From 00fb165cb4bdcbe4e3f2a4d2a84e401e6df3c8f5 Mon Sep 17 00:00:00 2001
From: Nicholas Tay <nick@windblume.net>
Date: Tue, 11 Jan 2022 20:09:04 +1100
Subject: Split out logic into nice functions

---
 passgen.c | 120 +++++++++++++++++++++++++++++++++++++-------------------------
 1 file changed, 71 insertions(+), 49 deletions(-)

diff --git a/passgen.c b/passgen.c
index c43ae8b..1215d3f 100644
--- a/passgen.c
+++ b/passgen.c
@@ -39,8 +39,63 @@
         break;
 
 
+void init_rng(void)
+{
+    /* For now, this is only needed on rand() */
+#ifndef USE_GETENTROPY
+    /*
+     * TODO: seed better RNG
+     * this isn't very good, but it's enough(?) for now
+     *
+     * on linux we use the `getrandom` api which is supposedly
+     * what crypto uses to generate. potentially on win we
+     * can use the crypto thing (but it's more complicated
+     * to invoke).
+     *
+     * anything else we could use on posix systems?
+     */
+    srand(time(NULL) + getpid() % 420 - 69);
+#endif
+}
+
+int get_rng(void)
+{
+#ifdef USE_GETENTROPY
+    int r;
+    getentropy(&r, sizeof(r));
+    return r;
+#else
+    return rand();
+#endif
+}
+
+char *build_grammar(int triplets, int specials, int numbers)
+{
+    if (triplets < 1) {
+        fprintf(stderr, "ERROR: Cannot have less than one triplet.");
+        return NULL;
+    }
+
+    int grammar_size = triplets * 3 + specials + numbers;
+    char *build = malloc(grammar_size + 1);
+    if (build == NULL) {
+        perror("malloc");
+        return NULL;
+    }
+    build[grammar_size] = 0;
+
+    memcpy(build, "Cvc", 3);
+    for (int i = 1; i < triplets; ++i)
+        memcpy(build + (i * 3), "cvc", 3);
+
+    memset(build + (triplets * 3), '!', specials);
+    memset(build + (triplets * 3) + specials, '#', numbers);
+    return build;
+}
+
 int main(int argc, char *argv[])
 {
+    bool err = false;
     bool custom_grammar = false;
     char *grammar = DEFAULT_GRAMMAR;
     int grammar_size = sizeof(DEFAULT_GRAMMAR) - 1;
@@ -54,53 +109,23 @@ int main(int argc, char *argv[])
          * Take arguments as triplets, specials, numbers
          * atoi might be scuffed but so be it (it just goes = 0 if invalid input)
          */
-        int triplets = atoi(argv[1]);
-        int specials = atoi(argv[2]);
-        int numbers = atoi(argv[3]);
-
-        if (triplets < 1) {
-            fprintf(stderr, "ERROR: Cannot have less than one triplet.");
-            return 1;
-        }
-
-        grammar_size = triplets * 3 + specials + numbers;
-        grammar = malloc(grammar_size + 1);
+        grammar = build_grammar(atoi(argv[1]), atoi(argv[2]), atoi(argv[3]));
         if (grammar == NULL) {
-            perror("malloc");
-            return 1;
+            err = true;
+            goto cleanup;
         }
-        grammar[grammar_size] = 0;
-
-        memcpy(grammar, "Cvc", 3);
-        for (int i = 1; i < triplets; ++i)
-            memcpy(grammar + (i * 3), "cvc", 3);
-
-        memset(grammar + (triplets * 3), '!', specials);
-        memset(grammar + (triplets * 3) + specials, '#', numbers);
         custom_grammar = true;
     }
 
     char *password = malloc(grammar_size + 1);
     if (password == NULL) {
         perror("malloc");
-        return 1;
+        err = true;
+        goto cleanup;
     }
     password[grammar_size] = 0;
 
-#ifndef USE_GETENTROPY
-    /*
-     * TODO: seed better RNG
-     * this isn't very good, but it's enough(?) for now
-     *
-     * on linux we use the `getrandom` api which is supposedly
-     * what crypto uses to generate. potentially on win we
-     * can use the crypto thing (but it's more complicated
-     * to invoke).
-     *
-     * anything else we could use on posix systems?
-     */
-    srand(time(NULL) + getpid() % 420 - 69);
-#endif
+    init_rng();
 
     for (int i = 0; i < grammar_size; ++i) {
         char c = grammar[i];
@@ -117,28 +142,25 @@ int main(int argc, char *argv[])
             CLASSES
         default:
             fprintf(stderr, "ERROR: Invalid grammar character '%c'.\n", c);
-            if (custom_grammar)
-                free(grammar);
-            free(password);
-            return 1;
+            err = true;
+            goto cleanup;
         }
 
         do {
-#ifdef USE_GETENTROPY
-            unsigned int r;
-            getentropy(&r, sizeof(r));
-#else
-            long r = rand();
-#endif
-            password[i] = class[r % class_size] - (caps ? 'a' - 'A' : 0);
+            password[i] = class[get_rng() % class_size] - (caps ? 'a' - 'A' : 0);
         } while (i != 0 && password[i] == password[i - 1]);
     }
 
+    printf("%s\n", password);
+
+cleanup:
     if (custom_grammar)
         free(grammar);
+    if (password)
+        free(password);
 
-    printf("%s\n", password);
-    free(password);
+    if (err)
+        return 1;
 
     return 0;
 }
-- 
cgit