Bug#37958 - test main.plugin crash on Mac OS X when selecting from EXAMPLE engine.

This patch contains fixes for two problems:

1. As originally reported, the server crashed on Mac OS X when trying to access
   an EXAMPLE table after the EXAMPLE plugin was installed.

   It turned out that the dynamically loaded EXAMPLE plugin called the
   function hash_earch() from a Mac OS X system library, instead of
   hash_earch() from MySQL's mysys library. Makefile.am in storage/example
   does not include libmysys. So the Mac OS X linker arranged the hash_search()
   function to be linked to the system library when the shared object is
   loaded.

   One possible solution would be to include libmysys into the linkage of
   dynamic plugins. But then we must have a libmysys.so, which must be
   used by the server too. This could have a minimal performance impact,
   but foremost the change seems to bee too risky at the current state of
   MySQL 5.1.

   The selected solution is to rename MySQL's hash_search() to my_hash_search()
   like it has been done before with hash_insert() and hash_reset().

   Since this is the third time, we need to rename a hash_*() function,
   I did renamed all hash_*() functions to my_hash_*().

   To avoid changing a zillion calls to these functions, and announcing
   this to hundreds of developers, I added defines that map the old names
   to the new names.

   This change is in hash.h and hash.c.

2. The other problem was improper implementation of the handlerton-to-plugin
   mapping. We use a fixed-size array to hold a plugin reference for each
   handlerton. On every install of a handler plugin, we allocated a new slot
   of the array. On uninstall we did not free it. After some uninstall/install
   cycles the array overflowed. We did not check for overflow.

   One fix is to check for overflow to stop the crashes.

   Another fix is to free the array slot at uninstall and search for a free slot
   at plugin install.

   This change is in handler.cc.



include/hash.h:
  Bug#37958 - test main.plugin crash on Mac OS X when selecting from EXAMPLE engine.
  Renamed hash_*() functions to my_hash_*().
  Added defines that map old names to new names.
mysys/hash.c:
  Bug#37958 - test main.plugin crash on Mac OS X when selecting from EXAMPLE engine.
  Renamed hash_*() functions to my_hash_*().
sql/handler.cc:
  Bug#37958 - test main.plugin crash on Mac OS X when selecting from EXAMPLE engine.
  Protect against a failing ha_initialize_handlerton() in ha_finalize_handlerton().
  Free hton2plugin slot on uninstall of a handler plugin.
  Reuse freed slost of the hton2plugin array.
  Protect against array overrun.

1 files changed, 70 insertions, 68 deletions

diff --git a/mysys/hash.c b/mysys/hash.c
index 9166ae6f788..65a60c9e341 100644
--- a/mysys/hash.c
+++ b/mysys/hash.c
@@ -33,7 +33,7 @@ typedef struct st_hash_info {
   uchar *data;					/* data for current entry */
 } HASH_LINK;
 
-static uint hash_mask(uint hashnr,uint buffmax,uint maxlength);
+static uint my_hash_mask(uint hashnr, uint buffmax, uint maxlength);
 static void movelink(HASH_LINK *array,uint pos,uint next_link,uint newlink);
 static int hashcmp(const HASH *hash, HASH_LINK *pos, const uchar *key,
                    size_t length);
@@ -46,19 +46,19 @@ static uint calc_hash(const HASH *hash, const uchar *key, size_t length)
 }
 
 my_bool
-_hash_init(HASH *hash,uint growth_size, CHARSET_INFO *charset,
-	   ulong size, size_t key_offset, size_t key_length,
-	   hash_get_key get_key,
-	   void (*free_element)(void*),uint flags CALLER_INFO_PROTO)
+_my_hash_init(HASH *hash, uint growth_size, CHARSET_INFO *charset,
+              ulong size, size_t key_offset, size_t key_length,
+              my_hash_get_key get_key,
+              void (*free_element)(void*), uint flags CALLER_INFO_PROTO)
 {
-  DBUG_ENTER("hash_init");
+  DBUG_ENTER("my_hash_init");
   DBUG_PRINT("enter",("hash: 0x%lx  size: %u", (long) hash, (uint) size));
 
   hash->records=0;
   if (my_init_dynamic_array_ci(&hash->array, sizeof(HASH_LINK), size,
                                growth_size))
   {
-    hash->free=0;				/* Allow call to hash_free */
+    hash->free=0;				/* Allow call to my_hash_free */
     DBUG_RETURN(1);
   }
   hash->key_offset=key_offset;
@@ -76,14 +76,14 @@ _hash_init(HASH *hash,uint growth_size, CHARSET_INFO *charset,
   Call hash->free on all elements in hash.
 
   SYNOPSIS
-    hash_free_elements()
+    my_hash_free_elements()
     hash   hash table
 
   NOTES:
     Sets records to 0
 */
 
-static inline void hash_free_elements(HASH *hash)
+static inline void my_hash_free_elements(HASH *hash)
 {
   if (hash->free)
   {
@@ -100,18 +100,18 @@ static inline void hash_free_elements(HASH *hash)
   Free memory used by hash.
 
   SYNOPSIS
-    hash_free()
+    my_hash_free()
     hash   the hash to delete elements of
 
-  NOTES: Hash can't be reused without calling hash_init again.
+  NOTES: Hash can't be reused without calling my_hash_init again.
 */
 
-void hash_free(HASH *hash)
+void my_hash_free(HASH *hash)
 {
-  DBUG_ENTER("hash_free");
+  DBUG_ENTER("my_hash_free");
   DBUG_PRINT("enter",("hash: 0x%lx", (long) hash));
 
-  hash_free_elements(hash);
+  my_hash_free_elements(hash);
   hash->free= 0;
   delete_dynamic(&hash->array);
   DBUG_VOID_RETURN;
@@ -131,7 +131,7 @@ void my_hash_reset(HASH *hash)
   DBUG_ENTER("my_hash_reset");
   DBUG_PRINT("enter",("hash: 0x%lxd", (long) hash));
 
-  hash_free_elements(hash);
+  my_hash_free_elements(hash);
   reset_dynamic(&hash->array);
   /* Set row pointers so that the hash can be reused at once */
   hash->blength= 1;
@@ -146,8 +146,8 @@ void my_hash_reset(HASH *hash)
 */
 
 static inline char*
-hash_key(const HASH *hash, const uchar *record, size_t *length,
-         my_bool first)
+my_hash_key(const HASH *hash, const uchar *record, size_t *length,
+            my_bool first)
 {
   if (hash->get_key)
     return (char*) (*hash->get_key)(record,length,first);
@@ -157,18 +157,18 @@ hash_key(const HASH *hash, const uchar *record, size_t *length,
 
 	/* Calculate pos according to keys */
 
-static uint hash_mask(uint hashnr,uint buffmax,uint maxlength)
+static uint my_hash_mask(uint hashnr, uint buffmax, uint maxlength)
 {
   if ((hashnr & (buffmax-1)) < maxlength) return (hashnr & (buffmax-1));
   return (hashnr & ((buffmax >> 1) -1));
 }
 
-static uint hash_rec_mask(const HASH *hash, HASH_LINK *pos,
-                          uint buffmax, uint maxlength)
+static uint my_hash_rec_mask(const HASH *hash, HASH_LINK *pos,
+                             uint buffmax, uint maxlength)
 {
   size_t length;
-  uchar *key= (uchar*) hash_key(hash,pos->data,&length,0);
-  return hash_mask(calc_hash(hash,key,length),buffmax,maxlength);
+  uchar *key= (uchar*) my_hash_key(hash, pos->data, &length, 0);
+  return my_hash_mask(calc_hash(hash, key, length), buffmax, maxlength);
 }
 
 
@@ -181,15 +181,15 @@ inline
 unsigned int rec_hashnr(HASH *hash,const uchar *record)
 {
   size_t length;
-  uchar *key= (uchar*) hash_key(hash,record,&length,0);
+  uchar *key= (uchar*) my_hash_key(hash, record, &length, 0);
   return calc_hash(hash,key,length);
 }
 
 
-uchar* hash_search(const HASH *hash, const uchar *key, size_t length)
+uchar* my_hash_search(const HASH *hash, const uchar *key, size_t length)
 {
   HASH_SEARCH_STATE state;
-  return hash_first(hash, key, length, &state);
+  return my_hash_first(hash, key, length, &state);
 }
 
 /*
@@ -199,18 +199,18 @@ uchar* hash_search(const HASH *hash, const uchar *key, size_t length)
    Assigns the number of the found record to HASH_SEARCH_STATE state
 */
 
-uchar* hash_first(const HASH *hash, const uchar *key, size_t length,
-                HASH_SEARCH_STATE *current_record)
+uchar* my_hash_first(const HASH *hash, const uchar *key, size_t length,
+                     HASH_SEARCH_STATE *current_record)
 {
   HASH_LINK *pos;
   uint flag,idx;
-  DBUG_ENTER("hash_first");
+  DBUG_ENTER("my_hash_first");
 
   flag=1;
   if (hash->records)
   {
-    idx=hash_mask(calc_hash(hash,key,length ? length : hash->key_length),
-		    hash->blength,hash->records);
+    idx= my_hash_mask(calc_hash(hash, key, length ? length : hash->key_length),
+                      hash->blength, hash->records);
     do
     {
       pos= dynamic_element(&hash->array,idx,HASH_LINK*);
@@ -223,7 +223,7 @@ uchar* hash_first(const HASH *hash, const uchar *key, size_t length,
       if (flag)
       {
 	flag=0;					/* Reset flag */
-	if (hash_rec_mask(hash,pos,hash->blength,hash->records) != idx)
+	if (my_hash_rec_mask(hash, pos, hash->blength, hash->records) != idx)
 	  break;				/* Wrong link */
       }
     }
@@ -234,10 +234,10 @@ uchar* hash_first(const HASH *hash, const uchar *key, size_t length,
 }
 
 	/* Get next record with identical key */
-	/* Can only be called if previous calls was hash_search */
+	/* Can only be called if previous calls was my_hash_search */
 
-uchar* hash_next(const HASH *hash, const uchar *key, size_t length,
-               HASH_SEARCH_STATE *current_record)
+uchar* my_hash_next(const HASH *hash, const uchar *key, size_t length,
+                    HASH_SEARCH_STATE *current_record)
 {
   HASH_LINK *pos;
   uint idx;
@@ -297,7 +297,7 @@ static int hashcmp(const HASH *hash, HASH_LINK *pos, const uchar *key,
                    size_t length)
 {
   size_t rec_keylength;
-  uchar *rec_key= (uchar*) hash_key(hash,pos->data,&rec_keylength,1);
+  uchar *rec_key= (uchar*) my_hash_key(hash, pos->data, &rec_keylength, 1);
   return ((length && length != rec_keylength) ||
 	  my_strnncoll(hash->charset, (uchar*) rec_key, rec_keylength,
 		       (uchar*) key, rec_keylength));
@@ -306,7 +306,7 @@ static int hashcmp(const HASH *hash, HASH_LINK *pos, const uchar *key,
 
 	/* Write a hash-key to the hash-index */
 
-my_bool my_hash_insert(HASH *info,const uchar *record)
+my_bool my_hash_insert(HASH *info, const uchar *record)
 {
   int flag;
   size_t idx;
@@ -321,8 +321,8 @@ my_bool my_hash_insert(HASH *info,const uchar *record)
 
   if (HASH_UNIQUE & info->flags)
   {
-    uchar *key= (uchar*) hash_key(info, record, &idx, 1);
-    if (hash_search(info, key, idx))
+    uchar *key= (uchar*) my_hash_key(info, record, &idx, 1);
+    if (my_hash_search(info, key, idx))
       return(TRUE);				/* Duplicate entry */
   }
 
@@ -341,7 +341,7 @@ my_bool my_hash_insert(HASH *info,const uchar *record)
       pos=data+idx;
       hash_nr=rec_hashnr(info,pos->data);
       if (flag == 0)				/* First loop; Check if ok */
-	if (hash_mask(hash_nr,info->blength,info->records) != first_index)
+	if (my_hash_mask(hash_nr, info->blength, info->records) != first_index)
 	  break;
       if (!(hash_nr & halfbuff))
       {						/* Key will not move */
@@ -413,7 +413,7 @@ my_bool my_hash_insert(HASH *info,const uchar *record)
   }
   /* Check if we are at the empty position */
 
-  idx=hash_mask(rec_hashnr(info,record),info->blength,info->records+1);
+  idx= my_hash_mask(rec_hashnr(info, record), info->blength, info->records + 1);
   pos=data+idx;
   if (pos == empty)
   {
@@ -424,7 +424,7 @@ my_bool my_hash_insert(HASH *info,const uchar *record)
   {
     /* Check if more records in same hash-nr family */
     empty[0]=pos[0];
-    gpos=data+hash_rec_mask(info,pos,info->blength,info->records+1);
+    gpos= data + my_hash_rec_mask(info, pos, info->blength, info->records + 1);
     if (pos == gpos)
     {
       pos->data=(uchar*) record;
@@ -449,18 +449,18 @@ my_bool my_hash_insert(HASH *info,const uchar *record)
 ** if there is a free-function it's called for record if found
 ******************************************************************************/
 
-my_bool hash_delete(HASH *hash,uchar *record)
+my_bool my_hash_delete(HASH *hash, uchar *record)
 {
   uint blength,pos2,pos_hashnr,lastpos_hashnr,idx,empty_index;
   HASH_LINK *data,*lastpos,*gpos,*pos,*pos3,*empty;
-  DBUG_ENTER("hash_delete");
+  DBUG_ENTER("my_hash_delete");
   if (!hash->records)
     DBUG_RETURN(1);
 
   blength=hash->blength;
   data=dynamic_element(&hash->array,0,HASH_LINK*);
   /* Search after record with key */
-  pos=data+ hash_mask(rec_hashnr(hash,record),blength,hash->records);
+  pos= data + my_hash_mask(rec_hashnr(hash, record), blength, hash->records);
   gpos = 0;
 
   while (pos->data != record)
@@ -491,7 +491,7 @@ my_bool hash_delete(HASH *hash,uchar *record)
   /* Move the last key (lastpos) */
   lastpos_hashnr=rec_hashnr(hash,lastpos->data);
   /* pos is where lastpos should be */
-  pos=data+hash_mask(lastpos_hashnr,hash->blength,hash->records);
+  pos= data + my_hash_mask(lastpos_hashnr, hash->blength, hash->records);
   if (pos == empty)			/* Move to empty position. */
   {
     empty[0]=lastpos[0];
@@ -499,7 +499,7 @@ my_bool hash_delete(HASH *hash,uchar *record)
   }
   pos_hashnr=rec_hashnr(hash,pos->data);
   /* pos3 is where the pos should be */
-  pos3= data+hash_mask(pos_hashnr,hash->blength,hash->records);
+  pos3= data + my_hash_mask(pos_hashnr, hash->blength, hash->records);
   if (pos != pos3)
   {					/* pos is on wrong posit */
     empty[0]=pos[0];			/* Save it here */
@@ -507,8 +507,8 @@ my_bool hash_delete(HASH *hash,uchar *record)
     movelink(data,(uint) (pos-data),(uint) (pos3-data),empty_index);
     goto exit;
   }
-  pos2= hash_mask(lastpos_hashnr,blength,hash->records+1);
-  if (pos2 == hash_mask(pos_hashnr,blength,hash->records+1))
+  pos2= my_hash_mask(lastpos_hashnr, blength, hash->records + 1);
+  if (pos2 == my_hash_mask(pos_hashnr, blength, hash->records + 1))
   {					/* Identical key-positions */
     if (pos2 != hash->records)
     {
@@ -536,26 +536,26 @@ exit:
 	  This is much more efficent than using a delete & insert.
 	  */
 
-my_bool hash_update(HASH *hash, uchar *record, uchar *old_key,
-                    size_t old_key_length)
+my_bool my_hash_update(HASH *hash, uchar *record, uchar *old_key,
+                       size_t old_key_length)
 {
   uint new_index,new_pos_index,blength,records,empty;
   size_t idx;
   HASH_LINK org_link,*data,*previous,*pos;
-  DBUG_ENTER("hash_update");
+  DBUG_ENTER("my_hash_update");
   
   if (HASH_UNIQUE & hash->flags)
   {
     HASH_SEARCH_STATE state;
-    uchar *found, *new_key= (uchar*) hash_key(hash, record, &idx, 1);
-    if ((found= hash_first(hash, new_key, idx, &state)))
+    uchar *found, *new_key= (uchar*) my_hash_key(hash, record, &idx, 1);
+    if ((found= my_hash_first(hash, new_key, idx, &state)))
     {
       do 
       {
         if (found != record)
           DBUG_RETURN(1);		/* Duplicate entry */
       } 
-      while ((found= hash_next(hash, new_key, idx, &state)));
+      while ((found= my_hash_next(hash, new_key, idx, &state)));
     }
   }
 
@@ -564,11 +564,11 @@ my_bool hash_update(HASH *hash, uchar *record, uchar *old_key,
 
   /* Search after record with key */
 
-  idx=hash_mask(calc_hash(hash, old_key,(old_key_length ?
-					      old_key_length :
-					      hash->key_length)),
-		  blength,records);
-  new_index=hash_mask(rec_hashnr(hash,record),blength,records);
+  idx= my_hash_mask(calc_hash(hash, old_key, (old_key_length ?
+                                              old_key_length :
+                                              hash->key_length)),
+                    blength, records);
+  new_index= my_hash_mask(rec_hashnr(hash, record), blength, records);
   if (idx == new_index)
     DBUG_RETURN(0);			/* Nothing to do (No record check) */
   previous=0;
@@ -618,7 +618,7 @@ my_bool hash_update(HASH *hash, uchar *record, uchar *old_key,
     DBUG_RETURN(0);
   }
   pos=data+new_index;
-  new_pos_index=hash_rec_mask(hash,pos,blength,records);
+  new_pos_index= my_hash_rec_mask(hash, pos, blength, records);
   if (new_index != new_pos_index)
   {					/* Other record in wrong position */
     data[empty] = *pos;
@@ -636,7 +636,7 @@ my_bool hash_update(HASH *hash, uchar *record, uchar *old_key,
 }
 
 
-uchar *hash_element(HASH *hash,ulong idx)
+uchar *my_hash_element(HASH *hash, ulong idx)
 {
   if (idx < hash->records)
     return dynamic_element(&hash->array,idx,HASH_LINK*)->data;
@@ -649,7 +649,8 @@ uchar *hash_element(HASH *hash,ulong idx)
   isn't changed
 */
 
-void hash_replace(HASH *hash, HASH_SEARCH_STATE *current_record, uchar *new_row)
+void my_hash_replace(HASH *hash, HASH_SEARCH_STATE *current_record,
+                     uchar *new_row)
 {
   if (*current_record != NO_RECORD)            /* Safety */
     dynamic_element(&hash->array, *current_record, HASH_LINK*)->data= new_row;
@@ -658,7 +659,7 @@ void hash_replace(HASH *hash, HASH_SEARCH_STATE *current_record, uchar *new_row)
 
 #ifndef DBUG_OFF
 
-my_bool hash_check(HASH *hash)
+my_bool my_hash_check(HASH *hash)
 {
   int error;
   uint i,rec_link,found,max_links,seek,links,idx;
@@ -671,7 +672,7 @@ my_bool hash_check(HASH *hash)
 
   for (i=found=max_links=seek=0 ; i < records ; i++)
   {
-    if (hash_rec_mask(hash,data+i,blength,records) == i)
+    if (my_hash_rec_mask(hash, data + i, blength, records) == i)
     {
       found++; seek++; links=1;
       for (idx=data[i].next ;
@@ -687,11 +688,12 @@ my_bool hash_check(HASH *hash)
 	}
 	hash_info=data+idx;
 	seek+= ++links;
-	if ((rec_link=hash_rec_mask(hash,hash_info,blength,records)) != i)
+	if ((rec_link= my_hash_rec_mask(hash, hash_info,
+                                        blength, records)) != i)
 	{
-	  DBUG_PRINT("error",
-		     ("Record in wrong link at %d: Start %d  Record: 0x%lx  Record-link %d",
-                      idx, i, (long) hash_info->data, rec_link));
+          DBUG_PRINT("error", ("Record in wrong link at %d: Start %d  "
+                               "Record: 0x%lx  Record-link %d",
+                               idx, i, (long) hash_info->data, rec_link));
 	  error=1;
 	}
 	else