From 52e3ab594b34bf309b8669fcaa855c295a00e114 Mon Sep 17 00:00:00 2001
From: Nicholas Hall <ngh@grandcare.com>
Date: Thu, 14 Sep 2017 16:42:29 -0500
Subject: DC414 meeting presentation files

---
 src/secret.c | 19 +++++++++++++++++++
 src/secret.h |  7 +++++++
 src/strcmp.c | 27 +++++++++++++++++++++++++++
 3 files changed, 53 insertions(+)
 create mode 100644 src/secret.c
 create mode 100644 src/secret.h
 create mode 100644 src/strcmp.c

(limited to 'src')

diff --git a/src/secret.c b/src/secret.c
new file mode 100644
index 0000000..d4113b2
--- /dev/null
+++ b/src/secret.c
@@ -0,0 +1,19 @@
+#include <stdio.h>
+#include <string.h>
+#include "secret.h"
+
+int main(int argc, char* argv[]){
+    if(argc <2){
+        printf("Usage: %s <secret_password>\n", argv[0]);
+        return 1;
+    }
+
+    UNHIDE_STR(pass);
+
+    if(! strcmp(pass, argv[1]))
+        printf("Access granted\n");
+    else
+        printf("Access denied\n");
+
+    return 0;
+}
diff --git a/src/secret.h b/src/secret.h
new file mode 100644
index 0000000..d6ee2ea
--- /dev/null
+++ b/src/secret.h
@@ -0,0 +1,7 @@
+#define A(c)            (c)-0x19
+#define UNHIDE_STR(str) do { char *p = str;  while (*p) *p++ += 0x19; } while (0)
+#define HIDE_STR(str)   do { char *p = str;  while (*p) *p++ -= 0x19; } while (0)
+
+char pass[] = {
+    A('c'), A('a'), A('t'), A('z'), A('r'), A('u'), A('l'), 0
+};
diff --git a/src/strcmp.c b/src/strcmp.c
new file mode 100644
index 0000000..d626bd3
--- /dev/null
+++ b/src/strcmp.c
@@ -0,0 +1,27 @@
+#include <stdio.h>
+/* Compare S1 and S2, returning less than, equal to or
+   greater than zero if S1 is lexicographically less than,
+   equal to or greater than S2.  */
+int strcmp (const char *p1, const char *p2)
+{
+  const unsigned char *s1 = (const unsigned char *) p1;
+  const unsigned char *s2 = (const unsigned char *) p2;
+  unsigned char c1, c2;
+
+  // print out input values
+  printf("strcmp('%s', '%s')", p1, p2);
+  do
+    {
+      c1 = (unsigned char) *s1++;
+      c2 = (unsigned char) *s2++;
+      if (c1 == '\0') {
+          // print return value
+          printf(" = %d\n", c1 - c2);
+          return c1 - c2;
+      }
+    }
+  while (c1 == c2);
+
+  printf(" = %d\n", c1 - c2);
+  return c1 - c2;
+}
-- 
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