From 5c5ef256b39665d1f882f12c76f54cbac6c807d0 Mon Sep 17 00:00:00 2001
From: Leo Yuriev <leo@yuriev.ru>
Date: Fri, 31 Mar 2017 16:20:38 +0300
Subject: [PATCH] mdbx: change mdbx_dkey().

---
 mdbx.h       |  2 +-
 src/mdbx.c   | 35 +++++++++++++++++++++--------------
 test/test6.c |  5 +++--
 3 files changed, 25 insertions(+), 17 deletions(-)

diff --git a/mdbx.h b/mdbx.h
index 3ebc59b3..301854e6 100644
--- a/mdbx.h
+++ b/mdbx.h
@@ -1625,7 +1625,7 @@ LIBMDBX_API int mdbx_reader_list(MDB_env *env, MDB_msg_func *func, void *ctx);
  */
 LIBMDBX_API int mdbx_reader_check(MDB_env *env, int *dead);
 
-LIBMDBX_API char *mdbx_dkey(MDB_val *key, char *buf);
+LIBMDBX_API char *mdbx_dkey(MDB_val *key, char *buf, const size_t bufsize);
 
 LIBMDBX_API int mdbx_env_close_ex(MDB_env *env, int dont_sync);
 
diff --git a/src/mdbx.c b/src/mdbx.c
index 2f4e17fb..8abf7666 100644
--- a/src/mdbx.c
+++ b/src/mdbx.c
@@ -332,7 +332,7 @@ txnid_t mdbx_debug_edge;
  *	@ingroup debug
  *	Invoke a function to display a key in hex.
  */
-#define DKEY(x) mdbx_dkey(x, kbuf)
+#define DKEY(x) mdbx_dkey(x, kbuf, sizeof(kbuf))
 
 /** An invalid page number.
  *	Mainly used to denote an empty tree.
@@ -821,7 +821,7 @@ static __inline pgno_t mdbx_dbg_pgno(MDB_page *mp) {
 * @param[in] buf the buffer to write into. Should always be #DKBUF.
 * @return The key in hexadecimal form.
 */
-char *mdbx_dkey(MDB_val *key, char *buf) {
+char *mdbx_dkey(MDB_val *key, char *buf, const size_t bufsize) {
 #ifdef _MSC_VER
   (void)key;
   (void)buf;
@@ -833,17 +833,24 @@ char *mdbx_dkey(MDB_val *key, char *buf) {
   if (!key)
     return "";
 
-  if (key->mv_size > DKBUF_MAXKEYSIZE)
-    return "MDB_MAXKEYSIZE";
-/* may want to make this a dynamic check: if the key is mostly
-* printable characters, print it as-is instead of converting to hex. */
-#if 1
-  buf[0] = '\0';
-  for (i = 0; i < key->mv_size; i++)
-    ptr += sprintf(ptr, "%02x", ((unsigned char *)key->mv_data)[i]);
-#else
-  sprintf(buf, "%.*s", key->mv_size, key->mv_data);
-#endif
+  const uint8_t *const data = key->mv_data;
+  bool is_ascii = true;
+  for (i = 0; is_ascii && i < key->mv_size; i++)
+    if (data[i] < ' ' || data[i] > 127)
+      is_ascii = false;
+
+  if (is_ascii)
+    snprintf(buf, bufsize, "%.*s",
+             (key->mv_size > INT_MAX) ? INT_MAX : (int)key->mv_size, data);
+  else {
+    buf[0] = '\0';
+    for (i = 0; i < key->mv_size; i++) {
+      int len = snprintf(ptr, bufsize - (ptr - buf), "%02x", data[i]);
+      if (len < 1)
+        break;
+      ptr += len;
+    }
+  }
   return buf;
 #endif /* _MSC_VER */
 }
@@ -6833,7 +6840,7 @@ static int mdbx_update_key(MDB_cursor *mc, MDB_val *key) {
     k2.mv_data = NODEKEY(node);
     k2.mv_size = node->mn_ksize;
     mdbx_debug("update key %u (ofs %u) [%s] to [%s] on page %zu", indx, ptr,
-               mdbx_dkey(&k2, kbuf2), DKEY(key), mp->mp_pgno);
+               mdbx_dkey(&k2, kbuf2, sizeof(kbuf2)), DKEY(key), mp->mp_pgno);
   }
 
   /* Sizes must be 2-byte aligned. */
diff --git a/test/test6.c b/test/test6.c
index e9d6dd3c..03b6f7d1 100644
--- a/test/test6.c
+++ b/test/test6.c
@@ -113,8 +113,9 @@ int main(int argc, char *argv[]) {
   E(mdbx_cursor_get(cursor, &key, &data, MDB_FIRST));
 
   do {
-    printf("key: %p %s, data: %p %.*s\n", key.mv_data, mdbx_dkey(&key, dkbuf),
-           data.mv_data, (int)data.mv_size, (char *)data.mv_data);
+    printf("key: %p %s, data: %p %.*s\n", key.mv_data,
+           mdbx_dkey(&key, dkbuf, sizeof(dkbuf)), data.mv_data,
+           (int)data.mv_size, (char *)data.mv_data);
   } while ((rc = mdbx_cursor_get(cursor, &key, &data, MDB_NEXT)) == 0);
   CHECK(rc == MDB_NOTFOUND, "mdbx_cursor_get");
   mdbx_cursor_close(cursor);