7 +133,7 @@ namespace Ryujinx.HLE.HOS.Services.Time.TimeZone
             return (t1 - t0) == SecondsPerRepeat;
         }
 
-        private static unsafe bool TimeTypeEquals(TimeZoneRule outRules, byte aIndex, byte bIndex)
+        private static bool TimeTypeEquals(TimeZoneRule outRules, byte aIndex, byte bIndex)
         {
             if (aIndex < 0 || aIndex >= outRules.TypeCount || bIndex < 0 || bIndex >= outRules.TypeCount)
             {
@@ -158,17 +143,14 @@ namespace Ryujinx.HLE.HOS.Services.Time.TimeZone
             TimeTypeInfo a = outRules.Ttis[aIndex];
             TimeTypeInfo b = outRules.Ttis[bIndex];
 
-            fixed (char* chars = outRules.Chars)
-            {
-                return a.GmtOffset              == b.GmtOffset &&
-                       a.IsDaySavingTime        == b.IsDaySavingTime &&
-                       a.IsStandardTimeDaylight == b.IsStandardTimeDaylight &&
-                       a.IsGMT                  == b.IsGMT &&
-                       StringUtils.CompareCStr(chars + a.AbbreviationListIndex, chars + b.AbbreviationListIndex) == 0;
-            }
+            return a.GmtOffset              == b.GmtOffset &&
+                   a.IsDaySavingTime        == b.IsDaySavingTime &&
+                   a.IsStandardTimeDaylight == b.IsStandardTimeDaylight &&
+                   a.IsGMT                  == b.IsGMT &&
+                   StringUtils.CompareCStr(outRules.Chars[a.AbbreviationListIndex..], outRules.Chars[b.AbbreviationListIndex..]) == 0;
         }
 
-        private static int GetQZName(char[] name, int namePosition, char delimiter)
+        private static int GetQZName(ReadOnlySpan<char> name, int namePosition, char delimiter)
         {
             int i = namePosition;
 
@@ -403,7 +385,7 @@ namespace Ryujinx.HLE.HOS.Services.Time.TimeZone
             return 0;
         }
 
-        private static bool ParsePosixName(Span<char> name, out TimeZoneRule outRules, bool lastDitch)
+        private static bool ParsePosixName(ReadOnlySpan<char> name, out TimeZoneRule outRules, bool lastDitch)
         {
             outRules = new TimeZoneRule
             {
@@ -414,9 +396,10 @@ namespace Ryujinx.HLE.HOS.Services.Time.TimeZone
             };
 
             int        stdLen;
-            Span<char> stdName      = name;
-            int        namePosition = 0;
-            int        stdOffset    = 0;
+
+            ReadOnlySpan<char> stdName = name;
+            int namePosition = 0;
+            int stdOffset = 0;
 
             if (lastDitch)
             {
@@ -433,7 +416,8 @@ namespace Ryujinx.HLE.HOS.Services.Time.TimeZone
 
                     int stdNamePosition = namePosition;
 
-                    namePosition = GetQZName(name.ToArray(), namePosition, '>');
+                    namePosition = GetQZName(name, namePosition, '>');
+
                     if (name[namePosition] != '>')
                     {
                         return false;
@@ -465,7 +449,7 @@ namespace Ryujinx.HLE.HOS.Services.Time.TimeZone
             int destLen   = 0;
             int dstOffset = 0;
 
-            Span<char> destName = name.Slice(namePosition);
+            ReadOnlySpan<char> destName = name.Slice(namePosition);
 
             if (TzCharsArraySize < charCount)
             {
@@ -903,7 +887,7 @@ namespace Ryujinx.HLE.HOS.Services.Time.TimeZone
             return ParsePosixName(name.ToCharArray(), out outRules, false);
         }
 
-        internal static unsafe bool ParseTimeZoneBinary(out TimeZoneRule outRules, Stream inputData)
+        internal static bool ParseTimeZoneBinary(out TimeZoneRule outRules, Stream inputData)
         {
             outRules = new TimeZoneRule
             {
@@ -967,12 +951,11 @@ namespace Ryujinx.HLE.HOS.Services.Time.TimeZone
 
             timeCount = 0;
 
-            fixed (byte* workBufferPtrStart = workBuffer)
             {
-                byte* p = workBufferPtrStart;
+                Span<byte> p = workBuffer;
                 for (int i = 0; i < outRules.TimeCount; i++)
                 {
-                    long at = Detzcode64((long*)p);
+                    long at = Detzcode64(p);
                     outRules.Types[i] = 1;
 
                     if (timeCount != 0 && at <= outRules.Ats[timeCount - 1])
@@ -988,13 +971,15 @@ namespace Ryujinx.HLE.HOS.Services.Time.TimeZone
 
                     outRules.Ats[timeCount++] = at;
 
-                    p += TimeTypeSize;
+                    p = p[TimeTypeSize..];
                 }
 
                 timeCount = 0;
                 for (int i = 0; i < outRules.TimeCount; i++)
                 {
-                    byte type = *p++;
+                    byte type = p[0];
+                    p = p[1..];
+
                     if (outRules.TypeCount <= type)
                     {
                         return false;
@@ -1011,18 +996,20 @@ namespace Ryujinx.HLE.HOS.Services.Time.TimeZone
                 for (int i = 0; i < outRules.TypeCount; i++)
                 {
                     TimeTypeInfo ttis = outRules.Ttis[i];
-                    ttis.GmtOffset = Detzcode32((int*)p);
-                    p += 4;
+                    ttis.GmtOffset = Detzcode32(p);
+                    p = p[sizeof(int)..];
 
-                    if (*p >= 2)
+                    if (p[0] >= 2)
                     {
                         return false;
                     }
 
-                    ttis.IsDaySavingTime = *p != 0;
-                    p++;
+                    ttis.IsDaySavingTime = p[0] != 0;
+                    p = p[1..];
+
+                    int abbreviationListIndex = p[0];
+                    p = p[1..];
 
-                    int abbreviationListIndex = *p++;
                     if (abbreviationListIndex >= outRules.CharCount)
                     {
                         return false;
@@ -1033,12 +1020,9 @@ namespace Ryujinx.HLE.HOS.Services.Time.TimeZone
                     outRules.Ttis[i] = ttis;
                 }
 
-                fixed (char* chars = outRules.Chars)
-                {
-                    Encoding.ASCII.GetChars(p, outRules.CharCount, chars, outRules.CharCount);
-                }
+                Encoding.ASCII.GetChars(p[..outRules.CharCount].ToArray()).CopyTo(outRules.Chars.AsSpan());
 
-                p += outRules.CharCount;
+                p = p[outRules.CharCount..];
                 outRules.Chars[outRules.CharCount] = '\0';
 
                 for (int i = 0; i < outRules.TypeCount; i++)
@@ -1049,14 +1033,14 @@ namespace Ryujinx.HLE.HOS.Services.Time.TimeZone
                     }
                     else
                     {
-                        if (*p >= 2)
+                        if (p[0] >= 2)
                         {
                             return false;
                         }
 
-                        outRules.Ttis[i].IsStandardTimeDaylight = *p++ != 0;
+                        outRules.Ttis[i].IsStandardTimeDaylight = p[0] != 0;
+                        p = p[1..];
                     }
-
                 }
 
                 for (int i = 0; i < outRules.TypeCount; i++)
@@ -1067,17 +1051,18 @@ namespace Ryujinx.HLE.HOS.Services.Time.TimeZone
                     }
                     else
                     {
-                        if (*p >= 2)
+                        if (p[0] >= 2)
                         {
                             return false;
                         }
 
-                        outRules.Ttis[i].IsGMT = *p++ != 0;
+                        outRules.Ttis[i].IsGMT = p[0] != 0;
+                        p = p[1..];
                     }
 
                 }
 
-                long position = (p - workBufferPtrStart);
+                long position = (workBuffer.Length - p.Length);
                 long nRead    = streamLength - position;
 
                 if (nRead < 0)
@@ -1107,77 +1092,75 @@ namespace Ryujinx.HLE.HOS.Services.Time.TimeZone
                         int abbreviationCount = 0;
                         charCount = outRules.CharCount;
 
-                        fixed (char* chars = outRules.Chars)
+                        Span<char> chars = outRules.Chars;
+
+                        for (int i = 0; i < tempRules.TypeCount; i++)
                         {
-                            for (int i = 0; i < tempRules.TypeCount; i++)
+                            ReadOnlySpan<char> tempChars = tempRules.Chars;
+                            ReadOnlySpan<char> tempAbbreviation = tempChars[tempRules.Ttis[i].AbbreviationListIndex..];
+
+                            int j;
+
+                            for (j = 0; j < charCount; j++)
                             {
-                                fixed (char* tempChars = tempRules.Chars)
+                                if (StringUtils.CompareCStr(chars[j..], tempAbbreviation) == 0)
                                 {
-                                    char* tempAbbreviation = tempChars + tempRules.Ttis[i].AbbreviationListIndex;
-                                    int j;
+                                    tempRules.Ttis[i].AbbreviationListIndex = j;
+                                    abbreviationCount++;
+                                    break;
+                                }
+                            }
 
-                                    for (j = 0; j < charCount; j++)
+                            if (j >= charCount)
+                            {
+                                int abbreviationLength = StringUtils.LengthCstr(tempAbbreviation);
+                                if (j + abbreviationLength < TzMaxChars)
+                                {
+                                    for (int x = 0; x < abbreviationLength; x++)
                                     {
-                                        if (StringUtils.CompareCStr(chars + j, tempAbbreviation) == 0)
-                                        {
-                                            tempRules.Ttis[i].AbbreviationListIndex = j;
-                                            abbreviationCount++;
-                                            break;
-                                        }
+                                        chars[j + x] = tempAbbreviation[x];
                                     }
 
-                                    if (j >= charCount)
-                                    {
-                                        int abbreviationLength = StringUtils.LengthCstr(tempAbbreviation);
-                                        if (j + abbreviationLength < TzMaxChars)
-                                        {
-                                            for (int x = 0; x < abbreviationLength; x++)
-                                            {
-                                                chars[j + x] = tempAbbreviation[x];
-                                            }
-
-                                            charCount = j + abbreviationLength + 1;
-
-                                            tempRules.Ttis[i].AbbreviationListIndex = j;
-                                            abbreviationCount++;
-                                        }
-                                    }
+                                    charCount = j + abbreviationLength + 1;
+
+                                    tempRules.Ttis[i].AbbreviationListIndex = j;
+                                    abbreviationCount++;
                                 }
                             }
+                        }
 
-                            if (abbreviationCount == tempRules.TypeCount)
-                            {
-                                outRules.CharCount = charCount;
+                        if (abbreviationCount == tempRules.TypeCount)
+                        {
+                            outRules.CharCount = charCount;
 
-                                // Remove trailing
-                                while (1 < outRules.TimeCount && (outRules.Types[outRules.TimeCount - 1] == outRules.Types[outRules.TimeCount - 2]))
-                                {
-                                    outRules.TimeCount--;
-                                }
+                            // Remove trailing
+                            while (1 < outRules.TimeCount && (outRules.Types[outRules.TimeCount - 1] == outRules.Types[outRules.TimeCount - 2]))
+                            {
+                                outRules.TimeCount--;
+                            }
 
-                                int i;
+                            int i;
 
-                                for (i = 0; i < tempRules.TimeCount; i++)
+                            for (i = 0; i < tempRules.TimeCount; i++)
+                            {
+                                if (outRules.TimeCount == 0 || outRules.Ats[outRules.TimeCount - 1] < tempRules.Ats[i])
                                 {
-                                    if (outRules.TimeCount == 0 || outRules.Ats[outRules.TimeCount - 1] < tempRules.Ats[i])
-                                    {
-                                        break;
-                                    }
+                                    break;
                                 }
+                            }
 
-                                while (i < tempRules.TimeCount && outRules.TimeCount < TzMaxTimes)
-                                {
-                                    outRules.Ats[outRules.TimeCount]   = tempRules.Ats[i];
-                                    outRules.Types[outRules.TimeCount] = (byte)(outRules.TypeCount + (byte)tempRules.Types[i]);
+                            while (i < tempRules.TimeCount && outRules.TimeCount < TzMaxTimes)
+                            {
+                                outRules.Ats[outRules.TimeCount] = tempRules.Ats[i];
+                                outRules.Types[outRules.TimeCount] = (byte)(outRules.TypeCount + (byte)tempRules.Types[i]);
 
-                                    outRules.TimeCount++;
-                                    i++;
-                                }
+                                outRules.TimeCount++;
+                                i++;
+                            }
 
-                                for (i = 0; i < tempRules.TypeCount; i++)
-                                {
-                                    outRules.Ttis[outRules.TypeCount++] = tempRules.Ttis[i];
-                                }
+                            for (i = 0; i < tempRules.TypeCount; i++)
+                            {
+                                outRules.Ttis[outRules.TypeCount++] = tempRules.Ttis[i];
                             }
                         }
                     }
@@ -1467,17 +1450,11 @@ namespace Ryujinx.HLE.HOS.Services.Time.TimeZone
             {
                 calendarAdditionalInfo.IsDaySavingTime = rules.Ttis[ttiIndex].IsDaySavingTime;
 
-                unsafe
-                {
-                    fixed (char* timeZoneAbbreviation = &rules.Chars[rules.Ttis[ttiIndex].AbbreviationListIndex])
-                    {
-                        int timeZoneSize = Math.Min(StringUtils.LengthCstr(timeZoneAbbreviation), 8);
-                        for (int i = 0; i < timeZoneSize; i++)
-                        {
-                            calendarAdditionalInfo.TimezoneName[i] = timeZoneAbbreviation[i];
-                        }
-                    }
-                }
+                ReadOnlySpan<char> timeZoneAbbreviation = rules.Chars.AsSpan()[rules.Ttis[ttiIndex].AbbreviationListIndex..];
+
+                int timeZoneSize = Math.Min(StringUtils.LengthCstr(timeZoneAbbreviation), 8);
+
+                timeZoneAbbreviation[..timeZoneSize].CopyTo(calendarAdditionalInfo.TimezoneName.AsSpan());
             }
 
             return result;

Ryujinx.HLE/HOS/Services/Time/TimeZone/Types/TzifHeader.cs

@@ -1,34 +1,19 @@
-using System.Runtime.InteropServices;
+using Ryujinx.Common.Memory;
+using System.Runtime.InteropServices;
 
 namespace Ryujinx.HLE.HOS.Services.Time.TimeZone
 {
     [StructLayout(LayoutKind.Sequential, Pack = 0x4, Size = 0x2C)]
     struct TzifHeader
     {
-        [MarshalAs(UnmanagedType.ByValArray, SizeConst = 4)]
-        public char[] Magic;
-
-        public char Version;
-
-        [MarshalAs(UnmanagedType.ByValArray, SizeConst = 15)]
-        public byte[] Reserved;
-
-        [MarshalAs(UnmanagedType.ByValArray, SizeConst = 4)]
-        public byte[] TtisGMTCount;
-
-        [MarshalAs(UnmanagedType.ByValArray, SizeConst = 4)]
-        public byte[] TtisSTDCount;
-
-        [MarshalAs(UnmanagedType.ByValArray, SizeConst = 4)]
-        public byte[] LeapCount;
-
-        [MarshalAs(UnmanagedType.ByValArray, SizeConst = 4)]
-        public byte[] TimeCount;
-
-        [MarshalAs(UnmanagedType.ByValArray, SizeConst = 4)]
-        public byte[] TypeCount;
-
-        [MarshalAs(UnmanagedType.ByValArray, SizeConst = 4)]
-        public byte[] CharCount;
+        public Array4<byte> Magic;
+        public byte Version;
+        private Array15<byte> _reserved;
+        public int TtisGMTCount;
+        public int TtisSTDCount;
+        public int LeapCount;
+        public int TimeCount;
+        public int TypeCount;
+        public int CharCount;
     }
 }

Ryujinx.HLE/Utilities/StringUtils.cs

@@ -36,6 +36,15 @@ namespace Ryujinx.HLE.Utilities
             return output;
         }
 
+        public static string ReadInlinedAsciiString(BinaryReader reader, int maxSize)
+        {
+            byte[] data = reader.ReadBytes(maxSize);
+
+            int stringSize = Array.IndexOf<byte>(data, 0);
+
+            return Encoding.ASCII.GetString(data, 0, stringSize < 0 ? maxSize : stringSize);
+        }
+
         public static byte[] HexToBytes(string hexString)
         {
             // Ignore last character if HexLength % 2 != 0.
@@ -107,7 +116,7 @@ namespace Ryujinx.HLE.Utilities
             }
         }
 
-        public static unsafe int CompareCStr(char* s1, char* s2)
+        public static int CompareCStr(ReadOnlySpan<char> s1, ReadOnlySpan<char> s2)
         {
             int s1Index = 0;
             int s2Index = 0;
@@ -121,7 +130,7 @@ namespace Ryujinx.HLE.Utilities
             return s2[s2Index] - s1[s1Index];
         }
 
-        public static unsafe int LengthCstr(char* s)
+        public static int LengthCstr(ReadOnlySpan<char> s)
         {
             int i = 0;