Prevent Mono.Posix from using multiple C runtimes on Windows

Since libMonoPosixHelper.dll is linked against ucrtbase.dll the C runtime
wrapper functions in it will call into ucrtbase.dll. Some pinvokes in
Mono.Unix.Native.Stdlib, however, bind directly to C runtime functions in
msvcrt. This is problematic if a resource (heap memory, file pointer, etc) is
allocated using one C runtime and then operated upon using funcitons form the
other C runtime. E.g., Stdlib.malloc() calls into a wrapper in
libMonoPosixHelper so it will use the ucrtbase heap while Stdlib.free() calls
directly into msvcrt's free() which will abort the process since it's called
with a pointer in an unknown heap.

This commit adds libMonoPosixHelper wrappers for all memory and file related
functions in Stdlib to ensure that all such functions use the same C runtime.

Some of the Mono.Posix tests still fail but at least the test suite doesn't
crash after this change. The test failures will be addressed in a future PR.

2 files changed, 46 insertions, 22 deletions

diff --git a/mcs/class/Mono.Posix/Mono.Unix.Native/Stdlib.cs b/mcs/class/Mono.Posix/Mono.Unix.Native/Stdlib.cs
index e4c34cba317..86cdb7126fe 100644
--- a/mcs/class/Mono.Posix/Mono.Unix.Native/Stdlib.cs
+++ b/mcs/class/Mono.Posix/Mono.Unix.Native/Stdlib.cs
@@ -675,7 +675,8 @@ namespace Mono.Unix.Native {
 				[MarshalAs (UnmanagedType.CustomMarshaler, MarshalTypeRef=typeof(FileNameMarshaler))]
 				string newpath);
 
-		[DllImport (LIBC, CallingConvention=CallingConvention.Cdecl, SetLastError=true)]
+		[DllImport (MPH, CallingConvention=CallingConvention.Cdecl,
+				SetLastError=true, EntryPoint="Mono_Posix_Stdlib_tmpfile")]
 		public static extern IntPtr tmpfile ();
 
 		private static object tmpnam_lock = new object ();
@@ -704,18 +705,22 @@ namespace Mono.Unix.Native {
 			}
 		}
 
-		[DllImport (LIBC, CallingConvention=CallingConvention.Cdecl, SetLastError=true)]
+		[DllImport (MPH, CallingConvention=CallingConvention.Cdecl,
+				SetLastError=true, EntryPoint="Mono_Posix_Stdlib_fclose")]
 		public static extern int fclose (IntPtr stream);
 
-		[DllImport (LIBC, CallingConvention=CallingConvention.Cdecl, SetLastError=true)]
+		[DllImport (MPH, CallingConvention=CallingConvention.Cdecl,
+				SetLastError=true, EntryPoint="Mono_Posix_Stdlib_fflush")]
 		public static extern int fflush (IntPtr stream);
 
-		[DllImport (LIBC, CallingConvention=CallingConvention.Cdecl, SetLastError=true)]
+		[DllImport (MPH, CallingConvention=CallingConvention.Cdecl,
+				SetLastError=true, EntryPoint="Mono_Posix_Stdlib_fopen")]
 		public static extern IntPtr fopen (
 				[MarshalAs (UnmanagedType.CustomMarshaler, MarshalTypeRef=typeof(FileNameMarshaler))]
 				string path, string mode);
 
-		[DllImport (LIBC, CallingConvention=CallingConvention.Cdecl, SetLastError=true)]
+		[DllImport (MPH, CallingConvention=CallingConvention.Cdecl,
+				SetLastError=true, EntryPoint="Mono_Posix_Stdlib_freopen")]
 		public static extern IntPtr freopen (
 				[MarshalAs (UnmanagedType.CustomMarshaler, MarshalTypeRef=typeof(FileNameMarshaler))]
 				string path, string mode, IntPtr stream);
@@ -741,8 +746,8 @@ namespace Mono.Unix.Native {
 			return setvbuf (stream, (IntPtr) buf, mode, size);
 		}
 
-		[DllImport (LIBC, CallingConvention=CallingConvention.Cdecl,
-				EntryPoint="fprintf")]
+		[DllImport (MPH, CallingConvention=CallingConvention.Cdecl,
+				EntryPoint="Mono_Posix_Stdlib_fprintf")]
 		private static extern int sys_fprintf (IntPtr stream, string format, string message);
 
 		public static int fprintf (IntPtr stream, string message)
@@ -846,11 +851,12 @@ namespace Mono.Unix.Native {
 		 *    vsscanf(3)
 		 */
 
-		[DllImport (LIBC, CallingConvention=CallingConvention.Cdecl, SetLastError=true)]
+		[DllImport (MPH, CallingConvention=CallingConvention.Cdecl,
+				SetLastError=true, EntryPoint="Mono_Posix_Stdlib_fgetc")]
 		public static extern int fgetc (IntPtr stream);
 
-		[DllImport (LIBC, CallingConvention=CallingConvention.Cdecl,
-				SetLastError=true, EntryPoint="fgets")]
+		[DllImport (MPH, CallingConvention=CallingConvention.Cdecl,
+				SetLastError=true, EntryPoint="Mono_Posix_Stdlib_fgets")]
 		private static extern IntPtr sys_fgets (StringBuilder sb, int size, IntPtr stream);
 
 		public static StringBuilder fgets (StringBuilder sb, int size, IntPtr stream)
@@ -866,22 +872,28 @@ namespace Mono.Unix.Native {
 			return fgets (sb, sb.Capacity, stream);
 		}
 
-		[DllImport (LIBC, CallingConvention=CallingConvention.Cdecl, SetLastError=true)]
+		[DllImport (MPH, CallingConvention=CallingConvention.Cdecl,
+				SetLastError=true, EntryPoint="Mono_Posix_Stdlib_fputc")]
 		public static extern int fputc (int c, IntPtr stream);
 
-		[DllImport (LIBC, CallingConvention=CallingConvention.Cdecl, SetLastError=true)]
+		[DllImport (MPH, CallingConvention=CallingConvention.Cdecl,
+				SetLastError=true, EntryPoint="Mono_Posix_Stdlib_fputs")]
 		public static extern int fputs (string s, IntPtr stream);
 
-		[DllImport (LIBC, CallingConvention=CallingConvention.Cdecl, SetLastError=true)]
-		public static extern int getc (IntPtr stream);
+		public static int getc (IntPtr stream)
+		{
+			return fgetc (stream);
+		}
 
 		[DllImport (LIBC, CallingConvention=CallingConvention.Cdecl, SetLastError=true)]
 		public static extern int getchar ();
 
 		/* SKIP: gets(3) */
 
-		[DllImport (LIBC, CallingConvention=CallingConvention.Cdecl, SetLastError=true)]
-		public static extern int putc (int c, IntPtr stream);
+		public static int putc (int c, IntPtr stream)
+		{
+			return fputc (c, stream);
+		}
 
 		[DllImport (LIBC, CallingConvention=CallingConvention.Cdecl, SetLastError=true)]
 		public static extern int putchar (int c);
@@ -889,7 +901,8 @@ namespace Mono.Unix.Native {
 		[DllImport (LIBC, CallingConvention=CallingConvention.Cdecl, SetLastError=true)]
 		public static extern int puts (string s);
 
-		[DllImport (LIBC, CallingConvention=CallingConvention.Cdecl, SetLastError=true)]
+		[DllImport (MPH, CallingConvention=CallingConvention.Cdecl,
+				SetLastError=true, EntryPoint="Mono_Posix_Stdlib_ungetc")]
 		public static extern int ungetc (int c, IntPtr stream);
 
 		[CLSCompliant (false)]
@@ -993,10 +1006,12 @@ namespace Mono.Unix.Native {
 				SetLastError=true, EntryPoint="Mono_Posix_Stdlib_clearerr")]
 		public static extern int clearerr (IntPtr stream);
 
-		[DllImport (LIBC, CallingConvention=CallingConvention.Cdecl)]
+		[DllImport (MPH, CallingConvention=CallingConvention.Cdecl,
+				SetLastError=true, EntryPoint="Mono_Posix_Stdlib_feof")]
 		public static extern int feof (IntPtr stream);
 
-		[DllImport (LIBC, CallingConvention=CallingConvention.Cdecl)]
+		[DllImport (MPH, CallingConvention=CallingConvention.Cdecl,
+				SetLastError=true, EntryPoint="Mono_Posix_Stdlib_ferror")]
 		public static extern int ferror (IntPtr stream);
 
 		[DllImport (MPH, CallingConvention=CallingConvention.Cdecl, 
@@ -1050,7 +1065,8 @@ namespace Mono.Unix.Native {
 				SetLastError=true, EntryPoint="Mono_Posix_Stdlib_calloc")]
 		public static extern IntPtr calloc (ulong nmemb, ulong size);
 
-		[DllImport (LIBC, CallingConvention=CallingConvention.Cdecl)]
+		[DllImport (MPH, CallingConvention=CallingConvention.Cdecl,
+				EntryPoint="Mono_Posix_Stdlib_free")]
 		public static extern void free (IntPtr ptr);
 
 		// malloc(3):
diff --git a/mcs/class/Mono.Posix/Mono.Unix/StdioFileStream.cs b/mcs/class/Mono.Posix/Mono.Unix/StdioFileStream.cs
index 7eed08157b0..1d0ef97e9f7 100644
--- a/mcs/class/Mono.Posix/Mono.Unix/StdioFileStream.cs
+++ b/mcs/class/Mono.Posix/Mono.Unix/StdioFileStream.cs
@@ -60,35 +60,43 @@ namespace Mono.Unix {
 
 		public StdioFileStream (string path)
 		{
+			if (path == null)
+				throw new ArgumentNullException ("path");
 			InitStream (Fopen (path, "rb"), true);
 		}
 
 		public StdioFileStream (string path, string mode)
 		{
+			if (path == null)
+				throw new ArgumentNullException ("path");
 			InitStream (Fopen (path, mode), true);
 		}
 
 		public StdioFileStream (string path, FileMode mode)
 		{
+			if (path == null)
+				throw new ArgumentNullException ("path");
 			InitStream (Fopen (path, ToFopenMode (path, mode)), true);
 		}
 
 		public StdioFileStream (string path, FileAccess access)
 		{
+			if (path == null)
+				throw new ArgumentNullException ("path");
 			InitStream (Fopen (path, ToFopenMode (path, access)), true);
 			InitCanReadWrite (access);
 		}
 
 		public StdioFileStream (string path, FileMode mode, FileAccess access)
 		{
+			if (path == null)
+				throw new ArgumentNullException ("path");
 			InitStream (Fopen (path, ToFopenMode (path, mode, access)), true);
 			InitCanReadWrite (access);
 		}
 
 		private static IntPtr Fopen (string path, string mode)
 		{
-			if (path == null)
-				throw new ArgumentNullException ("path");
 			if (path.Length == 0)
 				throw new ArgumentException ("path");
 			if (mode == null)