Parse arguments

.gitignore

@@ -1,2 +1,4 @@
 setuptools
 ._setuptools
+*.o
+dasm

Makefile

@@ -2,7 +2,8 @@ NAME = dasm
 CFLAGS = -Wall -Wextra -Wshadow
 LDFLAGS = 
 
-SRC = src/main.c
+SRC = src/main.c \
+	  src/dasm.c
 
 OBJ = $(SRC:%.c=%.o)
 

src/dasm.c

@@ -0,0 +1,20 @@
+#include <sys/types.h>
+#include <stdio.h>
+#include "dasm.h"
+
+void print_instruction(unsigned addr)
+{
+	printf("%X\n", addr);
+}
+
+int dasm(char *binary)
+{
+	int pc = 0;
+
+	while (*binary) {
+		instruction_t inst = *binary;
+		print_instruction(pc);
+		pc += inst.size;
+	}
+	return 0;
+}

src/dasm.h

@@ -0,0 +1,6 @@
+int dasm(char *binary);
+
+typedef struct instruction {
+	const char *name;
+	unsigned size;
+} instruction_t;

src/main.c

@@ -1,4 +1,50 @@
-int main()
+#include <stdio.h>
+#include <string.h>
+#include <stdlib.h>
+#include "dasm.h"
+
+char *open_and_read(char *path)
 {
-	
+	FILE *file = fopen(path, "r");
+	if (!file) {
+		dprintf(2, "Invalid path: %s. File does not exist.\n", path);
+		return NULL;
+	}
+
+	int rc = fseek(file, 0L, SEEK_END);
+	if (rc != 0) {
+		fclose(file);
+		return NULL;
+	}
+	long size = ftell(file);
+	if (size == -1) {
+		fclose(file);
+		return NULL;
+	}
+	rewind(file);
+
+	char *ret = malloc((size + 1) * sizeof(char));
+	size = fread(ret, sizeof(char), size, file);
+	ret[size] = '\0';
+
+	fclose(file);
+	return ret;
+}
+
+int main(int argc, char **argv)
+{
+	if (argc != 3 || strcmp(argv[1], "-d")) {
+		printf("Usage: %s -d <binary>\n", argv[0]);
+		return 2;
+	}
+
+	char *binary = open_and_read(argv[2]);
+	if (!binary) {
+		puts("Could not read binary file.");
+		return 2;
+	}
+
+	int ret = dasm(binary);
+	free(binary);
+	return ret;
 }