Added a trivial program to randomly corrupt RDB files in /utils.

utils/corrupt_rdb.c

@@ -0,0 +1,44 @@
+/* Trivia program to corrupt an RDB file in order to check the RDB check
+ * program behavior and effectiveness.
+ *
+ * Copyright (C) 2016 Salvatore Sanfilippo.
+ * This software is released in the 3-clause BSD license. */
+
+#include <stdio.h>
+#include <fcntl.h>
+#include <sys/stat.h>
+#include <stdlib.h>
+#include <unistd.h>
+#include <time.h>
+
+int main(int argc, char **argv) {
+    struct stat stat;
+    int fd, cycles;
+
+    if (argc != 3) {
+        fprintf(stderr,"Usage: <filename> <cycles>\n");
+        exit(1);
+    }
+
+    srand(time(NULL));
+    cycles = atoi(argv[2]);
+    fd = open("dump.rdb",O_RDWR);
+    if (fd == -1) {
+        perror("open");
+        exit(1);
+    }
+    fstat(fd,&stat);
+
+    while(cycles--) {
+        unsigned char buf[32];
+        unsigned long offset = rand()%stat.st_size;
+        int writelen = 1+rand()%31;
+        int j;
+
+        for (j = 0; j < writelen; j++) buf[j] = (char)rand();
+        lseek(fd,offset,SEEK_SET);
+        printf("Writing %d bytes at offset %lu\n", writelen, offset);
+        write(fd,buf,writelen);
+    }
+    return 0;
+}