1 files changed, 101 insertions, 0 deletions
diff --git a/klm/util/mmap.hh b/klm/util/mmap.hh
new file mode 100644
index 00000000..c9068ec9
--- /dev/null
+++ b/klm/util/mmap.hh
@@ -0,0 +1,101 @@
+#ifndef UTIL_MMAP__
+#define UTIL_MMAP__
+// Utilities for mmaped files.  
+
+#include "util/scoped.hh"
+
+#include <cstddef>
+
+#include <sys/types.h>
+
+namespace util {
+
+// (void*)-1 is MAP_FAILED; this is done to avoid including the mmap header here.  
+class scoped_mmap {
+  public:
+    scoped_mmap() : data_((void*)-1), size_(0) {}
+    scoped_mmap(void *data, std::size_t size) : data_(data), size_(size) {}
+    ~scoped_mmap();
+
+    void *get() const { return data_; }
+
+    const char *begin() const { return reinterpret_cast<char*>(data_); }
+    const char *end() const { return reinterpret_cast<char*>(data_) + size_; }
+    std::size_t size() const { return size_; }
+
+    void reset(void *data, std::size_t size) {
+      scoped_mmap other(data_, size_);
+      data_ = data;
+      size_ = size;
+    }
+
+    void reset() {
+      reset((void*)-1, 0);
+    }
+
+  private:
+    void *data_;
+    std::size_t size_;
+
+    scoped_mmap(const scoped_mmap &);
+    scoped_mmap &operator=(const scoped_mmap &);
+};
+
+/* For when the memory might come from mmap, new char[], or malloc.  Uses NULL
+ * and 0 for blanks even though mmap signals errors with (void*)-1).  The reset
+ * function checks that blank for mmap.  
+ */
+class scoped_memory {
+  public:
+    typedef enum {MMAP_ALLOCATED, ARRAY_ALLOCATED, MALLOC_ALLOCATED, NONE_ALLOCATED} Alloc;
+
+    scoped_memory() : data_(NULL), size_(0), source_(NONE_ALLOCATED) {}
+
+    ~scoped_memory() { reset(); }
+
+    void *get() const { return data_; }
+    const char *begin() const { return reinterpret_cast<char*>(data_); }
+    const char *end() const { return reinterpret_cast<char*>(data_) + size_; }
+    std::size_t size() const { return size_; }
+
+    Alloc source() const { return source_; }
+
+    void reset() { reset(NULL, 0, NONE_ALLOCATED); }
+
+    void reset(void *data, std::size_t size, Alloc from);
+
+    // realloc allows the current data to escape hence the need for this call
+    // If realloc fails, destroys the original too and get() returns NULL.
+    void call_realloc(std::size_t to);
+
+  private:
+
+    void *data_;
+    std::size_t size_;
+
+    Alloc source_;
+
+    scoped_memory(const scoped_memory &);
+    scoped_memory &operator=(const scoped_memory &);
+};
+
+struct scoped_mapped_file {
+  scoped_fd fd;
+  scoped_mmap mem;
+};
+
+// Wrapper around mmap to check it worked and hide some platform macros.  
+void *MapOrThrow(std::size_t size, bool for_write, int flags, bool prefault, int fd, off_t offset = 0);
+void *MapForRead(std::size_t size, bool prefault, int fd, off_t offset = 0);
+
+void *MapAnonymous(std::size_t size);
+
+// Open file name with mmap of size bytes, all of which are initially zero.  
+void MapZeroedWrite(const char *name, std::size_t size, scoped_fd &file, scoped_mmap &mem);
+inline void MapZeroedWrite(const char *name, std::size_t size, scoped_mapped_file &out) {
+  MapZeroedWrite(name, size, out.fd, out.mem);
+}
+ 
+} // namespace util
+
+#endif // UTIL_SCOPED__