From 61200ea6fe6e6df53479148801276e18cf4e9cd7 Mon Sep 17 00:00:00 2001
From: Tom Ryder <tom@sanctum.geek.nz>
Date: Tue, 7 Jan 2020 09:37:06 +1300
Subject: Refactor usage function and output

---
 crypt.c | 37 ++++++++++++++++++-------------------
 crypt.h |  3 +--
 2 files changed, 19 insertions(+), 21 deletions(-)

diff --git a/crypt.c b/crypt.c
index 54b90ce..22f82bd 100644
--- a/crypt.c
+++ b/crypt.c
@@ -8,38 +8,37 @@ int main (int argc, char **argv)
     /* The hash we will produce, hopefully */
     char *hash = NULL;
 
-    /* Assume user doesn't want help */
-    int help = 0;
+    /* Option character */
+    int opt;
 
     /* Iterate through any options */
-    int o;
-    while ((o = getopt(argc, argv, OPTSTRING)) != -1) {
-        switch (o) {
+    while ((opt = getopt(argc, argv, "h")) != -1) {
+        switch (opt) {
             case 'h':
-                help = 1;
+                usage(stdout, EXIT_SUCCESS);
                 break;
             case '?':
-                fprintf(stderr, "Unknown option\n");
+                usage(stderr, EXIT_FAILURE);
                 break;
             default:
                 abort();
         }
     }
 
-    /* If help was asked, give it */
-    if (help) {
-        fprintf(stdout, "%s\n", USAGE);
-        exit(EXIT_SUCCESS);
-    }
-
-    /* If we don't have three arguments, bail */
-    if (argc != 3) {
-        fprintf(stderr, "%s\n", USAGE);
-        exit(EXIT_FAILURE);
-    }
+    /* If we don't have three arguments left now, bail */
+    if (argc != 3)
+        usage(stderr, EXIT_FAILURE);
 
     /* All seems well, build the hash and print it */
     hash = crypt(argv[1], argv[2]);
-    fprintf(stdout, "%s\n", hash);
+    puts(hash);
     exit(EXIT_SUCCESS);
 }
+
+/*
+ * Show usage to given stream, and exit with given code
+ */
+void usage(FILE *stream, int status) {
+    fputs("USAGE: crypt [-h | KEY SALT]\n", stream);
+    exit(status);
+}
diff --git a/crypt.h b/crypt.h
index 2b8145d..6b2b7ca 100644
--- a/crypt.h
+++ b/crypt.h
@@ -4,5 +4,4 @@
 #include <stdlib.h>
 #include <unistd.h>
 
-#define OPTSTRING "h"
-#define USAGE "USAGE: crypt KEY SALT"
+void usage(FILE *, int);
-- 
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