Fix for linux mmap requiring MAP_PRIVATE

benoithudson · benoithudson · commit 156f55454d13 · 2018-10-02T16:34:37.000-04:00
mac mmap allows it, so just set it on both platforms.
diff --git a/src/runtime/typemanager.cs b/src/runtime/typemanager.cs
@@ -592,6 +592,7 @@ class UnixMemoryMapper : IMemoryMapper
             const int PROT_WRITE = 0x2;
             const int PROT_EXEC = 0x4;
 
+            const int MAP_PRIVATE = 0x2;
             int MAP_ANONYMOUS
             {
                 get
@@ -616,7 +617,9 @@ int MAP_ANONYMOUS
 
             public IntPtr MapWriteable(int numBytes)
             {
-                return mmap(IntPtr.Zero, new IntPtr(numBytes), PROT_READ | PROT_WRITE, MAP_ANONYMOUS, -1, IntPtr.Zero);
+                // MAP_PRIVATE must be set on linux, even though MAP_ANON implies it.
+                // It doesn't hurt on darwin, so just do it.
+                return mmap(IntPtr.Zero, new IntPtr(numBytes), PROT_READ | PROT_WRITE, MAP_PRIVATE | MAP_ANONYMOUS, -1, IntPtr.Zero);
             }
 
             public void SetReadExec(IntPtr mappedMemory, int numBytes)

Original file line number	Diff line number	Diff line change
`@@ -592,6 +592,7 @@ class UnixMemoryMapper : IMemoryMapper`
`592`	`592`	`const int PROT_WRITE = 0x2;`
`593`	`593`	`const int PROT_EXEC = 0x4;`
`594`	`594`
	`595`	`+ const int MAP_PRIVATE = 0x2;`
`595`	`596`	`int MAP_ANONYMOUS`
`596`	`597`	`{`
`597`	`598`	`get`
`@@ -616,7 +617,9 @@ int MAP_ANONYMOUS`
`616`	`617`
`617`	`618`	`public IntPtr MapWriteable(int numBytes)`
`618`	`619`	`{`
`619`		`- return mmap(IntPtr.Zero, new IntPtr(numBytes), PROT_READ \| PROT_WRITE, MAP_ANONYMOUS, -1, IntPtr.Zero);`
	`620`	`+ // MAP_PRIVATE must be set on linux, even though MAP_ANON implies it.`
	`621`	`+ // It doesn't hurt on darwin, so just do it.`
	`622`	`+ return mmap(IntPtr.Zero, new IntPtr(numBytes), PROT_READ \| PROT_WRITE, MAP_PRIVATE \| MAP_ANONYMOUS, -1, IntPtr.Zero);`
`620`	`623`	`}`
`621`	`624`
`622`	`625`	`public void SetReadExec(IntPtr mappedMemory, int numBytes)`