add pyesc, unhex, xor

hd.c

@@ -94,5 +94,3 @@ main(int argc, char *argv[])
 
   return 0;
 }
-
-    

pyesc.c

@@ -0,0 +1,26 @@
+#include <stdio.h>
+
+int
+main(int argc, char *argv[])
+{
+    while (1) {
+        int c = getchar();
+
+        switch (c) {
+            case EOF:
+                return 0;
+            case 134:
+                printf("\\\\");
+                break;
+            case 32 ... 91:
+            case 93 ... 126:
+                putchar(c);
+                break;
+            default:
+                printf("\\x%02x", c);
+                break;
+        }
+    }
+
+    return 0;
+}

unhex.c

@@ -0,0 +1,51 @@
+/* Hex Decoder -- 2012 Zephyr <zephyr@dirtbags.net>
+ * 
+ * This file is in the public domain.  I make no promises
+ * about the functionality of this program.
+ */
+
+#include <stdio.h>
+
+int
+main(int argc, char *argv[])
+{
+    unsigned char acc = 0;
+    unsigned char nybble = 0;
+    unsigned long int count = 0;
+
+    while (1) {
+        int c = getchar();
+
+        count += 1;
+
+        switch (c) {
+            case EOF:
+                return 0;
+            case '0' ... '9':
+                acc = (acc << 4) + c - '0';
+                nybble += 1;
+                break;
+            case 'a' ... 'f':
+                acc = (acc << 4) + c - 'a' + 10;
+                nybble += 1;
+                break;
+            case 'A' ... 'F':
+                acc = (acc << 4) + c - 'A' + 10;
+                nybble += 1;
+                break;
+            default:
+                if (nybble != 0) {
+                    fprintf(stderr, "Warning: non-hex character mid-octet at offset %lu\n", count);
+                }
+                break;
+        }
+
+        if (nybble == 2) {
+            putchar(acc);
+            acc = 0;
+            nybble = 0;
+        }
+    }
+
+    return 0;
+}

xor.c

@@ -0,0 +1,48 @@
+/* xor filter -- 2012 Zephyr <zephyr@dirtbags.net>
+ * 
+ * This file is in the public domain.  I make no promises
+ * about the functionality of this program.
+ */
+
+#include <stdio.h>
+#include <stdlib.h>
+#include <string.h>
+
+int
+main(int argc, char *argv[])
+{
+    int start = 1;
+    int base = 0;
+    int arg;
+
+    if (argc < 2) {
+        fprintf(stderr, "Usage: %s [-x] m1 [m2 ...]\n", argv[0]);
+        return 1;
+    }
+
+    if (0 == strcmp(argv[1], "-x")) {
+        base = 16;
+        start += 1;
+    }
+
+    arg = start;
+
+    while (1) {
+        int c = getchar();
+        unsigned char mask;
+        
+        if (! argv[arg]) {
+            arg = start;
+        }
+        mask = strtol(argv[arg++], NULL, base);
+
+        if (EOF == c) {
+            break;
+        }
+
+        c ^= mask;
+        putchar(c);
+    }
+
+    return 0;
+}