diff --git a/include/common.h b/include/common.h
new file mode 100644
index 0000000..befa1ce
--- /dev/null
+++ b/include/common.h
@@ -0,0 +1,24 @@
+#ifndef COMMON_H
+#define COMMON_H
+
+#include <string.h>
+#include <stdlib.h>
+#include <stdio.h>
+#include <stdint.h>
+#include <sys/stat.h>
+#include <math.h>
+#include <zlib.h>
+#include <errno.h>
+#include <dirent.h>
+#include <unistd.h>
+#include <fcntl.h>
+
+#define IS_ALPHA(c) ((c >= 'a' && c <= 'z') || (c >= 'A' && c <= 'Z'))
+#define IS_DIGIT(c) (c >= '0' && c <= '9')
+#define IS_ALNUM(c) (IS_ALPHA(c) || IS_DIGIT(c))
+#define IS_PUNCT(c) ((c >= 33 && c <= 47) || (c >= 58 && c <= 64) || (c >= 91 && c <= 96) || (c >= 123 && c <= 126))
+
+char* get_file_content(char*);
+char* get_file_content_with_size(char*, size_t*);
+
+#endif // COMMON_H
\ No newline at end of file
diff --git a/src/common.c b/src/common.c
new file mode 100644
index 0000000..a4622b9
--- /dev/null
+++ b/src/common.c
@@ -0,0 +1,43 @@
+#include "common.h"
+
+char* get_file_content(char* path) {
+    if (!path) return NULL;
+
+    FILE* file = fopen(path, "rb");
+    if (!file) { perror("ERROR: could not open file in get_file_content!"); return NULL; }
+    if (fseek(file, 0, SEEK_END) != 0) { fclose(file); return NULL; }
+    long file_size = ftell(file);
+    if (file_size < 0) { perror("ERROR: file size is negative in get_file_content!"); fclose(file); return NULL; }
+    if (fseek(file, 0, SEEK_SET) != 0) { fclose(file); return NULL; }
+    size_t n = (size_t)file_size;
+    char* buf = (char*)calloc(n + 1, 1);
+    if (!buf) { fclose(file); return NULL; }
+
+    size_t got = fread(buf, 1, n, file);
+    fclose(file);
+
+    buf[got] = '\0';
+
+    return buf;
+}
+
+char* get_file_content_with_size(char* path, size_t* size) {
+    if (!path || !size) return NULL;
+
+    FILE* file = fopen(path, "rb");
+    if (!file) { perror("ERROR: could not open file in get_file_content_with_size!"); return NULL; }
+    if (fseek(file, 0, SEEK_END) != 0) { fclose(file); return NULL; }
+    long file_size = ftell(file);
+    if (file_size < 0) { perror("ERROR: file size is negative in get_file_content_with_size!"); fclose(file); return NULL; }
+    if (fseek(file, 0, SEEK_SET) != 0) { fclose(file); return NULL; }
+    size_t n = (size_t)file_size;
+
+    char* buf = (char*)malloc(n);
+    if (!buf) { fclose(file); return NULL; }
+
+    size_t got = fread(buf, 1, n, file);
+    fclose(file);
+
+    *size = got;
+    return buf;
+}
\ No newline at end of file