StdLib/LibC/StdLib/Malloc.c

   1 /** @file
   2   Definitions for memory allocation routines: calloc, malloc, realloc, free.
   3
   4   The order and contiguity of storage allocated by successive calls to the
   5   calloc, malloc, and realloc functions is unspecified.  The pointer returned
   6   if the allocation succeeds is suitably aligned so that it may be assigned to
   7   a pointer of any type of object and then used to access such an object or an
   8   array of such objects in the space allocated (until the space is explicitly
   9   freed or reallocated).  Each such allocation shall yield a pointer to an
  10   object disjoint from any other object.  The pointer returned points to the
  11   start (lowest byte address) of the allocated space.  If the space can not be
  12   allocated, a null pointer is returned.  If the size of the space requested
  13   is zero, the behavior is implementation-defined; the value returned shall be
  14   either a null pointer or a unique pointer.  The value of a pointer that
  15   refers to freed space is indeterminate.
  16
  17 Copyright (c) 2010, Intel Corporation. All rights reserved.<BR>
  18 This program and the accompanying materials
  19 are licensed and made available under the terms and conditions of the BSD License
  20 which accompanies this distribution.  The full text of the license may be found at
  21 http://opensource.org/licenses/bsd-license.php
  22
  23 THE PROGRAM IS DISTRIBUTED UNDER THE BSD LICENSE ON AN "AS IS" BASIS,
  24 WITHOUT WARRANTIES OR REPRESENTATIONS OF ANY KIND, EITHER EXPRESS OR IMPLIED.
  25
  26  */
  27 #include  <Base.h>
  28 #include  <Uefi.h>
  29 #include  <Library/MemoryAllocationLib.h>
  30 #include  <Library/UefiBootServicesTableLib.h>
  31 #include  <Library/BaseMemoryLib.h>
  32 #include  <Library/DebugLib.h>
  33
  34 #include  <LibConfig.h>
  35
  36 #include  <assert.h>
  37 #include  <stdlib.h>
  38 #include  <errno.h>
  39
  40 /** The UEFI functions do not provide a way to determine the size of an
  41     allocated region of memory given just a pointer to the start of that
  42     region.  Since this is required for the implementation of realloc,
  43     the memory head structure from Core/Dxe/Mem/Pool.c has been reproduced
  44     here.
  45
  46     NOTE: If the UEFI implementation is changed, the realloc function may cease
  47           to function properly.
  48 **/
  49 #define POOL_HEAD_SIGNATURE   SIGNATURE_32('p','h','d','0')
  50 typedef struct {
  51   UINT32          Signature;
  52   UINT32          Size;
  53   EFI_MEMORY_TYPE Type;
  54   UINTN           Reserved;
  55   CHAR8           Data[1];
  56 } POOL_HEAD;
  57
  58 /****************************/
  59
  60 /** The malloc function allocates space for an object whose size is specified
  61     by size and whose value is indeterminate.
  62
  63     This implementation uses the UEFI memory allocation boot services to get a
  64     region of memory that is 8-byte aligned and of the specified size.  The
  65     region is allocated with type EfiLoaderData.
  66
  67     @param  size    Size, in bytes, of the region to allocate.
  68
  69     @return   NULL is returned if the space could not be allocated and errno
  70               contains the cause.  Otherwise, a pointer to an 8-byte aligned
  71               region of the requested size is returned.<BR>
  72               If NULL is returned, errno may contain:
  73               - EINVAL: Requested Size is zero.
  74               - ENOMEM: Memory could not be allocated.
  75 **/
  76 void *
  77 malloc(size_t Size)
  78 {
  79   void       *RetVal;
  80   EFI_STATUS  Status;
  81
  82   if( Size == 0) {
  83     errno = EINVAL;   // Make errno diffenent, just in case of a lingering ENOMEM.
  84     return NULL;
  85   }
  86
  87   Status = gBS->AllocatePool( EfiLoaderData, (UINTN)Size, &RetVal);
  88   if( Status != EFI_SUCCESS) {
  89     RetVal  = NULL;
  90     errno   = ENOMEM;
  91   }
  92   return RetVal;
  93 }
  94
  95 /** The calloc function allocates space for an array of Num objects, each of
  96     whose size is Size.  The space is initialized to all bits zero.
  97
  98     This implementation uses the UEFI memory allocation boot services to get a
  99     region of memory that is 8-byte aligned and of the specified size.  The
 100     region is allocated with type EfiLoaderData.
 101
 102     @param  Num     Number of objects to allocate.
 103     @param  Size    Size, in bytes, of the objects to allocate space for.
 104
 105     @return   NULL is returned if the space could not be allocated and errno
 106               contains the cause.  Otherwise, a pointer to an 8-byte aligned
 107               region of the requested size is returned.
 108 **/
 109 void *
 110 calloc(size_t Num, size_t Size)
 111 {
 112   void       *RetVal;
 113   size_t      NumSize;
 114
 115   NumSize = Num * Size;
 116   if (NumSize == 0) {
 117       return NULL;
 118   }
 119   RetVal = malloc(NumSize);
 120   if( RetVal != NULL) {
 121     (VOID)ZeroMem( RetVal, NumSize);
 122   }
 123   return RetVal;
 124 }
 125
 126 /** The free function causes the space pointed to by Ptr to be deallocated,
 127     that is, made available for further allocation.
 128
 129     If Ptr is a null pointer, no action occurs.  Otherwise, if the argument
 130     does not match a pointer earlier returned by the calloc, malloc, or realloc
 131     function, or if the space has been deallocated by a call to free or
 132     realloc, the behavior is undefined.
 133
 134     @param  Ptr     Pointer to a previously allocated region of memory to be freed.
 135
 136 **/
 137 void
 138 free(void *Ptr)
 139 {
 140   (void) gBS->FreePool (Ptr);
 141 }
 142
 143 /** The realloc function changes the size of the object pointed to by Ptr to
 144     the size specified by NewSize.
 145
 146     The contents of the object are unchanged up to the lesser of the new and
 147     old sizes.  If the new size is larger, the value of the newly allocated
 148     portion of the object is indeterminate.
 149
 150     If Ptr is a null pointer, the realloc function behaves like the malloc
 151     function for the specified size.
 152
 153     If Ptr does not match a pointer earlier returned by the calloc, malloc, or
 154     realloc function, or if the space has been deallocated by a call to the free
 155     or realloc function, the behavior is undefined.
 156
 157     If the space cannot be allocated, the object pointed to by Ptr is unchanged.
 158
 159     If NewSize is zero and Ptr is not a null pointer, the object it points to
 160     is freed.
 161
 162     This implementation uses the UEFI memory allocation boot services to get a
 163     region of memory that is 8-byte aligned and of the specified size.  The
 164     region is allocated with type EfiLoaderData.
 165
 166     The following combinations of Ptr and NewSize can occur:<BR>
 167       Ptr     NewSize<BR>
 168     --------  -------------------<BR>
 169     - NULL        0                 Returns NULL;
 170     - NULL      > 0                 Same as malloc(NewSize)
 171     - invalid     X                 Returns NULL;
 172     - valid   NewSize >= OldSize    Returns malloc(NewSize) with Oldsize bytes copied from Ptr
 173     - valid   NewSize <  OldSize    Returns new buffer with Oldsize bytes copied from Ptr
 174     - valid       0                 Return NULL.  Frees Ptr.
 175
 176
 177     @param  Ptr     Pointer to a previously allocated region of memory to be resized.
 178     @param  NewSize Size, in bytes, of the new object to allocate space for.
 179
 180     @return   NULL is returned if the space could not be allocated and errno
 181               contains the cause.  Otherwise, a pointer to an 8-byte aligned
 182               region of the requested size is returned.  If NewSize is zero,
 183               NULL is returned and errno will be unchanged.
 184 **/
 185 void *
 186 realloc(void *Ptr, size_t NewSize)
 187 {
 188   void       *RetVal = NULL;
 189   POOL_HEAD  *Head;
 190   UINTN       OldSize = 0;
 191   UINTN       NumCpy;
 192
 193   // Find out the size of the OLD memory region
 194   if( Ptr != NULL) {
 195     Head = BASE_CR (Ptr, POOL_HEAD, Data);
 196     assert(Head != NULL);
 197     if (Head->Signature != POOL_HEAD_SIGNATURE) {
 198       errno = EFAULT;
 199       return NULL;
 200     }
 201     OldSize = Head->Size;
 202   }
 203
 204   // At this point, Ptr is either NULL or a valid pointer to an allocated space
 205
 206   if( NewSize > 0) {
 207     RetVal = malloc(NewSize); // Get the NEW memory region
 208     if( Ptr != NULL) {          // If there is an OLD region...
 209       if( RetVal != NULL) {     // and the NEW region was successfully allocated
 210         NumCpy = OldSize;
 211         if( OldSize > NewSize) {
 212           NumCpy = NewSize;
 213         }
 214         (VOID)CopyMem( RetVal, Ptr, NumCpy);  // Copy old data to the new region.
 215         free( Ptr);                           // and reclaim the old region.
 216       }
 217     }
 218   }
 219   else {
 220     if( Ptr != NULL) {
 221       free( Ptr);                           // Reclaim the old region.
 222     }
 223   }
 224
 225   return RetVal;
 226 }