feat(hash): added basic hashing functions to gain object ideas for the object storage

include/hash.h

@@ -0,0 +1,18 @@
+#ifndef HASH_H
+#define HASH_H
+
+#include <stdio.h>
+#include <stdlib.h>
+#include <string.h>
+#include <openssl/sha.h>
+
+typedef enum {
+    FileObject,
+    TreeObject,
+    LogObject
+} ObjectType;
+
+void object_hash(ObjectType, char*, char*);
+void hash_to_hex(const unsigned char*, char*);
+
+#endif // HASH_H

src/hash.c

@@ -0,0 +1,43 @@
+#include "hash.h"
+
+static void compute_sha1_openssl(const char* data, size_t len, unsigned char* hash) {
+    SHA_CTX ctx;
+    SHA1_Init(&ctx);
+    SHA1_Update(&ctx, data, len);
+    SHA1_Final(hash, &ctx);
+}
+
+void hash_to_hex(const unsigned char* hash, char* hex_string) {
+    for (int i = 0; i < SHA_DIGEST_LENGTH; i++) {
+        sprintf(hex_string + (i * 2), "%02x", hash[i]);
+    }
+    hex_string[40] = '\0';
+}
+
+void object_hash(ObjectType obj_type, char* content, char* hex_hash) {
+    size_t content_len = strlen(content);
+
+    char header[64];
+    int header_len;
+    switch (obj_type) {
+        case FileObject: header_len = snprintf(header, sizeof(header), "file %zu", content_len); break;
+        case TreeObject: header_len = snprintf(header, sizeof(header), "tree %zu", content_len); break;
+        case LogObject:  header_len = snprintf(header, sizeof(header),  "log %zu", content_len); break;
+        default: header_len = 0; break;
+    }
+    header[header_len] = '\0';
+    header_len++;
+
+    size_t total_len = header_len + content_len;
+
+    char* full_content = malloc(total_len);
+    memcpy(full_content, header, header_len);
+    memcpy(full_content + header_len, content, content_len);
+
+    unsigned char hash[SHA_DIGEST_LENGTH];
+    compute_sha1_openssl(full_content, total_len, hash);
+
+    hash_to_hex(hash, hex_hash);
+
+    free(full_content);
+}