same for windows

tiledb/sm/filesystem/win.cc

@@ -462,11 +462,19 @@ Status Win::read(
         0) {
       auto gle = GetLastError();
       CloseHandle(file_h);
+
+      std::string err_msg;
+      if (gle != 0) {
+        err_msg = get_last_error_msg(gle, "ReadFile");
+      } else {
+        err_msg = "num_bytes_read " + std::to_string(num_bytes_read) +
+                  " != nbytes " + std::to_string(nbytes)
+      }
+
       return LOG_STATUS(Status_IOError(
-          "Cannot read from file '" + path + "'; File read error " +
-          (gle != 0 ? get_last_error_msg(gle, "ReadFile") :
-                      "num_bytes_read " + std::to_string(num_bytes_read) +
-                          " != nbyes " + std::to_string(nbytes))));
+          "Cannot read from file '" + path + "'; File read error '" + err_msg +
+          "' offset " + std::string(offset) + " nbytes " +
+          std::string(nbytes)));
     }
     byte_buffer += num_bytes_read;
     offset += num_bytes_read;
@@ -548,8 +556,9 @@ Status Win::write(
   uint64_t file_offset = file_size_lg_int.QuadPart;
   if (!write_at(file_h, file_offset, buffer, buffer_size).ok()) {
     CloseHandle(file_h);
-    return LOG_STATUS(
-        Status_IOError(std::string("Cannot write to file '") + path));
+    return LOG_STATUS(Status_IOError(
+        std::string("Cannot write to file '") + path + "'" + " file_offset " +
+        std::string(file_offset) + " buffer_size " + std::string(buffer_size)));
   }
   // Always close the handle.
   if (CloseHandle(file_h) == 0) {
@@ -588,9 +597,11 @@ Status Win::write_at(
             bytes_to_write,
             &bytes_written,
             &ov) == 0) {
+      // There's no guarantee that the bytes_written outarg was updated, when
+      // the write failed -- so let's not log it.
       return LOG_STATUS(Status_IOError(std::string(
-          "Cannot write to file; File writing error: " +
-          get_last_error_msg("WriteFile"))));
+          get_last_error_msg("WriteFile") + " bytes_to_write " +
+          std::string(bytes_to_write))));
     }
     remaining_bytes_to_write -= bytes_written;
     byte_idx += bytes_written;