Patch 1

src/lua/internal/sysbench.rand.lua

@@ -79,6 +79,15 @@ function sysbench.rand.varstring(min_len, max_len)
    return ffi.string(buf, nchars)
 end
 
+function sysbench.rand.hexadecimal(min_len, max_len)
+   assert(min_len <= max_len)
+   assert(max_len > 0)
+   local buflen = max_len
+   local buf = ffi.new("uint8_t[?]", buflen)
+   local nchars = ffi.C.sb_rand_hexadecimal(buf, min_len, max_len)
+   return ffi.string(buf, nchars)
+end
+
 function sysbench.rand.uniform_double()
    return ffi.C.sb_rand_uniform_double()
 end

src/sb_rand.c

@@ -305,6 +305,36 @@ uint32_t sb_rand_varstr(char *buf, uint32_t min_len, uint32_t max_len)
   return num_chars;
 }
 
+/*
+  Generates a random string of ASCII characters between '0' and 'f' of a length
+  between min and max. buf should have enough room for max len bytes. Returns
+  the number of characters written into the buffer.
+ */
+
+uint32_t sb_rand_hexadecimal(char *buf, uint32_t min_len, uint32_t max_len)
+{
+  unsigned int i;
+  char charset[] = "abcdef0123456789";
+  uint32_t num_chars;
+  if (max_len == 0) {
+    return 0; /* we can't be sure buf is long enough to populate, so be safe */
+  }
+  if (min_len > max_len)
+  {
+    min_len = 1;
+  }
+  int key;
+  int l = (int) (sizeof(charset) -1);
+
+  num_chars = sb_rand_uniform(min_len, max_len);
+  for (i=0; i < num_chars; i++)
+  {
+    key=rand() % l;
+    buf[i] = charset[key];
+  }
+  return num_chars;
+}
+
 /*
   Unique random sequence generator. This is based on public domain code from
   https://github.com/preshing/RandomSequence

src/sb_rand.h

@@ -70,5 +70,6 @@ uint32_t sb_rand_zipfian(uint32_t, uint32_t);
 uint32_t sb_rand_unique(void);
 void sb_rand_str(const char *, char *);
 uint32_t sb_rand_varstr(char *, uint32_t, uint32_t);
+uint32_t sb_rand_hexadecimal(char *, uint32_t, uint32_t);
 
 #endif /* SB_RAND_H */