1 files changed, 42 insertions, 0 deletions
diff --git a/lib/checksum.c b/lib/checksum.c
new file mode 100644
index 0000000..249d6cb
--- /dev/null
+++ b/lib/checksum.c
@@ -0,0 +1,42 @@
+/**
+ * @file checksum.c
+ */
+#include "spm.h"
+#include <openssl/sha.h>
+
+/**
+ *
+ * @param filename
+ * @return
+ */
+char *sha256sum(const char *filename) {
+    size_t bytes = 0;
+    unsigned char digest[SHA256_DIGEST_LENGTH];
+    char buf[BUFSIZ];
+    SHA256_CTX context;
+    SHA256_Init(&context);
+    FILE *fp = fopen(filename, "r");
+    if (!fp) {
+        perror(filename);
+        return NULL;
+    }
+    char *result = calloc(SHA256_DIGEST_STRING_LENGTH, sizeof(char));
+    if (!result) {
+        fclose(fp);
+        perror("SHA256 result");
+        return NULL;
+    }
+
+    while ((bytes = fread(buf, sizeof(char), BUFSIZ, fp)) != 0) {
+        SHA256_Update(&context, buf, bytes);
+    }
+    fclose(fp);
+
+    SHA256_Final(digest, &context);
+    char *rtmp = result;
+    for (int i = 0; i < SHA256_DIGEST_LENGTH; i++) {
+        snprintf(&rtmp[i * 2], 3, "%02x", digest[i]);
+    }
+
+    return result;
+}