From d779c0b056defcf7eb4d75ab510e168ee03b5d95 Mon Sep 17 00:00:00 2001
From: Tom Ryder <tom@sanctum.geek.nz>
Date: Tue, 7 Jan 2020 10:21:27 +1300
Subject: More refactoring and rearranging, commenting

---
 crypt.c | 40 ++++++++++++++++++++++++++--------------
 crypt.h |  6 ++++--
 2 files changed, 30 insertions(+), 16 deletions(-)

diff --git a/crypt.c b/crypt.c
index 29c4794..5e13fbd 100644
--- a/crypt.c
+++ b/crypt.c
@@ -1,36 +1,40 @@
 #include "crypt.h"
 
-/*
- * Main function
- */
 int main (int argc, char **argv)
 {
-	/* The hash we will produce, hopefully */
-	char *hash = NULL;
-
-	/* Option character */
+	char *hash, *key, *salt;
 	int opt;
 
-	/* Iterate through any options */
 	while ((opt = getopt(argc, argv, "h")) != -1) {
 		switch (opt) {
-			case 'h':
+			case 'h': /* Help */
 				usage(stdout, EXIT_SUCCESS);
 				break;
-			case '?':
+			case '?': /* Unknown option */
 				usage(stderr, EXIT_FAILURE);
 				break;
-			default:
+			default: /* Shouldn't happen */
 				abort();
 		}
 	}
 
-	/* If we don't have three arguments left now, bail */
+	/*
+	 * If we don't have three arguments left after processing the options,
+	 * exit with usage information and error status
+	 */
 	if (argc != 3)
 		usage(stderr, EXIT_FAILURE);
 
-	/* All seems well, build the hash and print it */
-	hash = crypt(argv[1], argv[2]);
+	key = argv[1];
+	salt = argv[2];
+
+	/*
+	 * Create the hash, but exit immediately with the system error string
+	 * if it returns a null pointer (error condition)
+	 */
+	if (!(hash = crypt(key, salt)))
+		error(strerror(errno));
+
 	puts(hash);
 	exit(EXIT_SUCCESS);
 }
@@ -42,3 +46,11 @@ void usage(FILE *stream, int status) {
 	fputs("USAGE: crypt [-h | KEY SALT]\n", stream);
 	exit(status);
 }
+
+/*
+ * Exit with error error message
+ */
+void error(char *message) {
+	fprintf(stderr, "%s\n", message);
+	exit(EXIT_FAILURE);
+}
diff --git a/crypt.h b/crypt.h
index 6b2b7ca..6612e01 100644
--- a/crypt.h
+++ b/crypt.h
@@ -1,7 +1,9 @@
 #define _XOPEN_SOURCE
-#include <ctype.h>
+#include <errno.h>
 #include <stdio.h>
 #include <stdlib.h>
-#include <unistd.h>
+#include <string.h> /* strerror(3) */
+#include <unistd.h> /* crypt(3) */
 
 void usage(FILE *, int);
+void error(char *);
-- 
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