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Fix error in realloc when memory is extended downward 

git-svn-id: https://nuttx.svn.sourceforge.net/svnroot/nuttx/trunk@295 7fd9a85b-ad96-42d3-883c-3090e2eb8679
This commit is contained in:
patacongo 2007-06-30 20:38:16 +00:00
parent 2f8be29403
commit 513b157ce0
3 changed files with 44 additions and 36 deletions
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2
nuttx/ChangeLog
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@ -190,5 +190,7 @@
on thread/task exit.
* Add environment variables APIs: environ, getenv, putenv, clearenv, setenv,
unsetenv
* Correct an error in realloc() when the block is extended "down" in memory.
In this case, the old memory contents need to be copied to the new location.
* Started m68322

2
nuttx/Documentation/NuttX.html
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@ -627,6 +627,8 @@ Other memory:
unsetenv
* Add environment variables APIs: environ, getenv, putenv, clearenv, setenv,
unsetenv
* Correct an error in realloc() when the block is extended "down" in memory.
In this case, the old memory contents need to be copied to the new location.
* Started m68322
</pre></ul>

76
nuttx/mm/mm_realloc.c
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@ -81,6 +81,7 @@ FAR void *realloc(FAR void *oldmem, size_t size)
size_t oldsize;
size_t prevsize = 0;
size_t nextsize = 0;
FAR void *newmem;
/* If oldmem is NULL, then realloc is equivalent to malloc */
@ -261,64 +262,67 @@ FAR void *realloc(FAR void *oldmem, size_t size)
if (takenext)
{
FAR struct mm_freenode_s *newnode;
FAR struct mm_allocnode_s *andbeyond;
FAR struct mm_freenode_s *newnode;
FAR struct mm_allocnode_s *andbeyond;
/* Get the chunk following the next node (which could be the tail chunk) */
/* Get the chunk following the next node (which could be the tail chunk) */
andbeyond = (FAR struct mm_allocnode_s*)((char*)next + nextsize);
andbeyond = (FAR struct mm_allocnode_s*)((char*)next + nextsize);
/* Remove the next node. There must be a predecessor,
* but there may not be a successor node.
*/
/* Remove the next node. There must be a predecessor,
* but there may not be a successor node.
*/
DEBUGASSERT(next->blink);
next->blink->flink = next->flink;
if (next->flink)
{
next->flink->blink = next->blink;
}
DEBUGASSERT(next->blink);
next->blink->flink = next->flink;
if (next->flink)
{
next->flink->blink = next->blink;
}
/* Extend the node into the previous next chunk */
/* Extend the node into the next chunk */
oldnode->size = oldsize + takenext;
newnode = (FAR struct mm_freenode_s *)((char*)oldnode + oldnode->size);
oldnode->size = oldsize + takenext;
newnode = (FAR struct mm_freenode_s *)((char*)oldnode + oldnode->size);
/* Did we consume the entire preceding chunk? */
/* Did we consume the entire preceding chunk? */
if (takenext < nextsize)
{
/* No, take what we need from the next chunk and return it
* to the free nodelist.
*/
if (takenext < nextsize)
{
/* No, take what we need from the next chunk and return it
* to the free nodelist.
*/
newnode->size = nextsize - takenext;
newnode->preceding = oldnode->size;
andbeyond->preceding = newnode->size | (andbeyond->preceding & MM_ALLOC_BIT);
newnode->size = nextsize - takenext;
newnode->preceding = oldnode->size;
andbeyond->preceding = newnode->size | (andbeyond->preceding & MM_ALLOC_BIT);
/* Add the new free node to the nodelist (with the new size) */
/* Add the new free node to the nodelist (with the new size) */
mm_addfreechunk(newnode);
}
else
{
/* Yes, just update some pointers. */
mm_addfreechunk(newnode);
}
else
{
/* Yes, just update some pointers. */
andbeyond->preceding = oldnode->size | (andbeyond->preceding & MM_ALLOC_BIT);
}
andbeyond->preceding = oldnode->size | (andbeyond->preceding & MM_ALLOC_BIT);
}
}
/* Now we have to move the user contents 'down' in memory. memcpy should
* should be save for this.
*/
newmem = (FAR void*)((FAR char*)oldnode + SIZEOF_MM_ALLOCNODE);
memcpy(newmem, oldmem, oldsize - SIZEOF_MM_ALLOCNODE);
mm_givesemaphore();
return (FAR void*)((FAR char*)oldnode + SIZEOF_MM_ALLOCNODE);
return newmem;
}
/* The current chunk cannot be extended. Just allocate a new chunk and copy */
else
{
FAR void *newmem;
/* Allocate a new block. On failure, realloc must return NULL but
* leave the original memory in place.
*/