git subrepo clone https://github.com/Atmosphere-NX/Atmosphere-libs libraries

subrepo:
  subdir:   "libraries"
  merged:   "07af583b"
upstream:
  origin:   "https://github.com/Atmosphere-NX/Atmosphere-libs"
  branch:   "master"
  commit:   "07af583b"
git-subrepo:
  version:  "0.4.0"
  origin:   "https://github.com/ingydotnet/git-subrepo"
  commit:   "5d6aba9"

libraries/libstratosphere/source/updater/updater_files.cpp

@@ -0,0 +1,68 @@
+/*
+ * Copyright (c) 2018-2019 Atmosphère-NX
+ *
+ * This program is free software; you can redistribute it and/or modify it
+ * under the terms and conditions of the GNU General Public License,
+ * version 2, as published by the Free Software Foundation.
+ *
+ * This program is distributed in the hope it will be useful, but WITHOUT
+ * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
+ * FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License for
+ * more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program.  If not, see <http://www.gnu.org/licenses/>.
+ */
+#include "updater_files.hpp"
+
+namespace ams::updater {
+
+    Result ReadFile(size_t *out_size, void *dst, size_t dst_size, const char *path) {
+        FILE *fp = fopen(path, "rb");
+        if (fp == NULL) {
+            return ResultInvalidBootImagePackage();
+        }
+        ON_SCOPE_EXIT { fclose(fp); };
+
+        std::memset(dst, 0, dst_size);
+        size_t read_size = fread(dst, 1, dst_size, fp);
+        if (ferror(fp)) {
+            return fsdevGetLastResult();
+        }
+        *out_size = read_size;
+        return ResultSuccess();
+    }
+
+    Result GetFileHash(size_t *out_size, void *dst_hash, const char *path, void *work_buffer, size_t work_buffer_size) {
+        FILE *fp = fopen(path, "rb");
+        if (fp == NULL) {
+            return ResultInvalidBootImagePackage();
+        }
+        ON_SCOPE_EXIT { fclose(fp); };
+
+        Sha256Context sha_ctx;
+        sha256ContextCreate(&sha_ctx);
+
+        size_t total_size = 0;
+        while (true) {
+            size_t read_size = fread(work_buffer, 1, work_buffer_size, fp);
+            if (ferror(fp)) {
+                return fsdevGetLastResult();
+            }
+            if (read_size == 0) {
+                break;
+            }
+
+            sha256ContextUpdate(&sha_ctx, work_buffer, read_size);
+            total_size += read_size;
+            if (read_size != work_buffer_size) {
+                break;
+            }
+        }
+
+        sha256ContextGetHash(&sha_ctx, dst_hash);
+        *out_size = total_size;
+        return ResultSuccess();
+    }
+
+}