Add: argument handling & PoC: echo command

src/libc/string.c

@@ -1,3 +1,5 @@
+#include "stdint.h"
+
 int strlen(const char* str)
 {
   int len = 0;
@@ -17,3 +19,52 @@ int strcmp(const char* str1, const char* str2)
   }
   return *(const unsigned char*)str1 - *(const unsigned char*)str2;
 }
+
+char* strchr(const char* str, int c)
+{
+	while (*str)
+	{
+		if (*str == (char)c)
+		{
+			return (char*)str;
+		}
+		str++;
+	}
+	if (c == '\0')
+	{
+		return (char*)str;
+	}
+	return NULL;
+}
+
+char* strtok(char* str, const char* delimiter)
+{
+	static char* last;
+	if (str)
+	{
+		last = str;
+	} else {
+		str = last;
+	}
+
+	if (!str || *str == '\0')
+	{
+		return NULL;
+	}
+
+	char* token_start = str;
+	while (*str && !strchr(delimiter, *str))
+	{
+		str++;
+	}
+
+	if (*str)
+	{
+		*str = '\0';
+		last = str + 1;
+	} else {
+		last = NULL;
+	}
+
+	return token_start;
+}