Splitting into separate files.

core.c

@@ -0,0 +1,60 @@
+#include <assert.h>
+#include <stddef.h>
+#include <stdio.h>
+#include <stdlib.h>
+#include <string.h>
+#include <unistd.h>
+
+#include "core.h"
+
+#ifdef	INCLUDE_STRNSTR
+/*
+ * Find the first occurrence of find in s, where the search is limited to the
+ * first slen characters of s.
+ */
+char *
+strnstr(const char *s, const char *find, size_t slen)
+{
+	char	 c, sc;
+	size_t	 len;
+
+	if ((c = *find++) != '\0') {
+		len = strlen(find);
+		do {
+			do {
+				if (slen-- < 1 || (sc = *s++) == '\0')
+					return (NULL);
+			} while (sc != c);
+			if (len > slen)
+				return (NULL);
+		} while (strncmp(s, find, len) != 0);
+		s--;
+	}
+	return ((char*)s);
+}
+#endif
+
+
+void
+kwrite(const int fd, const char* buf, const int len)
+{
+	int wlen = 0;
+
+	wlen = write(fd, buf, len);
+	assert(wlen != -1);
+	assert(wlen == len);
+	if (wlen == -1) {
+		abort();
+	}
+}
+
+
+void
+die(const char* s)
+{
+	kwrite(STDOUT_FILENO, "\x1b[2J", 4);
+	kwrite(STDOUT_FILENO, "\x1b[H", 3);
+
+	perror(s);
+	exit(1);
+}