release/src/router/mysql/mysys/my_lockmem.c

   1 /* Copyright (c) 2000, 2007 MySQL AB
   2
   3    This program is free software; you can redistribute it and/or modify
   4    it under the terms of the GNU General Public License as published by
   5    the Free Software Foundation; version 2 of the License.
   6
   7    This program is distributed in the hope that it will be useful,
   8    but WITHOUT ANY WARRANTY; without even the implied warranty of
   9    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  10    GNU General Public License for more details.
  11
  12    You should have received a copy of the GNU General Public License
  13    along with this program; if not, write to the Free Software
  14    Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA  02110-1301, USA */
  15
  16 /* Alloc a block of locked memory */
  17
  18 #include "mysys_priv.h"
  19 #include "mysys_err.h"
  20 #include <my_list.h>
  21
  22 #ifdef HAVE_MLOCK
  23 #include <sys/mman.h>
  24
  25 struct st_mem_list
  26 {
  27   LIST list;
  28   uchar *page;
  29   uint size;
  30 };
  31
  32 LIST *mem_list;
  33
  34 uchar *my_malloc_lock(uint size,myf MyFlags)
  35 {
  36   int success;
  37   uint pagesize=sysconf(_SC_PAGESIZE);
  38   uchar *ptr;
  39   struct st_mem_list *element;
  40   DBUG_ENTER("my_malloc_lock");
  41
  42   size=((size-1) & ~(pagesize-1))+pagesize;
  43   if (!(ptr=memalign(pagesize,size)))
  44   {
  45     if (MyFlags & (MY_FAE+MY_WME))
  46       my_error(EE_OUTOFMEMORY, MYF(ME_BELL+ME_WAITTANG),size);
  47     DBUG_RETURN(0);
  48   }
  49   success = mlock((uchar*) ptr,size);
  50   if (success != 0 && geteuid() == 0)
  51   {
  52     DBUG_PRINT("warning",("Failed to lock memory. errno %d\n",
  53                           errno));
  54     fprintf(stderr, "Warning: Failed to lock memory. errno %d\n",
  55             errno);
  56   }
  57   else
  58   {
  59     /* Add block in a list for munlock */
  60     if (!(element=(struct st_mem_list*) my_malloc(sizeof(*element),MyFlags)))
  61     {
  62       VOID(munlock((uchar*) ptr,size));
  63       free(ptr);
  64       DBUG_RETURN(0);
  65     }
  66     element->list.data=(uchar*) element;
  67     element->page=ptr;
  68     element->size=size;
  69     pthread_mutex_lock(&THR_LOCK_malloc);
  70     mem_list=list_add(mem_list,&element->list);
  71     pthread_mutex_unlock(&THR_LOCK_malloc);
  72   }
  73   DBUG_RETURN(ptr);
  74 }
  75
  76
  77 void my_free_lock(uchar *ptr,myf Myflags __attribute__((unused)))
  78 {
  79   LIST *list;
  80   struct st_mem_list *element=0;
  81
  82   pthread_mutex_lock(&THR_LOCK_malloc);
  83   for (list=mem_list ; list ; list=list->next)
  84   {
  85     element=(struct st_mem_list*) list->data;
  86     if (ptr == element->page)
  87     {                                           /* Found locked mem */
  88       VOID(munlock((uchar*) ptr,element->size));
  89       mem_list=list_delete(mem_list,list);
  90       break;
  91     }
  92   }
  93   pthread_mutex_unlock(&THR_LOCK_malloc);
  94   if (element)
  95     my_free((uchar*) element,MYF(0));
  96   free(ptr);                                    /* Free even if not locked */
  97 }
  98
  99 #endif /* HAVE_MLOCK */