mman style.

Author: evoskuil

src/memory/mman-win32/mman.cpp

@@ -35,12 +35,13 @@ static DWORD protect_page(int prot) noexcept
 
     if ((prot & PROT_EXEC) != 0)
     {
-        return ((prot & PROT_WRITE) != 0) ? PAGE_EXECUTE_READWRITE :
-            PAGE_EXECUTE_READ;
+        return ((prot & PROT_WRITE) != 0) ?
+            PAGE_EXECUTE_READWRITE : PAGE_EXECUTE_READ;
     }
     else
     {
-        return ((prot & PROT_WRITE) != 0) ? PAGE_READWRITE : PAGE_READONLY;
+        return ((prot & PROT_WRITE) != 0) ?
+            PAGE_READWRITE : PAGE_READONLY;
     }
 }
 
@@ -65,6 +66,8 @@ static DWORD protect_file(int prot) noexcept
 
 // public interface
 
+// TODO: FILE_FLAG_SEQUENTIAL_SCAN or FILE_FLAG_RANDOM_ACCESS.
+
 void* mmap(void* /*addr*/, size_t len, int prot, int flags, int fd,
     oft__ off) noexcept
 {
@@ -79,38 +82,37 @@ void* mmap(void* /*addr*/, size_t len, int prot, int flags, int fd,
     const auto file_lo = large ? (DWORD)((off)       & MAXDWORD) : (DWORD)off;
     const auto file_hi = large ? (DWORD)((off >> 32) & MAXDWORD) : (DWORD)0;
 
-    if (len == 0 || (flags & MAP_FIXED) != 0 || prot == PROT_EXEC)
+    // Disallow fixed, executable, and or anonymous mapping.
+    if (len == 0 ||
+        (prot == PROT_EXEC) ||
+        (flags & MAP_FIXED) != 0 ||
+        (flags & MAP_ANONYMOUS) != 0)
     {
         errno = EINVAL;
         return MAP_FAILED;
     }
 
     // Never call CloseHandle on the return value of this function.
-    const auto handle = ((flags & MAP_ANONYMOUS) == 0) ?
-        (HANDLE)_get_osfhandle(fd) : INVALID_HANDLE_VALUE;
-
-    if ((flags & MAP_ANONYMOUS) == 0 && handle == INVALID_HANDLE_VALUE)
+    const auto handle = (HANDLE)_get_osfhandle(fd);
+    if (handle == INVALID_HANDLE_VALUE)
     {
         errno = EBADF;
         return MAP_FAILED;
     }
 
-    const auto mapping = CreateFileMappingW(handle, NULL, protect, max_hi,
-        max_lo, NULL);
-
+    const auto mapping = CreateFileMappingW(handle, NULL, protect, max_hi, max_lo, NULL);
     if (mapping == NULL)
     {
         errno = last_error(EPERM);
         return MAP_FAILED;
     }
 
-    const auto map = MapViewOfFile(mapping, access, file_hi, file_lo, len);
-
     // "to fully close a file mapping object, an application must unmap all
     // mapped views of the file mapping object by calling UnmapViewOfFile and
     // close the file mapping object handle by calling CloseHandle. These
     // functions can be called in any order." - so we close the handle here and
     // retain only the map.
+    const auto map = MapViewOfFile(mapping, access, file_hi, file_lo, len);
     if (map == NULL || CloseHandle(mapping) == FALSE)
     {
         errno = last_error(EPERM);
@@ -121,6 +123,11 @@ void* mmap(void* /*addr*/, size_t len, int prot, int flags, int fd,
     return map;
 }
 
+// HACK: stub is not called for win32.
+void* mremap(void*, size_t, size_t, int) noexcept
+{
+}
+
 // HACK: fd parameter used to pass file descripter, not linux compatible.
 // HACK: No mremap equivalent, munmap and mmap are required to change size.
 void* mremap_(void* addr, size_t old_size, size_t new_size, int prot,
@@ -156,7 +163,6 @@ int mprotect(void* addr, size_t len, int prot) noexcept
 {
     DWORD old_protect = 0;
     const auto new_protect = protect_page(prot);
-
     if (VirtualProtect(addr, len, new_protect, &old_protect) == FALSE)
     {
         errno = last_error(EPERM);
@@ -271,4 +277,10 @@ int ftruncate(int fd, oft__ size) noexcept
     return 0;
 }
 
+// stub
+int sysconf(int) noexcept
+{
+    return {};
+}
+
 #endif // _WIN32

src/memory/mman-win32/mman.hpp

@@ -30,12 +30,17 @@ typedef size_t oft__;
 #define MS_SYNC         2
 #define MS_INVALIDATE   4
 
-// Flags for madvise (stub).
+// Flags and no-op stubs.
 #define MADV_RANDOM     0
+#define MADV_SEQUENTIAL 0
+#define _SC_PAGESIZE    0
+#define MREMAP_MAYMOVE  0
+int sysconf(int) noexcept;
+void* mremap(void*, size_t, size_t, int) noexcept;
 
-void* mmap(void* addr, size_t len, int prot, int flags, int fd, oft__ off) noexcept;
 void* mremap_(void* addr, size_t old_size, size_t new_size, int prot,
     int flags, int fd) noexcept;
+void* mmap(void* addr, size_t len, int prot, int flags, int fd, oft__ off) noexcept;
 int munmap(void* addr, size_t len) noexcept;
 int madvise(void* addr, size_t len, int advice) noexcept;
 int mprotect(void* addr, size_t len, int prot) noexcept;