added Pcpstream example

tests/streamtest.c

@@ -0,0 +1,72 @@
+#include <stdio.h>
+#include <stdlib.h>
+#include <limits.h>
+
+#include <pcp.h>
+
+int main() {
+  /* create a file with "encrypted" data */
+  FILE *out, *in;
+  unsigned char clear[8] = "ABCDEFGH";
+  unsigned char key[8]   = "IxD8Lq1K";
+  unsigned char crypt[8] = {0};
+  int blocks = 8;
+  int i = 0;
+
+  if((out = fopen("teststream.out", "wb+")) == NULL) {
+    fprintf(stderr, "oops, could not open file!\n");
+    return 1;
+  }
+  Pcpstream *pout = ps_new_file(out);
+
+  /* "encrypt" a couple of times into the file */
+  for(i=0; i<blocks; i++) {
+    memcpy(crypt, clear, 8);
+    _xorbuf(key, crypt, 8);
+    ps_write(pout, crypt, 8);
+  }
+  ps_close(pout);
+  fclose(out);
+
+  /* read it in again using an in and an out stream */
+  if((in = fopen("teststream.out", "rb")) == NULL) {
+    fprintf(stderr, "oops, could not open file!\n");
+    return 1;
+  }
+  Pcpstream *pin = ps_new_file(in);
+  
+  /* we'll use this stream to put the "decrypted" data in.
+     note, that this could be a file as well.  */
+  Pcpstream *pclear = ps_new_outbuffer();
+
+  /* read and "decrypt" */
+  for(i=0; i<blocks; i++) {
+    ps_read(pin, crypt, 8);
+    _xorbuf(key, crypt, 8);
+    ps_write(pclear, crypt, 8);
+  }
+  ps_close(pin);
+  fclose(in);
+
+  /* now extract the buffer from the output stream */
+  Buffer *result = ps_buffer(pclear);
+
+  /* and verify if it's "decrypted" (re-use crypt) */
+  for(i=0; i<blocks; i++) {
+    buffer_get_chunk(result, crypt, 8);
+    if(memcmp(crypt, clear, 8) != 0) {
+      fprintf(stderr, "Oops, block %d doesn't match\n", i);
+      goto error;
+    }
+  }
+
+  ps_close(pclear);
+
+  fprintf(stderr, "done\n");
+
+  return 0;
+
+ error:
+  ps_close(pclear);
+  return 1;
+}