Use IndexOf{Any} in a few more places (#70176)

* Use IndexOf{Any} in a few more places

* Address PR feedback

src/libraries/System.Console/src/System/TermInfo.cs

@@ -498,9 +498,8 @@ private static string ReadString(byte[] buffer, int pos)
             /// <summary>Finds the null-terminator for a string that begins at the specified position.</summary>
             private static int FindNullTerminator(byte[] buffer, int pos)
             {
-                int termPos = pos;
-                while (termPos < buffer.Length && buffer[termPos] != '\0') termPos++;
-                return termPos;
+                int i = buffer.AsSpan(pos).IndexOf((byte)'\0');
+                return i >= 0 ? pos + i : buffer.Length;
             }
         }
 

src/libraries/System.IO.FileSystem.Watcher/src/System/IO/FileSystemWatcher.Linux.cs

@@ -843,16 +843,11 @@ private string ReadName(int position, int nameLength)
                 Debug.Assert(position > 0);
                 Debug.Assert(nameLength >= 0 && (position + nameLength) <= _buffer.Length);
 
-                int lengthWithoutNullTerm = nameLength;
-                for (int i = 0; i < nameLength; i++)
+                int lengthWithoutNullTerm = _buffer.AsSpan(position, nameLength).IndexOf((byte)'\0');
+                if (lengthWithoutNullTerm < 0)
                 {
-                    if (_buffer[position + i] == '\0')
-                    {
-                        lengthWithoutNullTerm = i;
-                        break;
-                    }
+                    lengthWithoutNullTerm = nameLength;
                 }
-                Debug.Assert(lengthWithoutNullTerm <= nameLength); // should be null terminated or empty
 
                 return lengthWithoutNullTerm > 0 ?
                     Encoding.UTF8.GetString(_buffer, position, lengthWithoutNullTerm) :

src/libraries/System.Net.Http/src/System/Net/Http/HttpResponseMessage.cs

@@ -92,7 +92,7 @@ public HttpStatusCode StatusCode
             }
             set
             {
-                if ((value != null) && ContainsNewLineCharacter(value))
+                if ((value != null) && HttpRuleParser.ContainsNewLine(value))
                 {
                     throw new FormatException(SR.net_http_reasonphrase_format_error);
                 }
@@ -207,18 +207,6 @@ public override string ToString()
             return sb.ToString();
         }
 
-        private static bool ContainsNewLineCharacter(string value)
-        {
-            foreach (char character in value)
-            {
-                if ((character == HttpRuleParser.CR) || (character == HttpRuleParser.LF))
-                {
-                    return true;
-                }
-            }
-            return false;
-        }
-
         #region IDisposable Members
 
         protected virtual void Dispose(bool disposing)

src/libraries/System.Net.Mail/src/System/Net/Mail/MailBnfHelper.cs

@@ -379,23 +379,12 @@ private static bool CheckForUnicode(char ch, bool allowUnicode)
             return true;
         }
 
-        internal static bool IsAllowedWhiteSpace(char c)
-        {
+        internal static bool IsAllowedWhiteSpace(char c) =>
             // all allowed whitespace characters
-            return c == Tab || c == Space || c == CR || c == LF;
-        }
+            c == Tab || c == Space || c == CR || c == LF;
 
-        internal static bool HasCROrLF(string data)
-        {
-            for (int i = 0; i < data.Length; i++)
-            {
-                if (data[i] == '\r' || data[i] == '\n')
-                {
-                    return true;
-                }
-            }
-            return false;
-        }
+        internal static bool HasCROrLF(string data) =>
+            data.AsSpan().IndexOfAny(CR, LF) >= 0;
 
         // Is there a FWS ("\r\n " or "\r\n\t") starting at the given index?
         internal static bool IsFWSAt(string data, int index)

src/libraries/System.Private.CoreLib/src/System/Reflection/Emit/TypeNameBuilder.cs

@@ -246,11 +246,14 @@ private void SetUseAngleBracketsForGenerics(bool value)
 
         private void Append(string pStr)
         {
-            foreach (char c in pStr)
+            int i = pStr.IndexOf('\0');
+            if (i < 0)
             {
-                if (c == '\0')
-                    break;
-                _str.Append(c);
+                _str.Append(pStr);
+            }
+            else if (i > 0)
+            {
+                _str.Append(pStr.AsSpan(0, i));
             }
         }
 

src/libraries/System.Private.CoreLib/src/System/TimeZoneInfo.FullGlobalizationData.cs

@@ -9,23 +9,15 @@ public sealed partial class TimeZoneInfo
     {
         private static unsafe bool TryConvertIanaIdToWindowsId(string ianaId, bool allocate, out string? windowsId)
         {
-            if (GlobalizationMode.Invariant || GlobalizationMode.UseNls || ianaId is null)
+            if (GlobalizationMode.Invariant ||
+                GlobalizationMode.UseNls ||
+                ianaId is null ||
+                ianaId.AsSpan().IndexOfAny('\\', '\n', '\r') >= 0) // ICU uses these characters as a separator
             {
                 windowsId = null;
                 return false;
             }
 
-            foreach (char c in ianaId)
-            {
-                // ICU uses some characters as a separator and trim the id at that character.
-                // while we should fail if the Id contained one of these characters.
-                if (c == '\\' || c == '\n' || c == '\r')
-                {
-                    windowsId = null;
-                    return false;
-                }
-            }
-
             char* buffer = stackalloc char[100];
             int length = Interop.Globalization.IanaIdToWindowsId(ianaId, buffer, 100);
             if (length > 0)
@@ -54,15 +46,10 @@ private static unsafe bool TryConvertWindowsIdToIanaId(string windowsId, string?
                 return true;
             }
 
-            foreach (char c in windowsId)
+            if (windowsId.AsSpan().IndexOfAny('\\', '\n', '\r') >= 0) // ICU uses these characters as a separator
             {
-                // ICU uses some characters as a separator and trim the id at that character.
-                // while we should fail if the Id contained one of these characters.
-                if (c == '\\' || c == '\n' || c == '\r')
-                {
-                    ianaId = null;
-                    return false;
-                }
+                ianaId = null;
+                return false;
             }
 
             // regionPtr will point at the region name encoded as ASCII.