Eryk Sun <eryk...@gmail.com> added the comment:
For a concrete example, here's a rewrite of the Windows implementation that
incorporates the suggested changes.
#include <winternl.h>
#ifdef MS_WINDOWS
/* a named file mapping that's open more than once can't be resized */
/* this check could be moved into is_resizeable */
if (self->tagname) {
typedef NTSTATUS NTAPI ntqo_f(HANDLE, OBJECT_INFORMATION_CLASS,
PVOID, ULONG, PULONG);
ntqo_f *pNtQueryObject = (ntqo_f *)GetProcAddress(
GetModuleHandleW(L"ntdll"), "NtQueryObject");
if (pNtQueryObject) {
PUBLIC_OBJECT_BASIC_INFORMATION info;
NTSTATUS status = pNtQueryObject(self->map_handle,
ObjectBasicInformation, &info, sizeof(info), NULL);
if (NT_SUCCESS(status) && info.HandleCount > 1) {
PyErr_SetFromWindowsErr(ERROR_USER_MAPPED_FILE);
return NULL;
}
}
}
DWORD error = 0;
char *old_data = self->data;
LARGE_INTEGER offset;
offset.QuadPart = self->offset;
/* close the file mapping */
CloseHandle(self->map_handle);
self->map_handle = NULL;
/* if it's not the paging file, unmap the view and resize the file */
if (self->file_handle != INVALID_HANDLE_VALUE) {
UnmapViewOfFile(self->data);
self->data = NULL;
/* resize the file */
if (!SetFilePointerEx(self->file_handle, offset, NULL,
FILE_BEGIN) ||
!SetEndOfFile(self->file_handle)) {
/* resizing failed. try to remap the file */
error = GetLastError();
new_size = self->size;
}
}
/* create a new file mapping and map a new view */
LARGE_INTEGER max_size;
max_size.QuadPart = new_size;
/* FIXME: call CreateFileMappingW with wchar_t tagname */
self->map_handle = CreateFileMapping(self->file_handle, NULL,
PAGE_READWRITE, max_size.HighPart, max_size.LowPart,
self->tagname);
if (self->map_handle != NULL &&
GetLastError() != ERROR_ALREADY_EXISTS) {
self->data = MapViewOfFile(self->map_handle, FILE_MAP_WRITE,
offset.HighPart, offset.LowPart, new_size);
if (self->data != NULL) {
/* copy the old view if using the paging file */
if (self->file_handle == INVALID_HANDLE_VALUE) {
memcpy(self->data, old_data,
self->size < new_size ? self->size : new_size);
}
self->size = new_size;
} else {
error = GetLastError();
CloseHandle(self->map_handle);
self->map_handle = NULL;
}
} else {
error = GetLastError();
}
/* unmap the old view if using the paging file */
if (self->file_handle == INVALID_HANDLE_VALUE) {
UnmapViewOfFile(old_data);
}
if (error) {
PyErr_SetFromWindowsErr(error);
return NULL;
}
Py_RETURN_NONE;
#endif /* MS_WINDOWS */
----------
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Python tracker <rep...@bugs.python.org>
<https://bugs.python.org/issue40915>
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