From 427d06c98744dad1945430e45c5eea165c90b373 Mon Sep 17 00:00:00 2001
From: Benjamin Valentin <benjamin.valentin@ml-pa.com>
Date: Sat, 30 Apr 2022 18:14:20 +0200
Subject: [PATCH] sys/vfs_util: add vfs_file_sha256()

---
 sys/include/vfs_util.h  | 16 ++++++++++++++++
 sys/vfs_util/vfs_util.c | 24 ++++++++++++++++++++++++
 2 files changed, 40 insertions(+)

diff --git a/sys/include/vfs_util.h b/sys/include/vfs_util.h
index 594070e89b..a6ae1ec911 100644
--- a/sys/include/vfs_util.h
+++ b/sys/include/vfs_util.h
@@ -83,6 +83,22 @@ int vfs_file_md5(const char* file, void *digest,
  */
 int vfs_file_sha1(const char* file, void *digest,
                   void *work_buf, size_t work_buf_len);
+
+/**
+ * @brief   Compute the SHA256 message digest of a file
+ *
+ *          Requires the `hashes` module.
+ *
+ * @param[in]  file     Source file path
+ * @param[out] digest   Destination buffer, must fit @ref SHA256_DIGEST_LENGTH bytes
+ * @param[out] work_buf Work buffer
+ * @param[in] work_buf_len  Size of the work buffer
+ *
+ * @return  0 on success
+ * @return  negative error
+ */
+int vfs_file_sha256(const char* file, void *digest,
+                    void *work_buf, size_t work_buf_len);
 #endif
 
 #ifdef __cplusplus
diff --git a/sys/vfs_util/vfs_util.c b/sys/vfs_util/vfs_util.c
index a8f3585a95..adf7e7f13f 100644
--- a/sys/vfs_util/vfs_util.c
+++ b/sys/vfs_util/vfs_util.c
@@ -83,6 +83,7 @@ int vfs_file_to_buffer(const char* file, void* buf, size_t len)
 #if MODULE_HASHES
 #include "hashes/md5.h"
 #include "hashes/sha1.h"
+#include "hashes/sha256.h"
 
 int vfs_file_md5(const char* file, void *digest,
                  void *work_buf, size_t work_buf_len)
@@ -128,5 +129,28 @@ int vfs_file_sha1(const char* file, void *digest,
 
     return res > 0 ? 0 : res;
 
+}
+
+int vfs_file_sha256(const char* file, void *digest,
+                    void *work_buf, size_t work_buf_len)
+{
+    sha256_context_t ctx;
+    int res, fd = vfs_open(file, O_RDONLY, 0);
+
+    if (fd < 0) {
+        DEBUG("can't open %s for reading\n", file);
+        return fd;
+    }
+
+    sha256_init(&ctx);
+    while ((res = vfs_read(fd, work_buf, work_buf_len)) > 0) {
+        sha256_update(&ctx, work_buf, res);
+    }
+    sha256_final(&ctx, digest);
+
+    vfs_close(fd);
+
+    return res > 0 ? 0 : res;
+
 }
 #endif /* MODULE_HASHES */